Cu2O|NiOx nanocomposite as an inexpensive photocathode in photoelectrochemical water splitting
Cu2O|NiOx nanocomposite as an inexpensive photocathode in photoelectrochemical water splitting
复制标题
DOI：
10.1039/c2sc20874a
复制
发表时间：
2012-12-01
期刊：
影响因子：
8.4
通讯作者：
Reisner, Erwin
中科院分区：
文献类型：
--
作者：
Lin, Chia-Yu;Lai, Yi-Hsuan;Reisner, Erwin
提出了一种用于全面水分解的光电电池，该电池由二氧化硅纳米线光电阴极和氧化钨纳米片光电阳极修饰而成。将Cu(OH)(2)纳米线置于Cu箔上，在N-2条件下进行热退火，然后在Cu2O纳米线（宽高比bbb40）上沉积10 nm的NiOx薄膜，制备出光电阴极。XPS谱分析表明，NiOx的表面形态为NiO和Ni(OH)(2)的混合物，促进了Cu2O在光激发下的电荷分离。优化后的NiOx修饰的Cu2O电极在-0.33 V和-0.56 mA cm（-2）下的光电流密度分别为-4.98 mA cm（-2）和-0.56 mA cm（-2）。与普通氢电极（NHE）相比，在pH 6和25℃的水溶液中，白光照射（26 mW cm(-2)）， NiOx修饰的Cu2O电极只能通过气相色谱法观察到H-2气体的形成，而未修饰的Cu2O电极在长时间照射下无法检测到H-2气体的形成。纳米复合结构也使Cu2O的光稳定性提高了3倍；与NHE相比，0.1 V辐照20 min后，NiOx修饰的Cu2O电极的初始光电流密度仍为72 +/- 3%。优化后的光电阴极随后被用于双电极PEC电池，其n型WO3纳米片光阳极用于整体水分解。Cu2O （2ev）和WO3 （2.6 eV）的带隙不同，可实现高效互补的光吸收和阳光驱动的水分解。即使在没有外部偏压的情况下，p/n异质结PEC电池的输出电流也很小。我们证明了一种用于H-2演化的cu2o基电极可以在不含贵金属的情况下制备，并且我们展示了它在PEC水分解电池中的应用
A photoelectrochemical (PEC) cell for overall water splitting made of a Cu2O nanowire photocathode modified with a thin film of NiOx coupled to a WO3 nanosheet photoanode is presented. The photocathode was prepared by thermal annealing of Cu(OH)(2) nanowires on a Cu foil under N-2, followed by the deposition of a 10 nm NiOx film on the Cu2O nanowires (aspect ratio > 40). XPS spectra revealed that the surface species of NiOx is a mixture of NiO and Ni(OH)(2), which enhances charge separation in photoexcited Cu2O, as confirmed by electrochemical impedance spectroscopy. The optimized NiOx modified Cu2O electrode shows a photocurrent density up to -4.98 mA cm(-2) at -0.33 V and -0.56 mA cm(-2) at 0.1 V VS. the normal hydrogen electrode (NHE) under white-light irradiation (26 mW cm(-2)) in an aqueous electrolyte solution at pH 6 and 25 degrees C. The formation of H-2 gas was only observed by gas chromatography for NiOx-modified Cu2O and was not detectable for unmodified Cu2O electrodes during prolonged irradiation. The nanocomposite structure also resulted in a three-fold increase in photostability of Cu2O; 72 +/- 3% of the initial photocurrent density remained for the NiOx modified Cu2O electrode after 20 min irradiation at 0.1 V vs. NHE. The optimized photocathode was subsequently used in a two-electrode PEC cell with an n-type WO3 nanosheet photoanode for overall water splitting. The different band gap of Cu2O (2 eV) and WO3 (2.6 eV) permits for efficient and complementary light absorption and sunlight-driven water splitting. The p/n heterojunction PEC cell operates with a small output of electricity even in the absence of an external bias. We demonstrate that a Cu2O-based electrode for H-2 evolution can be prepared free of noble metals and we show its utilization in a PEC water splitting cell made solely from earth abundant