Edge-Sharing Octahedrally Coordinated Ni-Fe Dual Active Sites on ZnFe2O4 for Photoelectrochemical Water Oxidation

The structural properties of octahedral sites (B-Oh) in spinel oxides (AB(2)O(4)) play vital roles in the electrochemical performance of oxygen-related reactions. However, the precise manipulation of AB(2)O(4) remains challenging due to the complexity of their crystal structure. Here, a simple and versatile molten-salt-mediated strategy is reported to introduce Ni2+ in B-oh sites intentionally on the surface of zinc ferrite (ZnFe2O4, ZFO) to promote the active sites for photoelectrochemical (PEC) water splitting. The as-created photoanode (ZFO-MSNi) shows a remarkable cathodic shift of approximate to 450 mV (turn-on voltage of approximate to 0.6 V-RHE) as well as three times the 1-sun photocurrent density at 1.23 V-RHE for PEC water oxidation in comparison with bare ZFO. A comprehensive structural characterization clearly reveals the local structure of the introduced Ni2+ in ZFO-MSNi. Fewer surface trapping states are observed while the precisely introduced Ni2+ and associated neighboring Fe(3-sigma)+ (0