Defect-rich bimetallic yolk–shell metal-cyanide frameworks as efficient electrocatalysts for oxygen evolution reactions

Abstract

The rational design and construction of noble-metal-free electrocatalysts with high activity and robust durability for oxygen evolution reactions (OERs) have aroused immense interest in the past decades, but challenges remain. Herein, a reduction-induced dissolution–recrystallization (RIDR) strategy was developed to fabricate a defect-rich yolk–shell Prussian-blue analogue (YS-PBA) by a solvothermal process in isopropyl alcohol (IPA) in the presence of polyvinylpyrrolidone (PVP). The experimental result indicated that the defect-rich YS-PBA was formed via phase transformation from Co₃[Fe^III(CN)₆]₂ to Co₂Fe^II(CN)₆ induced by the reduction potential of the IPA-PVP couple. The newly synthesized YS-PBA exhibited outstanding OER performance with a low overpotential of 293 mV to deliver a current density of 10 mA cm⁻² and long-term durability (120 h) in alkaline media. Both experimental and density functional theory (DFT) results unveiled that the defects formed in YS-PBA cause a dramatic positive effect on the improvement of the OER activity.