Graphite-Supported Ptn Cluster Electrocatalysts: Major Change of Active Sites as a Function of the Applied Potential

The oxygen reduction reaction (ORR) plays a key role in renewable energy transformation processes. Unfortunately, it is inherently sluggish, which greatly limits its industrial application. Sub-nano-cluster-decorated electrode interfaces are promising candidate ORR electrocatalysts. However, understanding the nature of the active sites on these catalysts under electrocatalytic conditions presents a formidable challenge for both experiment and theory, due to their dynamic fluxional character. Here, we combine global optimization with the electronic Grand Canonical DFT to elucidate the structure and dynamics of subnano Ptn clusters deposited on electrified graphite. We show that, under electrochemical conditions, these clusters exist as statistical ensembles of multiple states, whose fluxionality is greatly affected by the applied potential, electrolyte, and adsorbate coverage. The results reveal the presence of potential-dependent active sites and, hence, reaction energetics.

Automated summary

The oxygen reduction reaction (ORR) is crucial for renewable energy transformation, but its slow kinetics limits its industrial applications. Sub-nano-cluster-decorated electrode interfaces are potential ORR electrocatalysts, but understanding their active sites under electrocatalytic conditions is challenging due to their dynamic nature. In this study, we used global optimization and Grand Canonical DFT to investigate the structure and dynamics of subnano Ptn clusters on electrified graphite. We found that these clusters exist as statistical ensembles of multiple states under electrochemical conditions, and their fluxionality is influenced by the applied potential, electrolyte, and adsorbate coverage.