Role of the Interfacial Effect between the Substrate and Co(OH)₂ Layer in Electrochemical Oxygen Evolution

The interface between the catalyst and the substrate for self-supported electrocatalysts is crucial to the overall catalytic performance, which has been less considered so far. Herein, we report the significant enhancement of the oxygen evolution reaction (OER) performance of electrodeposited Co­(OH)₂ on the Fe foil due to the in situ generated interfacial layer on the underlying metal substrate during the OER process. Experimental observations demonstrate that the OER electrocatalytic activity of Co­(OH)₂ on various metal substrates decreases in the order Fe > Ni > Co > Cu > Ag > Ti in the high current density region. Density functional theory calculations and experimental investigations demonstrate that the interfacial (oxy)­hydroxide/oxide layer on the surface of the metal substrate can affect total OER kinetics. We believe that theoretical understanding and experimental findings of the substrate effect can provide further insights into the catalyst–substrate interface for self-supported electrocatalysts. Thus, this work provides a new guideline to design high-performance electrodes, which can be achieved through the match of electrocatalytic species and the substrate.