Dynamic stability of active sites in hydr(oxy)oxides for the oxygen evolution reaction

Abstract

The poor activity and stability of electrode materials for the oxygen evolution reaction (OER) are the main bottlenecks in the water splitting reaction for H2 production. Here, by studying activity stability trends for the OER on conductive M1OxHy, Fe-M1OxHy and Fe-M1M2OxHy hydr(oxy)oxide clusters (M1= Ni, Co, Fe; M2= Mn, Co, Cu), we show that balancing the rates of Fe dissolution and redeposition over a MOxHy host establishes dynamically stable Fe active sites. Together with tuning the Fe content of the electrolyte, the strong interaction of Fe with the MOxHy host is the key to control the average number of Fe active sites present at the solid-liquid interface. We suggest that the Fe-M adsorption energy can therefore serve as a reaction descriptor that unifies OER catalysis on 3d transition metal hydr(oxy)oxides in alkaline media. Thus, introduction of dynamically stable active sites extends the design rules for making active and stable interfaces.