High-Throughput Screening of 2D Photocatalyst Heterostructures with Suppressed Electron–Hole Recombination for Solar Water Splitting

Efficient and scalable photocatalysts for solar water splitting remain a critical challenge in renewable energy research. The work presents a high-throughput first-principles discovery of two-dimensional (2D) type-II van der Waals heterostructures (vdWHs) optimized for visible-light-driven photocatalytic water splitting. We screened 482 heterostructures constructed from 60 experimentally realizable 2D monolayers and identified 148 stable type-II vdWHs with spatially separated valence and conduction band edges, of which 65 satisfy the thermodynamic redox conditions for water splitting over a broad pH range. Among these, the best two, MoTe 2 /Tl 2 O and MoSe 2 /WSe 2, exhibit a high visible-light absorption coefficient exceeding 0.6 × 10 6 cm –1, resulting in a high power conversion efficiency of ≈ 2%. Quantum kinetic analysis of the hydrogen evolution reaction (HER) reveals nearly barrierless free energy profiles (Δ G H less than 0.1 eV) across multiple adsorption sites. Our study further reveals that intrinsic interlayer electric fields in these vdWHs drive directional charge separation, suppressing carrier recombination. Our results establish a design framework for using type-II 2D heterostructures as tunable and experimentally accessible 2D photocatalysts for efficient hydrogen production.