Improvement in photocurrent performance remains the key subject to prepare a stable and efficient photocathode in photoelectrochemical cell (PEC) water splitting. Different to the ordinary methods, various annealing atmosphere gases were used to study the growth of CuO films on fluorine-doped tin oxide substrate; then, the photocurrent performance was studied when those CuO films were used as photocathodes in PEC. The scanning electron microscopy images indicate that all of the CuO films are composed of vertically arrayed CuO nanosheets, each individual nanosheet with a thickness of 100–500 nm. Those hierarchical CuO photoelectrodes in the PEC exhibit quite different photoelectrochemical activities in visible light, where the air-annealed CuO film has nearly 6 times enhancement in photocurrent (108 μA) at 0 V compared to that of film under oxygen atmosphere, and 34 times of argon. It has an acceptor concentration of 2.9 × 10²¹ cm^–3 from Mott–Schottky analysis, which is more than 2 times larger than that of the oxygen-annealed CuO film, and 37 times larger than that of the argon-annealed film. Ultraviolet photoelectron spectroscopy measurements were carried out to explain the improved photocurrent performance of the air-annealed CuO films, where the obtained valence band of 0.44 eV and work function of 4.92 eV well match the reduction reaction of electrolyte (H₂O).

中文翻译：

---

不同的退火气体对FTO衬底上生长的CuO薄膜的生长和光电流性能的影响

光电流性能的改善仍然是制备光电化学电池（PEC）中水分解稳定有效的光阴极的关键课题。与普通方法不同，使用各种退火气氛气体研究了掺氟氧化锡衬底上CuO薄膜的生长。然后，研究了将这些CuO薄膜用作PEC的光电阴极时的光电流性能。扫描电子显微镜图像表明，所有的CuO薄膜均由垂直排列的CuO纳米片组成，每个纳米片的厚度为100-500 nm。PEC中的那些分层CuO光电电极在可见光下表现出截然不同的光电化学活性，空气退火的CuO薄膜在0 V时的光电流（108μA）与氧气气氛下的薄膜相比提高了近6倍，而氩气则提高了34倍。受体浓度为2.9×10Mott–Schottky分析得出的²¹ cm ^–3，比氧退火的CuO薄膜大2倍，比氩气退火的薄膜大37倍。进行了紫外光电子能谱测量，以说明空气退火CuO薄膜的改进的光电流性能，其中获得的价带为0.44 eV，功函为4.92 eV与电解质（H ₂ O）的还原反应很好地匹配。