Understanding the Photoelectrochemical Properties of Theoretically Predicted Water-Splitting Catalysts for Effective Materials Discovery

Data-intensive discovery of water-splitting catalysts can accelerate the development of sustainable energy technologies, such as the photocatalytic and/or electrocatalytic production of renewable hydrogen fuel. Through computational screening, 13 materials were recently predicted as potential water-splitting photocatalysts: Cu₃NbS₄, CuYS₂, SrCu₂O₂, CuGaO₂, Na₃BiO_4, Sr₂PbO₄, LaCuOS, LaCuOSe, Na₂TeO₄, La₄O₄Se₃, Cu₂WS₄, BaCu₂O₂, and CuAlO₂. Herein, these materials are synthesized, their bandgaps and band alignments are experimentally determined, and their photoelectrocatalytic hydrogen evolution properties are assessed. Using cyclic voltammetry and chopped illumination experiments, 9 of the 13 materials are experimentally found to have bandgaps and band alignments that straddle the potentials required for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), as computationally predicted. During photocatalytic testing, 12 of the materials yield a measurable photocurrent. However, only three are found to be active for the HER, with Cu₃NbS₄, CuYS₂, and Cu₂WS₄ producing H₂ in amounts comparable to bare TiO₂; a benchmark photocatalyst. This study provides experimental validation of computational bandgap and band alignment predictions while also successfully identifying active photocatalysts.