Polarized 2D/2D Ti3CN/g-C3N4 heterojunction with directional charge transfer for efficient photocatalytic H2 evolution

Photocatalytic water splitting for green H 2 offers a renewable-energy route, yet efficiency is still limited by poor charge separation and slow reaction kinetics. Here, we report a 2D/2D Ti 3 CN/g-C 3 N 4 heterojunction with a built-in electric field, synthesized via Lewis acid molten-salt etching and electrostatic self-assembly. The heterojunction promotes directional electron transfer from g-C 3 N 4 to Ti 3 CN, while Ru nanoparticles further enhance charge density and reduce the reaction barrier. The optimized Ru/Ti 3 CN/g-C 3 N 4 photocatalyst delivers a H 2 evolution rate of 4254 μmol g −1 ·h −1 under visible light, 200 times higher than pristine g-C₃N₄, with excellent cycling stability. Experimental and theoretical analyses reveal that the synergistic effects of the polarized interface and Ru cocatalyst significantly improve charge separation and H 2 adsorption kinetics. This work offering a practical route to couple MXene co-catalysts with polarization-induced built-in electric fields for markedly accelerating solar-driven H 2 production.