Interfacial architecture of Ta 2 O 5 /Bio-MXene (Va) nano-hybrid for enhanced solar-driven hydrogen generation performance

Abstract MXenes, a family of two-dimensional carbides and nitrides based on transition metals derived from MAX phases, have emerged as promising materials for solar energy conversion due to their high metallic conductivity and tunable surface terminations. A sustainable route for synthesizing vanadium-based Bio-MXene (Va 2 CT x ) is developed here using lignocellulosic biomass-derived biochar as a renewable carbon precursor for MAX-phase formation, this is followed by controlled chemical exfoliation. The approach reduces reliance on fossil-derived carbon while enhancing surface functionality and phase purity. Structural and spectroscopic analyses (XRD, SEM–EDX, FTIR, PL, and UV–Vis) confirm effective removal of the Al layer, expansion of the interlayer spacing, the formation of oxygen-rich surface terminations, enhanced visible-light absorption, and bandgap narrowing. Integration with Ta 2 O 5 results in a Ta 2 O 5 /Bio-MXene (Va) composite that achieves a hydrogen evolution rate of 170 μmol g −1 h −1 under natural sunlight, corresponding to a cumulative yield of approximately 1020 μmol g −1 over 6 h, with about 93 % activity retained after 5 cycles. This improvement in performance is mainly attributed to better interfacial charge transfer and suppressed electron–hole recombination facilitated by the Bio-MXene framework, which provides additional electron-transport pathways and active sites. Taken together, these results suggest that biomass-derived MXene heterostructures are a promising and sustainable 2D platform for solar hydrogen generation.