Evaluation of individual metal contribution on active sites tailoring in multimetallic oxygen evolution catalytic system.

Synergistic effects among different metals have positioned multimetallic electrocatalysts as promising facilitators for enhancing the oxygen evolution reaction (OER), though understanding their precise mechanisms has remained elusive. Delving into the unique contributions of individual metals is crucial for comprehending the complex synergy within multimetallic systems. In this study, we employed quinary (Co, Ce, Fe, Cu, and Mn) molybdates as a model to systematically investigate the role of each metal species in tailoring active sites. Our systematic analyses unveiled the presence of crucial oxygen vacancies, which can be considered as the active sites in OER. Comparative analyses of the top-performing quinary molybdates and their quaternary counterparts highlighted distinct electronic interactions and varying densities of oxygen vacancies, indicative of the diverse electron and vacancy engineering capabilities inherent to different metals. Mott-schottky plots demonstrated the predominant contribution of Mn to specific catalytic activity, followed by Ce, Fe, Cu, and Co. Leveraging an in-situ methanol probing method, it was found that the introduction of Cu, Ce, Fe, and Mn weakened intermediate adsorption, with Mn and Ce having the most significant effects, whereas Co strengthened adsorption. This work can advance our comprehension of the role played by individual metals within multimetallic catalysts, thereby promoting a more profound understanding of synergistic effects.