Different Annealing Atmosphere Gases on the Growth andPhotocurrent Performance of CuO Films Grown on FTO Substrate

摘要

Improvement in photocurrent performanceremains the key subject to prepare a stable and efficientphotocathode in photoelectrochemical cell (PEC) watersplitting. Different to the ordinary methods, various annealingatmosphere gases were used to study the growth of CuO filmson fluorine-doped tin oxide substrate; then, the photocurrentperformance was studied when those CuO films were used asphotocathodes in PEC. The scanning electron microscopyimages indicate that all of the CuO films are composed ofvertically arrayed CuO nanosheets, each individual nanosheet with a thickness of 100?500 nm. Those hierarchical CuOphotoelectrodes in the PEC exhibit quite different photoelectrochemical activities in visible light, where the air-annealed CuOfilm has nearly 6 times enhancement in photocurrent (108 μA) at 0 V compared to that of film under oxygen atmosphere, and34 times of argon. It has an acceptor concentration of 2.9 × 1021 cm?3 from Mott?Schottky analysis, which is more than 2 timeslarger than that of the oxygen-annealed CuO film, and 37 times larger than that of the argon-annealed film. Ultravioletphotoelectron spectroscopy measurements were carried out to explain the improved photocurrent performance of the airannealed CuO films, where the obtained valence band of 0.44 eV and work function of 4.92 eV well match the reductionreaction of electrolyte (H2O).