Sulfate-Functionalized Core–Shell ZnO/CdS/Ag<sub>2</sub>S Nanorod Arrays with Dual-Charge-Transfer Channels for Enhanced Photoelectrochemical Performance
Xiaoyu Xie, Ru Wang, Yi Ma, Jinping Chen, Zengliang Shi, Qiannan Cui, Zhiyong Li, Chunxiang Xu
Abstract
Insufficient light absorption and fast charge recombination seriously restrain the photoelectrochemical (PEC) water splitting performance of semiconductor photoelectrodes. Herein, sulfate ([SO4])-functionalized CdS was decorated on ZnO nanorod arrays by one-step magnetron sputtering to construct a core–shell heterojunction, and then Ag2S nanoparticles were deposited by cation exchange. The in situ formed [SO4] as an active site is helpful to accelerate charge transfer and enhance PEC reaction kinetics. Additionally, Ag2S was modified on ZnO/CdS to suppress the photocorrosion of CdS while constructing two heterojunctions with a gradient energy band configuration for separating and transporting photogenerated charge carriers efficiently. Benefiting from the dual-charge-transfer channels in [SO4] and Ag2S co-modified ZnO/CdS nanorod arrays, the optimized photoanode presents high PEC performance, yielding a maximum photocurrent density of ∼6.82 mA cm–2 at 1.23 V vs reversible hydrogen electrode (RHE) under simulated air mass (AM) 1.5 solar light illumination, which is 7.75 times that of pristine ZnO photoanode. This work provides a synergetic in situ [SO4] modification and heterojunction construction strategy to design photoelectrodes with multicharge-transfer channels for enhanced PEC performance.