Spin state engineering of spinel oxides by integration of Cr doping and a p–n junction for water oxidation

Spinel Co3O4 has emerged as a promising electrocatalyst towards alkaline water oxidation, but its activity is restricted by the undesirable electronic configuration of the octahedral Co3+ site. Herein, we simultaneously manipulate Cr doping and p-n junction engineering on Co3O4 nanorods, which contributes to the formation of Co2+ and Ni3+ octahedral sites with optimal eg fillings, thus achieving a superior OER performance.