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

• A novel gallium-doped polymeric carbon nitride decorated with Ti 3 C 2 MXene photocatalyst was fabricated. • Highest H 2 O 2 -yield rate of 197.6 μmol·g −1 ·h −1 with an apparent quantum yield of 1.58% at 400 nm was achieved • Ga-N sites in the Ga-PCN facilitated the transfer of photoinduced charge carriers. • Enhanced catalytic performance was attributed to intimate interfacial contact and formation of Schottky junction. 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 H 2 O 2 generation remains a formidable challenge. Accordingly, here we present a novel Ga-PCN/Ti 3 C 2 Schottky junction, achieved by introducing gallium ions into tri-s-triazine repeating units of PCN and then decorating it with Ti 3 C 2 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 Ti 3 C 2 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 Ti 3 C 2 . As a result, an apparent quantum yield of 1.58 % at 400 nm together with a high H 2 O 2 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 H 2 O 2 , providing new insights into the development of advanced high-efficient photocatalysts.