A novel catalyst featuring highly stable cobalt and manganese nitride nanoclusters dispersed on single atom-anchored carbon nanotubes for hydrolytic release of hydrogen from ammonia borane

This study investigated the long-term stability of cobalt (Co) and manganese nitride (Mn 4 N) nanoclusters in the catalytic hydrolysis of a promising hydrogen (H 2 ) storage material, ammonia borane (H 3 NBH 3 ; AB), to release H 2 . It was previously found that Co nanoparticle/Co single-atom catalysts (Co NP/Co SACs) anchored on carbon nanotubes (CNT) exhibited excellent reactivity and stability towards AB hydrolysis and high performance in the H 2 evolution reaction in alkaline media. Therefore, the current study synthesised CoMn 4 N/Co-Mn-N x -CNT-200-800, a CoMn-based catalyst with Co and Mn 4 N nanocluster active sites, and examined its performance in AB hydrolysis. CoMn 4 N/Co-Mn-N x -CNT-200-800 generated three equivalents of H 2 from AB within 5 min, outperforming the catalytic activity of previously reported Co NPs/Co SACs. Moreover, CoMn 4 N/Co-Mn-N x -CNT-200-800 maintained over 90% of its initial activity after 50 cycles of AB hydrolysis. This exceptional long-term stability is attributable to CoMn 4 N/Co-Mn-N x -CNT-200-800 bearing Co/Mn 4 N nanoclusters that were strongly adhered onto graphitic layers, thereby preventing metal-atom aggregation and leakage during AB hydrolysis. Thus, CoMn 4 N/Co-Mn-N x -CNT-200-800 displayed a maximum effective H 2 generation rate of 8372 mL H2 ·g CoMn −1 ·min −1 . These results highlight the potential of dispersed bimetallic nanocluster catalysts, such as CoMn 4 N-based catalysts, for practical and sustainable H 2 generation via AB hydrolysis. In addition, the insights gained from this study can inform the design of highly active and stable non-precious metal-based catalysts for energy-related applications.