Engineering ionic Ru–F bonds in amorphous RuO2 nanosheets for enhanced alkaline hydrogen electrocatalysis

Overcoming the mismatched adsorption energies is critical for efficient alkaline hydrogen electrocatalysis, yet modulating the strong Ru–O covalency without compromising structural integrity remains a key challenge. Herein, we address this by introducing ionic Ru–F bonds into selected regions of RuO 2 via tailored chemical bond engineering for enhanced hydrogen evolution and oxidation reactions (HER/HOR). Using fluorine‑doped amorphous RuO 2 (F‑RuO 2 ) nanosheets as a model catalyst, we find that electrons around fluorine atoms can become highly localized, forming ionic-character Ru–F bonds. This design results in a low HER overpotential of 32 mV at 100 mA cm −2 and delivers a high HOR diffusion-limiting current density of 2.98 mA cm −2 , positioning F-RuO 2 among the best‑performing Ru‑based electrocatalysts yet reported. Moreover, the anion-exchange-membrane water electrolyzer with F-RuO 2 can maintain a cell voltage of 1.60 V at 100 mA cm −2 for over 300 h with negligible degradation. In-situ spectroscopic analysis and density functional theory calculations reveal that the formed Ru–F bonds weaken Ru–O covalency and moderately lower the Ru oxidation states, optimizing hydrogen‑intermediate adsorption toward the ideal range and enhancing both HER and HOR electrocatalysis. This work offers fundamental insights into covalent‑bond modulation in amorphous oxides and establishes a generalizable design paradigm for high-performance electrocatalysts in sustainable energy conversion. The ionic Ru–F bonds reduce the covalency of RuO 2 and optimize the adsorption behaviour of the Ru sites, enabling F‑RuO 2 to exhibit superior reaction kinetics and catalytic activity in both HER and HOR. Download: Download high-res image (166KB) Download: Download full-size image