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

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