Ligand‐Controlled Electrodeposition of Highly Intrinsically Active and Optically Transparent NiFeO x H y Film as a Water Oxidation Electrocatalyst

A highly intrinsically active and optically transparent NiFeO x H y water oxidation catalyst was prepared by electrodeposition of [Ni(C 12 ‐tpen)](ClO 4 ) 2 complex (Ni−C 12 ). This NiFeO x H y film has a current density of 10 mA cm −2 with an overpotential ( η ) of only 298 mV at nanomolar concentration and the current density of 10 mA cm −2 remains constant over 22 h in 1  m KOH. The extremely high turnover frequency of 0.51 s −1 was obtained with η of 300 mV. More importantly, such outstanding activity and transparency (optical loss <0.5 %) of the NiFeO x H y film are attributed to a ligand effect of the dodecyl substituent in Ni−C 12 , which enables its future application in solar water splitting.