Ag2CdP2S6 2D semiconductor photocatalyst: Pioneering efficient green hydrogen production through solar water splitting

Abstract

The escalating global pollution crisis, largely driven by fossil fuel consumption in industrial sectors responsible for approximately 75% of global greenhouse gas emissions, underscores the urgent need for sustainable clean energy solutions to achieve decarbonization targets. This study explores the potential of Ag 2 CdP 2 S 6 , a novel two-dimensional (2D) semiconductor, as an effective photocatalyst for green hydrogen production through solar water splitting. Using density functional theory (DFT) calculations, we confirm the material’s dynamic and thermal stability via phonon analysis and ab initio molecular dynamics (AIMD) simulations. Band structure analyses reveal a semiconducting nature with a direct band gap of approximately 1 . 95 eV and 3 . 15 eV at DFT-PBE and DFT-HSE06 levels, respectively. Notably, absorption coefficient analysis demonstrates significant peaks in the ultraviolet region ( 149620 cm − 1 , 8 . 57 eV ) alongside considerable visible light absorption ( 11564 cm − 1 , 3 . 26 eV ) . The conduction band minimum (CBM) is calculated at − 3 . 69 eV , and the valence band maximum (VBM) at − 6 . 84 eV , satisfying the criteria for effective hydrogen evolution reaction (HER). Under acidic conditions, optimal HER kinetics are observed at phosphorus (P) atom sites with a near-ideal Gibbs free energy change ( Δ G H ∗ ) of approximately − 0 . 02 eV . Meanwhile, tilted sulfur (S) sites exhibit superior water splitting efficiency at neutral ( p H = 7 ) and slightly alkaline conditions ( p H = 8 . 3 ), with Δ G H ∗ values of 0 . 66 eV and 0 . 51 eV , respectively. These findings highlight the versatility and efficiency of Ag 2 CdP 2 S 6 as photocatalyst across diverse pH conditions, characterized by enhanced charge transfer properties, thereby contributing to the advancement of renewable hydrogen production technologies. • DFT study of Ag 2 CdP 2 S 6 as a 2D semiconductor photocatalyst for solar water splitting. • Ag 2 CdP 2 S 6 fulfills the requisite criteria for effectively facilitating overall water splitting. • Ag 2 CdP 2 S 6 nanosheet demonstrates strong optical absorption in UV and visible light regions, enabling optimale solar energy conversion. • Phosphorus (P) sites show near-ideal Gibbs free energy ( Δ G H =−0.02eV) for HER under acidic conditions. • Tilted sulfur (S) sites enable efficient water splitting at neutral to slightly alkaline pH (7–8.3), including seawater environments.