Metal-support interactions alter the active species on IrOx for electrocatalytic water oxidation

Abstract

Constructing metal-support interaction (MSI) is a strategy of wide interest to promote the electrocatalytic performance of oxygen evolution reaction (OER). However, studies helping to understand the electrocatalytic behavior of reactive centers affected by the metal support and investigations to guide the construction of catalysts based on MSI are scarce. In situ surface-enhanced Raman spectroscopy (SERS) provides spectral evidence of reactive intermediates and information on the structural evolution of catalysts, which can help investigate the reaction pathway of catalysts. In this work, Au@MnO₂-IrO_x core–shell nanoparticles (NPs), possessing a specific nanostructure of highly dispersed IrO_x clusters on amorphous MnO₂ shells, were prepared by a simple method under ambient conditions and exhibited a low overpotential of 230 mV to reach the current density of 10 mA cm⁻², therefore outperforming the traditional Ir catalysts. The oxidation of Ir⁴⁺ and adsorption of *O on IrO_x at a low potential were revealed by in situ SERS, which indicated the pre-activation of Ir centers and the facilitated formation of superoxide species: *O–O⁻. Combined with density functional theory (DFT) calculations, we show that the MnO₂ substrate optimizes binding energies of intermediates on IrO_x, promoting O–O coupling and improving the OER rate. This work provides a strategy for utilizing in situ spectroscopy to investigate the OER mechanism and understand the electrocatalytic behavior impacted by MSI.