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

TL;DR

This study uses high-throughput first-principles calculations to identify stable 2D heterostructures with optimized properties for solar water splitting, highlighting their potential for efficient hydrogen production.

Contribution

It introduces a systematic screening approach to discover and analyze 2D type-II heterostructures suitable for photocatalytic water splitting, emphasizing their charge separation and light absorption capabilities.

Findings

148 stable type-II vdWHs identified from 482 candidates

65 heterostructures meet water splitting redox conditions

MoTe2/Tl2O and MoSe2/WSe2 show high visible-light absorption and efficiency

Abstract

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, out of which 65 satisfy the thermodynamic redox conditions for water splitting over a broad pH range. Among these, the best two, MoTe2/Tl2O and MoSe2/WSe2, exhibit a high visible-light absorption coefficient exceeding 0.6X10^6 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 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.