Over the span of years, improvements over various synthesis methods of graphene are constantly pursued to provide safer and more effective alternatives. Though the extraction of graphene through Hummers method is one ...Over the span of years, improvements over various synthesis methods of graphene are constantly pursued to provide safer and more effective alternatives. Though the extraction of graphene through Hummers method is one of the oldest techniques yet it is one of the most suitable methods for the formation of bulk graphene. Graphene can be obtained in the form of reduced Graphite oxide, sometimes also referred as Graphene oxide. The effectiveness of this oxidation process can be evaluated by the magnitude of carbon/oxygen ratio of the obtained graphene. Here, graphene oxide (GO) was prepared by oxidizing the purified natural flake graphite (NFG) by a modified Hummers method. The attempts have been made to synthesize GO having few layers by using a modified Hummers method where the amount of NaNO3 has been decreased, and the amount of KMnO4 is increased. The reaction has been performed in a 9:1 (by volume) mixture of H2SO4/H3PO4. This modification is successful in increasing the reaction yield and reducing the toxic gas evolution while using a varied proportion of KMnO4 and H2SO4 as those required by Hummers method. A new component of K2S2O8 has been introduced to the reaction system to maintain the pH value. Reduced graphene oxide (rGO) was thereafter extracted by thermal modification of GO. Here, GO has been used as a precursor for graphene synthesis by thermal reduction processes. The results of FTIR and Raman spectroscopy analysis show that the NFG when oxidized by strong oxidants like KMnO4 and NaNO3, introduced oxygen atoms into the graphite layers and formed bonds like C=O, C-H, COOH and C-O-C with the carbon atoms in the graphite layers. The structure and morphology of both GO and rGO were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy, Raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis and differential scanning calorimetry (展开更多
Developing lightweight and broadband microwave absorbers for dealing with serious electromagnetic radiation pollution is a great challenge.Here,a novel Fe-Co/N-doped carbon/reduced graphene oxide(Fe-Co/NC/rGO)composit...Developing lightweight and broadband microwave absorbers for dealing with serious electromagnetic radiation pollution is a great challenge.Here,a novel Fe-Co/N-doped carbon/reduced graphene oxide(Fe-Co/NC/rGO)composite with hierarchically porous structure was designed and synthetized by in situ growth of Fe-doped Cobased metal organic frameworks(Co-MOF)on the sheets of porous cocoon-like rGO followed by calcination.The Fe-Co/NC composites are homogeneously distributed on the sheets of porous rGO.The Fe-Co/NC/rGO composite with multiple components(Fe/Co/NC/rGO)causes magnetic loss,dielectric loss,resistance loss,interfacial polarization,and good impedance matching.The hierarchically porous structure of the Fe-Co/NC/rGO enhances the multiple reflections and scattering of microwaves.Compared with the Co/NC and Fe-Co/NC,the hierarchically porous Fe-Co/NC/rGO composite exhibits much better microwave absorption performances due to the rational composition and porous structural design.Its minimum reflection loss(RLmin)reaches?43.26 dB at 11.28 GHz with a thickness of 2.5 mm,and the effective absorption frequency(RL≤?10 dB)is up to 9.12 GHz(8.88-18 GHz)with the same thickness of 2.5 mm.Moreover,the widest effective bandwidth of 9.29 GHz occurs at a thickness of 2.63 mm.This work provides a lightweight and broadband microwave absorbing material while offering a new idea to design excellent microwave absorbers with multicomponent and hierarchically porous structures.展开更多
Due to the low concentration of indoor air contaminants, photocatalytic technology shows low efficiency for indoor air purification. The application of TiO2 for photocatalytic removal of formaldehyde is limited, becau...Due to the low concentration of indoor air contaminants, photocatalytic technology shows low efficiency for indoor air purification. The application of TiO2 for photocatalytic removal of formaldehyde is limited, because TiO2 can only absorb ultraviolet （UV） light. Immobilization of TiO2 nanoparticles on the surface of graphene can improve the visible light photocatalytic activity and the adsorption capacity. In this study, rGO （reduced graphene oxide）/TiO2 was synthesized through a hydrotherrnal method using titanium tetrabutoxide and graphene oxide as precursors, and was used for the degradation of low concentration formaldehyde in indoor air under visible light illumination. Characterization of the crystalline structure and morphology of rGO/TiO2 revealed that most GO was reduced to rGO during the hydrothermal treatment, and anatase TiO2 nanoparticles （with particle size of 15-30 nm） were dispersed well on the surface of the rGO sheets, rGO/TiO2 exhibited excellent photocatalyfic activity for degradation of formaldehyde in indoor air and this can be attributed to the role ofrGO, which can act as the electron sink and transporter for separating photo-generated electron-hole pairs through interfacial charge transfer. Furthermore, rGO could adsorb formaldehyde molecules from air to produce a high concentration of formaldehyde on the surface of rGO/ TiO2. Under visible light irradiation for 240 min, the concentration of formaldehyde could be reduced to 58.5 ppbV. rGO/TiO2 showed excellent moisture-resistance behavior, and after five cycles, rGO/TiO2 maintained high photocatalytic activity for the removal of formaldehyde （84.6%）. This work suggests that the synthesized rGO/TiO2 is a promising photocatalyst for indoor formaldehyde removal.展开更多
Lithium （Li） metal has been considered as the most attractive anode materials for Li-ion batteries （LIBs） due to its high theoretic specific capacity. The formation of unstable solid electrolyte interphase （SEI）...Lithium （Li） metal has been considered as the most attractive anode materials for Li-ion batteries （LIBs） due to its high theoretic specific capacity. The formation of unstable solid electrolyte interphase （SEI） and dendritic Li on the metal anode, however, hindered its practical application. Herein, to address the issues, a Li-free electrode with ultrathin Al2O3 coated on reduced graphene oxide （rGO） membrane that covers a Cu foil current collector was developed. The composite electrode exhibits excellent interfacial protection of lithium metal deposited between Cu foil and rGO electrochemically. Firstly, it affords good Li^＋ permeability from the electrolyte. Secondly, the ultrathin Al2O3 has sufficient mechanical strength to inhibit the penetration of Li dendrite. Li metal was observed uniformly deposited between rGO membrane and Cu collector, and stable cycle performance of Li plating/stripping with Coulombic efficiency of ~ 91.75% at the lOOth cycle is achieved in organic carbonate electrolyte without any additives.展开更多
MIL-100（V） is an inorganic-organic hybrid material composed of trimesic acid ligands and vanadium trimer supertetrahedra. MIL-100（V） is expected to be a good host for sulfur impregnation and an excellent sulfur ca...MIL-100（V） is an inorganic-organic hybrid material composed of trimesic acid ligands and vanadium trimer supertetrahedra. MIL-100（V） is expected to be a good host for sulfur impregnation and an excellent sulfur cathode host for Li-S batteries, not only because of its unique mesoporous structure, but also owing to the presence of vanadium ions with various valence states, which can offer different Lewis acid sites and allow for strong interactions with sulfur and lithium polysulfides. In this study, mesoporous M1L-100（V） and MIL-100（V）/ reduced graphene oxide （rGO） composites have been applied as novel hosts for Li-S batteries for the first time. When tested as cathodes for Li-S batteries, both S@MIL-100（V） and S@MIL-100（V）/rGO exhibit excellent electrochemical performance. The S@MIL-100（V） cathode has been demonstrated to have a reversible capacity of -550 mAh/g at 0.1 C （1 C = 1,675 mAh/g） after 200 cycles with low capacity fading of 0.17% per cycle. Moreover, S@MIL-100（V）/rGO maintains a capacity of 650 mAh/g at 0.1 C after 75 cycles, whereas at 0.5 C, the capacity is maintained at 500 mAh/g after 200 cycles and 450 mAh/g after 300 cycles. The above results reveal that the use of MIL-100（V） and MIL-100（V）/rGO as hosts for Li-S batteries can effectively enhance the cycling stability and improve the electrochemical performance of Li-S batteries.展开更多
In this study, the effect of reduced graphene oxide(rGO) on interconnected Co_3O_4 nanosheets and the improved supercapacitive behaviors is reported. By optimizing the experimental parameters, we achieved a specific c...In this study, the effect of reduced graphene oxide(rGO) on interconnected Co_3O_4 nanosheets and the improved supercapacitive behaviors is reported. By optimizing the experimental parameters, we achieved a specific capacitance of ~1016.4 F g^(-1) for the Co_3O_4/rGO/NF(nickel foam) system at a current density of 1 A g^(-1). However, the Co_3O_4/NF structure without rGO only delivers a specific capacitance of ~520.0 F g^(-1)at the same current density. The stability test demonstrates that Co_3O_4/rGO/NF retains ~95.5% of the initial capacitance value even after 3000 charge–discharge cycles at a high current density of 7 A g^(-1). Further investigation reveals that capacitance improvement for the Co_3O_4/rGO/NF structure is mainly because of a higher specific surface area(~87.8 m^2g^(-1))and a more optimal mesoporous size(4–15 nm) compared to the corresponding values of 67.1 m^2g^(-1) and 6–25 nm,respectively, for the Co_3O_4/NF structure. rGO and the thinner Co_3O_4 nanosheets benefit from the strain relaxation during the charge and discharge processes, improving the cycling stability of Co_3O_4/rGO/NF.展开更多
For a long time, there has been global concern over the environment and energy problems. Recently, the problems, which have brought about serious effect on the global living condition, have been in the ‘‘spotlight&q...For a long time, there has been global concern over the environment and energy problems. Recently, the problems, which have brought about serious effect on the global living condition, have been in the ‘‘spotlight" and given impetus to the universal's efforts to head for the same direction: stem the worst warming and strive for the renewable energy source. Hydrogen peroxide(H_2O_2) is undoubtedly a good choice,which holds the promise as a clean, efficient, safe and transferrable energy carrier. Octahedral coordination polymer, Cd_3(C_3N_3S_3)_2, was found to be a robust photocatalyst for H_2O_2 generation under visible light irradiation. To further improve the H_2O_2 generation efficiency, adhering the octahedron to reduced graphene(rGO) was applied as the strategy herein. The study shows that by adhering Cd_3(C_3N_3S_3)_2to rGO, the formation of H_2O_2 is 2.5-fold enhanced and its deformation is concurrently suppressed. This work not only demonstrates the effectiveness of adhering Cd_3(C_3N_3S_3)_2polymer to rGO for the improvement of the polymer's photocatalytic performance, but also proposes a general way for the fabrication of graphene/coordination compound hybrids for maximizing their synergy.展开更多
In this work, ultra-large sheet NiAl-layered double hydroxide(LDH)/reduced graphene oxide(RGO) nanocomposites were facilely synthesized via in situ growth of NiAl-LDH on a graphene surface without any surfactant or te...In this work, ultra-large sheet NiAl-layered double hydroxide(LDH)/reduced graphene oxide(RGO) nanocomposites were facilely synthesized via in situ growth of NiAl-LDH on a graphene surface without any surfactant or template. It was found that with a microwave-assisted method, NiAl-LDH nanosheets grew evenly on the surface of graphene. With this method, the formation of NiAl-LDH and reduction of graphene oxide were achieved in one step. The unique structure endows the electrode materials with a higher specific surface area, which is favorable for enhancing the capacity performance. The morphology and microstructure of the as-prepared composites were characterized by X-ray diffraction, Brunauer-EmmettTeller surface area measurement, and transmission electron microscopy. The specific surface area and pore volume of the RGO/LDH composite are 108.3 m^2 g^(-1) and 0.74 cm^3 g^(-1), respectively, which are much larger than those of pure LDHs(19.8 m^2 g^(-1) and 0.065 cm^3 g(-1), respectively). The capacitive properties of the synthesized electrodes were studied using cyclic voltammetry and electrochemical impedance spectroscopy in a three-electrode experimental setup. The specific capacitance of RGO/LDHs was calculated to be 1055 F g^(-1) at 1 Ag^(-1). It could be anticipated that the synthesized electrodes will find promising applications as novel electrode materials in supercapacitors and other devices because of their outstanding characteristics of controllable capacitance and facile synthesis.展开更多
Zinc(Zn)possesses desirable degradability and favorable biocompatibility,thus being recognized as a promising bone implant material.Nevertheless,the insufficient mechanical performance limits its further clinical appl...Zinc(Zn)possesses desirable degradability and favorable biocompatibility,thus being recognized as a promising bone implant material.Nevertheless,the insufficient mechanical performance limits its further clinical application.In this study,reduced graphene oxide(RGO)was used as reinforcement in Zn scaffold fabricated via laser additive manufacturing.Results showed that the homogeneously dispersed RGO simultaneously enhanced the strength and ductility of Zn scaffold.On one hand,the enhanced strength was ascribed to(i)the grain refinement caused by the pinning effect of RGO,(ii)the efficient load shift due to the huge specific surface area of RGO and the favorable interface bonding between RGO and Zn matrix,and(iii)the Orowan strengthening by the homogeneously distributed RGO.On the other hand,the improved ductility was owing to the RGO-induced random orientation of grain with texture index reducing from 20.5 to 7.3,which activated more slip systems and provided more space to accommodate dislocation.Furthermore,the cell test confirmed that RGO promoted cell growth and differentiation.This study demonstrated the great potential of RGO in tailoring the mechanical performance and cell behavior of Zn scaffold for bone repair.展开更多
文摘Over the span of years, improvements over various synthesis methods of graphene are constantly pursued to provide safer and more effective alternatives. Though the extraction of graphene through Hummers method is one of the oldest techniques yet it is one of the most suitable methods for the formation of bulk graphene. Graphene can be obtained in the form of reduced Graphite oxide, sometimes also referred as Graphene oxide. The effectiveness of this oxidation process can be evaluated by the magnitude of carbon/oxygen ratio of the obtained graphene. Here, graphene oxide (GO) was prepared by oxidizing the purified natural flake graphite (NFG) by a modified Hummers method. The attempts have been made to synthesize GO having few layers by using a modified Hummers method where the amount of NaNO3 has been decreased, and the amount of KMnO4 is increased. The reaction has been performed in a 9:1 (by volume) mixture of H2SO4/H3PO4. This modification is successful in increasing the reaction yield and reducing the toxic gas evolution while using a varied proportion of KMnO4 and H2SO4 as those required by Hummers method. A new component of K2S2O8 has been introduced to the reaction system to maintain the pH value. Reduced graphene oxide (rGO) was thereafter extracted by thermal modification of GO. Here, GO has been used as a precursor for graphene synthesis by thermal reduction processes. The results of FTIR and Raman spectroscopy analysis show that the NFG when oxidized by strong oxidants like KMnO4 and NaNO3, introduced oxygen atoms into the graphite layers and formed bonds like C=O, C-H, COOH and C-O-C with the carbon atoms in the graphite layers. The structure and morphology of both GO and rGO were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy, Raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis and differential scanning calorimetry (
基金the National Natural Science Foundation of China(No.21376029)and the Analysis&Testing Center,Beijing Institute of Technology for sponsoring this researchsupported by Beijing Key Laboratory for Chemical Power Source and Green Catalysis,Beijing Institute of Technology.
文摘Developing lightweight and broadband microwave absorbers for dealing with serious electromagnetic radiation pollution is a great challenge.Here,a novel Fe-Co/N-doped carbon/reduced graphene oxide(Fe-Co/NC/rGO)composite with hierarchically porous structure was designed and synthetized by in situ growth of Fe-doped Cobased metal organic frameworks(Co-MOF)on the sheets of porous cocoon-like rGO followed by calcination.The Fe-Co/NC composites are homogeneously distributed on the sheets of porous rGO.The Fe-Co/NC/rGO composite with multiple components(Fe/Co/NC/rGO)causes magnetic loss,dielectric loss,resistance loss,interfacial polarization,and good impedance matching.The hierarchically porous structure of the Fe-Co/NC/rGO enhances the multiple reflections and scattering of microwaves.Compared with the Co/NC and Fe-Co/NC,the hierarchically porous Fe-Co/NC/rGO composite exhibits much better microwave absorption performances due to the rational composition and porous structural design.Its minimum reflection loss(RLmin)reaches?43.26 dB at 11.28 GHz with a thickness of 2.5 mm,and the effective absorption frequency(RL≤?10 dB)is up to 9.12 GHz(8.88-18 GHz)with the same thickness of 2.5 mm.Moreover,the widest effective bandwidth of 9.29 GHz occurs at a thickness of 2.63 mm.This work provides a lightweight and broadband microwave absorbing material while offering a new idea to design excellent microwave absorbers with multicomponent and hierarchically porous structures.
基金financially supported by China Postdoctoral Science Foundation(No.2016M592496)Natural Science Foundation of Guangdong Province,China(Nos.2017A030310279,2014A030310431)+1 种基金National Natural Science Foundation of China(Nos.41501319,91645119,21207039,U1201231,51378218,51108187 and 50978103)Guangzhou science and technology plan(No.201607010095)
文摘Due to the low concentration of indoor air contaminants, photocatalytic technology shows low efficiency for indoor air purification. The application of TiO2 for photocatalytic removal of formaldehyde is limited, because TiO2 can only absorb ultraviolet （UV） light. Immobilization of TiO2 nanoparticles on the surface of graphene can improve the visible light photocatalytic activity and the adsorption capacity. In this study, rGO （reduced graphene oxide）/TiO2 was synthesized through a hydrotherrnal method using titanium tetrabutoxide and graphene oxide as precursors, and was used for the degradation of low concentration formaldehyde in indoor air under visible light illumination. Characterization of the crystalline structure and morphology of rGO/TiO2 revealed that most GO was reduced to rGO during the hydrothermal treatment, and anatase TiO2 nanoparticles （with particle size of 15-30 nm） were dispersed well on the surface of the rGO sheets, rGO/TiO2 exhibited excellent photocatalyfic activity for degradation of formaldehyde in indoor air and this can be attributed to the role ofrGO, which can act as the electron sink and transporter for separating photo-generated electron-hole pairs through interfacial charge transfer. Furthermore, rGO could adsorb formaldehyde molecules from air to produce a high concentration of formaldehyde on the surface of rGO/ TiO2. Under visible light irradiation for 240 min, the concentration of formaldehyde could be reduced to 58.5 ppbV. rGO/TiO2 showed excellent moisture-resistance behavior, and after five cycles, rGO/TiO2 maintained high photocatalytic activity for the removal of formaldehyde （84.6%）. This work suggests that the synthesized rGO/TiO2 is a promising photocatalyst for indoor formaldehyde removal.
基金financially supported by the National Natural Science Foundation of China(No.51772241)the Key Research Program of Shaanxi Province(No.2017ZDXM-GY-035)+2 种基金the Young Talent Support Plan of Xi’an Jiaotong University(No.DQ1J006)the Project from State Key Laboratory of Electrical Insulation and Power Equipment,Xi’an Jiaotong University(No.EIPE17306)the Fundamental Research Funds for the Central Universities(Nos.zrzd2017004,xjj2017076)for financial support
文摘Lithium （Li） metal has been considered as the most attractive anode materials for Li-ion batteries （LIBs） due to its high theoretic specific capacity. The formation of unstable solid electrolyte interphase （SEI） and dendritic Li on the metal anode, however, hindered its practical application. Herein, to address the issues, a Li-free electrode with ultrathin Al2O3 coated on reduced graphene oxide （rGO） membrane that covers a Cu foil current collector was developed. The composite electrode exhibits excellent interfacial protection of lithium metal deposited between Cu foil and rGO electrochemically. Firstly, it affords good Li^＋ permeability from the electrolyte. Secondly, the ultrathin Al2O3 has sufficient mechanical strength to inhibit the penetration of Li dendrite. Li metal was observed uniformly deposited between rGO membrane and Cu collector, and stable cycle performance of Li plating/stripping with Coulombic efficiency of ~ 91.75% at the lOOth cycle is achieved in organic carbonate electrolyte without any additives.
基金Acknowledgements This research is financial supported by the National Nature Science Foundation of China （No. 21471091）, Academy of Sciences large apparatus United Fund （No. 11179043）, the Fundamental Research Funds of Shandong University （No. 2015JC007）, and the Taishan Scholar Project of Shandong Province （No. ts201511004）.
文摘MIL-100（V） is an inorganic-organic hybrid material composed of trimesic acid ligands and vanadium trimer supertetrahedra. MIL-100（V） is expected to be a good host for sulfur impregnation and an excellent sulfur cathode host for Li-S batteries, not only because of its unique mesoporous structure, but also owing to the presence of vanadium ions with various valence states, which can offer different Lewis acid sites and allow for strong interactions with sulfur and lithium polysulfides. In this study, mesoporous M1L-100（V） and MIL-100（V）/ reduced graphene oxide （rGO） composites have been applied as novel hosts for Li-S batteries for the first time. When tested as cathodes for Li-S batteries, both S@MIL-100（V） and S@MIL-100（V）/rGO exhibit excellent electrochemical performance. The S@MIL-100（V） cathode has been demonstrated to have a reversible capacity of -550 mAh/g at 0.1 C （1 C = 1,675 mAh/g） after 200 cycles with low capacity fading of 0.17% per cycle. Moreover, S@MIL-100（V）/rGO maintains a capacity of 650 mAh/g at 0.1 C after 75 cycles, whereas at 0.5 C, the capacity is maintained at 500 mAh/g after 200 cycles and 450 mAh/g after 300 cycles. The above results reveal that the use of MIL-100（V） and MIL-100（V）/rGO as hosts for Li-S batteries can effectively enhance the cycling stability and improve the electrochemical performance of Li-S batteries.
基金financially supported from the National Natural Science Foundation of China (Grant Nos.: 61376068, 11304132, 11304133, and 11405144)the Specialized Research Fund of the Doctoral Program of Higher Education (Grant Nos.: 20120211120003 and 20130211120009)the Fundamental Research Funds for the Central Universities (Grant Nos.: lzujbky2013-36 and lzujbky-2014-30)
文摘In this study, the effect of reduced graphene oxide(rGO) on interconnected Co_3O_4 nanosheets and the improved supercapacitive behaviors is reported. By optimizing the experimental parameters, we achieved a specific capacitance of ~1016.4 F g^(-1) for the Co_3O_4/rGO/NF(nickel foam) system at a current density of 1 A g^(-1). However, the Co_3O_4/NF structure without rGO only delivers a specific capacitance of ~520.0 F g^(-1)at the same current density. The stability test demonstrates that Co_3O_4/rGO/NF retains ~95.5% of the initial capacitance value even after 3000 charge–discharge cycles at a high current density of 7 A g^(-1). Further investigation reveals that capacitance improvement for the Co_3O_4/rGO/NF structure is mainly because of a higher specific surface area(~87.8 m^2g^(-1))and a more optimal mesoporous size(4–15 nm) compared to the corresponding values of 67.1 m^2g^(-1) and 6–25 nm,respectively, for the Co_3O_4/NF structure. rGO and the thinner Co_3O_4 nanosheets benefit from the strain relaxation during the charge and discharge processes, improving the cycling stability of Co_3O_4/rGO/NF.
基金financially supported by the National Natural Science Foundation of China(21003021 and 21373051)
文摘For a long time, there has been global concern over the environment and energy problems. Recently, the problems, which have brought about serious effect on the global living condition, have been in the ‘‘spotlight" and given impetus to the universal's efforts to head for the same direction: stem the worst warming and strive for the renewable energy source. Hydrogen peroxide(H_2O_2) is undoubtedly a good choice,which holds the promise as a clean, efficient, safe and transferrable energy carrier. Octahedral coordination polymer, Cd_3(C_3N_3S_3)_2, was found to be a robust photocatalyst for H_2O_2 generation under visible light irradiation. To further improve the H_2O_2 generation efficiency, adhering the octahedron to reduced graphene(rGO) was applied as the strategy herein. The study shows that by adhering Cd_3(C_3N_3S_3)_2to rGO, the formation of H_2O_2 is 2.5-fold enhanced and its deformation is concurrently suppressed. This work not only demonstrates the effectiveness of adhering Cd_3(C_3N_3S_3)_2polymer to rGO for the improvement of the polymer's photocatalytic performance, but also proposes a general way for the fabrication of graphene/coordination compound hybrids for maximizing their synergy.
基金supported by the National Natural Science Foundation of China (21573119,21221062,21131004,21390393 and U1463202)the Postdoctoral Science Foundation of China (2014M550710)
文摘In this work, ultra-large sheet NiAl-layered double hydroxide(LDH)/reduced graphene oxide(RGO) nanocomposites were facilely synthesized via in situ growth of NiAl-LDH on a graphene surface without any surfactant or template. It was found that with a microwave-assisted method, NiAl-LDH nanosheets grew evenly on the surface of graphene. With this method, the formation of NiAl-LDH and reduction of graphene oxide were achieved in one step. The unique structure endows the electrode materials with a higher specific surface area, which is favorable for enhancing the capacity performance. The morphology and microstructure of the as-prepared composites were characterized by X-ray diffraction, Brunauer-EmmettTeller surface area measurement, and transmission electron microscopy. The specific surface area and pore volume of the RGO/LDH composite are 108.3 m^2 g^(-1) and 0.74 cm^3 g^(-1), respectively, which are much larger than those of pure LDHs(19.8 m^2 g^(-1) and 0.065 cm^3 g(-1), respectively). The capacitive properties of the synthesized electrodes were studied using cyclic voltammetry and electrochemical impedance spectroscopy in a three-electrode experimental setup. The specific capacitance of RGO/LDHs was calculated to be 1055 F g^(-1) at 1 Ag^(-1). It could be anticipated that the synthesized electrodes will find promising applications as novel electrode materials in supercapacitors and other devices because of their outstanding characteristics of controllable capacitance and facile synthesis.
基金The Natural Science Foundation of China(51935014,81871494,81871498)JiangXi Provincial Natural Science Foundation of China(20192ACB20005,2020ACB214004,20202BAB214011)+5 种基金The Provincial Key R&D Projects of Jiangxi(20201BBE51012)Guangdong Province Higher Vocational Colleges&Schools Pearl River Scholar Funded Scheme(2018)The Project of Hunan Provincial Science and Technology Plan(2017RS3008)Shenzhen Science and Technology Plan Project(JCYJ20170817112445033)Innovation Team Project on University of Guangdong Province(2018GKCXTD001)Technology Innovation Platform Project of Shenzhen Institute of Information Technology 2020(PT2020E002).
文摘Zinc(Zn)possesses desirable degradability and favorable biocompatibility,thus being recognized as a promising bone implant material.Nevertheless,the insufficient mechanical performance limits its further clinical application.In this study,reduced graphene oxide(RGO)was used as reinforcement in Zn scaffold fabricated via laser additive manufacturing.Results showed that the homogeneously dispersed RGO simultaneously enhanced the strength and ductility of Zn scaffold.On one hand,the enhanced strength was ascribed to(i)the grain refinement caused by the pinning effect of RGO,(ii)the efficient load shift due to the huge specific surface area of RGO and the favorable interface bonding between RGO and Zn matrix,and(iii)the Orowan strengthening by the homogeneously distributed RGO.On the other hand,the improved ductility was owing to the RGO-induced random orientation of grain with texture index reducing from 20.5 to 7.3,which activated more slip systems and provided more space to accommodate dislocation.Furthermore,the cell test confirmed that RGO promoted cell growth and differentiation.This study demonstrated the great potential of RGO in tailoring the mechanical performance and cell behavior of Zn scaffold for bone repair.
