Developing an excellent photocatalysis system to remove pesticides from water is an urgent problem in current environment purification field.Herein,a Z-scheme WO_(3)/g-C_(3)N_(4) photocatalyst was prepared by a facile...Developing an excellent photocatalysis system to remove pesticides from water is an urgent problem in current environment purification field.Herein,a Z-scheme WO_(3)/g-C_(3)N_(4) photocatalyst was prepared by a facile in-situ calcination method,and the photocatalytic activity was investigated for degradation of nitenpyram(NTP)under visible light.The optimal Z-scheme WO_(3)/g-C_(3)N_(4) photocatalyst displayed the highest rate constant(0.036 min-1),which is about 1.7 and 25 times higher than that of pure g-C_(3)N_(4) and WO_(3),respectively.The improvement of photocatalytic performance is attributed to fast transfer of photogene rated carriers in the Z-scheme structure,which are testified by electron spin resonance(ESR)experiments,photocurrent and electrochemical impedance spectra(EIS)measurements.Moreover,the effects of typical water environmental factors on the degradation NTP were systematically studied.And the possible degradation pathways of NTP were deduced by the intermediates detected by highperformance liquid chro matography-mass spectrometry(HPLC-MS).This work will not only contribute to understand the degradation mechanism of pesticides in real water environmental condition,but also promote the development of new technologies for pesticide pollution control as well as environmental remediation.展开更多
Experiments were carried out to investigate the influence of TiO2 surface fluorination on the photodegradation of a representative organic cationic compound, Methylene Blue （MB）. The eleetropositive MB shows poor ad...Experiments were carried out to investigate the influence of TiO2 surface fluorination on the photodegradation of a representative organic cationic compound, Methylene Blue （MB）. The eleetropositive MB shows poor adsorption on TiO2 surface; its degradation performs a HO. radical-mediated mechanism. In the F-modified system, the kinetic reaction rate enlarged more than 2.5 fold that was attributed mainly to the accumulating adsorption of MB and the increased photogenerated hole available on the F-modified TiO2 surface.展开更多
A layer of graphene(GR)particles was successfully deposited at the interface between Co(OH)2 nanoparticles and TiO2 nanotubes,aiming to improve the photoelectrochemical performance of the large-bandgap semiconductor T...A layer of graphene(GR)particles was successfully deposited at the interface between Co(OH)2 nanoparticles and TiO2 nanotubes,aiming to improve the photoelectrochemical performance of the large-bandgap semiconductor TiO2.The obtained Co(OH)2/GR/TiO2 was extensively characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),UV–vis absorption spectra and photoluminescence(PL)emission spectra.Electrochemical impedance spectra,photogenerated potential-time(E-t),photocurrent density-time(i-t)and i-E curves and open circuit potential(OCP)curves were measured to investigate the photoelectrochemical activities and photogenerated cathodic protection properties.The results revealed that Co(OH)2/GR/TiO2 exhibits excellent photoelectrochemical and photogenerated cathodic performance due to synergistic effect between Co(OH)2 and graphene.Co(OH)2 and graphene co-modified TiO2 photoanode could provide an effective protection for 304 stainless steel(304 SS)in 3.5 wt%Na Cl solution for 12 h,which would be promising for future practical applications in the field of marine corrosion protection.展开更多
Photocatalytic splitting of water over p-type semiconductors is a promising strategy for production of hydrogen.However,the determination of rate law is rarely reported.To this purpose,copper oxide(CuO)is selected as ...Photocatalytic splitting of water over p-type semiconductors is a promising strategy for production of hydrogen.However,the determination of rate law is rarely reported.To this purpose,copper oxide(CuO)is selected as a model photocathode in this study,and the photogenerated surface charge density,interfacial charge transfer rate constant and their relation to the water reduction rate(in terms of photocurrent)were investigated by a combination of(photo)electrochemical techniques.The results showed that the charge transfer rate constant is exponential-dependent on the surface charge density,and that the photocurrent equals to the product of the charge transfer rate constant and surface charge density.The reaction is first-order in terms of surface charge density.Such an unconventional rate law contrasts with the reports in literature.The charge density-dependent rate constant results from the Fermi level pinning(i.e.,Galvani potential is the main driving force for the reaction)due to accumulation of charge in the surface states and/or Frumkin behavior(i.e.,chemical potential is the main driving force).This study,therefore,may be helpful for further investigation on the mechanism of hydrogen evolution over a CuO photocathode and for designing more efficient CuO-based photocatalysts.展开更多
Photocatalytic cycloadditions of CO_(2)with epoxides are emerging as a significant platform for the green synthesis of valuable carbonates,where efficient catalytic systems with spatially separated charge carriers are...Photocatalytic cycloadditions of CO_(2)with epoxides are emerging as a significant platform for the green synthesis of valuable carbonates,where efficient catalytic systems with spatially separated charge carriers are demanded.Herein,a single p-block metal atom is proposed to be a candidate for photogenerated electron localization on a metal oxide substrate.By taking the Bi single-atom supported on ZnO nanosheet(Bi1/ZnO)as an example,we show that the Bi atom plays the role of an electron island in the sea of delocalized holes within ZnO.Meanwhile,the as-formed electron island could readily promote the rate-determining ring-opening process of cycloaddition reactions.Benefiting from the unique spatially separated electrons and holes,the Bi1/ZnO achieves a high yield of cyclic carbonates with almost 100%selectivity.This study provides a pioneering strategy for enhancing the performances of photocatalytic CO_(2)chemical fixation.展开更多
Organic conjugated polymers have received extensive attention due to their unique electronic properties.However,there have been relatively few reports on the dark photocatalytic reactions utilizing organic conjugated ...Organic conjugated polymers have received extensive attention due to their unique electronic properties.However,there have been relatively few reports on the dark photocatalytic reactions utilizing organic conjugated polymers.Herein,we report the successful synthesis of an organic conjugated polymer based on poly(heptazine imide)nanocrystals(CNNCs)for H_(2)O_(2)evolution and biomedical applications using a simple salt molten method and sonication-centrifugation process.The results show that these colloid CNNCs have the characteristics of photogenerated electrons accumulation and realize dark photocatalysis with high reducibility under visible light irradiation.Notably,these accumulating photogenerated electrons can reduce O_(2)in darkness to produce H_(2)O_(2).In addition,cytotoxicity tests were conducted and it was found that H_(2)O_(2)produced under dark conditions could oxidize L-arginine(L-Arg)to NO,which effectively killed tumors in the dark.This work provides an important strategy to construct organic conjugated semiconductor nanocrystals and applying them to future energy and biomedical fields.展开更多
The controllability of persistent photoconductance （PPC） and charge/energy storage of ZnO nanorod arrays （NRAs） were demonstrated experimentally by tuning the nanorod diameter. The dependency of the ZnO NRAs＇ pho...The controllability of persistent photoconductance （PPC） and charge/energy storage of ZnO nanorod arrays （NRAs） were demonstrated experimentally by tuning the nanorod diameter. The dependency of the ZnO NRAs＇ photoelectric characteristics on the nanorod diameter suggests that the Debye length and photon penetration depth in ZnO could spatially partition a standalone nanorod into three different photoelectric functional regions （PFRs）. Theoretically, a series of rate functions was employed to describe the different extrinsic/intrinsic carrier photogeneration/recombination dynamic sub-processes occurring in the different PFRs, associated with oxygen chemisorption/photodesorption, oxygen vacancy photoionization, and electron trapping by photoionized oxygen vacancies. On the basis of the coupled contributions of these different dynamic sub-processes in the photoelectric properties of the ZnO NRAs, a thorough-process photoelectric dynamic model （TPDM） was proposed using the simultaneous rate functions. Through solving the rate functions, the corresponding analytical equations could be employed to simulate the time-resolved PPC spectra of the ZnO NRAs, and then the quantitative parameters extracted to decipher the PPC and charge/energy storage mechanisms in the ZnO NRAs. In this way, the TPDM model provided a numerical-analytical method to quantitatively evaluate the photoelectric properties of ZnO NRA-based devices. Additionally, the TPDM model revealed how the different photoinduced carrier dynamics in the different PFRs could play functional roles in different optoelectronic applications, e.g., photodetectors, photocatalysts, solar cells and optical nonvolatile memories, and thus it illuminated a practical approach for the design of ZnO NRA-based devices via optimization of the modularized spatial configuration of the PFRs.展开更多
Microspheres can break the diffraction limit and magnify nano-structure imaging,and with its advantages of low cost and label-free operation,microsphere-assisted imaging has become an irreplaceable tool in the life sc...Microspheres can break the diffraction limit and magnify nano-structure imaging,and with its advantages of low cost and label-free operation,microsphere-assisted imaging has become an irreplaceable tool in the life sciences and for precision measurements.However,the tiny size and limited imaging field of traditional solid microspheres cause difficulties when imaging large sample areas.Alternatively,droplets have similar properties to those of microspheres,with large surface curvature and refractive-index difference from the surrounding environment,and they can also serve as lenses to focus light for observation and imaging.Previous work has shown that droplets with controllable size can be generated using an optical tweezer system and can be driven by optical traps to move precisely like solid microspheres.Here,a novel microdroplet-assisted imaging technology based on optical tweezers is proposed that better integrates the generation,manipulation,and utilization of droplets.展开更多
Photogenerated charge separation and transfer is one of the bottleneck steps in photocatalysis,and efficient charge separation strategies are strongly desired.Here,mimicking the electron transport chain in natural pho...Photogenerated charge separation and transfer is one of the bottleneck steps in photocatalysis,and efficient charge separation strategies are strongly desired.Here,mimicking the electron transport chain in natural photosynthesis,we report the design and fabrication of a charge transfer chain using bismuth-based semiconductor as a proof-of-concept.In view of the thermodynamic energy band positions and structural similarity based on the density functional theory(DFT)analysis,heterostructured combination ofα-Bi_(2)O_(3),perovskite-like Bi_(4)Ti_(3)O_(12),and sillenite Bi12TiO20 was designed for fabrication of charge transfer chain.By tuning the molar ratio of Bi and Ti precursors,the Bi_(4)Ti_(3)O_(12)and Bi12TiO20 particles were formed on the surface ofα-Bi_(2)O_(3)by an insitu transformation process,giving rise to Bi_(12)TiO_(20)-Bi_(4)Ti_(3)O_(12)/α-Bi_(2)O_(3)composites with charge transfer chain.We propose that the effective charge transfer is accomplished amongα-Bi_(2)O_(3),Bi12TiO20,and Bi_(4)Ti_(3)O_(12),which significantly improves the photogenerated charge separation and transfer,as indicated by photoluminescene,time-resolved photoluminescene,and electrochemical impedance spectra results.As expected,the Bi_(12)TiO_(20)-Bi_(4)Ti_(3)O_(12)/α-Bi_(2)O_(3)shows the superior photocatalytic activity for the degradation of environmental pollutants with high concentration.Even for the refractory pollutants like 4-chlorophenol,the optimal Bi_(12)TiO_(20)-Bi_(4)Ti_(3)O_(12)/α-Bi_(2)O_(3)composite shows 28 times higher than that ofα-Bi_(2)O_(3)for photocatalytic degradation,verifying the superiority of photogenerated charge transfer chain in photocatalysis.This work demonstrates the feasibility of the charge transfer chain strategy to boost the photogenerated charge separation,which is of great significance for designing energy and environmental-related materials in heterogonous photocatalysis.展开更多
Natural photosynthesis,which provides a green and high-efficiency energy conversion path by spatial separation of photogenerated carriers through combined actions of molecules ingeniously arranged in an efficient sola...Natural photosynthesis,which provides a green and high-efficiency energy conversion path by spatial separation of photogenerated carriers through combined actions of molecules ingeniously arranged in an efficient solar nanospace,highlights the importance of rational nanostructure design to realize artificial high-efficiency photosystem.Inspired by these unique features,we constructed a high-efficiency ternary photosystem by selectively decorating the{001}facets of 18-facet SrTiO_(3)with Au@CdS photosensitizers via a green photo-assisted method.Benefiting from the dual-facilitated charge carriers transportation in core-shell structured Au@CdS heterojunction and well-faceted 18-facet SrTiO_(3)nanocrystal,such a photo-catalyst could realize the effective spatial separation of photogenerated electrons and holes.As expected,the 18-facet SrTiO_(3)/Au@CdS photocatalyst exhibits superior activity in visible-light-driven photocatalytic hydrogen evolution(4.61 mmol h^(−1)g^(−1)),166%improvement in comparison with randomly deposited Au@CdS(1.73 mmol h^(−1)g^(−1)).This work offers new insight into the development of green and high-efficiency photocatalytic systems based on the rational nanostructure design by crystal facet engineering.展开更多
Water splitting is important to the conversion and storage of renewable energy,but slow kinetics of the oxygen evolution reaction(OER)greatly limits its utility.Here,under visible light illumination,the p-n WO_(3)/SnS...Water splitting is important to the conversion and storage of renewable energy,but slow kinetics of the oxygen evolution reaction(OER)greatly limits its utility.Here,under visible light illumination,the p-n WO_(3)/SnSe_(2)(WS)heterojunction significantly activates OER catalysis of CoFe-layered double hydroxide(CF)/carbon nanotubes(CNTs).Specifically,the catalyst achieves an overpotential of 224 mV at 10 mA cm^(-2)and a small Tafel slope of 47 mV dec^(-1),superior to RuO_(2)and most previously reported transition metal-based OER catalysts.The p-n WS heterojunction shows strong light absorption to produce photogenerated carriers.The photogenerated holes are trapped by CF to suppresses the charge recombination and facilitate charge transfer,which accelerates OER kinetics and boost the activity for the OER.This work highlights the possibility of using heterojunctions to activate OER catalysis and advances the design of energy-efficient catalysts for water oxidation systems using solar energy.展开更多
Heterostructure photocatalysts with a built-in electric field have become one of the most promising strategies to enhance photogenerated electron-hole pair separation. However, close contact between the two active com...Heterostructure photocatalysts with a built-in electric field have become one of the most promising strategies to enhance photogenerated electron-hole pair separation. However, close contact between the two active components of heterogeneous photocatalysts remains a problem. Herein, the in-situ fabrication of an SnO2/SnS2 heterostructure photocatalyst was performed;the structure showed enhanced photocatalytic performance resulting from the tight-contact heterostructures. The results of photoelectrochemical measurements further verified that a tight-contact heterostructure improved the separation of photogenerated electron-hole pairs. The results of EIS Bode plots also demonstrated that such in-situ fabricated SnO2/SnS2 samples exhibited the longest carrier lifetime(41.6 μs) owing to the intimate interface of SnO2/SnS2 heterostructures.展开更多
H_(2)O_(2)has been widely applied in the fields of chemical synthesis,medical sterilization,pollutant removal,etc.,due to its strong oxidizing property and the avoidable secondary pollution.Despite of the enhanced per...H_(2)O_(2)has been widely applied in the fields of chemical synthesis,medical sterilization,pollutant removal,etc.,due to its strong oxidizing property and the avoidable secondary pollution.Despite of the enhanced performance for H_(2)O_(2)generation over g-C_(3)N_(4)semiconductors through promoting the separation of photo-generated charge carriers,the effect of migration orientation of charge carriers is still ambiguous.For this emotion,surface modification of g-C_(3)N_(4)was employed to adjust the migration orientation of charge carriers,in order to investigate systematically its effect on the performance of H_(2)O_(2)generation.It was found that ultrathin g-C_(3)N_(4)(UCN)modified by boron nitride(BN),as an effective hole-attract agent,demonstrated a significantly enhanced performance.Particularly,for the optimum UCN/BN-40%catalyst,4.0-fold higher yield of H_(2)O_(2)was obtained in comparison with the pristine UCN.As comparison,UCN modified by carbon dust demonstrated a completely opposite tendency.The remarkably improved performance over UCN/BN was ascribed to the fact that more photo-generated electrons were remained inside of triazine structure of g-C_(3)N_(4),leading to the formation of larger amount of 1,4-endoxide.It is anticipated that our work could provide new insights for the design of photocatalyst with significantly improved performance for H_(2)O_(2)generation.展开更多
The optical-induced dielectric tunability properties of DAST crystal in THz range were experimentally demonstrated.The DAST crystal was grown by the spontaneous nucleation method(SNM) and characterized by infrared spe...The optical-induced dielectric tunability properties of DAST crystal in THz range were experimentally demonstrated.The DAST crystal was grown by the spontaneous nucleation method(SNM) and characterized by infrared spectrum. With the optimum wavelength of the exciting optical field, the transmission spectra of the DAST crystal excited by 532 nm laser under different power were measured by terahertz time-domain spectroscopy(THz-TDS) at room temperature. The transmitted THz intensity reduction of 26 % was obtained at 0.68 THz when the optical field was up to 80 m W. Meanwhile,the variation of refractive index showed an approximate quadratic behavior with the exciting optical field, which was related to the internal space charge field of photorefractive phenomenon in the DAST crystal caused by the photogenerated carrier.A significant enhancement of 13.7 % for THz absorption coefficient occurred at 0.68 THz due to the photogenerated carrier absorption effect in the DAST crystal.展开更多
Z-Schemc photocatalysts as a research locus pertomi strong redox capability and high photocatalytic peribnnance.WO3/KNbO3 photocatalysts were fabricated by ball milling method,and performed higlier photocatalytic acti...Z-Schemc photocatalysts as a research locus pertomi strong redox capability and high photocatalytic peribnnance.WO3/KNbO3 photocatalysts were fabricated by ball milling method,and performed higlier photocatalytic activity in liquid degradation(rhodamine B,methylene blue and bisphenol A),compared with WO3 or KNbO3 monomer.This is due to that Z-scheme heterojunction is lonned between WO3 and KNbO3,and the holes photo-excited in valence band of KNbO?are quickly combined with the electrons in conduction band of WO3.The electrons accumulated in conduction band of KNbO3 show high reducibility,thereby reducing O2 to·O 2-,and the holes in valence band of WO3 show high oxidative to oxidize H2O to·OH,respectively.Furthermore,it is proved by means of electron spin resonaiice(ESR)spectra,terephthalic acid photolumiiiescence probing technique(TA・PL),and UV-Vis absorption spectra of nitroblue tetrazolium.This work indicates that the iabrication of Z-scheme structure can improve the photocatalytic activity by efficiently separating the photogenerated electrons and holes in the photocatalytic reaction system,which is helpful to deeply understand the migration mechanism of photoexcited cairier(band-band transfer and Z-scheme transfer)in heterojunction photocatalysts.展开更多
Molecular self-assembly is a natured-inspired strategy to integrate individual functional molecules into supramolecular nanostructured materials through noncovalent bond interactions for solar to fuel conversion.Howev...Molecular self-assembly is a natured-inspired strategy to integrate individual functional molecules into supramolecular nanostructured materials through noncovalent bond interactions for solar to fuel conversion.However,the design and engineering of the morphology,size,and orderly stacking of supramolecular nanostructures remain a great challenge.In this study,regular porphyrin nanocrystals with different orderly stacked structures are synthesized through noncovalent self-assembly of Pt(II)meso-tetra(4-carboxyphenyl)porphine(PtTCPP),using surfactants with different electronegativity.The synergy of noncovalent bond interactions between porphyrin molecules,and between porphyrin molecules and surfactants resulted in different molecular packing patterns.Due to the spatial ordering of PtTCPP molecules,the different nanocrystals exhibit both collective optical properties and morphology-dependent activities in photocatalytic hydrogen production.The measurements of the photodeposition of dual cocatalysts showed that the photogenerated electrons and holes selectively aggregated at different active sites,revealing separation pathways and directional transfer of photogenerated electrons and holes in the assemblies.This study provides a new strategy to exert rational control over porphyrin self-assembly nanocrystals for highly efficient water splitting.展开更多
Tuning white-light emission via free radicals is still a challenge in molecular-based functional materials.Herein, a new photoactive Zn^(2+) oxalate-based chain containing a polypyridine ligand was designed and synthe...Tuning white-light emission via free radicals is still a challenge in molecular-based functional materials.Herein, a new photoactive Zn^(2+) oxalate-based chain containing a polypyridine ligand was designed and synthesized with remarkably bifunctional photochromism and photo-actuated greenish white-light emission after UV, sunlight or Xe lamp light irradiation at room temperature. The photo-actuated coloration process was induced by the photogeneration of stable radicals originated from intermolecular electron transfers from oxalate components to the protonated polypyridine units, as demonstrated by UV–vis, IR,electron spin resonance and X-ray photoelectron spectra and magnetic measurements. Importantly, the on/off greenish white light emission(WLE) could be reversibly switched by generation and elimination of radicals via light irradiation and heat treatment, providing a feasible strategy for designing photoswitchable light emission diodes materials.展开更多
Covalent organic frameworks(COFs)have lately emerged as a blooming class of potential materials for photocatalytic water splitting because of their high crystallinity,huge surface areas,and structural versatility.Howe...Covalent organic frameworks(COFs)have lately emerged as a blooming class of potential materials for photocatalytic water splitting because of their high crystallinity,huge surface areas,and structural versatility.However,the photocatalytic performance for most pure COFs face some limitations factors,such as the significant recombination of photogenerated carriers and slow charge transfer.Herein,a novel thioether-functionalized pyrene-based COF(S_(4)-COF)was effectively produced and chosen as a support for the immobilization of ultrafine gold nanoparticles(Au NPs).S_(4)-COF photocatalyst with Au as cocatalyst demonstrates remarkable photocatalytic activity with a H_(2) generation rate of 1377μmol g^(−1) h^(−1) under visible light(>420 nm),which is ca.4.5-fold increase comparing to that of pure S_(4)-COF(302μmol g^(−1) h^(−1)).Au NPs anchored on S_(4)-COF possess an ultrafine size distribution ranging from 1.75 to 6.25 nm with an average size centered at 3.8 nm,which benefits from the coordination interaction between thioether groups and Au.Meanwhile,the produced Au@S_(4)-COF can generate a stable photocatalytic H_(2) generation during the four recycles and preserve its crystallinity structure after the stability testing.The Au NPs anchored on the S_(4)-COF photocatalyst can greatly accelerate the separation of photogenerated carriers and increase charge transfer because of the combined function of Au NPs and thioether groups.Such a method can not only prevent the aggregation of Au NPs onto thioether-containing COFs to achieve long-term photostability but also allow uniform dispersion for an ordered structure of photocatalysts.This work provides a rational strategy for designing and preparing COF-based photocatalysts for solar-driven H_(2) production.展开更多
基金financially supported by the National Science Funds for Creative Research Groups of China(No.51421006)National Natural Science Foundation of China(No.51679063)+2 种基金the Key Program of National Natural Science Foundation of China(No.91647206)the National key Plan for Research and Development of China(No.2016YFC0502203)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(No.51479064)。
文摘Developing an excellent photocatalysis system to remove pesticides from water is an urgent problem in current environment purification field.Herein,a Z-scheme WO_(3)/g-C_(3)N_(4) photocatalyst was prepared by a facile in-situ calcination method,and the photocatalytic activity was investigated for degradation of nitenpyram(NTP)under visible light.The optimal Z-scheme WO_(3)/g-C_(3)N_(4) photocatalyst displayed the highest rate constant(0.036 min-1),which is about 1.7 and 25 times higher than that of pure g-C_(3)N_(4) and WO_(3),respectively.The improvement of photocatalytic performance is attributed to fast transfer of photogene rated carriers in the Z-scheme structure,which are testified by electron spin resonance(ESR)experiments,photocurrent and electrochemical impedance spectra(EIS)measurements.Moreover,the effects of typical water environmental factors on the degradation NTP were systematically studied.And the possible degradation pathways of NTP were deduced by the intermediates detected by highperformance liquid chro matography-mass spectrometry(HPLC-MS).This work will not only contribute to understand the degradation mechanism of pesticides in real water environmental condition,but also promote the development of new technologies for pesticide pollution control as well as environmental remediation.
文摘Experiments were carried out to investigate the influence of TiO2 surface fluorination on the photodegradation of a representative organic cationic compound, Methylene Blue （MB）. The eleetropositive MB shows poor adsorption on TiO2 surface; its degradation performs a HO. radical-mediated mechanism. In the F-modified system, the kinetic reaction rate enlarged more than 2.5 fold that was attributed mainly to the accumulating adsorption of MB and the increased photogenerated hole available on the F-modified TiO2 surface.
基金supported financially by the National Natural Science Foundation of China(Nos.51622106 and 51871049)the Fundamental Research Funds for the Central Universities(No.160708001).
文摘A layer of graphene(GR)particles was successfully deposited at the interface between Co(OH)2 nanoparticles and TiO2 nanotubes,aiming to improve the photoelectrochemical performance of the large-bandgap semiconductor TiO2.The obtained Co(OH)2/GR/TiO2 was extensively characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),UV–vis absorption spectra and photoluminescence(PL)emission spectra.Electrochemical impedance spectra,photogenerated potential-time(E-t),photocurrent density-time(i-t)and i-E curves and open circuit potential(OCP)curves were measured to investigate the photoelectrochemical activities and photogenerated cathodic protection properties.The results revealed that Co(OH)2/GR/TiO2 exhibits excellent photoelectrochemical and photogenerated cathodic performance due to synergistic effect between Co(OH)2 and graphene.Co(OH)2 and graphene co-modified TiO2 photoanode could provide an effective protection for 304 stainless steel(304 SS)in 3.5 wt%Na Cl solution for 12 h,which would be promising for future practical applications in the field of marine corrosion protection.
基金the National Basic Research Development of China(2011CB936003)the National Natural Science Foundation of China(50971116)。
文摘Photocatalytic splitting of water over p-type semiconductors is a promising strategy for production of hydrogen.However,the determination of rate law is rarely reported.To this purpose,copper oxide(CuO)is selected as a model photocathode in this study,and the photogenerated surface charge density,interfacial charge transfer rate constant and their relation to the water reduction rate(in terms of photocurrent)were investigated by a combination of(photo)electrochemical techniques.The results showed that the charge transfer rate constant is exponential-dependent on the surface charge density,and that the photocurrent equals to the product of the charge transfer rate constant and surface charge density.The reaction is first-order in terms of surface charge density.Such an unconventional rate law contrasts with the reports in literature.The charge density-dependent rate constant results from the Fermi level pinning(i.e.,Galvani potential is the main driving force for the reaction)due to accumulation of charge in the surface states and/or Frumkin behavior(i.e.,chemical potential is the main driving force).This study,therefore,may be helpful for further investigation on the mechanism of hydrogen evolution over a CuO photocathode and for designing more efficient CuO-based photocatalysts.
基金the National Natural Science Foundation of China(22127803,22222408,22174110 and 22001193)the Industrial Support Plan of Gansu Provincial Department of Education(2021cyzc-01)+1 种基金the Special Fund Project for Guiding Local Scientific and Technological Development by the Central Government(2020-2060503-17)the Qin Chuangyuan Innovation and Entrepreneurship Talent Project(QCYRCXM-2022-338)。
基金supported by the National Key R&D Program of China(2022YFA1502903,2021YFA1501502)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB0450000,XDB36000000)+4 种基金the National Natural Science Foundation of China(92163105,T2122004,U2032212,22275179,22305058)the Anhui Provincial Key Research and Development Program(2022a05020054)the Fundamental Research Funds for the Central Universities(WK2060000039,WK2060000068)the China Postdoctoral Science Foundation(2023TQ0341,2023M743369)the Postdoctoral Fellowship Program of CPSF(GZB20230706)。
文摘Photocatalytic cycloadditions of CO_(2)with epoxides are emerging as a significant platform for the green synthesis of valuable carbonates,where efficient catalytic systems with spatially separated charge carriers are demanded.Herein,a single p-block metal atom is proposed to be a candidate for photogenerated electron localization on a metal oxide substrate.By taking the Bi single-atom supported on ZnO nanosheet(Bi1/ZnO)as an example,we show that the Bi atom plays the role of an electron island in the sea of delocalized holes within ZnO.Meanwhile,the as-formed electron island could readily promote the rate-determining ring-opening process of cycloaddition reactions.Benefiting from the unique spatially separated electrons and holes,the Bi1/ZnO achieves a high yield of cyclic carbonates with almost 100%selectivity.This study provides a pioneering strategy for enhancing the performances of photocatalytic CO_(2)chemical fixation.
基金supported by the National Natural Science Foundation of China(Nos.22302154,U22A20391,22078256,22202043 and 82202355)Innovation Capability Support Program of Shanxi(No.2023-CX-TD-26)+3 种基金the Programme of Introducing Talents of Discipline to Universities(No.B23025)the“Young Talent Support Plan”of Xi’an Jiaotong University(No.HG6J030)the high-level innovation and entrepreneurship talent project of Qinchuangyuan(No.QCYRCXM-2023-98)the Young and Middle-aged Scholars Project of Fujian Province(No.JAT210368).
文摘Organic conjugated polymers have received extensive attention due to their unique electronic properties.However,there have been relatively few reports on the dark photocatalytic reactions utilizing organic conjugated polymers.Herein,we report the successful synthesis of an organic conjugated polymer based on poly(heptazine imide)nanocrystals(CNNCs)for H_(2)O_(2)evolution and biomedical applications using a simple salt molten method and sonication-centrifugation process.The results show that these colloid CNNCs have the characteristics of photogenerated electrons accumulation and realize dark photocatalysis with high reducibility under visible light irradiation.Notably,these accumulating photogenerated electrons can reduce O_(2)in darkness to produce H_(2)O_(2).In addition,cytotoxicity tests were conducted and it was found that H_(2)O_(2)produced under dark conditions could oxidize L-arginine(L-Arg)to NO,which effectively killed tumors in the dark.This work provides an important strategy to construct organic conjugated semiconductor nanocrystals and applying them to future energy and biomedical fields.
基金This work was supported by National Natural Science Foundation of China （No. 50927201） and the National Basic Research Program of China （Nos. 2009CB939705 and 2009CB939702）. The authors are also grateful to Analytical and Testing Center of Huazhong University of Science and Technology.
文摘The controllability of persistent photoconductance （PPC） and charge/energy storage of ZnO nanorod arrays （NRAs） were demonstrated experimentally by tuning the nanorod diameter. The dependency of the ZnO NRAs＇ photoelectric characteristics on the nanorod diameter suggests that the Debye length and photon penetration depth in ZnO could spatially partition a standalone nanorod into three different photoelectric functional regions （PFRs）. Theoretically, a series of rate functions was employed to describe the different extrinsic/intrinsic carrier photogeneration/recombination dynamic sub-processes occurring in the different PFRs, associated with oxygen chemisorption/photodesorption, oxygen vacancy photoionization, and electron trapping by photoionized oxygen vacancies. On the basis of the coupled contributions of these different dynamic sub-processes in the photoelectric properties of the ZnO NRAs, a thorough-process photoelectric dynamic model （TPDM） was proposed using the simultaneous rate functions. Through solving the rate functions, the corresponding analytical equations could be employed to simulate the time-resolved PPC spectra of the ZnO NRAs, and then the quantitative parameters extracted to decipher the PPC and charge/energy storage mechanisms in the ZnO NRAs. In this way, the TPDM model provided a numerical-analytical method to quantitatively evaluate the photoelectric properties of ZnO NRA-based devices. Additionally, the TPDM model revealed how the different photoinduced carrier dynamics in the different PFRs could play functional roles in different optoelectronic applications, e.g., photodetectors, photocatalysts, solar cells and optical nonvolatile memories, and thus it illuminated a practical approach for the design of ZnO NRA-based devices via optimization of the modularized spatial configuration of the PFRs.
基金supported by the National Natural Science Foundation of China(Grant Nos.52075383 and 61927808).
文摘Microspheres can break the diffraction limit and magnify nano-structure imaging,and with its advantages of low cost and label-free operation,microsphere-assisted imaging has become an irreplaceable tool in the life sciences and for precision measurements.However,the tiny size and limited imaging field of traditional solid microspheres cause difficulties when imaging large sample areas.Alternatively,droplets have similar properties to those of microspheres,with large surface curvature and refractive-index difference from the surrounding environment,and they can also serve as lenses to focus light for observation and imaging.Previous work has shown that droplets with controllable size can be generated using an optical tweezer system and can be driven by optical traps to move precisely like solid microspheres.Here,a novel microdroplet-assisted imaging technology based on optical tweezers is proposed that better integrates the generation,manipulation,and utilization of droplets.
基金supported by the National Natural Science Foundation of China(No.22172068)the Natural Science Foundation of Jiangsu Province(No.BK20221485)+2 种基金the Liaoning Revitalization Talents Program(No.XLYC1902065)the Scientific Research Fund of Liaoning Provincial Department of Education(No.LJKMZ20220747)the Talent Scientific Research Fund of LSHU(No.2016XJJ-012).
文摘Photogenerated charge separation and transfer is one of the bottleneck steps in photocatalysis,and efficient charge separation strategies are strongly desired.Here,mimicking the electron transport chain in natural photosynthesis,we report the design and fabrication of a charge transfer chain using bismuth-based semiconductor as a proof-of-concept.In view of the thermodynamic energy band positions and structural similarity based on the density functional theory(DFT)analysis,heterostructured combination ofα-Bi_(2)O_(3),perovskite-like Bi_(4)Ti_(3)O_(12),and sillenite Bi12TiO20 was designed for fabrication of charge transfer chain.By tuning the molar ratio of Bi and Ti precursors,the Bi_(4)Ti_(3)O_(12)and Bi12TiO20 particles were formed on the surface ofα-Bi_(2)O_(3)by an insitu transformation process,giving rise to Bi_(12)TiO_(20)-Bi_(4)Ti_(3)O_(12)/α-Bi_(2)O_(3)composites with charge transfer chain.We propose that the effective charge transfer is accomplished amongα-Bi_(2)O_(3),Bi12TiO20,and Bi_(4)Ti_(3)O_(12),which significantly improves the photogenerated charge separation and transfer,as indicated by photoluminescene,time-resolved photoluminescene,and electrochemical impedance spectra results.As expected,the Bi_(12)TiO_(20)-Bi_(4)Ti_(3)O_(12)/α-Bi_(2)O_(3)shows the superior photocatalytic activity for the degradation of environmental pollutants with high concentration.Even for the refractory pollutants like 4-chlorophenol,the optimal Bi_(12)TiO_(20)-Bi_(4)Ti_(3)O_(12)/α-Bi_(2)O_(3)composite shows 28 times higher than that ofα-Bi_(2)O_(3)for photocatalytic degradation,verifying the superiority of photogenerated charge transfer chain in photocatalysis.This work demonstrates the feasibility of the charge transfer chain strategy to boost the photogenerated charge separation,which is of great significance for designing energy and environmental-related materials in heterogonous photocatalysis.
基金This work was financially supported by the Natural Science Foundation of China(Nos.51832003 and 52003212)the Fun-damental Research Funds for the Central University(No.WUT 2020III034).
文摘Natural photosynthesis,which provides a green and high-efficiency energy conversion path by spatial separation of photogenerated carriers through combined actions of molecules ingeniously arranged in an efficient solar nanospace,highlights the importance of rational nanostructure design to realize artificial high-efficiency photosystem.Inspired by these unique features,we constructed a high-efficiency ternary photosystem by selectively decorating the{001}facets of 18-facet SrTiO_(3)with Au@CdS photosensitizers via a green photo-assisted method.Benefiting from the dual-facilitated charge carriers transportation in core-shell structured Au@CdS heterojunction and well-faceted 18-facet SrTiO_(3)nanocrystal,such a photo-catalyst could realize the effective spatial separation of photogenerated electrons and holes.As expected,the 18-facet SrTiO_(3)/Au@CdS photocatalyst exhibits superior activity in visible-light-driven photocatalytic hydrogen evolution(4.61 mmol h^(−1)g^(−1)),166%improvement in comparison with randomly deposited Au@CdS(1.73 mmol h^(−1)g^(−1)).This work offers new insight into the development of green and high-efficiency photocatalytic systems based on the rational nanostructure design by crystal facet engineering.
基金the National Natural Science Foundation of China(No.41807213)the Hydrogeo-logical Survey Project of Huangshui River(No.DD20190331).
文摘Water splitting is important to the conversion and storage of renewable energy,but slow kinetics of the oxygen evolution reaction(OER)greatly limits its utility.Here,under visible light illumination,the p-n WO_(3)/SnSe_(2)(WS)heterojunction significantly activates OER catalysis of CoFe-layered double hydroxide(CF)/carbon nanotubes(CNTs).Specifically,the catalyst achieves an overpotential of 224 mV at 10 mA cm^(-2)and a small Tafel slope of 47 mV dec^(-1),superior to RuO_(2)and most previously reported transition metal-based OER catalysts.The p-n WS heterojunction shows strong light absorption to produce photogenerated carriers.The photogenerated holes are trapped by CF to suppresses the charge recombination and facilitate charge transfer,which accelerates OER kinetics and boost the activity for the OER.This work highlights the possibility of using heterojunctions to activate OER catalysis and advances the design of energy-efficient catalysts for water oxidation systems using solar energy.
文摘Heterostructure photocatalysts with a built-in electric field have become one of the most promising strategies to enhance photogenerated electron-hole pair separation. However, close contact between the two active components of heterogeneous photocatalysts remains a problem. Herein, the in-situ fabrication of an SnO2/SnS2 heterostructure photocatalyst was performed;the structure showed enhanced photocatalytic performance resulting from the tight-contact heterostructures. The results of photoelectrochemical measurements further verified that a tight-contact heterostructure improved the separation of photogenerated electron-hole pairs. The results of EIS Bode plots also demonstrated that such in-situ fabricated SnO2/SnS2 samples exhibited the longest carrier lifetime(41.6 μs) owing to the intimate interface of SnO2/SnS2 heterostructures.
基金supported by the National Natural Science Foundation of China(No.21906132)Department of Science and Technology of Sichuan Province(Nos.2020YFG0158 and 2020YFH0162)the Engineering Research Center for the Development of Farmland Ecosystem Service Functions,Sichuan Province Institutions of Higher Education.
文摘H_(2)O_(2)has been widely applied in the fields of chemical synthesis,medical sterilization,pollutant removal,etc.,due to its strong oxidizing property and the avoidable secondary pollution.Despite of the enhanced performance for H_(2)O_(2)generation over g-C_(3)N_(4)semiconductors through promoting the separation of photo-generated charge carriers,the effect of migration orientation of charge carriers is still ambiguous.For this emotion,surface modification of g-C_(3)N_(4)was employed to adjust the migration orientation of charge carriers,in order to investigate systematically its effect on the performance of H_(2)O_(2)generation.It was found that ultrathin g-C_(3)N_(4)(UCN)modified by boron nitride(BN),as an effective hole-attract agent,demonstrated a significantly enhanced performance.Particularly,for the optimum UCN/BN-40%catalyst,4.0-fold higher yield of H_(2)O_(2)was obtained in comparison with the pristine UCN.As comparison,UCN modified by carbon dust demonstrated a completely opposite tendency.The remarkably improved performance over UCN/BN was ascribed to the fact that more photo-generated electrons were remained inside of triazine structure of g-C_(3)N_(4),leading to the formation of larger amount of 1,4-endoxide.It is anticipated that our work could provide new insights for the design of photocatalyst with significantly improved performance for H_(2)O_(2)generation.
基金Project supported by the National Basic Research Program of China(Grant No.2015CB755403)the National Natural Science Foundation of China(Grant Nos.61775160,61771332,61705162,51472251,and U1837202)
文摘The optical-induced dielectric tunability properties of DAST crystal in THz range were experimentally demonstrated.The DAST crystal was grown by the spontaneous nucleation method(SNM) and characterized by infrared spectrum. With the optimum wavelength of the exciting optical field, the transmission spectra of the DAST crystal excited by 532 nm laser under different power were measured by terahertz time-domain spectroscopy(THz-TDS) at room temperature. The transmitted THz intensity reduction of 26 % was obtained at 0.68 THz when the optical field was up to 80 m W. Meanwhile,the variation of refractive index showed an approximate quadratic behavior with the exciting optical field, which was related to the internal space charge field of photorefractive phenomenon in the DAST crystal caused by the photogenerated carrier.A significant enhancement of 13.7 % for THz absorption coefficient occurred at 0.68 THz due to the photogenerated carrier absorption effect in the DAST crystal.
基金Supported by the National Natural Science Foundation of China(Nos.51472005,51772118 and 21607027)the Natural Science Foundation of Anhui Province,China(No.1608085QB37)+3 种基金the Open Project Program of the State Key Laboratory of Photocatalysis on Energy and Environment,Fuzhou University,China(No.SKLPEE-KF201804)the Natural Science Foundation of Educational Conunittee of Anhui Province,China(Nos.KJ2018A0387 and KJ2019A0601)the Project of Aiiliui Province tor Excellent Young Talents in Universities,Cliina(No.gxyq2019029)the Graduate Innovation Foundation of Huaibei Nonnal University,China(No.ycx201901003)。
文摘Z-Schemc photocatalysts as a research locus pertomi strong redox capability and high photocatalytic peribnnance.WO3/KNbO3 photocatalysts were fabricated by ball milling method,and performed higlier photocatalytic activity in liquid degradation(rhodamine B,methylene blue and bisphenol A),compared with WO3 or KNbO3 monomer.This is due to that Z-scheme heterojunction is lonned between WO3 and KNbO3,and the holes photo-excited in valence band of KNbO?are quickly combined with the electrons in conduction band of WO3.The electrons accumulated in conduction band of KNbO3 show high reducibility,thereby reducing O2 to·O 2-,and the holes in valence band of WO3 show high oxidative to oxidize H2O to·OH,respectively.Furthermore,it is proved by means of electron spin resonaiice(ESR)spectra,terephthalic acid photolumiiiescence probing technique(TA・PL),and UV-Vis absorption spectra of nitroblue tetrazolium.This work indicates that the iabrication of Z-scheme structure can improve the photocatalytic activity by efficiently separating the photogenerated electrons and holes in the photocatalytic reaction system,which is helpful to deeply understand the migration mechanism of photoexcited cairier(band-band transfer and Z-scheme transfer)in heterojunction photocatalysts.
基金supported by the National Natural Science Foundation of China(Nos.21771055,U21A2085,and U1604139)the Zhongyuan High Level Talents Special Support Plan(No.204200510010)+1 种基金the Scientific and Technological Innovation Team in University of Henan Province(No.20IRTSTHN001)Science and Technique Foundation of Henan Province(No.222102310544).
文摘Molecular self-assembly is a natured-inspired strategy to integrate individual functional molecules into supramolecular nanostructured materials through noncovalent bond interactions for solar to fuel conversion.However,the design and engineering of the morphology,size,and orderly stacking of supramolecular nanostructures remain a great challenge.In this study,regular porphyrin nanocrystals with different orderly stacked structures are synthesized through noncovalent self-assembly of Pt(II)meso-tetra(4-carboxyphenyl)porphine(PtTCPP),using surfactants with different electronegativity.The synergy of noncovalent bond interactions between porphyrin molecules,and between porphyrin molecules and surfactants resulted in different molecular packing patterns.Due to the spatial ordering of PtTCPP molecules,the different nanocrystals exhibit both collective optical properties and morphology-dependent activities in photocatalytic hydrogen production.The measurements of the photodeposition of dual cocatalysts showed that the photogenerated electrons and holes selectively aggregated at different active sites,revealing separation pathways and directional transfer of photogenerated electrons and holes in the assemblies.This study provides a new strategy to exert rational control over porphyrin self-assembly nanocrystals for highly efficient water splitting.
基金the National Natural Science Foundation of China (Nos. 21901133, 22171155 and 22071126)the State Key Laboratory of Fine Chemicals (No. KF 1905)。
文摘Tuning white-light emission via free radicals is still a challenge in molecular-based functional materials.Herein, a new photoactive Zn^(2+) oxalate-based chain containing a polypyridine ligand was designed and synthesized with remarkably bifunctional photochromism and photo-actuated greenish white-light emission after UV, sunlight or Xe lamp light irradiation at room temperature. The photo-actuated coloration process was induced by the photogeneration of stable radicals originated from intermolecular electron transfers from oxalate components to the protonated polypyridine units, as demonstrated by UV–vis, IR,electron spin resonance and X-ray photoelectron spectra and magnetic measurements. Importantly, the on/off greenish white light emission(WLE) could be reversibly switched by generation and elimination of radicals via light irradiation and heat treatment, providing a feasible strategy for designing photoswitchable light emission diodes materials.
文摘Covalent organic frameworks(COFs)have lately emerged as a blooming class of potential materials for photocatalytic water splitting because of their high crystallinity,huge surface areas,and structural versatility.However,the photocatalytic performance for most pure COFs face some limitations factors,such as the significant recombination of photogenerated carriers and slow charge transfer.Herein,a novel thioether-functionalized pyrene-based COF(S_(4)-COF)was effectively produced and chosen as a support for the immobilization of ultrafine gold nanoparticles(Au NPs).S_(4)-COF photocatalyst with Au as cocatalyst demonstrates remarkable photocatalytic activity with a H_(2) generation rate of 1377μmol g^(−1) h^(−1) under visible light(>420 nm),which is ca.4.5-fold increase comparing to that of pure S_(4)-COF(302μmol g^(−1) h^(−1)).Au NPs anchored on S_(4)-COF possess an ultrafine size distribution ranging from 1.75 to 6.25 nm with an average size centered at 3.8 nm,which benefits from the coordination interaction between thioether groups and Au.Meanwhile,the produced Au@S_(4)-COF can generate a stable photocatalytic H_(2) generation during the four recycles and preserve its crystallinity structure after the stability testing.The Au NPs anchored on the S_(4)-COF photocatalyst can greatly accelerate the separation of photogenerated carriers and increase charge transfer because of the combined function of Au NPs and thioether groups.Such a method can not only prevent the aggregation of Au NPs onto thioether-containing COFs to achieve long-term photostability but also allow uniform dispersion for an ordered structure of photocatalysts.This work provides a rational strategy for designing and preparing COF-based photocatalysts for solar-driven H_(2) production.
