Rapid and In Situ Active Sites Regeneration for OER Activity Recovery and Greatly Prolonged Water-Splitting Performance

Inspired by the continuous regeneration of enzymes in living organisms that enables sustained long-term enzymatic reactions, we propose an active site regeneration strategy to rapidly and in situ recover the catalytic activity of oxygen evolution reaction (OER) for the electrode through switching anode solution, to substantially prolong the service life of the electrolytic cell. The OER activity of anodic NiFe(S)/NM catalyst synthesized by coating S-doped NiFe-LDH on nickel mesh (NM) exhibited excellent initial activity, then experienced gradual active site and activity losses due to the nanosheet detachment from NM after a long-term OER process. Attractively, such a damaged catalyst and its active sites can be effectively regenerated by an in situ redox reaction followed by electrochemical oxidation through switching the anode into the different solutions, resulting in the full recovery of the OER activity to its initial value. The recovered catalyst (R-NiFe(S)/NM) retains 90% of the initial activity and can be operated stably for over 80 h at 300 mA cm⁻² even after four cycles of being damaged and recovered, and the established electrolyzer equipped with in situ recovered catalyst can be operated at the identical current density and almost the same cell voltage to that of the initial one.