Electrostatically Guided Covalent Architectures for Stable Hydrogen Evolution at Ampere-Level Current Densities in...

Achieving stable operation at high current densities is a critical challenge for acidic water electrolysis, where intensified bubble evolution induces concentration polarization and mechanical stress that accelerate catalyst degradation. Here, we report Mo₂C nanoclusters in situ anchored onto nitrogen-doped carbon nanotubes (NCNTs) via strong Mo─C and Mo─N covalent bonds. The covalent integration, achieved through electrostatically guided self-assembly followed by carbonization, yields a porous and conductive network that combines efficient charge transport with resistance to acidic corrosion. The resulting catalyst delivers overpotentials of 256 mV at 500 mA cm^-2 and 396 mV at 1000 mA cm^-2 in 0.5 m H₂SO₄, and operates stably at 865 mA cm^-2 for over 240 h. In a proton exchange membrane water electrolyzer, it sustains overall water splitting at 1000 mA cm^-2 with a cell voltage of 2.03 V for more than 150 h. This hierarchical covalent design enhances conductivity, durability, and bubble management, representing a scalable strategy for next-generation electrocatalysts capable of ampere-level operation in acidic media.