Ru‐Doped ZrO 2 as Efficient Electrocatalyst for Hydrogen Evolution Reaction in Acid Electrolyte

The development of efficient and durable electrocatalysts for the hydrogen evolution reaction (HER) in acidic media is crucial for proton exchange membrane water electrolysis (PEMWE). While zirconium oxide (ZrO 2 ) is chemically stable in sulfuric acid, its poor intrinsic conductivity and sluggish reaction kinetics limit its practical application. Herein, we report a series of ruthenium‐doped zirconium oxide (ZrO 2 /Ru‐x) catalysts synthesized via a facile one‐step hydrothermal method and systematically investigate the effect of ruthenium (Ru) doping content on their HER performance in 0.5 M H 2 SO 4 . The characterization results confirm that Ru atoms are successfully incorporated into the ZrO 2 lattice. Electrochemical measurements reveal that the HER activity exhibits an inverted volcano‐shaped dependence on Ru doping level, while the electrochemical capacitance surface area (ECSA) values display a volcano‐shaped dependence on Ru doping level. Among the prepared catalysts, the optimal ZrO 2 /Ru‐0.75 composition demonstrates the most outstanding performance, with a low overpotential of only 302 mV to achieve 10 mA cm −2 and a small Tafel slope of 119 mV dec −1 , significantly outperforming pristine ZrO 2 and other doped counterparts. This enhanced activity is attributed to the synergistic effect of optimized Ru‐O‐Zr coordination, which promotes water dissociation and facilitates favorable hydrogen adsorption/desorption energetics, as further supported by electrochemical impedance spectroscopy (EIS). Moreover, the optimized catalyst exhibits excellent long‐term stability over 24 h of continuous electrolysis, underscoring its potential as a cost‐effective alternative to noble‐metal–based HER catalysts. This work provides a comprehensive understanding of the structure‐activity relationship in Ru‐doped ZrO 2 systems and offers a viable strategy for designing high‐performance acidic HER electrocatalysts.