Cu2ZnSn(S,Se)4(CZTSSe)solar cells have resource distribution and economic advantages.The main cause of their low efficiency is carrier loss resulting from recombination of photo-generated electron and hole.To overcome...Cu2ZnSn(S,Se)4(CZTSSe)solar cells have resource distribution and economic advantages.The main cause of their low efficiency is carrier loss resulting from recombination of photo-generated electron and hole.To overcome this,it is important to understand their electron-hole behavior characteristics.To determine the carrier separation characteristics,we measured the surface potential and the local current in terms of the absorber depth.The elemental variation in the intragrains(IGs)and at the grain boundaries(GBs)caused a band edge shift and bandgap(Eg)change.At the absorber surface and subsurface,an upward Ec and Ev band bending structure was observed at the GBs,and the carrier separation was improved.At the absorber center,both upward Ec and Ev and downward Ec-upward Ev band bending structures were observed at the GBs,and the carrier separation was degraded.To improve the carrier separation and suppress carrier recombination,an upward Ec and Ev band bending structure at the GBs is desirable.展开更多
Carrier separation in a solar cell usually relies on the p–n junction. Here we show that an n–n type inorganic semiconductor heterojunction is also able to separate the exciton for efficient solar cell applications....Carrier separation in a solar cell usually relies on the p–n junction. Here we show that an n–n type inorganic semiconductor heterojunction is also able to separate the exciton for efficient solar cell applications. The n–n type heterojunction was formed by hydrothermal deposition of Sb_(2)(S,Se)_(3) and thermal evaporation of Sb_(2)Se_(3). We found that the n–n junction is able to enhance the carrier separation by the formation of an electric field, reduce the interfacial recombination and generate optimized band alignment. The device based on this n–n junction shows 2.89% net efficiency improvement to 7.75%when compared with the device consisted of semiconductor absorber–metal contact. The study in the n–n type solar cell is expected to bring about more versatile materials utility, new interfacial engineering strategy and fundamental findings in the photovoltaic energy conversion process.展开更多
The increase in occurrence and severity of cyanobacteria blooms is causing increasing concern;moreover,human and animal health is affected by the toxic effects of Microcystin-LR released into the water.In this paper,a...The increase in occurrence and severity of cyanobacteria blooms is causing increasing concern;moreover,human and animal health is affected by the toxic effects of Microcystin-LR released into the water.In this paper,a floating photocatalyst for the photocatalytic inactivation of the harmful algae Microcystis aeruginosa(M.aeruginosa)was prepared using a simple sol-gel method,i.e.,coating g-C_(3)N_(4) coupled with Bi-doped TiO_(2) on Al_(2)O_(3)-modified expanded perlite(CBTA for short).The impact of different molar ratios of Bi/Ti on CBTA was considered.The results indicated that Bi doping in TiO_(2) inhibited photogenerated electron-hole pair recombination.With 6 h of visible light illumination,75.9%of M.aeruginosa(initial concentration=2.7106 cells/L)and 83.7%of Microcystin-LR(initial concentration=100μg/L)could be removed with the addition of 2 g/L CBTA1%(i.e.,Bi/Ti molar ratio=1%).The key reactive oxygen species(ROSs)in the photocatalytic inactivation process are h+andOH.The induction of the Bi^(4+)/Bi^(3+)species by the incorporation of Bi could narrow the bandgap of TiO_(2),trap electrons,and enhance the stability of CBTA-1%in the solutions with coexisting environmental substances.展开更多
In this paper, CuO/TiO_(2) p-n heterojunction was developed as a new surface enhanced Raman scattering(SERS) substrate to magnify Raman signal of 4-mercaptobenzoic acid(4-MBA) molecule. In the heterojunction-molecule ...In this paper, CuO/TiO_(2) p-n heterojunction was developed as a new surface enhanced Raman scattering(SERS) substrate to magnify Raman signal of 4-mercaptobenzoic acid(4-MBA) molecule. In the heterojunction-molecule system, CuO as an “electron capsule” can not only offer more electrons to inject into the surface state energy level of TiO_(2) and consequently bring additional charge transfer, but also improve photogenerated carrier separation efficiency itself due to strong interfacial coupling in the interface of heterojunction, which together boost SERS performance of the heterojunction substrate. As expected,owing to the enhanced charge collection capacity and the improvement of photogenerated carrier separation efficiency derived from internal electric field and strong interface coupling provided in the interface of heterojunction, this substrate exhibits excellent SERS detection sensitivity towards 4-MBA, with a detection limit as low as 1 × 10^(-10)mol/L and an enhancement factor of 8.87 × 10~6.展开更多
We investigate the tunnel coupling between the outer p-type GaAsSb shell and the n-type InAs core in catalyst-free InAs/lnP/GaAsSb core-dualshell nanowires.We present a device fabrication protocol based on wet-etching...We investigate the tunnel coupling between the outer p-type GaAsSb shell and the n-type InAs core in catalyst-free InAs/lnP/GaAsSb core-dualshell nanowires.We present a device fabrication protocol based on wet-etching processes on selected areas of the nanostructures that enables multiple configurations of measurements in the same nanowire-based device(i.e.shell-shell,core-core and core-shell).Low-temperature(4.2 K)transport in the shell-shell configuration in nanowires with 5 nm-thick InP barrier reveals a weak negative differential resistance.Differently,when the InP barrier thickness is increased to 10 nm,this negative differential resistance is fully quenched.The electrical resistance between the InAs core and the GaAsSb shell,measured in core-shell configuration,is significantly higher with respect to the resistance of the InAs core and of the GaAsSb shell.The field effect,applied via a back-gate,has an opposite impact on the electrical transport in the core and in the shell portions.Our results show that electron and hole free carriers populate the InAs and GaAsSb regions respectively and indicate InAs/InP/GaAsSb core-dualshell nanowires as an ideal system for the investigation of the physics of interacting electrons and holes at the nanoscale.展开更多
Three dispersion compensation schemes of an optical label switching transmission system were investigated, which employs 40 Gbit/s return zero differential phase-shift keying(RZ-DPSK) payload labeled with 2.5 Gbit/s...Three dispersion compensation schemes of an optical label switching transmission system were investigated, which employs 40 Gbit/s return zero differential phase-shift keying(RZ-DPSK) payload labeled with 2.5 Gbit/s on-off keying(OOK) signal based on the optical carrier suppression and separation(OCSS) techniq ue, In the system, proposed are the receiver sensi ti vity oS payload and label, achieving -- 32. 4 dBm and --38.5 dBm, respectively. Using the optimal dispersion compensation scheme, after transmitted over 160 km and 320 km SMF respectively, the label can be recovered without power penalty, while the payload can be recovered with less than 2 dB and 5 dB penalty, respectively.展开更多
Hydrogen peroxide(H_(2)O_(2))has gained widespread attention as a versatile oxidant and a mild disin-fectant.Here,an electrostatic self-assembly method is applied to couple ZnSe quantum dots(QDs)with a flower-like cov...Hydrogen peroxide(H_(2)O_(2))has gained widespread attention as a versatile oxidant and a mild disin-fectant.Here,an electrostatic self-assembly method is applied to couple ZnSe quantum dots(QDs)with a flower-like covalent organic framework(COF)to form a step-scheme(S-scheme)photocata-lyst for H_(2)O_(2)production.The as-prepared S-scheme photocatalyst exhibits a broad light absorption range with an edge at 810 nm owing to the synergistic effect between the ZnSe QDs and COF.The S-scheme charge-carrier transfer mechanism is validated by performing Fermi level calculations and in-situ X-ray photoelectron and femtosecond transient absorption spectroscopies.Photolumi-nescence,time-resolved photoluminescence,photocurrent response,electrochemical impedance spectroscopy,and electron paramagnetic resonance results show that the S-scheme heterojunction not only promotes charge carrier separation but also boosts the redox ability,resulting in enhanced photocatalytic performance.Remarkably,a 10%-ZnSe QD/COF has excellent photocatalytic H_(2)O_(2)-production activity,and the optimal S-scheme composite with ethanol as the hole scavenger yields a H_(2)O_(2)-production rate of 1895 mol g^(-1)h^(-1).This study presents an example of a high-performance organic/inorganic S-scheme photocatalyst for H_(2)O_(2)production.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
The synthesis of oxygen vacancies(OVs)-modified TiO_(2)under mild conditions is attractive.In this work,OVs were easily introduced in TiO_(2)lattice during the hydrothermal doping process of trivalent iron ions.Theore...The synthesis of oxygen vacancies(OVs)-modified TiO_(2)under mild conditions is attractive.In this work,OVs were easily introduced in TiO_(2)lattice during the hydrothermal doping process of trivalent iron ions.Theoretical calculations based on a novel charge-compensation structure model were employed with experimental methods to reveal the intrinsic photocatalytic mechanism of Fe-doped TiO_(2)(Fe-TiO_(2)).The OVs formation energy in Fe-TiO_(2)(1.12 eV)was only 23.6%of that in TiO_(2)(4.74 eV),explaining why Fe^(3+)doping could introduce OVs in the TiO_(2)lattice.The calculation results also indicated that impurity states introduced by Fe^(3+)and OVs enhanced the light absorption activity of TiO_(2).Additionally,charge carrier transport was investigated through the carrier lifetime and relative mass.The carrier lifetime of Fe-TiO_(2)(4.00,4.10,and 3.34 ns for 1at%,2at%,and 3at%doping contents,respectively)was longer than that of undoped TiO_(2)(3.22 ns),indicating that Fe^(3+) and OVs could promote charge carrier separation,which can be attributed to the larger relative effective mass of electrons and holes.Herein,Fe-TiO_(2)has higher photocatalytic indoor NO removal activity compared with other photocatalysts because it has strong light absorption activity and high carrier separation efficiency.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
In recent years, the preservation of fruits and vegetables in cold storage has become an issue of increasing concern, ethylene plays a leading role among them. We found ZnO has the effect of degrading gaseous ethylene...In recent years, the preservation of fruits and vegetables in cold storage has become an issue of increasing concern, ethylene plays a leading role among them. We found ZnO has the effect of degrading gaseous ethylene, however its effect is not particularly satisfactory. Therefore, we used simple photo-deposition procedure and low-temperature calcination method to synthesize Au, Ag, and Au Ag alloy supported ZnO to improve the photocatalytic efficiency. Satisfactorily, after ZnO loaded with sole Au or Ag particles, the efficiency of ethylene degradation was 17.5 and 26.8 times than that of pure ZnO, showing a large increase in photocatalytic activity. However, the photocatalytic stability of Ag/ZnO was very poor, because Ag can be easily photooxidized to Ag2O. Surprisingly, when ZnO was successfully loaded with the Au Ag alloy, not only the photocatalytic activity was further improved to 94.8 times than that of pure ZnO, but also the photocatalytic stability was very good after 10 times of cycles. Characterization results explained that the Au-Ag alloy NPs modified ZnO showed great visible-light absorption because of the surface plasmon resonance(SPR) effect. Meanwhile, the higher photocurrent density showed the effective carrier separation ability in Au Ag/ZnO. Therefore, the cooperative action of plasmonic Au Ag bimetallic alloy NPs and efficient carrier separation capability result in the outstanding photoactivity of ethylene oxidation. At the same time, the formation of the alloy produced a new crystal structure different from Au and Ag, which overcomes the problem of poor stability of Ag/ZnO, and finally obtains Au Ag/ZnO photocatalyst with high activity and high stability. This work proposes a new concept of using metal alloys to remove ethylene in actual production.展开更多
In this study,CuBi2O4 photocathodes were prepared using a simple electrodeposition method for photoelectrochemical(PEC)hydrogen production.The prepared photocathodes were modified with amorphous TiO2 and a Pt co‐cata...In this study,CuBi2O4 photocathodes were prepared using a simple electrodeposition method for photoelectrochemical(PEC)hydrogen production.The prepared photocathodes were modified with amorphous TiO2 and a Pt co‐catalyst,which resulted in the formation of CuBi2O4/TiO2 p‐n heterojunctions,and enhanced the activities of the as‐prepared photocathodes.The novel Pt/TiO2/CuBi2O4 photocathode exhibited a photocurrent of 0.35 mA/cm2 at 0.60 V vs.Reversible Hydrogen Electrode(RHE),which was nearly twice that of the Pt/CuBi2O4 photocathode.The present study provides a facile method for increasing the efficiency of photocathodes and provides meaningful guidance for the preparation of high‐performance CuBi2O4 photocathodes.展开更多
Structure manipulation of photocatalysts at an atomic scale is a promising way to improve its photocatalytic performance.Herein,we realize the anchoring of single Ni atoms on the ZnIn_(2)S_(4) nanosheets with rich sul...Structure manipulation of photocatalysts at an atomic scale is a promising way to improve its photocatalytic performance.Herein,we realize the anchoring of single Ni atoms on the ZnIn_(2)S_(4) nanosheets with rich sulfur vacancies.Experimental results demonstrate that single Ni atoms induce the formation of NiO-M(Zn/In) atomic interface,which can efficiently promote the carriers separation and prolong the carrier life time.In addition,in situ electron spin resonance spectroscopy(ESR) confirms that the single Ni atoms act as an electron trapping center for protons reduction.As a result,the single Ni atoms decorated ZnIn_(2)S_(4) nanosheets with rich sulfur vacancies(Ni/ZnIn_(2)S_(4)-RVs) shows a hydrogen evolution rate up to 89.4 μmol h^(-1), almost 5.7 and 2.3 times higher compared to that of ZnIn_(2)S_(4) nanosheets with poor sulfur vacancies and rich sulfur vacancies(denoted as ZnIn_(2)S_(4)-PVs and ZnIn_(2)S_(4)-RVs).This work opens up a new perspective manipulating the single-atom cocatalyst and sulfur vacancy on sulfide supports for improving photocatalytic hydrogen evolution.展开更多
Photosynthesis with the chloroplast works efficiently because of the envelope structure that serves to carry enzymes and to simultaneously maintain the spatial separation of photosynthesis and cellular respiration.Ins...Photosynthesis with the chloroplast works efficiently because of the envelope structure that serves to carry enzymes and to simultaneously maintain the spatial separation of photosynthesis and cellular respiration.Inspired by the spatially separated architecture,a chloroplast-like structured photocatalyst(PdS@CdS@MoS_(2)),in which the PdS and MoS_(2) function as enzymes in the chloroplast and CdS shell functions as the chloroplast envelope,was developed to improve the photocatalytic H_(2) evolution.In this unique nanoscale bionic structure,the poriferous CdS shell enhances light absorption,generates photoinduced carriers,and separates oxidation and reduction reactions.Meanwhile,PdS and MoS_(2) dual cocatalysts enhance the charge separation efficiency through forming a built-in electric field with CdS.We demonstrate that the separation efficiency of carriers,carrier lifetime,and the yield of H_(2) are both higher than that of CdS nanoparticles,evidencing the feasibility of the chloroplast-like structure in enhancing the photocatalyst activity.This work emphasizes the synergism of the three key processes of the photocatalytic reaction by simulating the chloroplast structure and provides a general synthesis strategy,the synthesis of novel structured for photocatalysts for diverse applications in the energy field.展开更多
The rational fabrication of heterostructures is one of efficient strategies for improving photocatalytic performance of semiconductor photocatalysts.Very recently,Domen and co-workers found that Ta_(3)N_(5) single cry...The rational fabrication of heterostructures is one of efficient strategies for improving photocatalytic performance of semiconductor photocatalysts.Very recently,Domen and co-workers found that Ta_(3)N_(5) single crystals grown on the surface of KTaO_(3) can accomplish photocatalytic overall water splitting for the first time.In order to comprehend the underlying mechanism of this photocatalytic system,we have performed a systematic study based on density functional theory first-principles calculations.Ta_(3)N_(5)(010)/KTaO_(3)(110)slab models have been built according to experimental observations by considering two common terminations of KTaO_(3)(110)surface,named as Ta_(3)N_(5)/O_(2) and Ta_(3)N_(5)/KTaO.The formations of interfacial bonds are thermodynamically stable,showing a covalent interaction between two components of a heterostructure.Ta_(3)N_(5)/O_(2) has a higher mobility of photogenerated charge carriers and lower recombination rate of charge carriers than Ta_(3)N_(5)/KTaO.The light absorption of heterostructures displays the feature of KTaO_(3) in the short wavelength region and the characteristic of Ta_(3)N_(5) in the long wavelength region.The calculated band offsets show that Ta_(3)N_(5)/O_(2) and Ta_(3)N_(5)/KTaO have distinct Type-II band alignments,with Ta_(3)N_(5) as the accumulator of photoinduced electrons in the former and the collector of photogenerated holes in the latter,respectively.The difference in charge density and electrostatic potential between two components acts as a driving force to promote the transfer of electrons and holes to different domains of the interface,which is beneficial to extend the lifetime of photoinduced carriers.Our results demonstrate that the function of Ta_(3)N_(5) in Ta_(3)N_(5)/KTaO_(3) photocatalytic system is determined by the termination property of KTaO_(3)(110)surface,which provides a likely reason of the observed photocatalytic activity of overall water splitting achieved by Ta_(3)N_(5) synthesized by using KTaO_(3) as a precursor for the nitridation reaction.展开更多
Lead halide perovskites MAPbX_(3)(MA = CH_(3)NH_(3) or Cs;X = I, Br, Cl) are well considered to be potential candidates for photocatalytic reaction due to its excellent photoelectrical properties, but they still suffe...Lead halide perovskites MAPbX_(3)(MA = CH_(3)NH_(3) or Cs;X = I, Br, Cl) are well considered to be potential candidates for photocatalytic reaction due to its excellent photoelectrical properties, but they still suffer from the low charge separation efficiency and slow catalytic reaction dynamics. To tackle the drawbacks, herein, MAPbBr_(3)/carbon sphere(CS) composite photocatalysts using glucose as the carbon source were elaborately designed and fabricated via a dry mechanochemical grinding process. The interfacial interaction Pb-O-C chemical bonds were constructed between MAPbBr_(3) and the carbon sphere surface containing organic functional groups. By optimizing the content of CSs, the enhanced photocatalytic degradation kinetic rate of Malachite Green(MG) pollutants(92% within 20 min) for MAPbBr_(3)/CS x( x = 17 wt.%) is about 3.6-fold of that for pristine MAPbBr_(3), which is attributed to the corporative adsorption and enhanced carrier transportation and separation of MAPbBr_(3)/CS x. Furthermore, the possible degradation mechanism was proposed on basis of the electrochemical, mass spectrometry and optical characterization results. Owing to the robust interfacial interaction, effective electron extraction rate( k et = 4.6 × 10^(7) sec^(-1)) from MAPbBr_(3) to CS can be established, which driven oxygen activation where superoxide radicals(·O^(2-)) played an important role in MG degradation. It is expected that mechanochemistry strategy may provide a new route to design efficient lead halide perovskite-carbon or metal oxide or sulfide composite photocatalysts.展开更多
Photocatalytic reduction of CO_(2)has attracted considerable interest owing to its potential to resolve the energy and environmental problems.Nevertheless,the lack of proficient photocatalysts has restricted the appli...Photocatalytic reduction of CO_(2)has attracted considerable interest owing to its potential to resolve the energy and environmental problems.Nevertheless,the lack of proficient photocatalysts has restricted the application of solar-driven photocatalytic CO_(2)reduction.Herein,we reported an S-scheme heterojunction by combining g-C_(3)N_(4)with La^(3+)and Rh^(3+)co-doped SrTiO_(3)through the electrostatic self-assembly method for the efficient photocatalytic CO_(2)reduction.In comparison with g-C_(3)N_(4),the asprepared CN/LRSTO-30 wt%S-scheme heterojunction not only possesses a broadened visible-light response due to the defect states in La,Rh co-doped SrTiO_(3)induced by codoped La^(3+)and Rh^(3+)but also has more adsorption sites for the capture and activation of CO_(2)molecules.Additionally,separation and transfer efficiency of the photoinduced charge carriers is much enhanced in the CN/LRSTO-30wt%S-scheme heterojunction via its robust internal electric field,which is firmly demonstrated by in situ irradiation X-ray photoelectron spectroscopy technology.Consequently,the prepared S-scheme heterojunction achieves impressive photocatalytic CO_(2)reduction performance with an average CO and CH4 evolution rate of4.1-1.8μmol·g^(-1)·h^(-1),respectively,which are~1.9 and~22.5-fold higher than those of pure g-C_(3)N_(4).This study provides innovative perspectives on the design of creative S-scheme heterojunctions for applications in photocatalytic CO_(2)reduction.展开更多
Phase separations have been studied for graded-indium content In_xGa_(1-x)N/GaN multiple quantum wells(MQWs) with different indium contents by means of photoluminescence(PL),cathodeluminescence(CL) and time-re...Phase separations have been studied for graded-indium content In_xGa_(1-x)N/GaN multiple quantum wells(MQWs) with different indium contents by means of photoluminescence(PL),cathodeluminescence(CL) and time-resolved PL(TRPL) techniques.Besides the main emission peaks,all samples show another 2 peaks at the high and low energy parts of the main peaks in PL when excited at 10 K.CL images show a clear contrast for 3 samples,which indicates an increasing phase separation with increasing indium content.TRPL spectra at 15 K of the main emissions show an increasing delay of rising time with indium content,which means a carrier transferring from low indium content structures to high indium content structures.展开更多
S-scheme possesses superior redox capabilities compared with the II-scheme,providing an effective method to solve the innate defects of g-C_(3)N_(4)(CN).In this study,S-doped g-C_(3)N_(4)/g-C_(3)N_(4)(SCN-tm/CN)S-sche...S-scheme possesses superior redox capabilities compared with the II-scheme,providing an effective method to solve the innate defects of g-C_(3)N_(4)(CN).In this study,S-doped g-C_(3)N_(4)/g-C_(3)N_(4)(SCN-tm/CN)S-scheme homojunction was constructed by rationally integrating morphology control with interfacial engineering to enhance the photocatalytic hydrogen evolution performance.In-situ Kelvin probe force microscopy(KPFM)confirms the transport of photo-generated electrons from CN to SCN.Density functional theory(DFT)calculations reveal that the generation of a built-in electric field between SCN and CN enables the carrier separation to be more efficient and effective.Femtosecond transient absorption spectrum(fs-TAS)indicates prolonged lifetimes of SCN-tm/CN_(3)(τ1:9.7,τ2:110,andτ3:1343.5 ps)in comparison to those of CN(τ1:4.86,τ2:55.2,andτ3:927 ps),signifying that the construction of homojunction promotes the separation and transport of electron hole pairs,thus favoring the photocatalytic process.Under visible light irradiation,the optimized SCN-tm/CN_(3)exhibits excellent photocatalytic activity with the hydrogen evolution rate of 5407.3μmol·g^(−1)·h^(−1),which is 20.4 times higher than that of CN(265.7μmol·g^(−1)·h^(−1)).Moreover,the homojunction also displays an apparent quantum efficiency of 26.8%at 435 nm as well as ultra-long and ultra-stable cycle ability.This work offers a new strategy to construct highly efficient photocatalysts based on the metal-free conjugated polymeric CN for realizing solar energy conversion.展开更多
Effective separation of photogenerated carriers plays a vital role in governing the efficiency of photo-electrocatalytic reactions.However,the advancement in enhancing the intrinsic carrier separation efficiency of se...Effective separation of photogenerated carriers plays a vital role in governing the efficiency of photo-electrocatalytic reactions.However,the advancement in enhancing the intrinsic carrier separation efficiency of semiconductors has shown limited progress.Herein,we reported the use of a magnetic field to improve the photoelectrochemical water splitting of a magnetic Co_(3)O_(4)/TiO_(2)photoanode by boosting the photogenerated carrier separation efficiency.In the presence of the magnetic field,oxygen evolution reaction occurs with a high photocurrent density of 0.86 mA cm^(−2)at 1.23 V versus VRHE,and an applied bias photon-to-current efficiency of 0.342%at 0.61 VRHE.Moreover,the photoanode maintains its oxygen evolution reaction for more than 400 h with photocurrent decays by ca.10%.Observations made in this effort show that the enhancement of photo-electrocatalytic efficiency by a magnetic field is a consequence of the effect of the Lorentz force generated by the magnetic field on photogenerated carriers and ions near the Co_(3)O_(4)/TiO_(2)photoanode,which improves the carrier separation efficiency and the bubble release rate.The results suggest that manipulating photoelectrode carriers by using a magnetic field is a promising strategy to design high-performance photoelectrochemical for water splitting.展开更多
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Ministry of Science and ICT(No.2022M3J1A1085371)by the DGIST R&D programs of the Ministry of Science and ICT(23-ET-08 and 23-CoE-ET-01)supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2018R1A6A1A03025340).
文摘Cu2ZnSn(S,Se)4(CZTSSe)solar cells have resource distribution and economic advantages.The main cause of their low efficiency is carrier loss resulting from recombination of photo-generated electron and hole.To overcome this,it is important to understand their electron-hole behavior characteristics.To determine the carrier separation characteristics,we measured the surface potential and the local current in terms of the absorber depth.The elemental variation in the intragrains(IGs)and at the grain boundaries(GBs)caused a band edge shift and bandgap(Eg)change.At the absorber surface and subsurface,an upward Ec and Ev band bending structure was observed at the GBs,and the carrier separation was improved.At the absorber center,both upward Ec and Ev and downward Ec-upward Ev band bending structures were observed at the GBs,and the carrier separation was degraded.To improve the carrier separation and suppress carrier recombination,an upward Ec and Ev band bending structure at the GBs is desirable.
基金Project supported by Institute of Energy, Hefei Comprehensive National Science Center (Grant No. 21KZS212)the National Key Research and Development Program of China (Grant No. 2019YFA0405600)+2 种基金the National Natural Science Foundation of China (Grant Nos. U19A2092 and 22005293)the China Postdoctoral Science Foundation (Grant No. 2021M693045)Collaborative Innovation Program of Hefei Science Center, Chinese Academy of Sciences。
文摘Carrier separation in a solar cell usually relies on the p–n junction. Here we show that an n–n type inorganic semiconductor heterojunction is also able to separate the exciton for efficient solar cell applications. The n–n type heterojunction was formed by hydrothermal deposition of Sb_(2)(S,Se)_(3) and thermal evaporation of Sb_(2)Se_(3). We found that the n–n junction is able to enhance the carrier separation by the formation of an electric field, reduce the interfacial recombination and generate optimized band alignment. The device based on this n–n junction shows 2.89% net efficiency improvement to 7.75%when compared with the device consisted of semiconductor absorber–metal contact. The study in the n–n type solar cell is expected to bring about more versatile materials utility, new interfacial engineering strategy and fundamental findings in the photovoltaic energy conversion process.
基金the support of this research by the National Natural Science Foundation of China(Grant Nos.22008057 and 51909165)financially supported by the PhD.Scientific Research Starting Foundation of Henan Normal University(No.5101219170135)ostdoctoral Research Foundation of Henan Normal University(No.5101219470222).
文摘The increase in occurrence and severity of cyanobacteria blooms is causing increasing concern;moreover,human and animal health is affected by the toxic effects of Microcystin-LR released into the water.In this paper,a floating photocatalyst for the photocatalytic inactivation of the harmful algae Microcystis aeruginosa(M.aeruginosa)was prepared using a simple sol-gel method,i.e.,coating g-C_(3)N_(4) coupled with Bi-doped TiO_(2) on Al_(2)O_(3)-modified expanded perlite(CBTA for short).The impact of different molar ratios of Bi/Ti on CBTA was considered.The results indicated that Bi doping in TiO_(2) inhibited photogenerated electron-hole pair recombination.With 6 h of visible light illumination,75.9%of M.aeruginosa(initial concentration=2.7106 cells/L)and 83.7%of Microcystin-LR(initial concentration=100μg/L)could be removed with the addition of 2 g/L CBTA1%(i.e.,Bi/Ti molar ratio=1%).The key reactive oxygen species(ROSs)in the photocatalytic inactivation process are h+andOH.The induction of the Bi^(4+)/Bi^(3+)species by the incorporation of Bi could narrow the bandgap of TiO_(2),trap electrons,and enhance the stability of CBTA-1%in the solutions with coexisting environmental substances.
基金supported by National Natural Science Foundation of China (Nos. 21804054, 21773080)Natural Science Foundation of Heilongjiang Province of China for Distinguished Young Scholars (No. JQ2019B002)+1 种基金Excellent Discipline Team Project of Jiamusi University (No. JDXKTD-2019007)Open Project of State Key Laboratory of Supramolecular Structure and Materials (No. sklssm2021026)。
文摘In this paper, CuO/TiO_(2) p-n heterojunction was developed as a new surface enhanced Raman scattering(SERS) substrate to magnify Raman signal of 4-mercaptobenzoic acid(4-MBA) molecule. In the heterojunction-molecule system, CuO as an “electron capsule” can not only offer more electrons to inject into the surface state energy level of TiO_(2) and consequently bring additional charge transfer, but also improve photogenerated carrier separation efficiency itself due to strong interfacial coupling in the interface of heterojunction, which together boost SERS performance of the heterojunction substrate. As expected,owing to the enhanced charge collection capacity and the improvement of photogenerated carrier separation efficiency derived from internal electric field and strong interface coupling provided in the interface of heterojunction, this substrate exhibits excellent SERS detection sensitivity towards 4-MBA, with a detection limit as low as 1 × 10^(-10)mol/L and an enhancement factor of 8.87 × 10~6.
基金This research activity was partially supported by the SUPERTOP project,QUANTERA ERA-NET Cofound in Quantum Technologies,and by the FET-OPEN project AndQC.
文摘We investigate the tunnel coupling between the outer p-type GaAsSb shell and the n-type InAs core in catalyst-free InAs/lnP/GaAsSb core-dualshell nanowires.We present a device fabrication protocol based on wet-etching processes on selected areas of the nanostructures that enables multiple configurations of measurements in the same nanowire-based device(i.e.shell-shell,core-core and core-shell).Low-temperature(4.2 K)transport in the shell-shell configuration in nanowires with 5 nm-thick InP barrier reveals a weak negative differential resistance.Differently,when the InP barrier thickness is increased to 10 nm,this negative differential resistance is fully quenched.The electrical resistance between the InAs core and the GaAsSb shell,measured in core-shell configuration,is significantly higher with respect to the resistance of the InAs core and of the GaAsSb shell.The field effect,applied via a back-gate,has an opposite impact on the electrical transport in the core and in the shell portions.Our results show that electron and hole free carriers populate the InAs and GaAsSb regions respectively and indicate InAs/InP/GaAsSb core-dualshell nanowires as an ideal system for the investigation of the physics of interacting electrons and holes at the nanoscale.
基金National Natural Science Foundation of China(60677004)National High Technology"863"Research and Development Program of China(2007AA01Z260)+4 种基金Key Project of Chinese Ministry of Education(107011)Key Laboratory of Broadband Optical Fiber Transmission and Communication Networks(Ministry of Education)Teaching and Scientific Research Foundation for the Returned Overseas Chinese Scholars(State Education Ministry)the Corporative Building Project of Beijing Educational Committee(XK100130737)Program for New Century Excellent Talents in University of China( NECT-07-0111)
文摘Three dispersion compensation schemes of an optical label switching transmission system were investigated, which employs 40 Gbit/s return zero differential phase-shift keying(RZ-DPSK) payload labeled with 2.5 Gbit/s on-off keying(OOK) signal based on the optical carrier suppression and separation(OCSS) techniq ue, In the system, proposed are the receiver sensi ti vity oS payload and label, achieving -- 32. 4 dBm and --38.5 dBm, respectively. Using the optimal dispersion compensation scheme, after transmitted over 160 km and 320 km SMF respectively, the label can be recovered without power penalty, while the payload can be recovered with less than 2 dB and 5 dB penalty, respectively.
文摘Hydrogen peroxide(H_(2)O_(2))has gained widespread attention as a versatile oxidant and a mild disin-fectant.Here,an electrostatic self-assembly method is applied to couple ZnSe quantum dots(QDs)with a flower-like covalent organic framework(COF)to form a step-scheme(S-scheme)photocata-lyst for H_(2)O_(2)production.The as-prepared S-scheme photocatalyst exhibits a broad light absorption range with an edge at 810 nm owing to the synergistic effect between the ZnSe QDs and COF.The S-scheme charge-carrier transfer mechanism is validated by performing Fermi level calculations and in-situ X-ray photoelectron and femtosecond transient absorption spectroscopies.Photolumi-nescence,time-resolved photoluminescence,photocurrent response,electrochemical impedance spectroscopy,and electron paramagnetic resonance results show that the S-scheme heterojunction not only promotes charge carrier separation but also boosts the redox ability,resulting in enhanced photocatalytic performance.Remarkably,a 10%-ZnSe QD/COF has excellent photocatalytic H_(2)O_(2)-production activity,and the optimal S-scheme composite with ethanol as the hole scavenger yields a H_(2)O_(2)-production rate of 1895 mol g^(-1)h^(-1).This study presents an example of a high-performance organic/inorganic S-scheme photocatalyst for H_(2)O_(2)production.
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 BJAST High-level Innovation Team Program (No.BGS202001)the Beijing Postdoctoral Research Foundation (No.2022-ZZ-046)+3 种基金the National Natural and Science Foundation of China (No.51972026)the Japan Society for the Promotion of Science (JSPS)Grant-in-Aid for the Scientific Research (KAKENHI,Nos.16H06439 and 20H00297)the Dynamic Alliance for Open Innovations Bridging Human,Environment and Materials,the Cooperative Research Program of“Network Joint Research Center for Materials and Devices.”the scholarship granted to a visiting Ph.D.student of the Inter-University Exchange Project by the China Scholarship Council (CSC,No.201906460113)。
文摘The synthesis of oxygen vacancies(OVs)-modified TiO_(2)under mild conditions is attractive.In this work,OVs were easily introduced in TiO_(2)lattice during the hydrothermal doping process of trivalent iron ions.Theoretical calculations based on a novel charge-compensation structure model were employed with experimental methods to reveal the intrinsic photocatalytic mechanism of Fe-doped TiO_(2)(Fe-TiO_(2)).The OVs formation energy in Fe-TiO_(2)(1.12 eV)was only 23.6%of that in TiO_(2)(4.74 eV),explaining why Fe^(3+)doping could introduce OVs in the TiO_(2)lattice.The calculation results also indicated that impurity states introduced by Fe^(3+)and OVs enhanced the light absorption activity of TiO_(2).Additionally,charge carrier transport was investigated through the carrier lifetime and relative mass.The carrier lifetime of Fe-TiO_(2)(4.00,4.10,and 3.34 ns for 1at%,2at%,and 3at%doping contents,respectively)was longer than that of undoped TiO_(2)(3.22 ns),indicating that Fe^(3+) and OVs could promote charge carrier separation,which can be attributed to the larger relative effective mass of electrons and holes.Herein,Fe-TiO_(2)has higher photocatalytic indoor NO removal activity compared with other photocatalysts because it has strong light absorption activity and high carrier separation efficiency.
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.
文摘In recent years, the preservation of fruits and vegetables in cold storage has become an issue of increasing concern, ethylene plays a leading role among them. We found ZnO has the effect of degrading gaseous ethylene, however its effect is not particularly satisfactory. Therefore, we used simple photo-deposition procedure and low-temperature calcination method to synthesize Au, Ag, and Au Ag alloy supported ZnO to improve the photocatalytic efficiency. Satisfactorily, after ZnO loaded with sole Au or Ag particles, the efficiency of ethylene degradation was 17.5 and 26.8 times than that of pure ZnO, showing a large increase in photocatalytic activity. However, the photocatalytic stability of Ag/ZnO was very poor, because Ag can be easily photooxidized to Ag2O. Surprisingly, when ZnO was successfully loaded with the Au Ag alloy, not only the photocatalytic activity was further improved to 94.8 times than that of pure ZnO, but also the photocatalytic stability was very good after 10 times of cycles. Characterization results explained that the Au-Ag alloy NPs modified ZnO showed great visible-light absorption because of the surface plasmon resonance(SPR) effect. Meanwhile, the higher photocurrent density showed the effective carrier separation ability in Au Ag/ZnO. Therefore, the cooperative action of plasmonic Au Ag bimetallic alloy NPs and efficient carrier separation capability result in the outstanding photoactivity of ethylene oxidation. At the same time, the formation of the alloy produced a new crystal structure different from Au and Ag, which overcomes the problem of poor stability of Ag/ZnO, and finally obtains Au Ag/ZnO photocatalyst with high activity and high stability. This work proposes a new concept of using metal alloys to remove ethylene in actual production.
基金the National Natural Science Foundation of China(51602179,21333006,21573135,11374190)the National Basic Research Program of China(973 Program,2013CB632401)~~
文摘In this study,CuBi2O4 photocathodes were prepared using a simple electrodeposition method for photoelectrochemical(PEC)hydrogen production.The prepared photocathodes were modified with amorphous TiO2 and a Pt co‐catalyst,which resulted in the formation of CuBi2O4/TiO2 p‐n heterojunctions,and enhanced the activities of the as‐prepared photocathodes.The novel Pt/TiO2/CuBi2O4 photocathode exhibited a photocurrent of 0.35 mA/cm2 at 0.60 V vs.Reversible Hydrogen Electrode(RHE),which was nearly twice that of the Pt/CuBi2O4 photocathode.The present study provides a facile method for increasing the efficiency of photocathodes and provides meaningful guidance for the preparation of high‐performance CuBi2O4 photocathodes.
基金the support of the National Natural Science Foundation of China(51702087,21673066)the Project funded by the China Postdoctoral Science Foundation(2019M652516)。
文摘Structure manipulation of photocatalysts at an atomic scale is a promising way to improve its photocatalytic performance.Herein,we realize the anchoring of single Ni atoms on the ZnIn_(2)S_(4) nanosheets with rich sulfur vacancies.Experimental results demonstrate that single Ni atoms induce the formation of NiO-M(Zn/In) atomic interface,which can efficiently promote the carriers separation and prolong the carrier life time.In addition,in situ electron spin resonance spectroscopy(ESR) confirms that the single Ni atoms act as an electron trapping center for protons reduction.As a result,the single Ni atoms decorated ZnIn_(2)S_(4) nanosheets with rich sulfur vacancies(Ni/ZnIn_(2)S_(4)-RVs) shows a hydrogen evolution rate up to 89.4 μmol h^(-1), almost 5.7 and 2.3 times higher compared to that of ZnIn_(2)S_(4) nanosheets with poor sulfur vacancies and rich sulfur vacancies(denoted as ZnIn_(2)S_(4)-PVs and ZnIn_(2)S_(4)-RVs).This work opens up a new perspective manipulating the single-atom cocatalyst and sulfur vacancy on sulfide supports for improving photocatalytic hydrogen evolution.
基金supported by the Gansu Provincial Development and Reform Commission(NDRC,No.2013-1336).
文摘Photosynthesis with the chloroplast works efficiently because of the envelope structure that serves to carry enzymes and to simultaneously maintain the spatial separation of photosynthesis and cellular respiration.Inspired by the spatially separated architecture,a chloroplast-like structured photocatalyst(PdS@CdS@MoS_(2)),in which the PdS and MoS_(2) function as enzymes in the chloroplast and CdS shell functions as the chloroplast envelope,was developed to improve the photocatalytic H_(2) evolution.In this unique nanoscale bionic structure,the poriferous CdS shell enhances light absorption,generates photoinduced carriers,and separates oxidation and reduction reactions.Meanwhile,PdS and MoS_(2) dual cocatalysts enhance the charge separation efficiency through forming a built-in electric field with CdS.We demonstrate that the separation efficiency of carriers,carrier lifetime,and the yield of H_(2) are both higher than that of CdS nanoparticles,evidencing the feasibility of the chloroplast-like structure in enhancing the photocatalyst activity.This work emphasizes the synergism of the three key processes of the photocatalytic reaction by simulating the chloroplast structure and provides a general synthesis strategy,the synthesis of novel structured for photocatalysts for diverse applications in the energy field.
基金financially supported by the Natural Science Foundation of Liaoning Province(Grant No.2019-ZD-0304)the Educational Department of Liaoning Province(Grant No.LJ2019009)+1 种基金Liaoning BaiQianWan Talents Program,Doctoral Start-up Foundation of Liaoning Province(Grant No.20170520231)the open fund of the State Key Laboratory of Molecular Reaction Dynamics in Dalian Institute of Chemical Physics(Grant No.SKLMRDK202001),Chinese Academy of Sciences。
文摘The rational fabrication of heterostructures is one of efficient strategies for improving photocatalytic performance of semiconductor photocatalysts.Very recently,Domen and co-workers found that Ta_(3)N_(5) single crystals grown on the surface of KTaO_(3) can accomplish photocatalytic overall water splitting for the first time.In order to comprehend the underlying mechanism of this photocatalytic system,we have performed a systematic study based on density functional theory first-principles calculations.Ta_(3)N_(5)(010)/KTaO_(3)(110)slab models have been built according to experimental observations by considering two common terminations of KTaO_(3)(110)surface,named as Ta_(3)N_(5)/O_(2) and Ta_(3)N_(5)/KTaO.The formations of interfacial bonds are thermodynamically stable,showing a covalent interaction between two components of a heterostructure.Ta_(3)N_(5)/O_(2) has a higher mobility of photogenerated charge carriers and lower recombination rate of charge carriers than Ta_(3)N_(5)/KTaO.The light absorption of heterostructures displays the feature of KTaO_(3) in the short wavelength region and the characteristic of Ta_(3)N_(5) in the long wavelength region.The calculated band offsets show that Ta_(3)N_(5)/O_(2) and Ta_(3)N_(5)/KTaO have distinct Type-II band alignments,with Ta_(3)N_(5) as the accumulator of photoinduced electrons in the former and the collector of photogenerated holes in the latter,respectively.The difference in charge density and electrostatic potential between two components acts as a driving force to promote the transfer of electrons and holes to different domains of the interface,which is beneficial to extend the lifetime of photoinduced carriers.Our results demonstrate that the function of Ta_(3)N_(5) in Ta_(3)N_(5)/KTaO_(3) photocatalytic system is determined by the termination property of KTaO_(3)(110)surface,which provides a likely reason of the observed photocatalytic activity of overall water splitting achieved by Ta_(3)N_(5) synthesized by using KTaO_(3) as a precursor for the nitridation reaction.
文摘Lead halide perovskites MAPbX_(3)(MA = CH_(3)NH_(3) or Cs;X = I, Br, Cl) are well considered to be potential candidates for photocatalytic reaction due to its excellent photoelectrical properties, but they still suffer from the low charge separation efficiency and slow catalytic reaction dynamics. To tackle the drawbacks, herein, MAPbBr_(3)/carbon sphere(CS) composite photocatalysts using glucose as the carbon source were elaborately designed and fabricated via a dry mechanochemical grinding process. The interfacial interaction Pb-O-C chemical bonds were constructed between MAPbBr_(3) and the carbon sphere surface containing organic functional groups. By optimizing the content of CSs, the enhanced photocatalytic degradation kinetic rate of Malachite Green(MG) pollutants(92% within 20 min) for MAPbBr_(3)/CS x( x = 17 wt.%) is about 3.6-fold of that for pristine MAPbBr_(3), which is attributed to the corporative adsorption and enhanced carrier transportation and separation of MAPbBr_(3)/CS x. Furthermore, the possible degradation mechanism was proposed on basis of the electrochemical, mass spectrometry and optical characterization results. Owing to the robust interfacial interaction, effective electron extraction rate( k et = 4.6 × 10^(7) sec^(-1)) from MAPbBr_(3) to CS can be established, which driven oxygen activation where superoxide radicals(·O^(2-)) played an important role in MG degradation. It is expected that mechanochemistry strategy may provide a new route to design efficient lead halide perovskite-carbon or metal oxide or sulfide composite photocatalysts.
基金financially supported by the Key-Area Research and Development Program of Guangdong Province(No.2021B0707050001)the Self-innovation Research Funding Project of Hanjiang Laboratory(No.HJL202202A001)。
文摘Photocatalytic reduction of CO_(2)has attracted considerable interest owing to its potential to resolve the energy and environmental problems.Nevertheless,the lack of proficient photocatalysts has restricted the application of solar-driven photocatalytic CO_(2)reduction.Herein,we reported an S-scheme heterojunction by combining g-C_(3)N_(4)with La^(3+)and Rh^(3+)co-doped SrTiO_(3)through the electrostatic self-assembly method for the efficient photocatalytic CO_(2)reduction.In comparison with g-C_(3)N_(4),the asprepared CN/LRSTO-30 wt%S-scheme heterojunction not only possesses a broadened visible-light response due to the defect states in La,Rh co-doped SrTiO_(3)induced by codoped La^(3+)and Rh^(3+)but also has more adsorption sites for the capture and activation of CO_(2)molecules.Additionally,separation and transfer efficiency of the photoinduced charge carriers is much enhanced in the CN/LRSTO-30wt%S-scheme heterojunction via its robust internal electric field,which is firmly demonstrated by in situ irradiation X-ray photoelectron spectroscopy technology.Consequently,the prepared S-scheme heterojunction achieves impressive photocatalytic CO_(2)reduction performance with an average CO and CH4 evolution rate of4.1-1.8μmol·g^(-1)·h^(-1),respectively,which are~1.9 and~22.5-fold higher than those of pure g-C_(3)N_(4).This study provides innovative perspectives on the design of creative S-scheme heterojunctions for applications in photocatalytic CO_(2)reduction.
基金Project supported by the National Natural Science Foundation of China(No.11174241)the Natural Science Foundation of Shandong Province,China(No.2009VRA06063)the Natural Science Foundation for Distinguished Young Scholars of Shandong Province, China(No.2008JQB01028)
文摘Phase separations have been studied for graded-indium content In_xGa_(1-x)N/GaN multiple quantum wells(MQWs) with different indium contents by means of photoluminescence(PL),cathodeluminescence(CL) and time-resolved PL(TRPL) techniques.Besides the main emission peaks,all samples show another 2 peaks at the high and low energy parts of the main peaks in PL when excited at 10 K.CL images show a clear contrast for 3 samples,which indicates an increasing phase separation with increasing indium content.TRPL spectra at 15 K of the main emissions show an increasing delay of rising time with indium content,which means a carrier transferring from low indium content structures to high indium content structures.
基金the Natural Science Foundation of Henan(No.232300421361)the National Natural Science Foundation of China(Nos.21671176 and 21001096).
文摘S-scheme possesses superior redox capabilities compared with the II-scheme,providing an effective method to solve the innate defects of g-C_(3)N_(4)(CN).In this study,S-doped g-C_(3)N_(4)/g-C_(3)N_(4)(SCN-tm/CN)S-scheme homojunction was constructed by rationally integrating morphology control with interfacial engineering to enhance the photocatalytic hydrogen evolution performance.In-situ Kelvin probe force microscopy(KPFM)confirms the transport of photo-generated electrons from CN to SCN.Density functional theory(DFT)calculations reveal that the generation of a built-in electric field between SCN and CN enables the carrier separation to be more efficient and effective.Femtosecond transient absorption spectrum(fs-TAS)indicates prolonged lifetimes of SCN-tm/CN_(3)(τ1:9.7,τ2:110,andτ3:1343.5 ps)in comparison to those of CN(τ1:4.86,τ2:55.2,andτ3:927 ps),signifying that the construction of homojunction promotes the separation and transport of electron hole pairs,thus favoring the photocatalytic process.Under visible light irradiation,the optimized SCN-tm/CN_(3)exhibits excellent photocatalytic activity with the hydrogen evolution rate of 5407.3μmol·g^(−1)·h^(−1),which is 20.4 times higher than that of CN(265.7μmol·g^(−1)·h^(−1)).Moreover,the homojunction also displays an apparent quantum efficiency of 26.8%at 435 nm as well as ultra-long and ultra-stable cycle ability.This work offers a new strategy to construct highly efficient photocatalysts based on the metal-free conjugated polymeric CN for realizing solar energy conversion.
基金supported by the National Key Research and Development Program of China(2022YFB3805600,2022YFB3805604)National Natural Science Foundation of China(52103285,22293020)+6 种基金Major Program(JD)of Hubei Province(2023BAA003)Natural Science Foundation of Hubei Province(2023AFB605)Dawning Program of Wuhan(2023020201020306)China Postdoctoral Science Foundation(2023M732722)National 111 Project(B20002)Jilin Province Science and Technology Development Plan(20220101248JC)Fundamental Research Funds for the Central Universities(WUT:2024IVA089).
文摘Effective separation of photogenerated carriers plays a vital role in governing the efficiency of photo-electrocatalytic reactions.However,the advancement in enhancing the intrinsic carrier separation efficiency of semiconductors has shown limited progress.Herein,we reported the use of a magnetic field to improve the photoelectrochemical water splitting of a magnetic Co_(3)O_(4)/TiO_(2)photoanode by boosting the photogenerated carrier separation efficiency.In the presence of the magnetic field,oxygen evolution reaction occurs with a high photocurrent density of 0.86 mA cm^(−2)at 1.23 V versus VRHE,and an applied bias photon-to-current efficiency of 0.342%at 0.61 VRHE.Moreover,the photoanode maintains its oxygen evolution reaction for more than 400 h with photocurrent decays by ca.10%.Observations made in this effort show that the enhancement of photo-electrocatalytic efficiency by a magnetic field is a consequence of the effect of the Lorentz force generated by the magnetic field on photogenerated carriers and ions near the Co_(3)O_(4)/TiO_(2)photoanode,which improves the carrier separation efficiency and the bubble release rate.The results suggest that manipulating photoelectrode carriers by using a magnetic field is a promising strategy to design high-performance photoelectrochemical for water splitting.