Self-assembly synthesis of gallium-doped polymeric carbon nitride/Ti3C2 MXene Schottky junction for efficient photosynthesis of hydrogen peroxide

Schottky junction has been widely recognized as one promising strategy for advancing photocatalytic processes, where an internal electric field generated by the Schottky barrier ensures the efficient transfer of charge carriers and enhances the activation capabilities of active sites for reactants, thereby improving solar-to-chemicals performance. However, integration of the Schottky junction into superior photocatalytic H2O2 generation remains a formidable challenge. Accordingly, here we present a novel Ga-PCN/Ti3C2 Schottky junction, achieved by introducing gallium ions into tri-s-triazine repeating units of PCN and then decorating it with Ti3C2 MXene through in-situ electrostatic assembly. Systematic analysis revealed that gallium atoms interlinked with nitrogen in the PCN matrix to construct Ga-N coordination sites, while metallic Ti3C2 served as an excellent electron transfer mediator. This configuration simultaneously promoted the separation of photoexcited carriers and shortened charge transport distance from Ga-PCN to Ti3C2. As a result, an apparent quantum yield of 1.58% at 400 nm together with a high H2O2 production rate up to 197.6 μmol·g−1·h−1 under visible light irradiation was achieved. This work highlights the synergistic effect between metal atom doping and Schottky junction construction in engineering carbon nitride/MXene-based nanocomposite catalysts for artificial photosynthesis of H2O2, providing new insights into the development of advanced high-efficient photocatalysts.