Enhancing Photocatalytic Activity for Solar‐to‐Fuel Conversion: A Study on S‐Scheme AgInS₂/CeVO₄@Biochar_x Heterojunctions

Abstract Rare earth vanadates are promising for solar‐to‐fuel conversions, yet their photocatalytic efficiency is limited by the substantial recombination of photo‐generated carriers. Constructing heterojunctions is recognized as an effective approach to improving charge carrier separation in vanadates. Nonetheless, inefficient charge transfer often results from the poor quality of interfaces and non‐directional charge transfer within these heterojunctions. Herein, an S‐scheme AgInS₂/CeVO₄@Biochar_x (AIS/CV@C_x) heterojunction photocatalyst is designed and synthesized through a straightforward freeze‐drying and calcination three‐step process, aimed at photocatalytic co‐production of xylonic acid and carbon monoxide (CO) from xylose. The AIS/CV@C₂ heterojunction achieves an optimal yield of 67.74% for xylonic acid and a CO release of 29.76 µmol from xylose. The enhanced photocatalytic performance of the AIS/CV@C₂ heterojunction is attributed to three key factors: I) the high‐quality interface and intimate contact within the AIS/CV@C₂ heterojunction significantly reduce undesirable carriers recombination, II) the staggered band structures and directed carriers transfer in the AIS/CV@C₂ heterojunction notably improve spatial carriers separation/migration, and III) the incorporation of biochar boosts the conductivity of the AIS/CV@C₂ heterojunction. This work presents a straightforward yet effective method for fabricating vanadate heterojunctions, highlighting the importance of quality interfacial contact and directed charge transfer in amplifying photocatalytic performance.