Well-structured V2C MXenes coupled g-C3N4 2D/2D nanohybrids for proficient charge separation with the role of triethanolamine (TEOA) as a protective barrier of g-C3N4 for stimulating photocatalytic H2 production

Vanadium-carbide (V2C) MXenes have received scientific attention for their thinner structure, multiple oxidation states, and excellent conductivity, which can effectively serve as electron-sinking sites to suppress the backward recombination of electrons and holes. Herein, well-structured V2C/g-C3N4 nanohybrids were designed to promote photocatalytic hydrogen production. Stronger interfacial contact between 2D/2D V2C/g-C3N4 proffers 4.23-fold more H2 yield than pristine g-C3N4 with a maximal rate of 360 μmol g−1 h−1. The loading of V2C improves the light absorption capability and facilitates the charge transfer for photo-redox reaction. However, h+ accumulation fosters the degradation kinetics over consecutive cycles, which drives the homolytic cleavage of the g-C3N4 by hydroxyl radical (• OH). The tremendous decline in the photostability test over methanol-containing sacrificial reagents is consistent with the reduction of g-C3N4 functional units, corroborating the structural breaking. Employing TEOA as a hole scavenger slows the homolytic decomposition of g-C3N4, which could act as a binding ligand in protecting the g-C3N4 surface. Stronger intermolecular forces between the heterogeneous molecules with excellent scavenging activity effectively trap accumulated h+ and slow down the degradation kinetics. The findings of this work not only contribute to the scientific understanding of vanadium-based MXenes in photocatalytic hydrogen production but also lay the foundation for understanding the mechanistic structure of g-C3N4.