Synergistic Hydrogen Evolution and Methanol Oxidation Over BiOIO ₃ /Zn ₃ In ₂ S ₆ Heterojunction Photocatalyst via Interfacial Charge Steering

ABSTRACT Because of superior transportability and high energy capacity, methanol is regarded as a potential hydrogen carrier. Photocatalytic methanol dehydrogenation offers a sustainable and cost‐effective method for releasing hydrogen. Conventional photocatalysts face challenging obstacles, including the low catalytic efficiency and rapid recombination of charge carriers. To overcome these challenges, noble‐metal‐free S‐scheme heterojunctions were constructed by integrating Zn 3 In 2 S 6 (ZIS) microspheres with BiOIO 3 (BIO) nanosheets in this work. The ZIS/BIO (ZB X ) heterojunction reaches a hydrogen evolution rate of 3.46 mmol g −1 h −1 in a 20 mL reaction mixture (75 vol% methanol–water) under light. Through advanced characterization tools, the interfacial charge transfer behaviors and reaction pathways are investigated systematically. Revealed by mechanistic studies, electrons in ZIS with strong reducing power and holes in BIO are preserved within the ZB X heterojunction, enabling efficient proton reduction and selective methanol oxidation to formaldehyde. Integrating hydrogen production with value‐added chemical synthesis under mild conditions, this work offers a new approach for designing inexpensive photocatalysts and advancing widespread applications for potential escalation and industrialization.