Dual confinement of LaCoOx modified Co nanoparticles for superior and stable ammonia decomposition

In this work, we report the rational design of amorphous LaCoOx modified Co nanoparticles confined in both nitrogen-doped carbon (NC) matrix and two-dimensional (2D) mesoporous silica (LaCoOx/[email protected]/SBA-15(2D)) via in situ confined pyrolysis of nano-sized La doped ZIF-67 in the mesopores of SBA-15(2D) as a novel dual-spatially-confined composite catalyst with superior activity and stability toward ammonia decomposition to produce hydrogen. It achieves a NH3 conversion efficiency close to 100 % at a high gas hourly space velocity (GHSV) of 60,000 gcat-1 h-1 with an encouraging H2 production rate of 446 mmol gCo-1 min-1 at 600 ℃ and can maintain stable catalytic activity for 200 h, almost outperforming all Co-based catalysts reported so far. Various characterizations and theoretical calculation results reveal that the outstanding ammonia decomposition performance mainly origins from the dual-spatially-confined configuration, fully exposed active sites and high mass transfer efficiency, and the synergy of amorphous LaCoOx, Co nanoparticles and NC matrix.