d‐orbital charge density regulation of SiO _<i>x</i> /RuCoO _<i>x</i> nanoparticles to boost water splitting in acidic media

Abstract Hydrogen has emerged as a promising clean energy carrier, and the development of cost‐effective electrocatalysts that retain high activity under acidic media is crucial for advancing proton exchange membrane water electrolysis (PEMWE). Here, we propose the SiO x /RuCoO x nanoparticles (SiO x /RuCoO x NPs) as bifunctional electrocatalysts for efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under acidic media. The Ru‐O‐Si interface, along with charge transfer between Ru and Co, modulates the d‐band electronic structure of the Ru site, achieving superior performance with a low HER overpotential of 18 mV at 10 mA·cm −2 and a turnover frequency of 8.86 H 2 ·s −1 at 100 mV. For OER, the overpotential is 217 mV at 10 mA·cm −2 . SiO x /RuCoO x NPs exhibit a cell voltage of 1.482 V at 10 mA·cm −2 with an energy conversion efficiency of 83.0%. This work takes a significant step toward achieving efficient and cost‐effective bifunctional electrocatalysts for water splitting, playing a critical role in the transition to clean energy technologies.