In the pursuit of renewable energy solutions, the development of efficient and scalable photocatalysts for solar water splitting remains a significant challenge. Recent research has presented a promising avenue through the exploration of two-dimensional (2D) type-II van der Waals heterostructures (vdWHs), which could potentially revolutionize the field of photocatalytic water splitting.
The study, conducted through high-throughput first-principles screening, evaluated 482 heterostructures constructed from 60 experimentally realizable 2D monolayers. The goal was to identify structures optimized for visible-light-driven photocatalytic water splitting. Out of the 482 heterostructures, 148 stable type-II vdWHs were identified, characterized by spatially separated valence and conduction band edges. Among these, 65 satisfied the thermodynamic redox conditions necessary for water splitting over a broad pH range.
The most promising candidates, MoTe2/Tl2O and MoSe2/WSe2, exhibited high visible-light absorption coefficients exceeding 0.6X10^6 cm-1, resulting in a power conversion efficiency of 2%. This efficiency is a notable achievement in the quest for effective solar water splitting.
Quantum kinetic analysis of the hydrogen evolution reaction (HER) revealed nearly barrierless free energy profiles across multiple adsorption sites, indicating that these heterostructures facilitate the water-splitting process with minimal energy barriers. Furthermore, the study found that intrinsic interlayer electric fields in these vdWHs drive directional charge separation, effectively suppressing carrier recombination. This suppression is crucial for enhancing the efficiency of photocatalytic processes.
The findings establish a design framework for using type-II 2D heterostructures as tunable and experimentally accessible 2D photocatalysts. This research not only advances our understanding of photocatalytic materials but also brings us closer to achieving efficient and scalable hydrogen production from solar energy. The implications for the energy sector are significant, as this technology could contribute to the development of clean, renewable energy sources, reducing dependence on fossil fuels and mitigating the impacts of climate change.
This research was published on arXiv and can be read in full [here](http://arxiv.org/abs/2508.17483v1).