Competitive Adsorption Mechanism of Defect‐Induced d‐Orbital Single Electrons in SrRuO₃ for Alkaline Hydrogen Evolution Reaction

Abstract

In the alkaline hydrogen evolution reaction (HER), the dissociation energy barrier of water, and the easy adsorption of OH on the catalyst are key factors that limit the catalytic activity. This work proposes a novel competing adsorption mechanism driven by dz2 electrons in the context of the alkaline HER. The high concentration of oxygen vacancies in Co doped SrRuO3 (V‐SRCO) results in the electron filling in the Ru 4dz2 orbital. Under alkaline conditions, the V‐SRCO exhibits a low overpotential of only 57.8 mV with a Tafel slope of 35 mV dec−1. Moreover, it exhibits sustained high activity for 60 h. The high HER activity of V‐SRCO can be attributed to the presence of a single electron in the dz2 orbital, which reduces the energy barrier for water dissociation. More importantly, the active electrons in the dz2 orbital can inject into the antibonding orbitals of OH, creating an unfavorable environment for OH adsorption on the catalyst. This work provides favorable conditions for efficient HER.

Laser Irradiation in Liquid-Generated PtNiRu@C Nanoparticles for Water Hydrolysis

“…Figure 5a demonstrates the corresponding differential charge density color-filled optimized configurations, which show that PtNiRu@C (111) underwent more significant electronic interactions and electron redistribution upon adsorption of water with respect to that in PtNiRu (111) and PtNi (111), suggesting that the dissociation of water and the enhanced HER performance were associated with higher charge transfer. 55 From the viewpoint of kinetics, a low H 2 O dissociation energy indicates that sufficient hydrogen protons can be subsequently provided for the subsequent H recombination key step. As shown in Figures 5b and S12, the H 2 O dissociation energy was reduced after the introduction of Ru (0.92 to 0.70 eV) and further greatly lowered by the confinement of the carbon layer (0.70 to 0.27 eV), indicating the critical role of Ru and the carbon layer for H 2 O dissociation in the key Volmer step.…”

“…To gain insights into the effect of Ru doping and carbon layer confinement in alkaline media, density functional theory (DFT) calculations were employed to investigate the origin of prominent HER performance on PtNi (111), PtNiRu (111), and PtNiRu@C (111) from the thermodynamic and kinetics aspects; the related slab models are shown in Figure S11. Figure a demonstrates the corresponding differential charge density color-filled optimized configurations, which show that PtNiRu@C (111) underwent more significant electronic interactions and electron redistribution upon adsorption of water with respect to that in PtNiRu (111) and PtNi (111), suggesting that the dissociation of water and the enhanced HER performance were associated with higher charge transfer . From the viewpoint of kinetics, a low H 2 O dissociation energy indicates that sufficient hydrogen protons can be subsequently provided for the subsequent H recombination key step.…”