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 % H₂ content is widely considered a safe and efficient medium for H₂ 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_xCu_1-x@NC@mSiO₂) were synthesized using a facile mSiO₂-confined thermal pyrolysis strategy. The obtained product, an optimized Co_0.8Cu_0.2@NC@mSiO₂ 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_0.8Cu_0.2@NC@mSiO₂ 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.