Engineered MAX Phase‐Assisted Ti 2 AlN/TiO 2 Heterostructures With Tunable Interfacial Electronic Coupling for Enhanced Photocatalytic Water Splitting Toward H 2 Production

This study presents titanium aluminum nitride (Ti 2 AlN) MAX phase as a promising cocatalyst in photocatalytic hydrogen production. Its layered structure and metallic ceramic properties offer high thermal stability, oxidation resistance, and favorable charge transport characteristics. Ti 2 AlN/TiO 2 composite was fabricated by two different approaches using commercial anatase TiO 2 and sol–gel‐derived TiO 2 to investigate the effect of precursor characteristics on photocatalytic performance. The optimized loading was found to be 10% Ti 2 AlN on TiO 2 among the different loadings tested. The highest hydrogen rate was obtained up to 709 μmol g −1 h −1 for 10‐Ti 2 AlN/TiO 2 ‐S, which is 4.7‐fold higher than its pure TiO 2 counterpart and 709 times higher than pure Ti 2 AlN with methanol as the sacrificial agent. More specifically, when commercial TiO 2 was used, only 16 and 35 μmol g −1 h −1 hydrogen rates were achieved by pure TiO 2 and the corresponding composite with Ti 2 AlN. Coupling Ti 2 AlN into TiO 2 enabled efficient electron migration and also acts as an electron reservoir, thereby reducing the recombination of charged species and enhancing light absorption, favoring proton reduction kinetics for hydrogen production. This work establishes Ti 2 AlN as an effective and noble metal‐free cocatalyst that provides new insight into MAX phase conductivity to engineer advanced TiO 2 ‐based heterostructures for hydrogen generation.