Potential-Driven Coordinated Oxygen Migration in an Electrocatalyst for Sustainable H₂O₂ Synthesis.

Abstract

Local coordination environment (LCE) manipulation has emerged as a significant approach for modulating the electrocatalytic behavior of low-dimensional nanomaterials. However, challenges persist in accurately identifying active sites and understanding dynamic changes during operation. Here, we underscore the influence of LCE on the electrochemical production of H₂O₂, utilizing the Pd cluster as a model catalyst. Density functional theory (DFT) calculations illustrate the role of first- and second-coordinated sulfur and oxygen in modulating the binding strength of HOO*. Guided by DFT screening, the as-prepared Pd cluster (Pd_<i>x</i>/HMCS) catalyst presents exceptional catalytic performance with a high mass activity of 4.06 A mg^-1 at 0.45 V and selectivity above 94%. The Pd_<i>x</i>/HMCS catalyst also delivers promising potential for industrial practices with a production rate of 16.3 mol g_cat^-1 h^-1 in flow cell evaluation. Elaborated in situ characterizations confirm that under operation, oxygen migrates from the second coordination sphere (CS) to the first CS to achieve oxygen coverage on the catalyst surface. Such an oxygen migration phenomenon and the optimized first and second coordination environment give rise to the outstanding performance.