Silica-assisted mesoporous [email protected] nanoplates derived from ZIF-67 crystals and their enhanced catalytic activity

Highlights: • Mesoporous [email protected] nanoplates derived from ZIF-67 crystals were facilely prepared. • Mesopore and nanoplates microstructure were created with the aid of silica template. • Mesoporous, nanoplates structure and basicity of carbon are responsible to superior activity. - Abstract: Mesoporous [email protected] nanoplates, derived from zeolitic imidazolate framework-67 (ZIF-67) crystals, were facilely prepared via a ^silica-assisted strategy. Through introducing and removing colloidal silica during synthetic process, the [email protected] nanocomposites (CoO_x@CS) exhibited mesopores characteristic and nanoplates. By comparison, the [email protected] nanocomposites (CoO_x@C), obtained by a direct pyrolysis of ZIF-67, exhibited micropores characteristic and assembled microsphere. In catalytic decomposition of ammonia, it was found that the CoO_x@CS nanocomposites showed excellent catalytic activity. Nearly 60% NH₃ conversion was achieved at 500 °C with a space velocity of 6000 h⁻¹, whereas only ~ 30% NH₃ conversion was achieved under the same reaction conditions for CoO_x@C nanocomposites. The enhanced activity should be attributed to mesoporous characteristic, nanoplates-like microstructure and basicity of carbon support. This study provides new insights into the development of controlling the structural orders of MOFs-derived carbon-based materials.