Oxygen Vacancy-Enhanced Photoelectrochemical Water Splitting of WO<sub>3</sub>/NiFe-Layered Double Hydroxide Photoanodes
Wei Lin, Yue Yu, Yaoxun Fang, Jianqiao Liu, Xinran Li, Jiangpeng Wang, Yilin Zhang, Chao Wang, Lin Wang, Xuelian Yu
Abstract
Photoelectrochemical (PEC) water splitting serves as one of the promising approaches for producing clean and renewable energy, and their solar–hydrogen energy conversion efficiency depends on the interfacial charge separation and carrier mobility. Herein, we report an effective strategy to promote the PEC performance by fabricating a WO3 photoanode rich in oxygen vacancies (Ov) modified by NiFe-based layered double hydroxide (LDH). When WO3–Ov/NiFe-LDH is used as a photoanode, the maximum photocurrent density at 1.8 V versus RHE has been significantly enhanced to 2.58 mA·cm–2, which is 4.3 times higher than that of WO3. In addition, analogues were studied in controlled experiments without Ov, which further demonstrated that the synergistic effect of NiFe-LDH and Ov resulted in increased carrier concentration and driving force. According to electrical impedance spectroscopy, X-ray photoelectron spectroscopy, and Mott–Schottky analysis, the built-in electronic field in WO3 homojunction, along with the accelerated hole capture by the NiFe-LDH cocatalyst contributes to the improved charge separation and transport in the WO3–Ov/NiFe-LDH electrode. This work proposes an efficient and valuable strategy for designing the structure of WO3-based photoelectrodes.