Converting solar energy into clean and sustainable chemical fuels is a promising strategy for exploiting renewable energy.The application of photocatalytic water splitting technology in hydrogen production is importan...Converting solar energy into clean and sustainable chemical fuels is a promising strategy for exploiting renewable energy.The application of photocatalytic water splitting technology in hydrogen production is important for sustainable energy development and environmental protection.In this study,for the first time,2D Cu7S4 co-catalysts were coupled on the surface of a CdS nanosheet photocatalyst by a one-step ultrasonic-assisted electrostatic self-assembly method at room temperature.The as-fabricated 2D^-2D CdS/Cu7S4 layered heterojunctions were demonstrated to be advanced composite photocatalysts that enhance the water splitting efficiency toward hydrogen production.The highest hydrogen evolution rate of the 2D^-2D CdS/2%Cu7S4 binary heterojunction photocatalyst was up to 27.8 mmol g^-1 h^-1 under visible light irradiation,with an apparent quantum efficiency of 14.7%at 420 nm,which was almost 10.69 times and 2.65 times higher than those of pure CdS nanosheets(2.6 mmol g^-1 h^-1)and CdS-2%CuS(10.5 mmol g^-1 h^-1),respectively.The establishment of the CdS/Cu7S4 binary-layered heterojunction could not only enhance the separation of photogenerated electron-hole(e--h+)pairs,improve the transfer of photo-excited electrons,and prolong the life-span of photo-generated electrons,but also enhance the light absorption and hydrogen-evolution kinetics.All these factors are important for the enhancement of the photocatalytic activity.Expectedly,the 2D^-2D interface coupling strategy based on CdS NSs can be extensively exploited to improve the hydrogen-evolution activity over various kinds of conventional semiconductor NSs.展开更多
In this work,a set of novel Cu2ZnSnS4/Bi2WO6(CZTS/BWO)two-dimensional(2 D)/two-dimensional(2 D)type-Ⅱheterojunctions with different CZTS weight ratios(1%,2%,and 5%)were successfully synthesized via a brief secondary ...In this work,a set of novel Cu2ZnSnS4/Bi2WO6(CZTS/BWO)two-dimensional(2 D)/two-dimensional(2 D)type-Ⅱheterojunctions with different CZTS weight ratios(1%,2%,and 5%)were successfully synthesized via a brief secondary solvothermal process.The successful formation of the heterojunctions was affirmed by characterization methods such as X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy.The photocatalytic activity results showed that the prepared CZTS/BWO heterojunctions had excellent photocatalytic behaviors for organic degradation,especially when the mass fraction of CZTS with respect to BWO in the composite was 2%.Moreover,the addition of hydrogen peroxide(H2O2)could further improve the dye and antibiotic degradation efficiencies.The reinforced photocatalytic and photo-Fenton degradation performance were primarily attributable to the introduction of BWO,which afforded increased active sites,expanded the solar spectral response range,and accelerated the cycle of Cu(Ⅱ)/Cu(Ⅰ);after four cycling times,its catalytic activity did not decrease significantly.In addition,reasonable hypotheses of the photocatalytic and photo-Fenton catalytic mechanisms were formulated.This study is expected to provide a visual approach for designing a novel photo-Fenton catalyst to jointly utilize the photocatalytic and Fenton activities,which can be better applied to the purification of residual organics in wastewater.展开更多
Photoreduction of CO_(2) to solar fuels has caused great interest,but suffers from low catalytic efficiency and poor selectivity.Herein,we designed a S-scheme heterojunction(Cu-TiO_(2)/WO_(3))with Cu single atom to si...Photoreduction of CO_(2) to solar fuels has caused great interest,but suffers from low catalytic efficiency and poor selectivity.Herein,we designed a S-scheme heterojunction(Cu-TiO_(2)/WO_(3))with Cu single atom to significantly boost the photoreduction of CO_(2).Notably,the developed Cu-TiO_(2)/WO_(3) achieved the solardriven conversion of CO_(2) to CH_(4) with an evolution rate of 98.69μmol g^(−1) h^(−1),and the electron selectivity of CH_(4) reached 88.5%.The yield was much higher than those of pristine WO_(3),TiO_(2)/WO_(3) and Cu-TiO_(2) samples.Experimental and theoretical analysis suggested that the S-scheme heterojunction accelerated charge migration and inhibited the recombination of electron-hole pairs.Importantly,the charge separation effect of the heterojunction meliorated the position of the d-band.The uplifted d-band centers of Cu and Ti on Cu-TiO_(2)/WO_(3) not only improved the electron interaction between Cu single atoms and substrate-TiO_(2),accelerated the adsorption and activation of CO_(2) on the active sites of Cu single atom,but also optimized the Gibbs free energies of CH 4 formation pathway,leading to excellent selectivity toward CH_(4).This work provides new insights into the design of photocatalyst systems with high photocatalytic performance.展开更多
The electron transfer mechanism in the process of peroxymonosulfate(PMS)activation using heterojunction catalyst was controversial.In this work,magnetic heterojunction Cu_(2)O/CoFe_(2)O_(4)(CC)was first synthesized to...The electron transfer mechanism in the process of peroxymonosulfate(PMS)activation using heterojunction catalyst was controversial.In this work,magnetic heterojunction Cu_(2)O/CoFe_(2)O_(4)(CC)was first synthesized to activate PMS.An innovative reaction mechanism based on built-in electric field-driven electron migration from Cu2O to CoFe2O4 and effective magnetic moment of CC for enhancing PMS activation was proposed.Meanwhile,the CC/PMS system was used for efficient removal of antibiotic tetracycline(TC).Under optimal conditions,98.0%TC could be removed using CC/PMS catalytic system after only 30 min.The catalytic activity was higher than that of Cu_(2)O/PMS and CoFe_(2)O_(4)/PMS.Meanwhile,the impact of solution pH on TC removal was insignificant,suggesting the pH-insensitive PMS activation ability of CC.Besides,the coexisting inorganic ions in the environment,such as HCO_(3)-,H_(2)PO4-,NO_(3)-,Cl-and humic acid(HA)as representative of natural organic matter,did not inhibit TC removal in CC/PMS system.Furthermore,CC/PMS system exhibited excellent reusability with more than94.0%TC removal after the 5th reuse.Electron paramagnetic resonance(EPR)tests and quenching experiments showed that O_(2)·-and 1O_(2) played vital roles in TC removal.The intermediate products and corresponding toxicity assessment revealed that this catalytic system could reduce TC toxicity.This work provided new insights into the PMS activation mechanism using heterogeneous magnetic catalysts,including transition metal oxide.展开更多
The Cu2O/TiO2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu 2 O nanoparticles on the surface of TiO 2 nanotubes via anodic oxidation and constant current deposition.Field emission scannin...The Cu2O/TiO2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu 2 O nanoparticles on the surface of TiO 2 nanotubes via anodic oxidation and constant current deposition.Field emission scanning electron microscopy(SEM)and high-resolution transmission electron microscopy(HRTEM)analyses showed that Cu 2 O nanoparticles not only deposited on the surface of TiO 2 nanotube array,but also on the wall of TiO 2 nanotubes.The Cu 2 O deposition amount could be adjusted by changing the deposition time.The photoelectrochemical cathodic protection(PECCP)performance of the prepared photoelectrodes for 316L stainless steel(SS)was tested under visible light.The constant current deposition time had a signifi cant eff ect on the PECCP performance of Cu 2 O/TiO 2-X photoelectrodes and Cu 2 O/TiO 2-20 had the best PECCP performance for the coupled 316L SS.This was attributed to the appropriate amount and thickness of Cu 2 O to form p-n heterojunctions with TiO 2,in which separation of the photogenerated carriers was accelerated and transfer of the photogenerated electrons to 316L SS for PECCP was facilitated.展开更多
Attempts to remove environmentally harmful materials in mass production industries are always a major issue and draw attention if the substitution guarantees a chance to lower fabrication cost and to improve device pe...Attempts to remove environmentally harmful materials in mass production industries are always a major issue and draw attention if the substitution guarantees a chance to lower fabrication cost and to improve device performance,as in a wide bandgap Zn_(1-x)Mg_(x)O(ZMO)to replace the CdS buffer in Cu(In_(1-x),Ga_(x))Se_(2)(CIGSe)thin-film solar cell structure.ZMO is one of the candidates for the buffer material in CIGSe thin-film solar cells with a wide and controllable bandgap depending on the Mg content,which can be helpful in attaining a suitable conduction band offset.Hence,compared to the fixed and limited bandgap of a CdS buffer,a ZMO buffer may provide advantages in V_(oc) and J_(sc) based on its controllable and wide bandgap,even with a relatively wider bandgap CIGSe thin-film solar cell.In addition,to solve problems with the defect sites at the ZMO/CIGSe junction interface,a few-nanometer ZnS layer is employed for heterojunction interface passivation,forming a ZMO/ZnS buffer structure by atomic layer deposition(ALD).Finally,a Cd-free all-dry-processed CIGSe solar cell with a wider bandgap(1.25 eV)and ALD-grown buffer structure exhibited the best power conversion efficiency of 19.1%,which exhibited a higher performance than the CdS counterpart.展开更多
Although Cu possesses many unique advantages for electrocatalytic CO_(2) reduction reaction(CO_(2)RR),it is not suitable for electrosynthesis of urea from CO_(2) and NO3−because of high energy barriers for the formati...Although Cu possesses many unique advantages for electrocatalytic CO_(2) reduction reaction(CO_(2)RR),it is not suitable for electrosynthesis of urea from CO_(2) and NO3−because of high energy barriers for the formation of ^(*)COOH and ^(*)CO intermediates and C-N bonds.Herein,Cr_(2)O_(3) nanoparticle(NP)/Cu nanosheet(NS)heterojunction electrocatalysts are reported for highly efficient electrocatalytic co-reduction of CO_(2) and NO3−toward urea production.The strongly coupled heterostructure interface between Cr_(2)O_(3) NPs and Cu NSs exhibits synergistic effect and optimizes the adsorption of intermediates.The resultant heterojunction electrocatalysts could achieve a high urea Faradaic efficiency(FEurea)of 62%at an ultralow applied potential of 0 V vs.reversible hydrogen electrode(RHE),which is among the best results reported to date.Moreover,the electrocatalysts showed good recycling stability.The in-situ Fourier transform infrared(FTIR)spectroscopy and density functional theory(DFT)calculations revealed that the Cr_(2)O_(3) NPs/Cu NSs heterostructure could not only reduce formation energy barriers of ^(*)COOH and ^(*)CO intermediates but also promote the coupling of ^(*)CO and ^(*)NH_(2) to form C-N bonds,leading to a high FEurea.This study demonstrates a heterojunction engineering strategy for the rational design of high-performance Cu-based electrocatalysts for urea generation.展开更多
We describe significant improvements of the photovoltaic properties that were achieved in Al-doped ZnO（AZO）/n-type oxide semiconductor/p-type Cu_2O heterojunction solar cells fabricated using p-type Cu_2O sheets pre...We describe significant improvements of the photovoltaic properties that were achieved in Al-doped ZnO（AZO）/n-type oxide semiconductor/p-type Cu_2O heterojunction solar cells fabricated using p-type Cu_2O sheets prepared by thermally oxidizing Cu sheets. The multicomponent oxide thin film used as the n-type semiconductor layer was prepared with various chemical compositions on non-intentionally heated Cu_2O sheets under various deposition conditions using a pulsed laser deposition method. In Cu_2O-based heterojunction solar cells fabricated using various ternary compounds as the n-type oxide thin-film layer, the best photovoltaic performance was obtained with an n-ZnGa_2O_4 thin-film layer. In most of the Cu_2O-based heterojunction solar cells using multicomponent oxides composed of combinations of various binary compounds, the obtained photovoltaic properties changed gradually as the chemical composition was varied. However, with the ZnO–MgO and Ga_2O_3–Al_2O_3systems, higher conversion efficiencies（á/ as well as a high open circuit voltage（Voc/ were obtained by using a relatively small amount of MgO or Al_2O_3, e.g.,（ZnO）0：91–（MgO）0：09 and（Ga_2O_3/0：975–（Al_2O_3/0：025, respectively. When Cu_2O-based heterojunction solar cells were fabricated using Al_2O_3–Ga_2O_3–MgO–ZnO（AGMZO）multicomponent oxide thin films deposited with metal atomic ratios of 10, 60, 10 and 20 at.% for the Al, Ga, Mg and Zn, respectively, a high Vocof 0.98 V and an á of 4.82% were obtained. In addition, an enhanced á and an improved fill factor could be achieved in AZO/n-type multicomponent oxide/p-type Cu_2O heterojunction solar cells fabricated using Na-doped Cu_2O（Cu_2O：Na） sheets that featured a resistivity controlled by optimizing the post-annealing temperature and duration. Consequently, an á of 6.25% and a Vocof 0.84 V were obtained in a Mg F2/AZO/n-（Ga_2O_3–Al_2O_3//p-Cu_2O：Na heterojunction solar cell fabricated using a Cu_2O：Na sheet with a resistivity of approximately 10 cm and a（Ga_（0：975）A_（l0：025）/2O3 thin film with a thickness of approximately 60 nm.In addition, a Vocof 0.96 V and an á of 5.4% were obtained in a Mg F_2/AZO/n-AGMZO/p-Cu_2O：Na heterojunction solar cell.展开更多
基金the National Natural Science Foundation of China(21975084,51672089)Special Funding on Applied Science and Technology in Guangdong(2017B020238005)+2 种基金the State Key Laboratory of Advanced Technology for Material Synthesis and Processing(Wuhan University of Technology)(2015-KF-7)State Scholarship Fund of China Scholarship Council(200808440114)the Ding Ying Talent Project of South China Agricultural University for their support
文摘Converting solar energy into clean and sustainable chemical fuels is a promising strategy for exploiting renewable energy.The application of photocatalytic water splitting technology in hydrogen production is important for sustainable energy development and environmental protection.In this study,for the first time,2D Cu7S4 co-catalysts were coupled on the surface of a CdS nanosheet photocatalyst by a one-step ultrasonic-assisted electrostatic self-assembly method at room temperature.The as-fabricated 2D^-2D CdS/Cu7S4 layered heterojunctions were demonstrated to be advanced composite photocatalysts that enhance the water splitting efficiency toward hydrogen production.The highest hydrogen evolution rate of the 2D^-2D CdS/2%Cu7S4 binary heterojunction photocatalyst was up to 27.8 mmol g^-1 h^-1 under visible light irradiation,with an apparent quantum efficiency of 14.7%at 420 nm,which was almost 10.69 times and 2.65 times higher than those of pure CdS nanosheets(2.6 mmol g^-1 h^-1)and CdS-2%CuS(10.5 mmol g^-1 h^-1),respectively.The establishment of the CdS/Cu7S4 binary-layered heterojunction could not only enhance the separation of photogenerated electron-hole(e--h+)pairs,improve the transfer of photo-excited electrons,and prolong the life-span of photo-generated electrons,but also enhance the light absorption and hydrogen-evolution kinetics.All these factors are important for the enhancement of the photocatalytic activity.Expectedly,the 2D^-2D interface coupling strategy based on CdS NSs can be extensively exploited to improve the hydrogen-evolution activity over various kinds of conventional semiconductor NSs.
基金supported by the National Natural Science Foundation of China(21663030,21666039)the Open Project of State Key Laboratory of Organic-Inorganic Composites Beijing Key Laboratory,Beijing University of Chemical Technology(oic-201901009)+2 种基金the Project of Science&Technology Office of Shannxi Province(2018TSCXL-NY-02-01,2013K11-08,2013SZS20-P01)Industrial Key Project of Yan’an Science and Technology Bureau(2018KG-04)the Project of Yan’an Science Graduate Innovation Project of Yan’an University(YCX201988)~~
文摘In this work,a set of novel Cu2ZnSnS4/Bi2WO6(CZTS/BWO)two-dimensional(2 D)/two-dimensional(2 D)type-Ⅱheterojunctions with different CZTS weight ratios(1%,2%,and 5%)were successfully synthesized via a brief secondary solvothermal process.The successful formation of the heterojunctions was affirmed by characterization methods such as X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy.The photocatalytic activity results showed that the prepared CZTS/BWO heterojunctions had excellent photocatalytic behaviors for organic degradation,especially when the mass fraction of CZTS with respect to BWO in the composite was 2%.Moreover,the addition of hydrogen peroxide(H2O2)could further improve the dye and antibiotic degradation efficiencies.The reinforced photocatalytic and photo-Fenton degradation performance were primarily attributable to the introduction of BWO,which afforded increased active sites,expanded the solar spectral response range,and accelerated the cycle of Cu(Ⅱ)/Cu(Ⅰ);after four cycling times,its catalytic activity did not decrease significantly.In addition,reasonable hypotheses of the photocatalytic and photo-Fenton catalytic mechanisms were formulated.This study is expected to provide a visual approach for designing a novel photo-Fenton catalyst to jointly utilize the photocatalytic and Fenton activities,which can be better applied to the purification of residual organics in wastewater.
基金supported by the grants from the National Natural Science Foundation of China(Nos.21872102 and 22172080)the Tianjin“Project+Team”innovation team,2020.
文摘Photoreduction of CO_(2) to solar fuels has caused great interest,but suffers from low catalytic efficiency and poor selectivity.Herein,we designed a S-scheme heterojunction(Cu-TiO_(2)/WO_(3))with Cu single atom to significantly boost the photoreduction of CO_(2).Notably,the developed Cu-TiO_(2)/WO_(3) achieved the solardriven conversion of CO_(2) to CH_(4) with an evolution rate of 98.69μmol g^(−1) h^(−1),and the electron selectivity of CH_(4) reached 88.5%.The yield was much higher than those of pristine WO_(3),TiO_(2)/WO_(3) and Cu-TiO_(2) samples.Experimental and theoretical analysis suggested that the S-scheme heterojunction accelerated charge migration and inhibited the recombination of electron-hole pairs.Importantly,the charge separation effect of the heterojunction meliorated the position of the d-band.The uplifted d-band centers of Cu and Ti on Cu-TiO_(2)/WO_(3) not only improved the electron interaction between Cu single atoms and substrate-TiO_(2),accelerated the adsorption and activation of CO_(2) on the active sites of Cu single atom,but also optimized the Gibbs free energies of CH 4 formation pathway,leading to excellent selectivity toward CH_(4).This work provides new insights into the design of photocatalyst systems with high photocatalytic performance.
基金financially supported by the Science and Technology Research Program of Chongqing Municipal Education Commission(Nos.KJQN202204508 and KJQN201901401)Guizhou Province First-class Discipline(Group)Construction-Mining Engineering(No.XKTJ[2020]23)+5 种基金the National Natural Science Foundation of China(No.21906008)Science and Technology Fund Project of Guizhou Province(No.[2018]1415)Key Laboratory of Gas Prevention and Control in Coal Mines of Guizhou Province(No.KY[2019]054)Key Laboratory of Coalbed Methane Development and Utilization(No.52020-2018-03-06)Science and Technology Fund Project of Guizhou Province(No.[2018]1142)the Natural Science Foundation of Yongchuan District(No.2021yc-jckx20021)。
文摘The electron transfer mechanism in the process of peroxymonosulfate(PMS)activation using heterojunction catalyst was controversial.In this work,magnetic heterojunction Cu_(2)O/CoFe_(2)O_(4)(CC)was first synthesized to activate PMS.An innovative reaction mechanism based on built-in electric field-driven electron migration from Cu2O to CoFe2O4 and effective magnetic moment of CC for enhancing PMS activation was proposed.Meanwhile,the CC/PMS system was used for efficient removal of antibiotic tetracycline(TC).Under optimal conditions,98.0%TC could be removed using CC/PMS catalytic system after only 30 min.The catalytic activity was higher than that of Cu_(2)O/PMS and CoFe_(2)O_(4)/PMS.Meanwhile,the impact of solution pH on TC removal was insignificant,suggesting the pH-insensitive PMS activation ability of CC.Besides,the coexisting inorganic ions in the environment,such as HCO_(3)-,H_(2)PO4-,NO_(3)-,Cl-and humic acid(HA)as representative of natural organic matter,did not inhibit TC removal in CC/PMS system.Furthermore,CC/PMS system exhibited excellent reusability with more than94.0%TC removal after the 5th reuse.Electron paramagnetic resonance(EPR)tests and quenching experiments showed that O_(2)·-and 1O_(2) played vital roles in TC removal.The intermediate products and corresponding toxicity assessment revealed that this catalytic system could reduce TC toxicity.This work provided new insights into the PMS activation mechanism using heterogeneous magnetic catalysts,including transition metal oxide.
基金Supported by the National Natural Science Foundation of China(Nos.41576114,41676069)the State Key Laboratory for Marine Corrosion and Protection,Luoyang Ship Material Research Institute,China(No.614290101011703)the Qingdao Innovative Leading Talent Foundation(No.15-10-3-15-(39)-zch)。
文摘The Cu2O/TiO2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu 2 O nanoparticles on the surface of TiO 2 nanotubes via anodic oxidation and constant current deposition.Field emission scanning electron microscopy(SEM)and high-resolution transmission electron microscopy(HRTEM)analyses showed that Cu 2 O nanoparticles not only deposited on the surface of TiO 2 nanotube array,but also on the wall of TiO 2 nanotubes.The Cu 2 O deposition amount could be adjusted by changing the deposition time.The photoelectrochemical cathodic protection(PECCP)performance of the prepared photoelectrodes for 316L stainless steel(SS)was tested under visible light.The constant current deposition time had a signifi cant eff ect on the PECCP performance of Cu 2 O/TiO 2-X photoelectrodes and Cu 2 O/TiO 2-20 had the best PECCP performance for the coupled 316L SS.This was attributed to the appropriate amount and thickness of Cu 2 O to form p-n heterojunctions with TiO 2,in which separation of the photogenerated carriers was accelerated and transfer of the photogenerated electrons to 316L SS for PECCP was facilitated.
基金conducted under the framework of the research and development program of the Korea Institute of Energy Research(C4-2412 and C4-2413)supported by the National Research Foundation of Korea(grant number 2022M3J1A1063019)funded by the Ministry of Science and ICT.
文摘Attempts to remove environmentally harmful materials in mass production industries are always a major issue and draw attention if the substitution guarantees a chance to lower fabrication cost and to improve device performance,as in a wide bandgap Zn_(1-x)Mg_(x)O(ZMO)to replace the CdS buffer in Cu(In_(1-x),Ga_(x))Se_(2)(CIGSe)thin-film solar cell structure.ZMO is one of the candidates for the buffer material in CIGSe thin-film solar cells with a wide and controllable bandgap depending on the Mg content,which can be helpful in attaining a suitable conduction band offset.Hence,compared to the fixed and limited bandgap of a CdS buffer,a ZMO buffer may provide advantages in V_(oc) and J_(sc) based on its controllable and wide bandgap,even with a relatively wider bandgap CIGSe thin-film solar cell.In addition,to solve problems with the defect sites at the ZMO/CIGSe junction interface,a few-nanometer ZnS layer is employed for heterojunction interface passivation,forming a ZMO/ZnS buffer structure by atomic layer deposition(ALD).Finally,a Cd-free all-dry-processed CIGSe solar cell with a wider bandgap(1.25 eV)and ALD-grown buffer structure exhibited the best power conversion efficiency of 19.1%,which exhibited a higher performance than the CdS counterpart.
基金supported by the National Natural Science Foundation of China(Nos.52371196 and 21673160)the Central Government Guiding Local Science and Technology Development Funds(No.2025ZY012029).
文摘Although Cu possesses many unique advantages for electrocatalytic CO_(2) reduction reaction(CO_(2)RR),it is not suitable for electrosynthesis of urea from CO_(2) and NO3−because of high energy barriers for the formation of ^(*)COOH and ^(*)CO intermediates and C-N bonds.Herein,Cr_(2)O_(3) nanoparticle(NP)/Cu nanosheet(NS)heterojunction electrocatalysts are reported for highly efficient electrocatalytic co-reduction of CO_(2) and NO3−toward urea production.The strongly coupled heterostructure interface between Cr_(2)O_(3) NPs and Cu NSs exhibits synergistic effect and optimizes the adsorption of intermediates.The resultant heterojunction electrocatalysts could achieve a high urea Faradaic efficiency(FEurea)of 62%at an ultralow applied potential of 0 V vs.reversible hydrogen electrode(RHE),which is among the best results reported to date.Moreover,the electrocatalysts showed good recycling stability.The in-situ Fourier transform infrared(FTIR)spectroscopy and density functional theory(DFT)calculations revealed that the Cr_(2)O_(3) NPs/Cu NSs heterostructure could not only reduce formation energy barriers of ^(*)COOH and ^(*)CO intermediates but also promote the coupling of ^(*)CO and ^(*)NH_(2) to form C-N bonds,leading to a high FEurea.This study demonstrates a heterojunction engineering strategy for the rational design of high-performance Cu-based electrocatalysts for urea generation.
文摘We describe significant improvements of the photovoltaic properties that were achieved in Al-doped ZnO（AZO）/n-type oxide semiconductor/p-type Cu_2O heterojunction solar cells fabricated using p-type Cu_2O sheets prepared by thermally oxidizing Cu sheets. The multicomponent oxide thin film used as the n-type semiconductor layer was prepared with various chemical compositions on non-intentionally heated Cu_2O sheets under various deposition conditions using a pulsed laser deposition method. In Cu_2O-based heterojunction solar cells fabricated using various ternary compounds as the n-type oxide thin-film layer, the best photovoltaic performance was obtained with an n-ZnGa_2O_4 thin-film layer. In most of the Cu_2O-based heterojunction solar cells using multicomponent oxides composed of combinations of various binary compounds, the obtained photovoltaic properties changed gradually as the chemical composition was varied. However, with the ZnO–MgO and Ga_2O_3–Al_2O_3systems, higher conversion efficiencies（á/ as well as a high open circuit voltage（Voc/ were obtained by using a relatively small amount of MgO or Al_2O_3, e.g.,（ZnO）0：91–（MgO）0：09 and（Ga_2O_3/0：975–（Al_2O_3/0：025, respectively. When Cu_2O-based heterojunction solar cells were fabricated using Al_2O_3–Ga_2O_3–MgO–ZnO（AGMZO）multicomponent oxide thin films deposited with metal atomic ratios of 10, 60, 10 and 20 at.% for the Al, Ga, Mg and Zn, respectively, a high Vocof 0.98 V and an á of 4.82% were obtained. In addition, an enhanced á and an improved fill factor could be achieved in AZO/n-type multicomponent oxide/p-type Cu_2O heterojunction solar cells fabricated using Na-doped Cu_2O（Cu_2O：Na） sheets that featured a resistivity controlled by optimizing the post-annealing temperature and duration. Consequently, an á of 6.25% and a Vocof 0.84 V were obtained in a Mg F2/AZO/n-（Ga_2O_3–Al_2O_3//p-Cu_2O：Na heterojunction solar cell fabricated using a Cu_2O：Na sheet with a resistivity of approximately 10 cm and a（Ga_（0：975）A_（l0：025）/2O3 thin film with a thickness of approximately 60 nm.In addition, a Vocof 0.96 V and an á of 5.4% were obtained in a Mg F_2/AZO/n-AGMZO/p-Cu_2O：Na heterojunction solar cell.
