Hydrogen-Bonded Perovskite Heterojunction Photocatalytic Membrane with Efficient Proton Supply for Boosting CO₂...

Efficient proton supply and enhanced *CO intermediate adsorption are crucial strategies for boosting CO₂ methanation. Herein, we construct a hydrogen-bonded (H-bonded) photocatalytic membrane by integrating a MAPbBr₃/cyano-g-C₃N₄ (MPB/CN-g-CN) heterojunction with ethyl cellulose (ECE) binder through a simple sol-gel process, achieving significantly enhanced CO₂ methanation efficiency. ECE functions as a novel proton source, with hydroxyl (-OH) groups that are readily oxidized by photogenerated holes, resulting in efficient proton supply compared to H₂O. Moreover, ECE facilitates membrane assembly via interfacial H-bonding between the -OH moieties of ECE and the modified nitrogen sites of MPB/CN-g-CN, generating proton-rich interfaces and local H-bond microenvironments that synergistically enhance proton supply and CO adsorption, thus steering the reaction toward CH₄ production. As a result, the MPB/CN-g-CN membrane achieves a remarkable increase in CH₄ yield from 0.01 to 35.85 µmol g^-1 h^-1 and selectivity from 0.4% to 82% compared to the pristine heterojunction. Furthermore, the MPB/CN-g-CN/ECE membrane demonstrates exceptional recyclability through a re-crosslinking membrane formation process, effectively reactivating proton-supply sites while maintaining superior CH₄ selectivity across multiple operational cycles.