Nickel-Rhodium Nanoparticles as Active and Durable Catalysts for Hydrogen Liberation

Abstract

Herein, synthesis, characterization, and catalytic utilization of rather efficient carboxymethyl cellulose-stabilized nickel-rhodium nanoparticles (4.5 +/- 0.7 nm) in hydrogen liberation from ammonia borane and hydrazine borane by hydrolysis are reported. The catalysts are prepared by simultaneous reduction of appropriate nickel and rhodium salts in aqueous solution by sodium borohydride by using carboxymethyl cellulose as a stabilizer. Transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy are used to characterize the catalysts. The catalysts are highly durable and effective to liberate hydrogen from ammonia borane and hydrazine borane in aqueous solution at lower concentrations and temperature. Among prepared catalysts, Ni0.50Rh0.50@CMC provides 200 min(-1) and 188 min(-1) of average turnover frequencies and 46.8 +/- 2 kJ/mol and 60.3 +/- 2 kJ/mol of activation energies for ammonia borane and hydrazine borane hydrolysis reactions, respectively.