Redox-Mediated Oxygen Evolution Mechanism in Atomically Dispersed Pt-Supported NiO: Defying the Hydroxyl-Mediated Mechanism of NiO

This paper represents the comparative study of NiO and Pt nanoparticle-supported NiO (Pt/NiO) for the oxygen evolution reaction (OER). The approach is to harness the metal-support interaction for high OER activity. NiO is a known electrocatalyst for the OER in a basic medium, and herein, we have increased the catalytic activity of NiO by supporting Pt nanoparticles over it. This results in high activity and very low overvoltage (220 mV at 10 mA cm^-2) in 0.5 M KOH for the OER. Noticeably, NiO alone is less active than Pt/NiO, and Pt alone is poorly active for the OER. However, the Pt-NiO combination is super active, confirming that the metal-support interaction phenomenon is underplaying. It is anticipated that the electron transfer between Pt and NiO is more facile (as confirmed by the impedance study) due to this interaction, resulting in high OER activity. This proves that chemical factors are more responsible than physical factors, such as surface area and porosity. Finally, the XPS investigation demonstrates a mechanism that is different from the conventional route for the OER over the NiO electrocatalyst.