One-Step Synthesis of Nb₂O₅/C/Nb₂C (MXene) Composites and Their Use as Photocatalysts for Hydrogen Evolution

Hydrogen production through facile photocatalytic water splitting is regarded as a promising strategy to solve global energy problems. Transition-metal carbides (MXenes) have recently drawn attention as potential co-catalyst candidates for photocatalysts. Here, we report niobium pentoxide/carbon/niobium carbide (MXene) hybrid materials (Nb₂O₅/C/Nb₂C) as photocatalysts for hydrogen evolution from water splitting. The Nb₂O₅/C/Nb₂C composites were synthesized by one-step CO₂ oxidation of Nb₂CT_x. Nb₂O₅ grew homogeneously on Nb₂C after mild oxidation, during which some amorphous carbon was also formed. With an optimized oxidation time of 1.0 h, Nb₂O₅/C/Nb₂C showed the highest hydrogen generation rate (7.81 μmol h⁻¹ g_cat⁻¹), a value that was four times higher than that of pure Nb₂O₅. The enhanced performance of Nb₂O₅/C/Nb₂C was attributed to intimate contact between Nb₂O₅ and conductive Nb₂C and the separation of photogenerated charge carriers at the Nb₂O₅/Nb₂C interface; the results presented herein show that transition-metal carbide are promising co-catalysts for photocatalytic hydrogen production.