Design and strain engineering of stable 2D TiSi₂N₄ photocatalyst: first-principles insights into water splitting and visible-light absorption

Solar-driven water splitting for hydrogen generation is regarded as a significant approach to harness clean energy. In this study, by means of first-principles calculations, we suggest that a TiSi₂N₄ monolayer demonstrates the capability to achieve the overall water splitting reaction for hydrogen generation. Notably, the monolayer possesses a suitable band gap of 2.6 eV, and the band alignments effectively cover the water redox potentials. Higher carrier mobility, as opposed to pure monolayers, encourages surface charge transfer and lessens carrier recombination. Phonon dispersion spectra and ab initio molecular dynamic calculations reveal that monolayer is both dynamically and thermally stable. Additionally, the absorption spectra show that monolayer absorb more solar light in the visible area. Our theoretical results demonstrate that proposed monolayer can provide improved functionality for new optoelectronic and photovoltaic devices.