Surface Hydroxylated S/O Dual‐Vacancy S‐Scheme Hollow [In₂S_3‐x/In₂O_3‐x](OH)_y Heterojunction for Photothermal‐promoted Low‐Temperature Methanol/Water Reforming into Hydrogen

Abstract To enable highly efficient in situ hydrogen release from methanol/water reforming at lower temperature, the integration of solar‐energy offers a promising approach to activate methanol/water and substantially lower the activation energy of this reaction. Herein, we present a novel dual‐vacancy defective hollow heterostructure derived from Metal–Organic Frameworks, featuring abundant surface hydroxyl groups and S/O vacancies, for photothermal‐promoted methanol solution reforming into hydrogen. The [In 2 S 3‐x /In 2 O 3‐x ](OH) y exhibits exceptional photothermal H 2 evolution activity, achieving a production rate of 215.2 mmolg cat −1 h −1 , 16‐fold higher than its thermocatalytic activity, with an apparent quantum efficiency of 66.8 % at 365 nm and solar‐to‐hydrogen efficiency (STH) of 1.1 % under AM 1.5G simulated solar illumination, and excellent durability over 82 h, cumulating 2.61×10 3 mmolg cat −1 . The synergistic effects of dual‐vacancies and the hollow heterostructure significantly enhance the photothermal effect, lowering the activation energy barrier for methanol/water, enabling H 2 production at temperatures even as 80 °C under non‐alkaline conditions. Furthermore, the incorporated surface hydroxyl groups facilitate the generation of active surface hydroxyls from water, further driving activation and cleavage of C−H bonds in methanol, thereby markedly reducing the apparent reaction activation energy by 12.5 %. This work provides a new strategy for effective H 2 production from aqueous methanol reforming under mild conditions, holding great promise for energy‐demanding industrial applications.