Strain-engineered TiS2/BC2N van der Waals heterostructures for high-efficiency type-II photocatalytic water splitting

The development of efficient photocatalysts for solar-driven water splitting is critical for sustainable energy conversion. However, limitations in carrier separation efficiency, band gap alignment, and pH sensitivity hinder practical applications. Here, we have proposed a TiS 2 /BC 2 N van der Waals heterostructure engineered via carbon doping in BN to address these challenges. Density functional theory calculations demonstrate that the optimized TiS 2 /BC 2 N heterostructure possesses an ideal indirect bandgap (1.81 eV) and exhibits type-II band alignment, effectively achieving spatial separation of photogenerated carriers. The band edges fully span water redox potentials under acidic conditions (pH = 0–7), enabling simultaneous hydrogen and oxygen evolution. Crucially, biaxial strain modulates the band structure and optical absorption, achieving a record solar-to-hydrogen efficiency ( η STH ) of 42.23 % at 4 % tensile strain. This work demonstrates defect and strain engineering as powerful strategies for designing high-performance photocatalysts.