- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Poly(1,4-di(2-thienyl))benzene Facilitating Complete Light-Driven Water Splitting under Visible Light at High pH
摘要： The recent discovery that metal-free polyterthiophene (PTTh) prepared by iodine-vapor-assisted polymerization (IVP) can catalyze the hydrogen evolution reaction (HER) when illuminated, and this light-enhanced electrolysis expresses a non-Nernstian relation with pH, provides the foundation for further improvement of the photovoltage of the reaction by engineering the band structure of the light-absorbing polymer. Deviating from an all-thiophene backbone, using poly(1,4-di(2-thienyl))benzene (PDTB) lowers the highest occupied molecular orbital level by ≈0.3 eV compared with polythiophene, and PDTB simultaneously maintains the photoelectrocatalytic properties without an all-thiophene backbone, resulting in very high conversion rate of 600 mmol(H2) h?1 g?1 at 0 V versus the reversible hydrogen electrode (RHE) at pH 11. PDTB shows the same non-Nernstian behavior as PTTh with increasing onset potential (versus RHE) at higher pH, and the open circuit potential on PDTB under visible light reaches 1.4 V versus RHE at pH 12. The PDTB photocathode thus produces a photovoltage above the theoretical potential for the complete water-splitting (1.229 V) and is indeed able to produce hydrogen in a one-photon-per-electron light-driven water splitting setup with MnOx as the anode at a rate of 6.4 mmol h?1 gPDTB?1.
关键词： high pH,photocathodes,water splitting,hydrogen evolution,poly(1,4-di(2-thienyl))benzene
更新于2025-11-19 16:51:07
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Femtosecond pump-probe spectroscopy investigation of carrier dynamics in GaAlAs photocathods
摘要： Based on the study of GaAs photocathode, the carrier dynamics of re?ection-mode GaAlAs photocathode has been investigated. In this paper, the re?ection-mode GaAlAs/GaAs photocathode is grown by metal organic chemical vapor deposition (MOCVD) epitaxial technology. The femtosecond pump-probe spectroscopy is performed to measure carrier dynamics in GaAlAs and GaAs photocathods. After laser excitation the surfaces of GaAlAs/GaAs photocathode, the re?ectivity of photocathode surface is changed. At the same time, the dynamic processes of the non-equilibrium carrier distribution in semiconductor material is obtained by the transient re?ectance spectrum. Compared with GaAs photocathode, the Al element in GaAlAs photocathode is unfavorable to photoemission under some conditions, while it solves the problem that the spectrum response range of binary compounds is not adjustable. The change trend of initial relaxation transient of GaAs photocathode in the 22 ps range is the same as GaAlAs, while the change of GaAs and GaAlAs relaxation state is signi?cantly di?erent with the change of delay time after 22 ps. The results show that the GaAlAs increases band gap due to a signi?cantly slower than GaAs photocathode in initial process. Meanwhile, this paper provides a reference for the preparation of the GaAlAs photocathode that only respond to blue and green light range.
关键词： Re?ectivity,Dynamic processes,Femtosecond,Re?ection-mode,Photocathodes
更新于2025-09-23 15:23:52
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Photoelectrochemical water splitting with p-type metal oxide semiconductor photocathodes Youn Jeong Jang[a] and Jae Sung Lee*[a]
摘要： Photoelectrochemical (PEC) water splitting is a promising way to produce clean and sustainable hydrogen fuel. Solar hydrogen production using p-type metal oxide semiconductor photocathodes has not been studied as extensively as n-type metal oxide semiconductor photoanodes and p-type PV-grade non-oxide semiconductor photocathodes. Copper-based oxide photocathodes show relatively good conductivity but suffer from instability in an aqueous solution under illumination. On the other hands, Fe-based metal oxide photocathodes demonstrate more stable PEC performance, but have problems in charge separation and transport. In this mini-review article, we provide an overview of the recent progress in p-type metal oxide-based photocathodes for PEC water reduction. Although these materials are not fully developed up to their potential performance, the involved challenges have been identified and strategies to overcome the limitations have been proposed. Future research in this field should address these issues and challenges in addition to discovery of new materials.
关键词： metal oxides,p-type semiconductors,photoelectrochemical cell,photocathodes,solar water splitting
更新于2025-09-23 15:22:29
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Nanostructuring Strategies To Increase the Photoelectrochemical Water Splitting Activity of Silicon Photocathodes
摘要： Photoelectrochemical water splitting is a promising route for sustainable hydrogen production. Herein, we demonstrate a photoelectrode motif that enables a nanostructured large-surface area electrocatalyst without requiring a nanostructured semiconductor surface with the goal of promoting electrocatalysis while minimizing surface recombination. We compare the photoelectrochemical H2 evolution activity of two silicon photocathode nanostructuring strategies: (1) direct nanostructuring of the silicon surface and (2) incorporation of nanostructured zinc oxide to increase the electrocatalyst surface area on planar silicon. We observed that silicon photocathodes that utilized nanostructured ZnO supports outperformed nanostructured silicon electrodes by ～50 mV at open circuit under 1 sun illumination and demonstrated comparable electrocatalytic activity.
关键词： photocathodes,silicon nanowires,hydrogen evolution,molybdenum disulfide,zinc oxide nanowires,photoelectrochemical water splitting
更新于2025-09-23 15:22:29
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Plasmonic nanostar photocathodes for optically-controlled directional currents
摘要： Plasmonic nanocathodes offer unique opportunities for optically driving, switching, and steering femtosecond photocurrents in nanoelectronic devices and pulsed electron sources. However, angular photocurrent distributions in nanoplasmonic systems remain poorly understood and are therefore difficult to anticipate and control. Here, we provide a direct momentum-space characterization of multiphoton photoemission from plasmonic gold nanostars and demonstrate all-optical control over these currents. Versatile angular control is achieved by selectively exciting different tips on single nanostars via laser frequency or linear polarization, thereby rotating the tip-aligned directional photoemission as observed with angle-resolved 2D velocity mapping and 3D reconstruction. Classical plasmonic field simulations combined with quantum photoemission theory elucidate the role of surface-mediated nonlinear excitation for plasmonic field enhancements highly concentrated at the sharp tips (Rtip = 3.4 nm). We thus establish a simple mechanism for femtosecond spatiotemporal current control in designer nanosystems.
关键词： Plasmonic nanostars,gold nanostars,photocathodes,optically-controlled directional currents,multiphoton photoemission
更新于2025-09-23 15:19:57
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Unassisted Water Splitting Using Standard Silicon Solar Cells Stabilized with Copper and Bi-functional NiFe Electrocatalysts
摘要： Silicon photovoltaic cells functionalized with water splitting electro-catalysts are promising candidates for unassisted water splitting. In these devices, the total surface of silicon solar cell is covered with electrocatalyst causing issues with i) stabilizing silicon solar cell in water and ii) device efficiency due to parasitic optical absorption in electrocatalyst. We describe and validate a water splitting device concept using a crystalline silicon solar cell where the front-side is covered with insulating Si3N5 antireflection coating. The Ag contacts, fired through the antireflection coating, are removed and subsequently substituted with NiFe layered double hydroxide (LDH) or Cu/NiFe-LDH electrocatlysts. In this device only the site of Ag contacts, nearly 2% of total device area is covered by the electrocatalyst. We found this small area of catalyst does not limit device performance and addition of a Cu interlayer between Si and NiFe-LDH improves device performance and stability. The unassisted water splitting efficiency of 11.31%, measured without separating the evolved gases, is achieved using a device composed of three series-connected silicon solar cells and a NiFe-LDH/Cu/Ni-foam counter electrode in a highly alkaline electrolyte.
关键词： NiFe layered double hydroxides,Photoelectrochemical Cells,Unassisted Water Splitting,Crystalline Silicon Solar Cell,Si Photocathodes
更新于2025-09-23 15:19:57
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Highdetectivity AlInSb Midinfrared Photodiode Sensors with Dislocation Filter Layers for Gas Sensing
摘要： A midinfrared photodiode is developed for methane gas sensing based on the highly mismatched AlInSb/GaAs system. Inserting optimized dislocation filter layers (DFLs) in the buffer layer reduced the threading dislocation density in the active layer to less than one-third of that in the photodiode without DFLs. This improvement produces a high normal incidence detectivity of 1.8 (cid:1) 109 cm p (cid:3)1 at 3.3 μm, which is more than twice the highest detectivity previously obtained for a photodiode without DFLs.
关键词： bialkali,quantum efficiency enhancements,accelerator technologies,graphene,antimonide photocathodes
更新于2025-09-16 10:30:52
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[IEEE 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Sydney, Australia (2018.11.10-2018.11.17)] 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC) - Development of Sealed Tube Microchannel Plate Detectors with Cross Strip Readouts
摘要： Cross strip readout anodes provide a novel high spatial resolution image encoding system for microchannel plate sensors. We have developed cross strip readouts with metal & ceramic layers for 50 mm format sealed tubes based on the “Planacon” concept. These have next generation atomic layer deposited microchannel plates for amplification and selected photocathodes covering the UV and optical regimes. These devices will be relevant for the next generation of moderate and large NASA astrophysics instruments that are baselining 50 mm to 200 mm format detectors. The critical elements of the sensors are high QE, high spatial resolution and large event rate limits, with long lifetimes. Our photocathode work includes customization of bialkali semitransparent cathodes with response from 120 nm to 320 nm and a sharp 360 nm cutoff. Opaque alkali halide photocathodes on the atomic layer deposited microchannel plates have shown high quantum efficiencies (50% @ 115 nm) and could be used simultaneously with bialkali photocathodes. The atomic layer deposited microchannel plates have borosilicate substrates which are robust and can be be produced in large formats (20 × 20 cm) with high open area ratios (~73%). These MCPs have very low intrinsic background (<0.06 events/sec/cm2), high gain, and very good lifetime stability. With the cross strip readout and encoding electronics we achieve high spatial resolutions (<20 μm FWHM) over both 50 mm and 100 mm formats at event rates exceeding 5 MHz, providing a powerful baseline for future NASA UV/optical instruments.
关键词： photocathodes,atomic layer deposited microchannel plates,Cross strip readout,UV and optical regimes,microchannel plate sensors,NASA astrophysics instruments
更新于2025-09-16 10:30:52
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Ion Beam Defect Engineering on ReS <sub/>2</sub> /Si Photocathode with Significantly Enhanced Hydrogen Evolution Reaction
摘要： Loading 2D layered transition metal dichalcogenides (TMDs) on p-type silicon photocathode is suitable for hydrogen production in solar-driven photoelectrochemical (PEC) water splitting. Similarly, various nanostructured TMDs exposing more active sites are widely explored for improving the PEC performances of composite photoelectrodes. Here, defect engineering using a controllable argon ion beam bombardment is presented on ReS2/Si photocathode. The atomic vacancy defects are introduced on the 2D ReS2 to realize high-density active sites, which significantly enhance the solar-driven hydrogen evolution reaction performance of ReS2/Si photocathode. The highest photocurrent density of 18.5 mA cm?2 (at 0 V vs reversible hydrogen electrode) is achieved, under a simulated sun irradiation.
关键词： ion beam bombardment,defect engineering,photocathodes,photoelectrochemical water splitting,ReS2
更新于2025-09-09 09:28:46
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Child-Langmuir law for photoinjectors
摘要： The space-charge ?eld at the cathode limits the current density extracted from particle sources such as photoinjectors. For a long time, the maximum current has been estimated by using the classical Child-Langmuir law, which is derived with an assumption inconsistent with the conditions of modern laser-driven electron guns. Here, we introduce a theoretical model that accurately accounts for space-charge effects in transversely con?ned particle beams emerging from photocathodes. The model enables us to (i) determine the maximum current density extractable from the photocathode for an arbitrary cathode radius, (ii) reveal its dependence on the transverse pro?le of the particle beam, and (iii) predict its upper limit for structured beams such as the ones produced by surface-plasmon resonance-enhanced photocathodes.
关键词： photocathodes,space-charge effects,Child-Langmuir law,photoinjectors,surface-plasmon resonance
更新于2025-09-09 09:28:46