Anti-photocorrosive photoanode with RGO/PdS as hole extraction layer
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Published online 21 April 2020 | https://doi.org/10.1007/s40843-020-1307-x
Anti-photocorrosive photoanode with RGO/PdS as hole extraction layer 1†
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Guo-Qiang Liu , Yi Li , Yuan Yang , Feng-Jia Fan , Guang-Hao Ding , Liang Wu , Jun Hu , 4 3 3 1* Jin-Lan Peng , Qian Xu , Jun-Fa Zhu and Shu-Hong Yu ABSTRACT Photoelectrochemical (PEC) hydrogen production is of great interest as an ideal avenue towards clean and renewable energy. However, the instability and low energy conversion efficiency of photoanodes hinder their practical applications. Here we address these issues by introducing a hole extraction layer (HEL) which could rapidly transfer and consume photogenerated holes. The HEL is constructed by reduced graphene oxide (RGO) and other cocatalysts that enable rapid transfer and subsequent consumption of holes, respectively. Specifically, we showcase a high-stability photoanode composed of CdSeTe nanowires (CST NWs) and RGO/ PdS nanoparticles (PdS NPs) based HEL. The photoanode achieves excellent photocorrosion resistance, which allows stable hydrogen evolution for > 2 h at 0.5 VRHE. Keywords: CdSeTe, photoelectrochemistry, hole extraction layer, photocorrosion, photoanode
INTRODUCTION Photoelectrochemical (PEC) hydrogen production provides a highly promising and eco-friendly way of solving the energy crisis [1–13]. Among multitudinous semiconductors, II-VI semiconductors CdX (X= Se, Te) with energy band gaps of 1.4–1.7 eV have strong absorptions for visible and near-infrared light [14–16]. The suitable 5 −1 band gap and high absorption coefficient (α, 10 cm ) endow these materials with the potential to act as efficient photoelectrodes [16–19]. Unfortunately, the cadmium chalcogenides, such as
CdTe and CdSe, often suffer from a detrimental photocorrosion due to the photogenerated holes, resulting in severe performance degradation during operation [20– 22]. The photocorrosion in chalcogenide semiconductors origins from poor hole transfer and the subsequent sluggish redox reactions at photoelectrode-electrolyte interface. To date, there are two approaches to prevent the photocorrosion of cadmium chalcogenides. One is to introduce physical barriers, such as an inert passivation layer (for instance, SiO2 and TiO2), that can isolate semiconductors from the electrolyte [23,24]. However, the concomitantly retarded interfacial charge transfer and blocked surface reaction sites discount their solar conversion efficiency. The other is to accelerate hole transfer and subsequent redox reactions with electrolytes to a level kinetically competitive to the photocorrosion process. The most common strategy in this respect is to introduce hetero/homojunctions for hole transfer [23,25,26], cocatalysts for hole-involved reactions [27–29], and combinations thereof, giving rise to some encouraging results. Whereas, efforts in improving the solar conversion efficiency and anti-photocorrosion capability of CdSe/CdTebased photoanodes remains unsatisfying, due to the absence of suitable hole extraction layers (HELs). We,
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