Architecture and Kinetic Studies of Photocatalytic H ₂ O ₂ Generation and H ₂ Evolution through Regulation of Spatial Charge Transfer via Z-Scheme Path over a (001) Facet Engineered TiO ₂ @MXene/B- g -C ₃ N ₄ Ternary Hybrid

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Spatial charge separation and migration are the critical shortcomings dominating the core energy conversion corridors of photocatalytic systems. Here, a biomimetic multi-interfacial architecture providing strong coupled interaction and rapid charge transmission for photostable and competent photocatalytic H 2 O 2 production and H 2 evolution is proposed. The triple-hybrid all-solid-state Z-scheme system was formed with the (001) facet exposed TiO 2 nanosheets derived from MXene layers and B- g -C 3 N 4 nanosheets (M/(001)TiO 2 @BCN) through an electrostatic self-assembly strategy with intimate electronic interaction due to Ti orbital modulation and proper stacking among the hybrids. The metallic and highly conductive MXene layers act as solid state electron mediators in the Z-scheme heterojunction that promote electron–hole separation and migration efficiency. Specifically, the MTBCN-12.5 composite provides optimum yield of H 2 O 2 up to 1480.1 μmol h –1 g –1 and a H 2 evolution rate of 408.4 μmol h –1 (with ACE 6.7%), which are 4 and 20 fold greater than the pristine BCN, respectively. The enhanced photocatalytic performance is systematically identified by the increased surface area, higher cathodic and anodic current densities of −1.01 and 2.27 mA cm –2, delayed charge recombination as supported by PL and EIS measurement, and excellent photostability. The Z-scheme charge transfer mechanism is validated by time-resolved photoluminescence (TRPL) analysis, cyclic voltametric analysis, and the radical trapping experiment as detected by PL analysis. This research marks a substantial advancement and establishes the foundation for future design ideas in accelerating charge transfer.