Regulating interfacial coupling of 1D crystalline g-C3N4 nanorods with 2D Ti3C2T MXene for boosting photocatalytic CO2 reduction

Two-dimensional (2D) layered photocatalysts coupled with 2D Ti3C2Tx (T = OH, O, or F) MXene cocatalysts in 2D/2D configuration have been extensively studied for use in artificial photosynthesis. Unfortunately, the overall photoreaction efficiency of these cocatalysts is often limited by weak 2D/2D interfacial van der Waals interactions, high interfacial electrostatic barriers, and slow interfacial charge transfer. In this study, 1D crystalline g-C3N4 (CCN) nanorods are grown along the c-axis using the molten-salt method and assembled onto a 2D Ti3C2Tx substrate by freeze-drying-assisted interfacial coupling, forming a unique Schottky junction photocatalyst in a 1D/2D configuration with interfacial hydrogen bonds. Transfer of photoelectrons in the CCN nanorods could along the radial π-conjugated plane to the hydrogen-bonded 2D Ti3C2Tx in the 1D/2D configuration is more efficient than the slow interlayer charge transfer in catalysts with a conventional 2D/2D configuration. Consequently, the optimized 1D-CCN/2D-Ti3C2Tx hybrid photocatalyst assembled by freeze-drying (TC/CCN-FD) exhibited an outstanding photocatalytic CO2 reduction activity at a rate of 2.13 μmol g1 h1, being 5.6 and 8.9 times more efficient than the pristine 1D CCN and 2D bulk g-C3N4 counterparts, respectively. Moreover, the selectivity towards the multielectron reduction product (CH4) was significantly enhanced over TC/CCN-FD owing to the faster interfacial charge transfer across the CCN/Ti3C2Tx interface and the higher density of photoelectrons on the Ti3C2Tx cocatalysts. This work will inspire further studies on suppressing the interfacial charge transfer barrier by matching the interfacial crystal orientation and strengthening the interfacial interactions.