The mechanical and tribological properties of hot-pressed copper-based composites containing different amounts of graphene nanosheets（GNSs） are compared with those of copper-graphite（Gr） composites fabricated by t...The mechanical and tribological properties of hot-pressed copper-based composites containing different amounts of graphene nanosheets（GNSs） are compared with those of copper-graphite（Gr） composites fabricated by the same method.The results show that the Cu-GNSs composites exhibit higher relative density,microhardness and bending strength compared with Cu-Gr composites with the same volume fraction of GNSs and Gr.Moreover,the friction coefficients and wear rates reduce significantly by the addition of GNSs,whereas the limited impact on reducing friction and wear is found on graphite.The abrasive and delamination wear are the dominant wear mechanisms of the composites.It is believed that the superior mechanical and tribological performances of Cu-GNSs composites are attributed to the unique strengthening effect as well as the higher lubricating efficiency of graphene nanosheets compared with those of graphite,which demonstrates that GNS is an ideal filler for copper matrix composites,acting as not only an impactful lubricant but also a favorable reinforcement.展开更多
Exploring bifunctional catalysts for the hydrogen and oxygen evolution reactions （HER and OER） with high efficiency, low cost, and easy integration is extremely crucial for future renewable energy systems. Herein, t...Exploring bifunctional catalysts for the hydrogen and oxygen evolution reactions （HER and OER） with high efficiency, low cost, and easy integration is extremely crucial for future renewable energy systems. Herein, ternary NiCoP nanosheet arrays （NSAs） were fabricated on 3D Ni foam by a facile hydrothermal method followed by phosphorization. These arrays serve as bifunctional alkaline catalysts, exhibiting excellent electrocatalytic performance and good working stability for both the HER and OER. The overpotentials of the NiCoP NSA electrode required to drive a current density of 50 mA/cm2 for the HER and OER are as low as 133 and 308 mV, respectively, which is ascribed to excellent intrinsic electrocatalytic activity, fast electron transport, and a unique superaerophobic structure. When NiCoP was integrated as both anodic and cathodic material, the electrolyzer required a potential as low as -1.77 V to drive a current density of 50 mA/cm2 for overall water splitting, which is much smaller than a reported electrolyzer using the same kind of phosphide-based material and is even better than the combination of Pt/C and Ir/C, the best known noble metal-based electrodes. Combining satisfactory working stability and high activity, this NiCoP electrode paves the way for exploring overall water splitting catalysts.展开更多
TiO2 nanosheets with highly reactive {001} facets （{001}-TiO2） have attracted great attention in the fields of science and technology because of their unique properties. In recent years, many efforts have been made ...TiO2 nanosheets with highly reactive {001} facets （{001}-TiO2） have attracted great attention in the fields of science and technology because of their unique properties. In recent years, many efforts have been made to synthesize {001}-TiO2 and to explore their applications in photocatalysis. In this review, we summarize the recent progress in preparing {001}-TiO2 using different techniques such as hydrothermal, solvothermal, alcohothermal, chemical vapor deposition （CVD）, and sol gel-based techniques. Furthermore, the enhanced efficiency of {001}-TiO2 by modification of carbon materials, surface deposition of transition metals, and non-metal doping is reviewed. Then, the applications of {001}-TiOR-based photocatalysts in the degradation of organic dyes, hydrogen evolution, carbon dioxide （CO2） reduction, bacterial disinfection, and dye-sensitized solar cells are summarized. We believe this entire review on TiO2 nanosheets with {001] facets can further inspire researchers in associated fields.展开更多
The rapid recombination of photo-generated electron-hole pairs,insufficient active sites,and strong photocorrosion have considerably restricted the practical application of Cd S in photocatalytic fields.Herein,we desi...The rapid recombination of photo-generated electron-hole pairs,insufficient active sites,and strong photocorrosion have considerably restricted the practical application of Cd S in photocatalytic fields.Herein,we designed and constructed a 2D/2D/2D layered heterojunction photocatalyst with cascaded 2D coupling interfaces.Experiments using electron spin resonance spectroscopy,ultraviolet photoelectron spectroscopy,and in-situ irradiation X-ray photoelectron spectroscopy were conducted to confirm the 2D layered CdS/WO_(3) step-scheme(S-scheme)heterojunctions and CdS/MX ohmic junctions.Impressively,it was found that the strong interfacial electric fields in the S-scheme heterojunction photocatalysts could effectively promote spatially directional charge separation and transport between CdS and WO_(3) nanosheets.In addition,2D Ti_(3)C_(2) MXene nanosheets with a smaller work function and excellent metal conductivity when used as a co-catalyst could build ohmic junctions with Cd S nanosheets,thus providing a greater number of electron transfer pathways and hydrogen evolution sites.Results showed that the highest visible-light hydrogen evolution rate of the optimized MX-Cd S/WO_(3) layered multi-heterostructures could reach as high as 27.5 mmol/g/h,which was 11.0 times higher than that of pure CdS nanosheets.Notably,the apparent quantum efficiency reached 12.0% at 450 nm.It is hoped that this study offers a reliable approach for developing multifunctional photocatalysts by integrating S-scheme and ohmic-junction built-in electric fields and rationally designing a 2D/2D interface for efficient light-to-hydrogen fuel production.展开更多
A cobaltosic-oxide-nanosheets/reduced-graphene-oxide composite （CoNSs@RGO） was successfully prepared as a light-weight broadband electromagnetic wave absorber. The effects of the sample thickness and amount of compo...A cobaltosic-oxide-nanosheets/reduced-graphene-oxide composite （CoNSs@RGO） was successfully prepared as a light-weight broadband electromagnetic wave absorber. The effects of the sample thickness and amount of composite added to paraffin samples on the absorption properties were thoroughly investigated. Due to the nanosheet-like structure of Co3O4, the surface-to-volume ratio of the wave absorption material was very high, resulting in a large enhancement in the absorption properties. The maximum refection loss of the CoNSs@RGO composite was -45.15 dB for a thickness of 3.6 mm, and the best absorption bandwidth with a reflection loss below -10 dB was 7.14 GHz with a thickness of 2.9 mm. In addition, the peaks of microwave absorption shifted towards the low frequency region with increasing thickness of the absorbing coatings. The mechanism of electromagnetic wave absorption was attributed to impedance matching of CoNSs@RGO as well as the dielectric relaxation and polarization of RGO. Compared to previously reported absorbing materials, CoNSs@RGO showed better performance as a lightweight and highly efficient absorbing material for application in the high frequency band.展开更多
Graphene nanosheets（GNSs） strengthened AgCuTi composite filler（AgCuTiG） was used to braze C/C composite and Ti-6Al-4V. The effects of GNSs on the wettability of AgCuTiG filler on the C/C composite surface and the ...Graphene nanosheets（GNSs） strengthened AgCuTi composite filler（AgCuTiG） was used to braze C/C composite and Ti-6Al-4V. The effects of GNSs on the wettability of AgCuTiG filler on the C/C composite surface and the interfacial microstructure and mechanical properties of brazed joints were investigated. The results indicate that the addition of GNSs reduced the wettability of AgCuTiG. The interfacial microstructure of brazed joints evolved with the addition of GNSs, where Ti3Cu4 and TiCu4 were converted to TiCu and the thickness of the reaction layer adjacent to the base material decreased. The maximum shear strength of joints brazed at 0.3 wt% GNSs was 23.3 MPa（880℃/10 min）. Further adding GNSs deteriorated the shear strength of the joints. Fracture of the joints occurred in the C/C composite substrate and the TiC layer adjacent to C/C composite.展开更多
Novel SiO2/BiOCl composites were fabricated by decorating BiOCl nanosheets with SiO2 nanoparticles via a simple hydrothermal process. The as-prepared pure BiOCl and SiO2/BiOCl composites were intensively characterized...Novel SiO2/BiOCl composites were fabricated by decorating BiOCl nanosheets with SiO2 nanoparticles via a simple hydrothermal process. The as-prepared pure BiOCl and SiO2/BiOCl composites were intensively characterized by various techniques such as XRD, FT-IR, SEM/TEM, BET, UV-vis, DRS, XPS, and photocurrent measurements. The SiO2/BiOCl composite nanosheets displayed high photocatalytic activity and excellent stability in the degradation of organic pollutants such as phenol, bisphenol A (BPA), and rhodamine B (RhB). With respect to those over bare BiOCl, the degradation rates of RhB, BPA, and phenol over 1.88% SiO2/BiOCl increased 16.5%, 29.0%, and 38.7%, respectively. Radical capturing results suggested that h^+ is the major reactive species and that hydroxyl (·OH) and superoxide (·O2^-) radicals could also be involved in the degradation of organic pollutants. The enhanced photocatalytic performances of SiO2/BiOCl composites can be mainly attributed to the improved texture and the formation of intimate SiO2/BiOCl interfaces, which largely promoted the adsorption of organic pollutants, enhanced the light harvesting, and accelerated the separation of e^– and h^+.展开更多
Photocatalysis is considered to be a clean, green and efficient method to purify water. In this report, we first developed a highly efficient ultrafine TiO2 nanorods/g-C3N4 nanosheets （TiO2 NR/CN NS） composites via ...Photocatalysis is considered to be a clean, green and efficient method to purify water. In this report, we first developed a highly efficient ultrafine TiO2 nanorods/g-C3N4 nanosheets （TiO2 NR/CN NS） composites via a simple hydrothermal method. Tiny TiO2 nanorods （diameter： ～1.5 nm and length： ～8.3 nm） were first loaded in situ on the CN NS by adding graphitic carbon nitride （g-C3N4） to the reaction solution. The TiO2 NR/CN NS composites present high charge separation efficiency and broader light absorbance than P25 TiO2. Furthermore, we illustrate that the TiO2 NR/CN NS catalyst possesses high performance for the photocatalytic degradation of the common and stubborn pollutants in water, such as the rhodamine B （RhB） dye and phenol. Under visible light （λ 〉 420 nm） irradiation, the apparent rate of the TiO2 NR/CN NR is 172 and 41 times higher than that of the P25 TiO2 and TiO2 NR, respectively. Additionally, we speculated that the heterojunction formed between TiO2 NR and CN NS, which is the basis for the experiments we have designed and the corresponding results. We demonstrated that reactive oxidative species such as superoxide anion radical and holes play critical roles in the degradation, and the hydroxyl radical contributes nothing to the degradation.展开更多
Two-dimensional (2D) layered vanadium disulfide (VS2) is a promising anode material for lithium ion batteries (LIBs) due to the high theoretical capacity.However,it remains a challenge to synthesize monodispersed ultr...Two-dimensional (2D) layered vanadium disulfide (VS2) is a promising anode material for lithium ion batteries (LIBs) due to the high theoretical capacity.However,it remains a challenge to synthesize monodispersed ultrathin VS2 nanosheets to realize the full potential.Herein,a novel solvothermal method has been developed to prepare the monodispersed bowl-shaped NH3-inserted VS2 nanosheets (VS2).The formation of such a unique structure is caused by the blocked growth of (001) or (002) crystal planes in combination with a ripening process driven by the thermodynamics.The annealing treatment in Ar/H2creates porous monodispersed VS2(H-VS2),which is subsequently integrated with graphene oxide to form porous monodispersed H-VS2/rGO composite coupled with a reduction process.As an anode material for LIBs,H-VS2/rGO delivers superior rate performance and longer cycle stability:a high average capacity of 868/525 mAh g^-1 at a current density of 1/10 A g^-1;a reversible capacity of 1177/889 mAh g^-1 after 150/500 cycles at 0.2/1 A g^-1.Such excellent electrochemical performance may be attributed to the increased active sites available for lithium storage,the alleviated volume variations and the shortened Li-ion diffusion induced from the porous structure with large specific surface area,as well as the protective effect from graphene nanosheets.展开更多
WS2 nanomaterials have attracted great attention in the field of electromagnetic wave absorption due to their high specific surface area,layered structure,and peculiar electronic properties.However,further improvement...WS2 nanomaterials have attracted great attention in the field of electromagnetic wave absorption due to their high specific surface area,layered structure,and peculiar electronic properties.However,further improvements on their limited electromagnetic absorbing(EMA)capacity and bandwidth are urgently required for their practical application as EMA absorbents.In this work,WS2/NiO hybrids with heterostructures are prepared by a hydrothermal method and developed into EMA absorbents.The maximum reflection loss of the hybrids with 20%NiO loading could reach-53.31 dB at a thickness of 4.30 mm;the bandwidth with a reflection loss value of less than-10 dB is determined to be13.46 GHz(4.54–18 GHz)when the thickness of the absorbent is between 3.5 and 5.5 mm.It is found that the enhanced EMA performance of WS2/NiO hybrids is caused by the addition of magnetic NiO,which could result in the interfaces between WS2 and NiO being responsible for the synergetic magnetic loss and dielectric loss in the hybrids.This work provides a new approach for the design of excellent EMA materials for practical applications.展开更多
As a low-cost visible-light-driven metal-free catalyst, graphitic carbon nitride(g-CN) has attracted increasing attention due to its wide applications for solar energy conversion, environmental purification,and organi...As a low-cost visible-light-driven metal-free catalyst, graphitic carbon nitride(g-CN) has attracted increasing attention due to its wide applications for solar energy conversion, environmental purification,and organic photosynthesis. In particular, the catalytic performance of g-CNcan be easily modulated by modifying morphology, doping, and copolymerization. Simultaneous optimization, however, has little been achieved. Herein, a facile one-pot strategy is developed to synthesize porous B-doped g-CNnanosheets by using HBOand urea as the precursor during thermal polymerization. The resultant B-doped g-CNnanosheets retain the original framework of bulk g-CN, while induce prominently enhanced visible light harvesting and narrowing band gap by 0.32 eV compared to pure g-CN. Moreover, the adsorption capacity and photodegradation kinetics of methylene blue(MB) under visible light irradiation over B-doped g-CNnanosheets can be improved by 20.5 and 17 times, respectively. The synthesized porous B-doped g-CNnanosheets also exhibit higher activities than pure g-CNas bifunctional electrocatalyst for both oxygen evolution reaction(OER) and oxygen reduction reaction(ORR). The enhanced catalyst performance of porous B-doped g-CNnanosheets stems from the strong synergistic effect originating from the larger exposed active sites generated by the exfoliation of g-CNinto nanosheets and the porous structure, as well as the better conductivity owing to B-doping. This work provides a simple, effective, and robust method for the synthesis of g-CN-based nanomaterial with superior properties to meet the needs of various applications.展开更多
Photocatalytic hydrogen production represents a promising strategy for clean, sustainable, and environmentfriendly energy supply. Up to now, great efforts have been devoted to designing the photocatalysts with noble m...Photocatalytic hydrogen production represents a promising strategy for clean, sustainable, and environmentfriendly energy supply. Up to now, great efforts have been devoted to designing the photocatalysts with noble metal as co-catalyst for visible-light-driven hydrogen evolution, while more efficient photocatalytic systems are still a major challenge. Herein, we report a facile strategy for synthesizing faceto-face ultrathin Pd nanosheets-amorphous carbon nitride(Pd NSs-ACN) structure with large contacting interface and short electronic transmission pathway, which can work as an efficient photocatalyst for hydrogen production. The synthesis starts with the growth of ultrathin Pd NSs, followed by assembly with the visible-light-response ACN through a simple stirring and annealing procedure. The resultant two dimensional face-to-face structures deliver an average hydrogen generation rate of 1.45 mmol h-1g-1 at a temperature of 25℃,almost 2.6 times higher than that of Pd Nps-ACN with particle-to-face structural feature. The efficient photocatalytic activity is ascribed to the formation of high-density of active sites between ultrafine face-to-face contacted Pd NSs and the ACN, which cooperate more synergistically towards photocatalytic hydrogen production. The face-to-face engineered Pd NSs-ACN hybrids also offer a good stability revealed by photocatalytic hydrogen production measurements. The extraordinary performance highlights a powerful engineering model for designing other face-to-face contacting co-catalyst/photocatalysts, which will be a great impetus to optimize new catalytic transformations.展开更多
The assembly of thin films （TFs） having long-lasting luminescence can be expected to play an important role in the development of new-generation smart sensors, anti-counterfeiting materials, and information-encrypti...The assembly of thin films （TFs） having long-lasting luminescence can be expected to play an important role in the development of new-generation smart sensors, anti-counterfeiting materials, and information-encryption systems. However, such films are limited compared with their powder and solution counterparts. In this study, by exploiting the self-organization of phosphors in the two-dimensional （2D） galleries between clay nanosheets, we developed a method for the ordered assembly of long-afterglow TFs by utilizing a hydrogen-bonding layer-by-layer （LBL） process. Compared with the pristine powder, the TFs exhibit high polarization and up-conversion room-temperature phosphorescence （RTP）, as well as enhanced quantum yields and luminescence lifetimes, allowing them to be used as room-temperature phosphorescent sensors for humidity and oxygen. Moreover, modified clay-based hybrids with multicolor RTP can serve as anti-counterfeiting marks and triple-mode 2D barcode displays. We anticipate that the LBL assembly process can be extended to the fabrication of other inorganic--organic room-temperature phosphorescent hybrids with smart luminescent sensor and antiforgery applications.展开更多
Near-infrared （NIR） photothermal therapy has developed very quickly in recent years. However, its clinical applications are hindered by many practical problems, such as low accumulation in tumors, high laser power d...Near-infrared （NIR） photothermal therapy has developed very quickly in recent years. However, its clinical applications are hindered by many practical problems, such as low accumulation in tumors, high laser power density and high biotoxicity in vivo. Herein, a versatile system combining chemotherapy with photothermal therapy for cancer therapy using ultrasmall Pd nanosheets （SPNS） has been developed. The SPNS can serve as pH-responsive drug carriers to efficiently deliver DOX into cancer cells and tumors. On the other hand, the coordinative loading of DOX on SPNS enhances its accumulation in tumor tissue. So we can efficiently ablate tumor using low-intensity laser radiation. Importantly, with ultrasmall size （-4.4 nm）, SPNS surface-functionalized with reduced glutathione （GSH） can be cleared from the body through the renal system into the urine. This cancer therapeutic nanosystem, which exhibits a significant synergistic effect and low systemic toxicity, has great potential for clinical applications.展开更多
Magnetic/dielectric@porous carbon composites,derived from metal–organic frameworks(MOFs)with adjustable composition ratio,have attracted wide attention due to their unique magnetoelectric properties.In addition,MOFs-...Magnetic/dielectric@porous carbon composites,derived from metal–organic frameworks(MOFs)with adjustable composition ratio,have attracted wide attention due to their unique magnetoelectric properties.In addition,MOFs-derived porous carbon-based materials can meet the needs of lightweight feature.This paper reports a simple process for synthesizing stacked CoxNiy@C nanosheets derived from CoxNiy-MOFs nanosheets with multiple interfaces,which is good to the microwave response.The CoxNiy@C with controllable composition can be obtained by adjusting the ratio of Co^2+ and Ni^2+.It is supposed that the increased Co content is benefit to the dielectric and magnetic loss.Additionally,the bandwidth of CoNi@C nanosheets can take up almost the whole Ku band.Moreover,this composite has better environmental stability in air,which characteristic provides a sustainable potential for the practical application.展开更多
Graphene reinforced copper matrix composites （Gr/Cu） were fabricated by electrostatic self-assembly and powder metallurgy. The morphology and structure of graphene oxide, graphene oxide-Cu powders and Gr/Cu composit...Graphene reinforced copper matrix composites （Gr/Cu） were fabricated by electrostatic self-assembly and powder metallurgy. The morphology and structure of graphene oxide, graphene oxide-Cu powders and Gr/Cu composites were characterized by scanning electronic microscopy, transmission electronic microscopy, X-ray diffraction and Raman spectroscopy, respectively. The effects of graphene contents, applied loads and sliding speeds on the tribological behavior of the composites were investigated. The results indicate that the coefficient of friction of the composites decreases first and then increases with increasing the graphene content. The lowest friction coefficient is achieved in 0.3 wt~ Gr/Cu composite, which decreases by 65% compared to that of pure copper. The coefficient of friction of the composite does not have significant change with increasing the applied load, however, it increases with increasing the sliding speed. The tribological mechanisms of the composite under different conditions were also investigated.展开更多
Nanomaterial shapes can have profound effects on material properties, and therefore offer an efficient way to improve the performances of designed materials and devices. The rational fabrication of multidimensional ar...Nanomaterial shapes can have profound effects on material properties, and therefore offer an efficient way to improve the performances of designed materials and devices. The rational fabrication of multidimensional architectures such as one dimensional （1D）-two dimensional （2D） hybrid nanomaterials can integrate the merits of individual components and provide enhanced functionality. However, it is still very challenging to fabricate 1D/2D architectures because of the different growth mechanisms of the nanostructures. Here, we present a new solvent- mediated, surface reaction-driven growth route for synthesis of CdS nanowire （NW）/CdIn2S4 nanosheet （NS） 1D/2D architectures. The as-obtained CdS NW/ CdIn2S4 NS structures exhibit much higher visible-light-responsive photocatalytic activities for water splitting than the individual components. The CdS NW/CdIn2S4 NS heterostructure was further fabricated into photoelectrodes, which achieved a considerable photocurrent density of 2.85 mA·cm^-2 at 0 V vs. the reversible hydrogen electrode （RHE） without use of any co-catalysts. This represents one of the best results from a CdS-based photoelectrochemical （PEC） cell. Both the multidimensional nature and type II band alignment of the 1D/2D CdS/CdIn2S4 heterostructure contribute to the enhanced photocatalyfic and photoelectrochemical activity. The present work not only provides a new strategy for designing multidimensional 1D/2D heterostructures, but also documents the development of highly efficient energy conversion catalysts.展开更多
A possible mechanism for boosting the visible-light photoactivities of graphitic carbon nitride(g-C3N4)nanosheets for CO2 reduction via coupling with the electron donor Co-metal-organic framework(MOF)is proposed in th...A possible mechanism for boosting the visible-light photoactivities of graphitic carbon nitride(g-C3N4)nanosheets for CO2 reduction via coupling with the electron donor Co-metal-organic framework(MOF)is proposed in this study.Specifically,Co-MOF as an electron donor is capable of transferring the photogenerated electrons in the lowest unoccupied molecular orbital(LUMO)to the conduction band of g-C3N4 to facilitate charge separation.As expected,the prepared Co-MOF/g-C3N4 nanocomposites display excellent visible-light-driven photocatalytic CO2 reduction activities.The CO production rate of 6.75μmol g–1 h–1 and CH4 evolution rate of 5.47μmol g–1 h–1 are obtained,which are approximately 2 times those obtained with the original g-C3N4 under the same conditions.Based on a series of analyses,it is shown that the introduction of Co-MOF not only broadens the range of visible-light absorption but also enhances the charge separation,which improves the photocatalytic activity of g-C3N4 to a higher level.In particular,the hydroxyl radical(·OH)experiment was operated under 590 nm(single-wavelength)irradiation,which further proved that the photogenerated electrons in the LUMO of Co-MOF can successfully migrate to g-C3N4.This work may provide an important strategy for the design of highly efficient g-C3N4-based photocatalysts for CO2 reduction.展开更多
Two-dimensional(2D)nanomaterials are categorized as a new class of microwave absorption(MA)materials owing to their high specific surface area and peculiar electronic properties.In this study,2D WS2-reduced graphene o...Two-dimensional(2D)nanomaterials are categorized as a new class of microwave absorption(MA)materials owing to their high specific surface area and peculiar electronic properties.In this study,2D WS2-reduced graphene oxide(WS2-rGO)heterostructure nanosheets were synthesized via a facile hydrothermal process;moreover,their dielectric and MA properties were reported for the first time.Remarkably,the maximum reflection loss(RL)of the sample-wax composites containing 40 wt% WS2-rGO was-41.5 dB at a thickness of 2.7 mm;furthermore,the bandwidth where RL<-10 dB can reach up to 13.62 GHz(4.38-18 GHz).Synergistic mechanisms derived from the interfacial dielectric coupling and multiple-interface scattering after hybridization of WS2 with rGO were discussed to explain the drastically enhanced microwave absorption performance.The results indicate these lightweight WS2-rGO nanosheets to be potential materials for practical electromagnetic wave-absorbing applications.展开更多
文摘The mechanical and tribological properties of hot-pressed copper-based composites containing different amounts of graphene nanosheets（GNSs） are compared with those of copper-graphite（Gr） composites fabricated by the same method.The results show that the Cu-GNSs composites exhibit higher relative density,microhardness and bending strength compared with Cu-Gr composites with the same volume fraction of GNSs and Gr.Moreover,the friction coefficients and wear rates reduce significantly by the addition of GNSs,whereas the limited impact on reducing friction and wear is found on graphite.The abrasive and delamination wear are the dominant wear mechanisms of the composites.It is believed that the superior mechanical and tribological performances of Cu-GNSs composites are attributed to the unique strengthening effect as well as the higher lubricating efficiency of graphene nanosheets compared with those of graphite,which demonstrates that GNS is an ideal filler for copper matrix composites,acting as not only an impactful lubricant but also a favorable reinforcement.
基金This work was support by the National Natural Science Foundation of China （Nos. 21125101 and 21520102002）, the Program for Changjiang Scholars and Innovative Research Team in the University, and the Fundamental Research Funds for the Central Universities, and the long-term subsidy mechanism from the Ministry of Finance and the Ministry of Education of PRC.
文摘Exploring bifunctional catalysts for the hydrogen and oxygen evolution reactions （HER and OER） with high efficiency, low cost, and easy integration is extremely crucial for future renewable energy systems. Herein, ternary NiCoP nanosheet arrays （NSAs） were fabricated on 3D Ni foam by a facile hydrothermal method followed by phosphorization. These arrays serve as bifunctional alkaline catalysts, exhibiting excellent electrocatalytic performance and good working stability for both the HER and OER. The overpotentials of the NiCoP NSA electrode required to drive a current density of 50 mA/cm2 for the HER and OER are as low as 133 and 308 mV, respectively, which is ascribed to excellent intrinsic electrocatalytic activity, fast electron transport, and a unique superaerophobic structure. When NiCoP was integrated as both anodic and cathodic material, the electrolyzer required a potential as low as -1.77 V to drive a current density of 50 mA/cm2 for overall water splitting, which is much smaller than a reported electrolyzer using the same kind of phosphide-based material and is even better than the combination of Pt/C and Ir/C, the best known noble metal-based electrodes. Combining satisfactory working stability and high activity, this NiCoP electrode paves the way for exploring overall water splitting catalysts.
基金This work was supported by the National Basic Research Program of China （No. 2013CB632402）, and the National Natural Science Foundation of China （Nos. 51272199, 51320105001, 51372190, and 21433007）. Also, this work was financially supported by the Natural Science Foundation of Hubei Province of China （Nos. 2015CFA001 and 2014CFB164）, Deanship of Scientific Research （DSR） of King Abdulaziz University （No. 90-130-35-HiCi）, the Fundamental Research Funds for the Central Universities （Nos. WUT： 2014-VII-010, 2014-IV-058, 2014-IV-155）, Self-determined and Innova- tive Research Funds of SKLWUT （No. 2013-ZD-1）, and a WUT Start-Up Grant.
文摘TiO2 nanosheets with highly reactive {001} facets （{001}-TiO2） have attracted great attention in the fields of science and technology because of their unique properties. In recent years, many efforts have been made to synthesize {001}-TiO2 and to explore their applications in photocatalysis. In this review, we summarize the recent progress in preparing {001}-TiO2 using different techniques such as hydrothermal, solvothermal, alcohothermal, chemical vapor deposition （CVD）, and sol gel-based techniques. Furthermore, the enhanced efficiency of {001}-TiO2 by modification of carbon materials, surface deposition of transition metals, and non-metal doping is reviewed. Then, the applications of {001}-TiOR-based photocatalysts in the degradation of organic dyes, hydrogen evolution, carbon dioxide （CO2） reduction, bacterial disinfection, and dye-sensitized solar cells are summarized. We believe this entire review on TiO2 nanosheets with {001] facets can further inspire researchers in associated fields.
文摘The rapid recombination of photo-generated electron-hole pairs,insufficient active sites,and strong photocorrosion have considerably restricted the practical application of Cd S in photocatalytic fields.Herein,we designed and constructed a 2D/2D/2D layered heterojunction photocatalyst with cascaded 2D coupling interfaces.Experiments using electron spin resonance spectroscopy,ultraviolet photoelectron spectroscopy,and in-situ irradiation X-ray photoelectron spectroscopy were conducted to confirm the 2D layered CdS/WO_(3) step-scheme(S-scheme)heterojunctions and CdS/MX ohmic junctions.Impressively,it was found that the strong interfacial electric fields in the S-scheme heterojunction photocatalysts could effectively promote spatially directional charge separation and transport between CdS and WO_(3) nanosheets.In addition,2D Ti_(3)C_(2) MXene nanosheets with a smaller work function and excellent metal conductivity when used as a co-catalyst could build ohmic junctions with Cd S nanosheets,thus providing a greater number of electron transfer pathways and hydrogen evolution sites.Results showed that the highest visible-light hydrogen evolution rate of the optimized MX-Cd S/WO_(3) layered multi-heterostructures could reach as high as 27.5 mmol/g/h,which was 11.0 times higher than that of pure CdS nanosheets.Notably,the apparent quantum efficiency reached 12.0% at 450 nm.It is hoped that this study offers a reliable approach for developing multifunctional photocatalysts by integrating S-scheme and ohmic-junction built-in electric fields and rationally designing a 2D/2D interface for efficient light-to-hydrogen fuel production.
基金This work was supported by the National Basic Research Program of China （No. 2013CB932602）, the Program of Introducing Talents of Discipline to Universities （No. B14003）, National Natural Science Foundation of China （Nos. 51527802 and 51232001）, Beijing Municipal Science ＆ Technology Commission, and the Fundamental Research Funds for Central Universities.
文摘A cobaltosic-oxide-nanosheets/reduced-graphene-oxide composite （CoNSs@RGO） was successfully prepared as a light-weight broadband electromagnetic wave absorber. The effects of the sample thickness and amount of composite added to paraffin samples on the absorption properties were thoroughly investigated. Due to the nanosheet-like structure of Co3O4, the surface-to-volume ratio of the wave absorption material was very high, resulting in a large enhancement in the absorption properties. The maximum refection loss of the CoNSs@RGO composite was -45.15 dB for a thickness of 3.6 mm, and the best absorption bandwidth with a reflection loss below -10 dB was 7.14 GHz with a thickness of 2.9 mm. In addition, the peaks of microwave absorption shifted towards the low frequency region with increasing thickness of the absorbing coatings. The mechanism of electromagnetic wave absorption was attributed to impedance matching of CoNSs@RGO as well as the dielectric relaxation and polarization of RGO. Compared to previously reported absorbing materials, CoNSs@RGO showed better performance as a lightweight and highly efficient absorbing material for application in the high frequency band.
基金supports to this study from the National Natural Science Foundation of China–China (Nos.51505105 and 51775138)the Natural Science Foundation of Shandong Province–China (No.ZR2014EEQ001)the International Science & Technology Cooperation Program of China–China (No.2015DFA50470)
文摘Graphene nanosheets（GNSs） strengthened AgCuTi composite filler（AgCuTiG） was used to braze C/C composite and Ti-6Al-4V. The effects of GNSs on the wettability of AgCuTiG filler on the C/C composite surface and the interfacial microstructure and mechanical properties of brazed joints were investigated. The results indicate that the addition of GNSs reduced the wettability of AgCuTiG. The interfacial microstructure of brazed joints evolved with the addition of GNSs, where Ti3Cu4 and TiCu4 were converted to TiCu and the thickness of the reaction layer adjacent to the base material decreased. The maximum shear strength of joints brazed at 0.3 wt% GNSs was 23.3 MPa（880℃/10 min）. Further adding GNSs deteriorated the shear strength of the joints. Fracture of the joints occurred in the C/C composite substrate and the TiC layer adjacent to C/C composite.
基金funding from the National Natural Science Foundation of China (21567008, 21707055)the Program for Innovative Research Team of Guangdong University of Petrochemical Technology+4 种基金the Yangfan talents Project of Guangdong Provincethe Innovation-driven “5511” Program in Jiangxi Province (20165BCB18014)the Funding Program for Academic and Technological Leaders of Major Disciplines in Jiangxi Province (20172BCB22018)the Program for New Century Excellent Talents in Fujian Province Universitythe Natural Science Foundation for Distinguished Young Scholars of Hunan Province, China (2017JJ1026)~~
文摘Novel SiO2/BiOCl composites were fabricated by decorating BiOCl nanosheets with SiO2 nanoparticles via a simple hydrothermal process. The as-prepared pure BiOCl and SiO2/BiOCl composites were intensively characterized by various techniques such as XRD, FT-IR, SEM/TEM, BET, UV-vis, DRS, XPS, and photocurrent measurements. The SiO2/BiOCl composite nanosheets displayed high photocatalytic activity and excellent stability in the degradation of organic pollutants such as phenol, bisphenol A (BPA), and rhodamine B (RhB). With respect to those over bare BiOCl, the degradation rates of RhB, BPA, and phenol over 1.88% SiO2/BiOCl increased 16.5%, 29.0%, and 38.7%, respectively. Radical capturing results suggested that h^+ is the major reactive species and that hydroxyl (·OH) and superoxide (·O2^-) radicals could also be involved in the degradation of organic pollutants. The enhanced photocatalytic performances of SiO2/BiOCl composites can be mainly attributed to the improved texture and the formation of intimate SiO2/BiOCl interfaces, which largely promoted the adsorption of organic pollutants, enhanced the light harvesting, and accelerated the separation of e^– and h^+.
基金supported by the Beijing Municipal High Level Innovative Team Building Program(IDHT20180504)the National Natural Science Foundation of China(21671011)+4 种基金Beijing High Talent ProgramBeijing Natural Science Foundation(KZ201710005002)the Large-scale Instrument and Equipment Platform of Beijing University of TechnologyChina Postdoctoral Science FoundationBeijing Postdoctoral Research Foundation
文摘Photocatalysis is considered to be a clean, green and efficient method to purify water. In this report, we first developed a highly efficient ultrafine TiO2 nanorods/g-C3N4 nanosheets （TiO2 NR/CN NS） composites via a simple hydrothermal method. Tiny TiO2 nanorods （diameter： ～1.5 nm and length： ～8.3 nm） were first loaded in situ on the CN NS by adding graphitic carbon nitride （g-C3N4） to the reaction solution. The TiO2 NR/CN NS composites present high charge separation efficiency and broader light absorbance than P25 TiO2. Furthermore, we illustrate that the TiO2 NR/CN NS catalyst possesses high performance for the photocatalytic degradation of the common and stubborn pollutants in water, such as the rhodamine B （RhB） dye and phenol. Under visible light （λ 〉 420 nm） irradiation, the apparent rate of the TiO2 NR/CN NR is 172 and 41 times higher than that of the P25 TiO2 and TiO2 NR, respectively. Additionally, we speculated that the heterojunction formed between TiO2 NR and CN NS, which is the basis for the experiments we have designed and the corresponding results. We demonstrated that reactive oxidative species such as superoxide anion radical and holes play critical roles in the degradation, and the hydroxyl radical contributes nothing to the degradation.
基金the Natural Science Foundation of Hunan Province(Grant no.2017JJ1008)the Key Research and Development Program of Hunan Province of China under Grant 2018GK2031。
文摘Two-dimensional (2D) layered vanadium disulfide (VS2) is a promising anode material for lithium ion batteries (LIBs) due to the high theoretical capacity.However,it remains a challenge to synthesize monodispersed ultrathin VS2 nanosheets to realize the full potential.Herein,a novel solvothermal method has been developed to prepare the monodispersed bowl-shaped NH3-inserted VS2 nanosheets (VS2).The formation of such a unique structure is caused by the blocked growth of (001) or (002) crystal planes in combination with a ripening process driven by the thermodynamics.The annealing treatment in Ar/H2creates porous monodispersed VS2(H-VS2),which is subsequently integrated with graphene oxide to form porous monodispersed H-VS2/rGO composite coupled with a reduction process.As an anode material for LIBs,H-VS2/rGO delivers superior rate performance and longer cycle stability:a high average capacity of 868/525 mAh g^-1 at a current density of 1/10 A g^-1;a reversible capacity of 1177/889 mAh g^-1 after 150/500 cycles at 0.2/1 A g^-1.Such excellent electrochemical performance may be attributed to the increased active sites available for lithium storage,the alleviated volume variations and the shortened Li-ion diffusion induced from the porous structure with large specific surface area,as well as the protective effect from graphene nanosheets.
基金supported by the National Natural Science Foundation of China(51272110,51772160,and 51977009).
文摘WS2 nanomaterials have attracted great attention in the field of electromagnetic wave absorption due to their high specific surface area,layered structure,and peculiar electronic properties.However,further improvements on their limited electromagnetic absorbing(EMA)capacity and bandwidth are urgently required for their practical application as EMA absorbents.In this work,WS2/NiO hybrids with heterostructures are prepared by a hydrothermal method and developed into EMA absorbents.The maximum reflection loss of the hybrids with 20%NiO loading could reach-53.31 dB at a thickness of 4.30 mm;the bandwidth with a reflection loss value of less than-10 dB is determined to be13.46 GHz(4.54–18 GHz)when the thickness of the absorbent is between 3.5 and 5.5 mm.It is found that the enhanced EMA performance of WS2/NiO hybrids is caused by the addition of magnetic NiO,which could result in the interfaces between WS2 and NiO being responsible for the synergetic magnetic loss and dielectric loss in the hybrids.This work provides a new approach for the design of excellent EMA materials for practical applications.
文摘As a low-cost visible-light-driven metal-free catalyst, graphitic carbon nitride(g-CN) has attracted increasing attention due to its wide applications for solar energy conversion, environmental purification,and organic photosynthesis. In particular, the catalytic performance of g-CNcan be easily modulated by modifying morphology, doping, and copolymerization. Simultaneous optimization, however, has little been achieved. Herein, a facile one-pot strategy is developed to synthesize porous B-doped g-CNnanosheets by using HBOand urea as the precursor during thermal polymerization. The resultant B-doped g-CNnanosheets retain the original framework of bulk g-CN, while induce prominently enhanced visible light harvesting and narrowing band gap by 0.32 eV compared to pure g-CN. Moreover, the adsorption capacity and photodegradation kinetics of methylene blue(MB) under visible light irradiation over B-doped g-CNnanosheets can be improved by 20.5 and 17 times, respectively. The synthesized porous B-doped g-CNnanosheets also exhibit higher activities than pure g-CNas bifunctional electrocatalyst for both oxygen evolution reaction(OER) and oxygen reduction reaction(ORR). The enhanced catalyst performance of porous B-doped g-CNnanosheets stems from the strong synergistic effect originating from the larger exposed active sites generated by the exfoliation of g-CNinto nanosheets and the porous structure, as well as the better conductivity owing to B-doping. This work provides a simple, effective, and robust method for the synthesis of g-CN-based nanomaterial with superior properties to meet the needs of various applications.
基金financially supported by the National Natural Science Foundation of China (51772255)Hunan Natural Science Foundation (2016JJ3123)+2 种基金the National Key Research and Development Program of China (2016YFB0100201)the start-up supports from Peking UniversityYoung Thousand Talented Program
文摘Photocatalytic hydrogen production represents a promising strategy for clean, sustainable, and environmentfriendly energy supply. Up to now, great efforts have been devoted to designing the photocatalysts with noble metal as co-catalyst for visible-light-driven hydrogen evolution, while more efficient photocatalytic systems are still a major challenge. Herein, we report a facile strategy for synthesizing faceto-face ultrathin Pd nanosheets-amorphous carbon nitride(Pd NSs-ACN) structure with large contacting interface and short electronic transmission pathway, which can work as an efficient photocatalyst for hydrogen production. The synthesis starts with the growth of ultrathin Pd NSs, followed by assembly with the visible-light-response ACN through a simple stirring and annealing procedure. The resultant two dimensional face-to-face structures deliver an average hydrogen generation rate of 1.45 mmol h-1g-1 at a temperature of 25℃,almost 2.6 times higher than that of Pd Nps-ACN with particle-to-face structural feature. The efficient photocatalytic activity is ascribed to the formation of high-density of active sites between ultrafine face-to-face contacted Pd NSs and the ACN, which cooperate more synergistically towards photocatalytic hydrogen production. The face-to-face engineered Pd NSs-ACN hybrids also offer a good stability revealed by photocatalytic hydrogen production measurements. The extraordinary performance highlights a powerful engineering model for designing other face-to-face contacting co-catalyst/photocatalysts, which will be a great impetus to optimize new catalytic transformations.
基金Acknowledgements This work was supported by the National Basic Research Program of China （973 Program） （No. 2014CB932103）, the National Natural Science Foundation of China （Nos. 21301016 and 21473013）, the Beijing Municipal Natural Science Foundation （No. 2152016）, and the Fundamental Research Funds for the Central Universities.
文摘The assembly of thin films （TFs） having long-lasting luminescence can be expected to play an important role in the development of new-generation smart sensors, anti-counterfeiting materials, and information-encryption systems. However, such films are limited compared with their powder and solution counterparts. In this study, by exploiting the self-organization of phosphors in the two-dimensional （2D） galleries between clay nanosheets, we developed a method for the ordered assembly of long-afterglow TFs by utilizing a hydrogen-bonding layer-by-layer （LBL） process. Compared with the pristine powder, the TFs exhibit high polarization and up-conversion room-temperature phosphorescence （RTP）, as well as enhanced quantum yields and luminescence lifetimes, allowing them to be used as room-temperature phosphorescent sensors for humidity and oxygen. Moreover, modified clay-based hybrids with multicolor RTP can serve as anti-counterfeiting marks and triple-mode 2D barcode displays. We anticipate that the LBL assembly process can be extended to the fabrication of other inorganic--organic room-temperature phosphorescent hybrids with smart luminescent sensor and antiforgery applications.
文摘Near-infrared （NIR） photothermal therapy has developed very quickly in recent years. However, its clinical applications are hindered by many practical problems, such as low accumulation in tumors, high laser power density and high biotoxicity in vivo. Herein, a versatile system combining chemotherapy with photothermal therapy for cancer therapy using ultrasmall Pd nanosheets （SPNS） has been developed. The SPNS can serve as pH-responsive drug carriers to efficiently deliver DOX into cancer cells and tumors. On the other hand, the coordinative loading of DOX on SPNS enhances its accumulation in tumor tissue. So we can efficiently ablate tumor using low-intensity laser radiation. Importantly, with ultrasmall size （-4.4 nm）, SPNS surface-functionalized with reduced glutathione （GSH） can be cleared from the body through the renal system into the urine. This cancer therapeutic nanosystem, which exhibits a significant synergistic effect and low systemic toxicity, has great potential for clinical applications.
基金Financial supports from the National Nature Science Foundation of China(No.51971111)the foundation of Jiangsu Provincial Key Laboratory of Bionic Functional Materials are gratefully acknowledged.
文摘Magnetic/dielectric@porous carbon composites,derived from metal–organic frameworks(MOFs)with adjustable composition ratio,have attracted wide attention due to their unique magnetoelectric properties.In addition,MOFs-derived porous carbon-based materials can meet the needs of lightweight feature.This paper reports a simple process for synthesizing stacked CoxNiy@C nanosheets derived from CoxNiy-MOFs nanosheets with multiple interfaces,which is good to the microwave response.The CoxNiy@C with controllable composition can be obtained by adjusting the ratio of Co^2+ and Ni^2+.It is supposed that the increased Co content is benefit to the dielectric and magnetic loss.Additionally,the bandwidth of CoNi@C nanosheets can take up almost the whole Ku band.Moreover,this composite has better environmental stability in air,which characteristic provides a sustainable potential for the practical application.
基金financially supported by the Natural Science Foundation of Heilongjiang Province,China(No.LC2015020)Technology Foundation for Selected Overseas Chinese Scholar,Ministry of Personnel of China(No.2015192)+1 种基金the Innovative Talent Fund ofHarbin City(No.2016RAQXJ185)Science Funds for the Young Innovative Talents of HUST(No.201604)
文摘Graphene reinforced copper matrix composites （Gr/Cu） were fabricated by electrostatic self-assembly and powder metallurgy. The morphology and structure of graphene oxide, graphene oxide-Cu powders and Gr/Cu composites were characterized by scanning electronic microscopy, transmission electronic microscopy, X-ray diffraction and Raman spectroscopy, respectively. The effects of graphene contents, applied loads and sliding speeds on the tribological behavior of the composites were investigated. The results indicate that the coefficient of friction of the composites decreases first and then increases with increasing the graphene content. The lowest friction coefficient is achieved in 0.3 wt~ Gr/Cu composite, which decreases by 65% compared to that of pure copper. The coefficient of friction of the composite does not have significant change with increasing the applied load, however, it increases with increasing the sliding speed. The tribological mechanisms of the composite under different conditions were also investigated.
基金This work was financially supported by the National Natural Science Foundation of China （Nos. 51372173, 21673160, and 51420105002）, Natural Science Foundation of Zhejiang for Distinguished Young Scholars （No. LR16B010002）, Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure （No. SKL201409SIC）, and startup funds of Syracuse University.
文摘Nanomaterial shapes can have profound effects on material properties, and therefore offer an efficient way to improve the performances of designed materials and devices. The rational fabrication of multidimensional architectures such as one dimensional （1D）-two dimensional （2D） hybrid nanomaterials can integrate the merits of individual components and provide enhanced functionality. However, it is still very challenging to fabricate 1D/2D architectures because of the different growth mechanisms of the nanostructures. Here, we present a new solvent- mediated, surface reaction-driven growth route for synthesis of CdS nanowire （NW）/CdIn2S4 nanosheet （NS） 1D/2D architectures. The as-obtained CdS NW/ CdIn2S4 NS structures exhibit much higher visible-light-responsive photocatalytic activities for water splitting than the individual components. The CdS NW/CdIn2S4 NS heterostructure was further fabricated into photoelectrodes, which achieved a considerable photocurrent density of 2.85 mA·cm^-2 at 0 V vs. the reversible hydrogen electrode （RHE） without use of any co-catalysts. This represents one of the best results from a CdS-based photoelectrochemical （PEC） cell. Both the multidimensional nature and type II band alignment of the 1D/2D CdS/CdIn2S4 heterostructure contribute to the enhanced photocatalyfic and photoelectrochemical activity. The present work not only provides a new strategy for designing multidimensional 1D/2D heterostructures, but also documents the development of highly efficient energy conversion catalysts.
基金supported by the National Natural Science Foundation of China(21871079,21501052)the Outstanding Youth Project of Natural Science Foundation of Heilongjiang Province(YQ2019B006)~~
文摘A possible mechanism for boosting the visible-light photoactivities of graphitic carbon nitride(g-C3N4)nanosheets for CO2 reduction via coupling with the electron donor Co-metal-organic framework(MOF)is proposed in this study.Specifically,Co-MOF as an electron donor is capable of transferring the photogenerated electrons in the lowest unoccupied molecular orbital(LUMO)to the conduction band of g-C3N4 to facilitate charge separation.As expected,the prepared Co-MOF/g-C3N4 nanocomposites display excellent visible-light-driven photocatalytic CO2 reduction activities.The CO production rate of 6.75μmol g–1 h–1 and CH4 evolution rate of 5.47μmol g–1 h–1 are obtained,which are approximately 2 times those obtained with the original g-C3N4 under the same conditions.Based on a series of analyses,it is shown that the introduction of Co-MOF not only broadens the range of visible-light absorption but also enhances the charge separation,which improves the photocatalytic activity of g-C3N4 to a higher level.In particular,the hydroxyl radical(·OH)experiment was operated under 590 nm(single-wavelength)irradiation,which further proved that the photogenerated electrons in the LUMO of Co-MOF can successfully migrate to g-C3N4.This work may provide an important strategy for the design of highly efficient g-C3N4-based photocatalysts for CO2 reduction.
基金financially supported by the National Natural Science Foundation of China (Nos. 51272110, 51772160, and 51771123)the Shenzhen Peacock Innovation Project (No. KQJSCX20170327151307811)+1 种基金the support of China Scholarship Council (No. 201506100018)the START project of Japan Science and Technology Agency (JST)
文摘Two-dimensional(2D)nanomaterials are categorized as a new class of microwave absorption(MA)materials owing to their high specific surface area and peculiar electronic properties.In this study,2D WS2-reduced graphene oxide(WS2-rGO)heterostructure nanosheets were synthesized via a facile hydrothermal process;moreover,their dielectric and MA properties were reported for the first time.Remarkably,the maximum reflection loss(RL)of the sample-wax composites containing 40 wt% WS2-rGO was-41.5 dB at a thickness of 2.7 mm;furthermore,the bandwidth where RL<-10 dB can reach up to 13.62 GHz(4.38-18 GHz).Synergistic mechanisms derived from the interfacial dielectric coupling and multiple-interface scattering after hybridization of WS2 with rGO were discussed to explain the drastically enhanced microwave absorption performance.The results indicate these lightweight WS2-rGO nanosheets to be potential materials for practical electromagnetic wave-absorbing applications.
