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We investigated the effects of stoichiometry on photovoltages and photocurrents in CuBi2O4 thin-film photocathodes grown by pulsed laser deposition under different oxygen partial pressures to manipulate their stoichiometry. While the X-ray diffraction patterns show crystalline phases in the CuBi2O4 thin films, it is found that the Cu/Bi ratio of the CuBi2O4 thin films varied from ~0.3 to ~0.5 which are analyzed by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. The slightly off-stoichiometric CuBi2O4 thin-film photocathode with a Cu/Bi ratio of ~0.44 shows the highest photocurrent density in the CuBi2O4 thin films. More interestingly, the off-stoichiometric CuBi2O4 thin-film photocathode with a Cu/Bi ratio of ~0.44 exhibited a stable open-circuit voltage difference of ~0.2 V RHE without severe degradation over time. On the other hand, the photovoltage of the stoichiometric CuBi2O4 thin-film photocathode with a Cu/Bi ratio of ~0.5 gradually decreased as a function of time. Our results suggest that stoichiometry manipulation can be one of the promising strategies to achieve long-term stable Cu-based oxide photocathodes with the maintenance of a stable photovoltage.

Photoelectrochemical (PEC) biomass oxidation by the substitution of an oxygen evolution reaction is considered a promising strategy for efficient hydrogen production.

The coupling of transition metal dichalcogenides (TMDs) and other materials offers significant synergistic effects; however, the fabrication of artificial multiheterojunction (MHJ) TMDs is a signif...

Herein, we present a facile synthesis of ZnO microrods and surface decoration with gold nanoparticles using a low-cost deposition apparatus. The ZnO microrods were fabricated via a single-step solid-state reaction, and the gold nanoparticles were synthesized on the surface of the microrods by the deposition of gold thin films and sequential heat treatment. The size of the gold nanoparticles was controlled by varying the thickness of the gold thin films and the annealing temperature. The intensity of green emission in the photoluminescence spectra decreased with increasing gold nanoparticle size. A surface plasmon resonance peak originating from the gold nanoparticles appeared at ~570 nm in the absorption spectra, and the peak redshifted as the nanoparticle size increased. The ultraviolet (UV) on–off current ratio and response speed of single ZnO microrod photodetectors significantly increased after surface decoration by gold nanoparticles. However, the performance of the photodetector degraded as the size of the gold nanoparticles increased owing to the absorption of incident UV light. The enhanced photodetector performance of the surface-modified ZnO microrods is explained by the transfer of energetic electrons excited by surface plasmon resonance from the defect level to the conduction band of the ZnO microrods.