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 are the main bottlenecks in the water-splitting reaction for H-2 production. Here, by studying the activity-stability trends for the oxygen evolution reaction on conductive (MOxHy)-O-1, Fe-(MOxHy)-O-1 and Fe-(MMOxHy)-M-1-O-2 hydr(oxy)oxide clusters (M-1 = Ni, Co, Fe; M-2 = 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 controlling 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 oxygen evolution reaction catalysis on 3d transition-metal hydr(oxy)oxides in alkaline media. Thus, the introduction of dynamically stable active sites extends the design rules for creating active and stable interfaces. Understanding what underpins the activity and stability of oxygen evolution catalysts is an ongoing issue in the field of water splitting. Now, researchers show that balancing the rate of Fe dissolution and deposition over a metal hydr(oxy)oxide host yields dynamically stable Fe active sites, with the Fe-host interaction key to the performance.