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

Abstract

The effect of Fe content in electroless-deposited Co[sbnd]Ni-Fe x -P alloy catalysts (x = 5.5–11.8 at.%)from the hydrolysis of NaBH 4 is investigated in alkaline sodium borohydride solution. The electroless-deposited Co[sbnd]Ni[sbnd]Fe 5.5 -P and Co[sbnd]Ni[sbnd]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[sbnd]Ni[sbnd]Fe[sbnd]P catalyst is transformed from FCC to BCC. Among all the Co[sbnd]Ni-Fe x -P alloy catalysts, the Co[sbnd]Ni-Fe x -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% NaBH 4 at 303 K. For the optimized catalyst, the activation energy of the hydrolysis of NaBH 4 is calculated to be 54.26 kJ mol −1 . Additionally, in this work, we report a new hydrolysis using Mg(BH 4 ) 2 and Ca(BH 4 ) 2 . As a result, the Mg(BH 4 ) 2 is stored unstably in an alkaline solution, whereas the Ca(BH 4 ) 2 is stored stably. When optimizing the hydrogen production kinetics from the hydrolysis of Ca(BH 4 ) 2 , the rate is 784 ml min −1 g −1 catalyst in 10 wt% NaOH + 3 wt% Ca(BH 4 ) 2 solution. © 2019 Hydrogen Energy Publications LLC