Determining the hydrogen production potential of Co_nMo₆Se₈ chevrel phases

Abstract In this study, the Co n Mo 6 Se 8 (n = 1, 2, 3, and 4) Chevrel phases are investigated by using Density Functional Theory (DFT) to reveal their potential for photocatalytic hydrogen production. The stability conditions of these phases reveal that CoMo 6 Se 8 , Co 2 Mo 6 Se 8 , and Co 3 Mo 6 Se 8 satisfy the thermodynamic and mechanic stability properties, while Co 4 Mo 6 Se 8 does not satisfy any of these properties. Furthermore, the formation enthalpy of these phases shows that CoMo 6 Se 8 , Co 2 Mo 6 Se 8 , and Co 3 Mo 6 Se 8 can be synthesized experimentally due to having negative formation enthalpy values. Furthermore, the thermal stabilities of the machine-learning (ML) force fields are investigated by ab-initio molecular dynamics (AIMD) calculations. The electronic properties of these phases are also investigated in detail, and it is found that Co 3 Mo 6 Se 8 has a suitable band gap for photocatalytic water splitting. Concerning the investigation of the valence band and conduction band levels, it is shown that Co 3 Mo 6 Se 8 has a conduction band minimum level suitable for producing hydrogen. This study is the first attempt to reveal the hydrogen production performance of the Co n Mo 6 Se 8 (n = 1, 2, 3, and 4) Chevrel phases as far as the literature is concerned, paving the ground for future investigations in this field.