Stability and kinetic studies of MOF-derived carbon-confined ultrafine Co catalyst for sodium borohydride hydrolysis

A mesoporous carbon-confined cobalt (Co@C) catalyst was fabricated by pyrolysis of macroscale Co-metal-organic framework (MOF) crystals and used to catalyze NaBH4 hydrolysis for hydrogen production. To reveal the structural changes of cobalt nanoparticles, we characterized the fresh and used Co@C catalysts using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and N-2 adsorption. This MOF-derived Co@C exhibits high and stable activity toward NaBH4 hydrolysis. No obvious agglomeration of Co nanoparticles occurred after five consecutive runs, implying good resistance of Co@C composite to metal aggregation. The kinetics of NaBH4 hydrolysis was experimentally studied by changing initial NaBH4 concentration, NaOH concentration, and catalyst dosage, respectively. It was found that the hydrogen generation rate follows a power law: r = A exp (-45.0/RT)[NaBH4](0.985)[cat](1.169)[NaOH](-0.451).