A high-performance S-scheme based Ti₃C₂Tx Mxene-enhanced S-g-C₃N₄/NiAl layered double hydroxide ternary heterojunction photocatalyst for sustainable hydrogen production

The search for economical, long-lasting, and useful photocatalysts for hydrogen (H₂) generation has continued for decades. A new S-scheme ternary heterojunction photocatalyst is developed in this study by incorporating (Ti₃C₂Tx) Mxene into the binary heterojunction of sulfur-doped graphitic carbon nitride (S-g-C₃N₄) and NiAl-layered double hydroxide (NiAl-LDH). The ternary heterojunction, made using the hydrothermal process, demonstrated superior structural layering and optimally intimate interfacial connections, significantly improving the photocatalytic generation of H₂ upon visible light irradiation. By systematic investigations at various catalyst loadings, the optimal formulation of the developed step-scheme (S-scheme) hybrid heterojunction Mxene/S-g-C₃N₄/NiAl-LDH (12 wt% Mxene) heterojunction has an impressive photocatalytic activity of 72.63 mmol H₂ g⁻¹h⁻¹ exhibiting a remarkably elevated apparent quantum yield (AQY) of 79.88 % and solar-to-hydrogen (STH) conversion efficiency of 31.86 % at 420 nm. In addition to recyclability, Mxene/S-g-C₃N₄/NiAl-LDH heterojunction showed outstanding photostability of 192 h in continuous operation. The long-lasting photostability can be ascribed to reduced electron-hole recombination and enhanced charge migration due to the close contact between Mxene and S-g-C₃N₄ via suitable S-scheme heterojunction formation. Our findings underline the optimum layered structure and intimate interfacial contact of the component materials to promote photocatalytic H₂ production and open a promising route toward sustainable H₂ generation technologies.