Porous bimetallic cobalt-iron phosphide nanofoam for efficient and stable oxygen evolution catalysis

Developing oxygen evolution reaction (OER) catalysts with high activity and long-term stability is critical to achieving efficient hydrogen production from water electrolysis. Herein, a porous bimetallic cobalt-iron phosphide (CoFe-P) nanofoam is synthesized via a novel one-pot glucose-blowing followed by oxidization and then phosphidization process. The CoFe-P nanofoam presents a porous nanostructure which contributes to contact with electrolytes and release of generated gas during electrocatalytic reactions. As OER catalysts in alkaline, the bimetallic porous CoFe-P nanofoam exhibit a lower overpotential (258 mV@10 mA cm^-2) as well as outstanding stability (70 h@100 mA cm^-2), which surpasses the RuO₂ and is comparable to many high-performance Co and Fe-based catalysts. It is demonstrated that the surface of CoFe-P undergo a reconstruction process and form new high active (Co_xFe_1-x)OOH. Density functional theory (DFT) calculations reveal that the elevated activity is caused by the bimetal Co and Fe optimizing the d-band center (E_d) energy levels and thus balancing the adsorption-desorption capacities for OER intermediates. This work through constructing porous bimetallic nanofoam offers a feasible strategy to facilitate the reaction activity and prolong the long-term stability of OER.