A dynamically stable self-assembled CoFe (oxy)hydroxide-based nanocatalyst with boosted electrocatalytic performance for the oxygen-evolution reaction

Surface reconstruction or elemental leaching is generally involved in the oxygen evolution reaction (OER) process on transition metal-based oxides during alkaline water electrolysis, which gives rise to both opportunities and challenges for the development of OER electrocatalysts. Reaction-derived metal (oxy)hydroxides have been proven to be the actual active species for many metal oxides but have suffered from the dissolution of active elements. Here, the construction of a dynamically stable CoFe (oxy)hydroxide OER nanocatalyst is proposed, which delivers a low overpotential of 253 mV at 10 mA cm⁻² and high mass activity (3.78 A mg⁻¹ at an overpotential of 300 mV), among the highest of all the hydroxides reported previously. The in situ synthesized nanocatalyst acts as a stable CoO_xH_y host for Fe adsorption and facilitates active Co-O-Fe motif formation. The weak metal-O coordination environment and hydrophilic surface morphology lead to superficial mass transfer. The drawbacks of Fe depletion for conventional CoFe (oxy)hydroxides are overcome, attributed to tardy lattice oxygen ion diffusion and dynamic Fe-saturated dual metal active sites, which lead to a stable performance for over 100 h. This study provides a design strategy for OER electrocatalysts with both high mass activity and durability, which shows application prospects for large-scale electrochemical water splitting.