Cooperatively interface role of surface atoms and aqueous media on single atom catalytic property for H₂O₂ synthesis

Direct electrosynthesis of hydrogen peroxide (H₂O₂) from H₂ and O₂ is a promising alternative to currently industrial Riedl-Pfleiderer route. Utilizing a combination of density functional theory (DFT) and ab-initio-molecular dynamic simulation (AIMD), we presented an effective computational framework to identify the cooperative role of surface atoms(e.g. O, N and S) and aqueous media on catalytic performance of single-atom catalysts (SACs) supported Nb₂C MXenes. Computational results shown that both Ni/Nb₂CN₂ and Co/Nb₂CS₂ have low overpotentials of 0.17 V and 0.20 V, and the barrier of 0.89 eV and 0.67 eV for 2e^- ORR under gas phase, respectively, while in aqueous phase, hydrogen bond framework on the surface promotes the transfer of proton, resulting in the lower 2e^- ORR overpotential (0.05 V) in Co/Nb₂CS₂ and lower barrier (almost 0.01 eV) for rate-determining step (RDS) in Ni/Nb₂CN₂. Electronically, we found that the less-electronegativity N and S relative to O more benefit to mediate the activation degree of O₂ on SACs and thereby improve catalytic selectivity. Thus, it is concluded that both surface atom and aqueous medium synergistically promote catalytic property for H₂O₂ synthesis.