This paper presents a p-n heterojunction photoanode based on a p-type porphyrin metal-organic framework (MOF) thin film and an n-type rutile titanium dioxide nanorod array for photoelectrochemical water splitting. The...This paper presents a p-n heterojunction photoanode based on a p-type porphyrin metal-organic framework (MOF) thin film and an n-type rutile titanium dioxide nanorod array for photoelectrochemical water splitting. The TiO2@MOF core-shell n anorod array is formed by coati ng an 8 nm thick MOF layer on a vertically aligned TiO2 nanorod array scaffold via a layer-by-layer self-assembly method. This vertically aligned core-shell nanorod array enables a long optical path length but a short path length for extraction of photogenerated minority charge carriers (holes) from TiO2 to the electrolyte. A p-n junction is formed between TiO2 and MOF, which improves the extraction of photogenerated electr ons and holes out of the TiO2 nano rods. In additi on, the MOF coati ng sign ificantly improves the efficie ncy of charge in jecti on at the photoanode/electrolyte interface. Introduction of Co(lll) into the MOF layer further enhances the charge extraction in the photoanode and improves the charge injection efficiency. As a result, the photoelectrochemical cell with the TiO2@Co-MOF nanorod array photoanode exhibits a photocurrent density of 2.93 mA/cm^2 at 1.23 V (vs. RHE), which is ~ 2.7 times the photocurrent achieved with bare T1O2 nanorod array under irradiation of an unfiltered 300 W Xe lamp with an output power density of 100 mW/cm^2.展开更多
Developing efficient heterostructured photocatalysts to accelerate charge separation and transfer is crucial to improving photocatalytic hydrogen generation using solar energy. Herein, we report for the first time tha...Developing efficient heterostructured photocatalysts to accelerate charge separation and transfer is crucial to improving photocatalytic hydrogen generation using solar energy. Herein, we report for the first time that p-type copper phosphide（Cu3P） coupled with n-type graphitic carbon nitride（g-C3N4） forms a p-n junction to accelerate charge separation and transfer for enhanced photocatalytic activity.The optimized Cu3P/g-C3N4 p-n heterojunction photocatalyst exhibits 95 times higher activity than bare g-C3N4, with an apparent quantum efficiency of 2.6% at 420 nm. A detail analysis of the reaction mechanism by photoluminescence,surface photovoltaics and electrochemical measurements revealed that the improved photocatalytic activity can be ascribed to efficient separation of photo-induced charge carriers. This work demonstrates that p-n junction structure is a useful strategy for developing efficient heterostructured photocatalysts.展开更多
Two-dimensional(2D)semiconductor heterojunctions are considered as an effective strategy to achieve fast separation of photoinduced carriers.Herein,a novel CoWO_(4)/g-C_(3)N_(4)(CWO/CN)p–n junction was synthesized us...Two-dimensional(2D)semiconductor heterojunctions are considered as an effective strategy to achieve fast separation of photoinduced carriers.Herein,a novel CoWO_(4)/g-C_(3)N_(4)(CWO/CN)p–n junction was synthesized using an electrostatic selfassembly method.The constructed 2D/2D p–n heterostructure had a rich hetero-interface,increased charge density,and fast separation efficiency of photoinduced carriers.The in-situ Kelvin probe force microscopy confirmed that the separation pathway of photoinduced carriers through the interface obeyed an II-scheme charge transfer mechanism.Experimental results and density functional theory calculations indicated the differences of work function between CWO and CN induced the generation of built-in electric field,ensuring an efficient separation and transfer process of photoinduced carriers.Under the optimized conditions,the CWO/CN heterojunction displayed enhanced photocatalytic H_(2)generation activity under full spectrum and visible lights irradiation,respectively.Our study provides a novel approach to design 2D/2D hetero-structured photocatalysts based on p–n type semiconductor for photocatalytic H_(2)generation.展开更多
Highly ordered Cu2O coated silicon nanowire arrays （SiNWAs） were fabricated as photocatalyst via depositing Cu nanoparticles on silver-assisted electroless-etched SiNWAs and subsequently annealing. The as-prepared s...Highly ordered Cu2O coated silicon nanowire arrays （SiNWAs） were fabricated as photocatalyst via depositing Cu nanoparticles on silver-assisted electroless-etched SiNWAs and subsequently annealing. The as-prepared samples have been characterized by scanning electron microscopy, X-ray diffraction and UV-VIS-NIR spectrophotometry. The photocatalytic properties of the Cu2O coated SiNWAs were investigated by degradation of Rhodamine B （RhB） under simulated solar light with a cut-off filter （λ 〉 420 nm）. The results indicated that H2O2 could greatly improve the photocatalytic properties of Cu2O coated SiNWAs, and exhibited strong synergy effect between them. The hybrid nanowire arrays will be promising photocatalytic materials in the field of energy and environment.展开更多
Polymer-derived porous carbon was used as a support of iron and nickel species with an objective to obtain an efficient oxygen reduction reaction(OER)catalyst.The surface features were extensively characterized using ...Polymer-derived porous carbon was used as a support of iron and nickel species with an objective to obtain an efficient oxygen reduction reaction(OER)catalyst.The surface features were extensively characterized using X-ray diffraction,X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy.On FeNi-modified carbon the overpotential for OER was very low(280 mV)and comparable to that on noble metal catalyst IrO_(2).The electrochemical properties have been investigated to reveal the difference between the binary alloy-and single metal-doped carbons.This work demonstrates a significant step for the development of low-cost,environmentally-friendly and highly-efficient OER catalysts.展开更多
Acetone,as widely used reagents in industry and laboratories,are extremely harmful to the human.So the detection of acetone gas concentrations and leaks in special environments at room temperature is essential.Herein,...Acetone,as widely used reagents in industry and laboratories,are extremely harmful to the human.So the detection of acetone gas concentrations and leaks in special environments at room temperature is essential.Herein,the nanocomposite combining SnO-SnO_(2)(p-n junction)and Ti_(3)C_(2)T_(x) MXene was successfully synthesized by a one-step hydrothermal method.Because of the existence of a small amount of oxygen during the hydrothermal conditions,part of the p-type SnO was oxidized to n-type SnO_(2),forming in-situ p-n junctions on the surface of Sn O.The hamburger-like SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensor exhibited improved acetone gas sensing response of 12.1(R_(g)/R_(a))at room temperature,which were nearly 11 and 4 times higher than those of pristine Ti_(3)C_(2)T_(x) and pristine SnO-SnO_(2),respectively.Moreover,it expressed a short recovery time(9 s)and outstanding reproducibility.Because of the different work functions,the Schottky barrier was formed between the SnO and the Ti_(3)C_(2)T_(x) nanosheets,acting as a hole accumulation layer(HALs)between Ti_(3)C_(2)T_(x) and tin oxides.Herein,the sensing mechanism based on the formation of hetero-junctions and high conductivity of the metallic phase of Ti_(3)C_(2)T_(x) MXene in SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensors was discussed in detail.展开更多
Two-dimensional （2D） materials have attracted substantial attention in electronic and optoelectronic applications with the superior advantages of being flexible, transparent, and highly tunable. Gapless graphene exh...Two-dimensional （2D） materials have attracted substantial attention in electronic and optoelectronic applications with the superior advantages of being flexible, transparent, and highly tunable. Gapless graphene exhibits ultra-broadband and fast photoresponse while the 2D semiconducting MoS2 and GaTe exhibit high sensitivity and tunable responsivity to visible light. However, the device yield and repeatability call for further improvement to achieve large-scale uniformity. Here, we report a layer-by-layer growth of wafer-scale GaTe with a high hole mobility of 28.4 cm^2/（V.s） by molecular beam epitaxy. The arrayed p-n ）unctions were developed by growing few-layer GaTe directly on fhree-inch Si wafers. The resultant diodes reveal good rectifying characteristics and a high photovoltaic external quantum efficiency up to 62% at 4.8 μW under zero bias. The photocurrent reaches saturation fast enough to capture a time constant of 22 μs and shows no sign of device degradation after 1.37 million cycles of operation. Most strikingly, such high performance has been achieved across the entire wafer, making the volume production of devices accessible. Finally, several photoimages were acquired by the GaTe/Si photodiodes with reasonable contrast and spatial resolution, demonstrating the potential of integrating the 2D materials with silicon technology for novel optoelectronic devices.展开更多
Nanosecond (ns) photoelectric effects have been observed in all-oxide p-n junctions of La0.9Sr0.1MnO3/SrNb0.01Ti0.99O3 for the first time. The rise time was about 23 ns and the full width at half maximum was about 125...Nanosecond (ns) photoelectric effects have been observed in all-oxide p-n junctions of La0.9Sr0.1MnO3/SrNb0.01Ti0.99O3 for the first time. The rise time was about 23 ns and the full width at half maximum was about 125 ns for the open-circuit photovoltaic pulse when the La0.9Sr0.1MnO3 thin film in the p-n junction was irradiated by a laser of ~20 ns pulse duration and 308 nm wavelength. The photovoltaic sensitivity was 80 mV/mJ for a 308 nm laser pulse.展开更多
Neuromorphic machine vision has attracted extensive attention on wide fields.However,both current and emerging strategies still suffer from power/time inefficiency,and/or low compatibility,complex device structure.Her...Neuromorphic machine vision has attracted extensive attention on wide fields.However,both current and emerging strategies still suffer from power/time inefficiency,and/or low compatibility,complex device structure.Here we demonstrate a driving-voltage-free optoelectronic synaptic device using non-volatile reconfigurable photovoltaic effect based on MoTe_(2)/α-In_(2)Se_(3) ferroelectric p-n junctions.This function comes from the non-volatile reconfigurable built-in potential in the p-n junction that is related to the ferroelectric polarization inα-In_(2)Se_(3).Reconfigurable rectification behavior and photovoltaic effect are demonstrated firstly.Notably,the figure-of-merits for photovoltaic effect like photoelectrical conversion efficiency non-volatilely increases more than one order.Based on this,retina synapse-like vision functions are mimicked.Optoelectronic short-term and long-term plasticity,as well as basic neuromorphic learning and memory rule are achieved without applying driving voltage.Our work highlights the potential of ferroelectric p-n junctions for enhanced solar cell and low-power optoelectronic synaptic device for neuromorphic machine vision.展开更多
文摘This paper presents a p-n heterojunction photoanode based on a p-type porphyrin metal-organic framework (MOF) thin film and an n-type rutile titanium dioxide nanorod array for photoelectrochemical water splitting. The TiO2@MOF core-shell n anorod array is formed by coati ng an 8 nm thick MOF layer on a vertically aligned TiO2 nanorod array scaffold via a layer-by-layer self-assembly method. This vertically aligned core-shell nanorod array enables a long optical path length but a short path length for extraction of photogenerated minority charge carriers (holes) from TiO2 to the electrolyte. A p-n junction is formed between TiO2 and MOF, which improves the extraction of photogenerated electr ons and holes out of the TiO2 nano rods. In additi on, the MOF coati ng sign ificantly improves the efficie ncy of charge in jecti on at the photoanode/electrolyte interface. Introduction of Co(lll) into the MOF layer further enhances the charge extraction in the photoanode and improves the charge injection efficiency. As a result, the photoelectrochemical cell with the TiO2@Co-MOF nanorod array photoanode exhibits a photocurrent density of 2.93 mA/cm^2 at 1.23 V (vs. RHE), which is ~ 2.7 times the photocurrent achieved with bare T1O2 nanorod array under irradiation of an unfiltered 300 W Xe lamp with an output power density of 100 mW/cm^2.
基金financial support from the National Natural Science Foundation of China (21606175)the grant support from China Postdoctoral Science Foundation (2014M560768)China Fundamental Research Funds for the Central Universities (xjj2015041)
文摘Developing efficient heterostructured photocatalysts to accelerate charge separation and transfer is crucial to improving photocatalytic hydrogen generation using solar energy. Herein, we report for the first time that p-type copper phosphide（Cu3P） coupled with n-type graphitic carbon nitride（g-C3N4） forms a p-n junction to accelerate charge separation and transfer for enhanced photocatalytic activity.The optimized Cu3P/g-C3N4 p-n heterojunction photocatalyst exhibits 95 times higher activity than bare g-C3N4, with an apparent quantum efficiency of 2.6% at 420 nm. A detail analysis of the reaction mechanism by photoluminescence,surface photovoltaics and electrochemical measurements revealed that the improved photocatalytic activity can be ascribed to efficient separation of photo-induced charge carriers. This work demonstrates that p-n junction structure is a useful strategy for developing efficient heterostructured photocatalysts.
基金Outstanding Talent Research Fund of Zhengzhou University,China Postdoctoral Science Foundation(Nos.2020TQ0277 and 2020M682328)Central Plains Science and Technology Innovation Leader Project(No.214200510006)Postdoctoral Science Foundation of Henan province(No.202002010).
文摘Two-dimensional(2D)semiconductor heterojunctions are considered as an effective strategy to achieve fast separation of photoinduced carriers.Herein,a novel CoWO_(4)/g-C_(3)N_(4)(CWO/CN)p–n junction was synthesized using an electrostatic selfassembly method.The constructed 2D/2D p–n heterostructure had a rich hetero-interface,increased charge density,and fast separation efficiency of photoinduced carriers.The in-situ Kelvin probe force microscopy confirmed that the separation pathway of photoinduced carriers through the interface obeyed an II-scheme charge transfer mechanism.Experimental results and density functional theory calculations indicated the differences of work function between CWO and CN induced the generation of built-in electric field,ensuring an efficient separation and transfer process of photoinduced carriers.Under the optimized conditions,the CWO/CN heterojunction displayed enhanced photocatalytic H_(2)generation activity under full spectrum and visible lights irradiation,respectively.Our study provides a novel approach to design 2D/2D hetero-structured photocatalysts based on p–n type semiconductor for photocatalytic H_(2)generation.
基金supported by the National Natural Science Foundation of China (Grant No.50772006)
文摘Highly ordered Cu2O coated silicon nanowire arrays （SiNWAs） were fabricated as photocatalyst via depositing Cu nanoparticles on silver-assisted electroless-etched SiNWAs and subsequently annealing. The as-prepared samples have been characterized by scanning electron microscopy, X-ray diffraction and UV-VIS-NIR spectrophotometry. The photocatalytic properties of the Cu2O coated SiNWAs were investigated by degradation of Rhodamine B （RhB） under simulated solar light with a cut-off filter （λ 〉 420 nm）. The results indicated that H2O2 could greatly improve the photocatalytic properties of Cu2O coated SiNWAs, and exhibited strong synergy effect between them. The hybrid nanowire arrays will be promising photocatalytic materials in the field of energy and environment.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.21421001,21875118)the 111 Project(Grant No.B12015).
文摘Polymer-derived porous carbon was used as a support of iron and nickel species with an objective to obtain an efficient oxygen reduction reaction(OER)catalyst.The surface features were extensively characterized using X-ray diffraction,X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy.On FeNi-modified carbon the overpotential for OER was very low(280 mV)and comparable to that on noble metal catalyst IrO_(2).The electrochemical properties have been investigated to reveal the difference between the binary alloy-and single metal-doped carbons.This work demonstrates a significant step for the development of low-cost,environmentally-friendly and highly-efficient OER catalysts.
基金supported financially by the National Natural Science Foundation of China(Nos.,51572158 and 51972200)the Graduate Innovation Fund of Shaanxi University of Science&Technology+2 种基金funded by the Japan Society for the Promotion of Science(JSPS)Grant-in-Aid for the Scientific Research(KAKENHI Nos.20H00297 and Innovative Area“Mixed Anion”(No.16H06439))the Nippon Sheet Glass Foundation for Materials Science and Engineeringby the Dynamic Alliance for Open Innovations Bridging Human,Environment and Materials,the Cooperative Research Program of“Network Joint Research Center for Materials and Devices”。
文摘Acetone,as widely used reagents in industry and laboratories,are extremely harmful to the human.So the detection of acetone gas concentrations and leaks in special environments at room temperature is essential.Herein,the nanocomposite combining SnO-SnO_(2)(p-n junction)and Ti_(3)C_(2)T_(x) MXene was successfully synthesized by a one-step hydrothermal method.Because of the existence of a small amount of oxygen during the hydrothermal conditions,part of the p-type SnO was oxidized to n-type SnO_(2),forming in-situ p-n junctions on the surface of Sn O.The hamburger-like SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensor exhibited improved acetone gas sensing response of 12.1(R_(g)/R_(a))at room temperature,which were nearly 11 and 4 times higher than those of pristine Ti_(3)C_(2)T_(x) and pristine SnO-SnO_(2),respectively.Moreover,it expressed a short recovery time(9 s)and outstanding reproducibility.Because of the different work functions,the Schottky barrier was formed between the SnO and the Ti_(3)C_(2)T_(x) nanosheets,acting as a hole accumulation layer(HALs)between Ti_(3)C_(2)T_(x) and tin oxides.Herein,the sensing mechanism based on the formation of hetero-junctions and high conductivity of the metallic phase of Ti_(3)C_(2)T_(x) MXene in SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensors was discussed in detail.
基金This work was supported by the National Young 1000 Talent Plan, Pujiang Talent Plan in Shanghai, National Natural Science Foundation of China （Nos. 61322407, 11474058, and 11322441）, the Chinese Na- tional Science Fund for Talent Training in Basic Science （No. J1103204）, and Ten Thousand Talents Program for young talents. Part of the sample fabrication was performed at Fudan Nano-fabrication Laboratory. We acknowledge Yuanbo Zhang, Yizheng Wu, Zuimin Jiang, Likai Li, Boliang Chen for great assistance during the device fabrication and measurements.
文摘Two-dimensional （2D） materials have attracted substantial attention in electronic and optoelectronic applications with the superior advantages of being flexible, transparent, and highly tunable. Gapless graphene exhibits ultra-broadband and fast photoresponse while the 2D semiconducting MoS2 and GaTe exhibit high sensitivity and tunable responsivity to visible light. However, the device yield and repeatability call for further improvement to achieve large-scale uniformity. Here, we report a layer-by-layer growth of wafer-scale GaTe with a high hole mobility of 28.4 cm^2/（V.s） by molecular beam epitaxy. The arrayed p-n ）unctions were developed by growing few-layer GaTe directly on fhree-inch Si wafers. The resultant diodes reveal good rectifying characteristics and a high photovoltaic external quantum efficiency up to 62% at 4.8 μW under zero bias. The photocurrent reaches saturation fast enough to capture a time constant of 22 μs and shows no sign of device degradation after 1.37 million cycles of operation. Most strikingly, such high performance has been achieved across the entire wafer, making the volume production of devices accessible. Finally, several photoimages were acquired by the GaTe/Si photodiodes with reasonable contrast and spatial resolution, demonstrating the potential of integrating the 2D materials with silicon technology for novel optoelectronic devices.
基金supported by the National Natural Science Foundation of China(Grant No.10334070).
文摘Nanosecond (ns) photoelectric effects have been observed in all-oxide p-n junctions of La0.9Sr0.1MnO3/SrNb0.01Ti0.99O3 for the first time. The rise time was about 23 ns and the full width at half maximum was about 125 ns for the open-circuit photovoltaic pulse when the La0.9Sr0.1MnO3 thin film in the p-n junction was irradiated by a laser of ~20 ns pulse duration and 308 nm wavelength. The photovoltaic sensitivity was 80 mV/mJ for a 308 nm laser pulse.
基金This work was supported by the National Key R&D Program of China(Nos.2018YFA0703700 and 2016YFA0200700)the National Natural Science Foundation of China(Nos.91964203,61625401,61851403,61974036,61804146,and 61804035)+1 种基金the strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB30000000)CAS Key Laboratory of Nanosystem and Hierarchical Fabrication.The authors also gratefully acknowledge the support of Youth Innovation Promotion Association CAS.
文摘Neuromorphic machine vision has attracted extensive attention on wide fields.However,both current and emerging strategies still suffer from power/time inefficiency,and/or low compatibility,complex device structure.Here we demonstrate a driving-voltage-free optoelectronic synaptic device using non-volatile reconfigurable photovoltaic effect based on MoTe_(2)/α-In_(2)Se_(3) ferroelectric p-n junctions.This function comes from the non-volatile reconfigurable built-in potential in the p-n junction that is related to the ferroelectric polarization inα-In_(2)Se_(3).Reconfigurable rectification behavior and photovoltaic effect are demonstrated firstly.Notably,the figure-of-merits for photovoltaic effect like photoelectrical conversion efficiency non-volatilely increases more than one order.Based on this,retina synapse-like vision functions are mimicked.Optoelectronic short-term and long-term plasticity,as well as basic neuromorphic learning and memory rule are achieved without applying driving voltage.Our work highlights the potential of ferroelectric p-n junctions for enhanced solar cell and low-power optoelectronic synaptic device for neuromorphic machine vision.
