SIn2Te/TeIn2Se: a type-II heterojunction as a water-splitting photocatalyst with high solar energy harvesting

The search for photocatalysts is crucial for the production of renewable hydrogen from water. The loading of semiconductors in a junction architecture is a promising strategy to improve charge separation. Using first-principles calculations with the HSE06 functional, we propose the type-II semiconductor heterojunction SIn2Te/TeIn2Se as a promising solar-driven water-splitting photocatalyst with a high utilization rate for solar power. Its band edges straddle the redox potential of the water-splitting reaction, satisfying the requirements for water-splitting photocatalysts. Its type-II band alignment promotes the separation of photo-generated electron–hole pairs. The high optical absorption coefficient (5 × 104 cm−1), high absorbance (20.6%) in the visible region, high solar power conversion efficiency (18.5%) and significant excitonic effects indicate that SIn2Te/TeIn2Se can efficiently utilize solar power. Because of its weak interlayer coupling, its electronic, optical and photocatalytic properties remain outstanding under an external force field, guaranteeing its applicability under the actual experimental environment. Furthermore, its stability in liquid water and low reaction barrier for the hydrogen evolution reaction (HER) also support the promise of SIn2Te/TeIn2Se as a photocatalyst for the water-splitting reaction.