Regulating the Oxygen Vacancy of 3R-Phase Iridium Oxide by Loading Platinum Nanoparticles for Efficient Hydrogen Evolution
Ruiqi Guo, Jiajie Wang, Jiayi Li, Huaqing Li, Huihua Wang, Yi Cao, Jinxin Chen, Tao Cheng, Hao Yang, Minqi Sheng
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-IrO 2 ) is recognized as a potential competitor for the acidic oxygen evolution reaction (OER), its other catalytic activities have not been explored. Herein, 3R-IrO 2 modified by Pt nanoparticles (Pt@3R-IrO 2 ) exhibits certain catalytic activity toward the acidic HER. The Pt@3R-IrO 2 with 15 wt % Pt loading (15 wt % Pt@3R-IrO 2 ) 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 mg Ir+Pt –1 and considerable economic effect of 5.54 A $ –1 at −0.03 V vs RHE. Moreover, the 15 wt % Pt@3R-IrO 2 electrocatalyst can maintain the HER process in 0.5 M H 2 SO 4 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-IrO 2, mainly for the following two reasons: (i) loading Pt atoms/clusters on 3R-IrO 2 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-IrO 2 is moderately modified, indicating that it is beneficial to weaken the Gibbs free energy of hydrogen adsorption (Δ G *H ).