Effect of iron content on the hydrogen production kinetics of electroless-deposited Co-Ni-Fe-P alloy catalysts from the hydrolysis of sodium borohydride, and a study of its feasibility in a new hydrolysis using magnesium and calcium borohydrides

摘要

The effect of Fe content in electroless-deposited Co-Ni-Fey-P alloy catalysts (x = 5.5 -11.8 at.%) from the hydrolysis of NaBH4 is investigated in alkaline sodium borohydride solution. The electroless-deposited Co-Ni-Fe-5.5-P and Co-Ni-Fe-7.6-P alloy catalysts are composed of flake-like micron particles; however, with an increase in Fe content to 11.8 at.%, the flake-like morphology is changed to a spherical shape and the crystal structure of the electroless-deposited Co-Ni-Fe-P catalyst is transformed from FCC to BCC. Among all the Co-Ni-Fey-P alloy catalysts, the Co-Ni-Fey-P (x = 7.6 at.%) catalyst has the highest hydrogen production rate of 1128 ml min(-1) g(-1)catalyst in alkaline solution containing 1 wt% NaOH + 10 wt% NaBH4 at 303 K. For the optimized catalyst, the activation energy of the hydrolysis of NaBH4 is calculated to be 54.26 kJ mol(-1). Additionally, in this work, we report a new hydrolysis using Mg(BH4)(2) and Ca(BH4)(2). As a result, the Mg(BH4)(2) is stored unstably in an alkaline solution, whereas the Ca(BH4)(2) is stored stably. When optimizing the hydrogen production kinetics from the hydrolysis of Ca(BH4)(2), the rate is 784 ml min(-1) g(-1) catalyst in 10 wt% NaOH + 3 wt% Ca(BH4)(2) solution. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.