Revealing The Role of Electronic Asymmetricity on Supported Ru Nanoclusters for Alkaline Hydrogen Evolution Reaction

초록

Modulating the electronic asymmetricity of catalysts is an effective method for optimizating the elementary steps of water dissociation and hydrogen adsorption/desorption process for the alkaline hydrogen evolution reaction (HER). Herein, uniform Ru nanoclusters anchored on N doped ultrathin carbon nanosheets (Ru/NC) are synthesized to optimize the asymmetricity electronic properties of supported Ru for efficient HER. It is found that Ru and NC with a large work function difference (Delta phi) leading to the formation of stronger asymmetrical charge distributions of Ru that electron-deficient high-valence Ru (Run+) coupling with low-valence Ru (Ru0). Experimental and theoretical studies indicate the Run+ sites lowered the energy barrier for water dissociation and provided enough hydrogen proton to promote the hydrogen spillover from the Run+ to Ru0 sites, and Ru0 sites can enhance H desorption process, thus synergistically enhancing the hydrogen evolution activity. Notably, the Ru/NC catalyst exhibits a high alkaline HER activity (21.9 mV@10 mA cm-2, 29.03 mV dec-1). The role of electronic asymmetricity on supported Ru nanoclusters for the alkaline HER are demonstrated, which will provide guidelines for the rational design of high-efficiency alkaline HER catalysts. The large work function difference between Ru and NC leads to the formation asymmetrical charge distributions of supported Ru that electron-deficient high-valence Ru (Run+) coupling with low-valence Ru (Ru0). The Run+ sites lowered the energy barrier for water dissociation and Ru0 sites can enhance H desorption process, thus, synergistically enhancing the hydrogen evolution activity.image

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