Nearly Barrierless Four-Hole Water Oxidation Catalysis on Semiconductor Photoanodes with High Density of Accumulated Surface Holes

作者：Siqin Liu, Kun Dang, Lei Wu, Shuming Bai, Yuchao Zhang, Jincai Zhao · 发表于：Journal of the American Chemical Society · 年份：2025 · DOI：10.1021/jacs.4c16443 · 被引用次数：22 · 研究领域：Advanced Photocatalysis Techniques、Copper-based nanomaterials and applications、Electronic and Structural Properties of Oxides

The sluggish water oxidation reaction (WOR) is considered the kinetic bottleneck of artificial photosynthesis due to the complicated four-electron and four-proton transfer process. Herein, we find that the WOR can be kinetically nearly barrierless on four representative photoanodes (i.e., α-Fe 2 O 3, TiO 2, WO 3, and BiVO 4 ) under concentrated light irradiation, wherein the rate-limiting O–O bond formation step is driven by accumulated surface photogenerated holes that exhibit a superior fourth-order kinetics. The activation energy is about 0.03 eV for the fourth-order kinetic pathway, which is quantitatively estimated by combining the Population model and Butler–Volmer model with the Eyring-like equation and is further confirmed by density functional theory calculations. The WOR rate under this condition shows more than 1 order of magnitude enhancement compared with that of first-, second-, or third-order kinetics. Focusing on α-Fe 2 O 3, the accumulated high-density surface holes form adjacent Fe V ═O intermediates that effectively activate surface-adsorbed H 2 O molecules via the hydrogen-bonding effect, as revealed by operando Raman measurements and ab initio molecular dynamics simulations. This work discloses a systematic understanding of the internal relations between activation energy and reaction orders of surface holes for future WOR study.