Silica Confinement for Stable and Magnetic Co−Cu Alloy Nanoparticles in Nitrogen‐Doped Carbon for Enhanced Hydrogen Evolution

Abstract Ammonia borane (AB) with 19.6 wt % H 2 content is widely considered a safe and efficient medium for H 2 storage and release. Co‐based nanocatalysts present strong contenders for replacing precious metal‐based catalysts in AB hydrolysis due to their high activity and cost‐effectiveness. However, precisely adjusting the active centers and surface properties of Co‐based nanomaterials to enhance their activity, as well as suppressing the migration and loss of metal atoms to improve their stability, presents many challenges. In this study, mesoporous‐silica‐confined bimetallic Co−Cu nanoparticles embedded in nitrogen‐doped carbon (Co x Cu 1−x @NC@mSiO 2 ) were synthesized using a facile mSiO 2 ‐confined thermal pyrolysis strategy. The obtained product, an optimized Co 0.8 Cu 0.2 @NC@mSiO 2 catalyst, exhibits enhanced performance with a turnover frequency of 240.9 mol H2 ⋅ mol metal ⋅ min −1 for AB hydrolysis at 298 K, surpassing most noble‐metal‐free catalysts. Moreover, Co 0.8 Cu 0.2 @NC@mSiO 2 demonstrates magnetic recyclability and extraordinary stability, with a negligible decline of only 0.8 % over 30 cycles of use. This enhanced performance was attributed to the synergistic effect between Co and Cu, as well as silica confinement. This work proposes a promising method for constructing noble‐metal‐free catalysts for AB hydrolysis.