Immobilization of Covalent Triazine Framework into Hydrogels for Photothermal‐Promoted Gas‐Solid Photocatalytic Hydrogen Production

Organic photocatalysts generally suffer from insufficient near-infrared light absorption and undesirable photogenerated charge transport properties, resulting in unfavorable hydrogen evolution performance from water splitting. Hydrogen evolution reaction (HER) is also known to be significantly influenced by the interfacial charge and mass transfer in a catalyst/H₂O biphase system. Herein, for the first time, a highly stable and floating hydrogen-water cogeneration hybrid hydrogel that utilizes photothermal-induced interface microenvironment variation to accelerate sluggish photocatalytic water splitting reaction is reported. Supported by solar-powered interfacial evaporation and efficient vapor generation, the rationally designed hydrogel effectively transforms the conventional liquid-solid interface into a gas-solid photocatalytic interface. The presence of gas-liquid coexistence state offers a disordered and loose hydrogen-bond network while preserving the proton transfer channel, greatly reducing reaction activation energy and interfacial energy barriers. The improved heat and mass transfer together with optimized charge transfer pathways suppress electron-hole recombination, the integrated photothermal-coupled solar photocatalytic hydrogel exhibits excellent operational stability and self-adaptive rotation in seawater, mitigating salt accumulation and achieving an exceptional vapor generation rate of 4.71 kg m^-2 h^-1 and a hydrogen-evolving rate of 1961.25 µmol g^-1 h^-1 under one sun illumination.