Photocatalytic performance of the two-dimensional material ZnGeSeO for the hydrogen evolution reaction: A first-principles study

The photocatalytic production of green hydrogen (H 2 ) through water splitting offers a sustainable pathway to convert solar renewable energy into storable chemical fuel while reducing environmental pollution. In this study, first-principles density functional theory calculations were conducted to investigate the structural and electronic properties of the Janus material ZnGeSeO. The electronic structure calculation without spin–orbit coupling shows that ZnGeSeO is an indirect band gap semiconductor, with a gap value of 1.46 eV using PBE and 2.13 eV using HSE06. The inclusion of SOC does not affect the nature of the band gap; however, its value decreases by 0.2 eV. These values, which lie within the visible light spectrum, are favorable for photocatalysis. The material exhibits strong optical absorption in the visible region, with a coefficient of 8 . 4 × 1 ⁢ 0 4 cm −1 , which becomes even more pronounced in the ultraviolet range. Band edge alignment analysis demonstrates that the conduction band minimum (–3.37 eV) and valence band maximum (–5.81 eV) properly straddle the redox potentials of water under both acidic and neutral conditions. Moreover, both surfaces of ZnGeSeO are capable of simultaneously driving hydrogen and oxygen evolution reactions at pH values above 3. Thus, the Gibbs free energy calculated for the hydrogen evolution reaction is positive and close to zero ( 𝛥 ⁢ 𝐺 = 0 . 1 7 eV), and becomes 𝛥 ⁢ 𝐺 = − 0 . 1 7 eV under illumination conditions. However, the material exhibits low activity for the oxygen evolution reaction, which is limited by the first step corresponding to the adsorption of OH*. These results highlight the potential of ZnGeSeO as a promising photocathode for the efficient conversion of solar energy into hydrogen and for the sustainable production of green hydrogen. These findings highlight ZnGeSeO as a promising photocatalyst for efficient solar-to-hydrogen conversion and the sustainable generation of green hydrogen.