Single atom Cu-O <sub>2</sub>N bridge between BiVO <sub>4</sub> and COFs toward photoelectrochemical seawater splitting
Zicong Zhang, Gaohang Song, Wenming Sun, Zhaorui Hua, Yang Tian
Abstract
Photoelectrochemical (PEC) water splitting has great potential for solar energy conversion to hydrogen. However, the slow charge transfer in the photoanodes remains a core issue limiting the PEC performance. In this study, we address this issue by constructing a single-atom bridge (SAB) Cu-O<sub>2</sub>N at the interface between BiVO<sub>4</sub> and covalent organic framework (COF) layer. X-ray absorption fine spectra and theoretical calculations demonstrate that the single-atom bridge is formed by the interfacial coordination reconstruction between BiVO<sub>4</sub> and COF layers and create intermediate electronic states to facilitate the hole extraction. As a result, the SAB photoanode exhibits enhanced PEC water oxidation performance. Specifically, it achieves a photocurrent density of 4.84 mA·cm<sup>−2</sup> at 1.23 V vs. reversible hydrogen electrode (RHE) in PEC simulant seawater splitting with a cocatalyst, higher than nearly all the previously reported BiVO<sub>4</sub>-based photoanodes. This work offers valuable insights into fast charge transfer in PEC systems and proposes a promising strategy for designing efficient photoelectrodes for seawater splitting.