Regulating the Oxygen Vacancy of 3R-Phase Iridium Oxide by Loading Platinum Nanoparticles for Efficient Hydrogen Evolution

Abstract

Balancing the activity and stability of electrocatalytic composites in the acidic hydrogen evolution reaction (HER) is still a great challenge. Although 3R-phase iridium oxide (3R-IrO2) is recognized as a potential competitor for the acidic oxygen evolution reaction (OER), its other catalytic activities have not been explored. Herein, 3R-IrO2 modified by Pt nanoparticles (Pt@3R-IrO2) exhibits certain catalytic activity toward the acidic HER. The Pt@3R-IrO2 with 15 wt % Pt loading (15 wt % Pt@3R-IrO2) displays high HER activity with a low overpotential (η@–10 mA cm–2) of 19.0 mV, a high mass activity of 0.77 A mgIr+Pt–1 and considerable economic effect of 5.54 A $–1 at −0.03 V vs RHE. Moreover, the 15 wt % Pt@3R-IrO2 electrocatalyst can maintain the HER process in 0.5 M H2SO4 for more than 300 h under continuous current changes. Theoretical calculations prove that loading Pt nanoparticles can properly regulate the HER catalytic activity of 3R-IrO2, mainly for the following two reasons: (i) loading Pt atoms/clusters on 3R-IrO2 can reduce the formation energy of oxygen vacancy, thus facilitating the exposure of unsaturated Ir atoms as the active sites, and (ii) the Ir 5d band center for Pt@3R-IrO2 is moderately modified, indicating that it is beneficial to weaken the Gibbs free energy of hydrogen adsorption (ΔG*H).