Defect-engineered Cu 2 O/Co x O heterostructures with built-in electric fields for high-current-density alkaline water splitting

A Cu 2 O/Co x O@NF catalyst is fabricated via phytic acid etching and NaBH 4 reduction, with a built-in electric field (Δ Φ = 0.13 eV) and abundant defects. The catalyst shows low OER overpotentials (194 mV@10 mA cm −2 ) and superior stability.