One-Step Synthesis of Nb₂ O₅ /C/Nb₂ C (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 (Nb₂ O₅ /C/Nb₂ C) as photocatalysts for hydrogen evolution from water splitting. The Nb₂ O₅ /C/Nb₂ C composites were synthesized by one-step CO₂ oxidation of Nb₂ CT_x . Nb₂ O₅ grew homogeneously on Nb₂ C after mild oxidation, during which some amorphous carbon was also formed. With an optimized oxidation time of 1.0 h, Nb₂ O₅ /C/Nb₂ C 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 Nb₂ O₅ . The enhanced performance of Nb₂ O₅ /C/Nb₂ C was attributed to intimate contact between Nb₂ O₅ and conductive Nb₂ C and the separation of photogenerated charge carriers at the Nb₂ O₅ /Nb₂ C interface; the results presented herein show that transition-metal carbide are promising co-catalysts for photocatalytic hydrogen production.