Efficient oxygen evolution activity of CoFe-PBA heterojunctions using a bimetallic probe (Mo/Cu) at room temperature: construction of multilayered activated structures and cationic vacancies†

The development of efficient and stable active agents is key to accelerating the four-electron process of the oxygen evolution reaction (OER). The application of Prussian blue (PBA) in electrocatalysis is greatly limited by its electrocatalytic inertness to the oxygen evolution reaction. Herein, multilayered active heterojunctions were constructed by introducing a third metal probe into a CoFe-PBA precursor, and the doping of the metal probe can greatly promote the recombination and vacancy pairing of other metal cations. Since molybdenum and copper are highly conductive and nonferromagnetic, they can be easily neutralized with CoFe-based Prussian blue to activate the inert recombinant heterojunction. A more noteworthy point is the discovery of multilayered active heterojunctions in molybdenum-induced CoFe-PBA, which can form multimetallic controllable sites. Being different from Mo atoms, density-functional theory (DFT) calculations show that Cu-induced CoFe-PBA can alter the coordination of metal Co to some extent, thereby inducing a high concentration of Fe³⁺–CN oxidation states. Thus, the Mo/Cu bimetal acts as an active probe to induce highly active PBA and OERs. Further development of more efficient catalysts for water splitting by doping various types of isotropic metals at room temperature to induce a remodeling process on the catalyst surface will be an effective method, thereby elucidating the cause of the catalytic effect.