Effect of bath composition on properties of electroless deposited Co–P/Ni foam catalyst for hydrolysis of sodium borohydride solution

The effect of bath composition on the properties of electroless deposited Co–P/Ni foam catalyst for hydrolysis of sodium borohydride solution was investigated by varying the bath composition. The NaH2PO2/CoCl2 and NH2CH2COOH/CoCl2 concentration ratio had a strong effect on the catalyst properties. The effect of NH2CH2COOH/CoCl2 was larger than that of NaH2PO2/CoCl2 for the concentration ratio range with practical deposition rates. The optimum concentration ratio of the coating bath was CoCl2:NH2CH2COOH:NaH2PO2 = 1:4:10. As the concentration of each component increased at the optimum concentration ratio, the coating bath decomposed on its own. As the amount of solute dissolved in the coating bath increased, the coating bath became unstable. The optimum composition of the stable coating bath to realize Co–P/Ni foam catalyst with good catalytic activity was 0.1 m (molality, mol/kg) CoCl2, 0.4 m NH2CH2COOH, and 1.0 m NaH2PO2. The weight percent of the deposited catalyst and hydrogen generation rate per deposited catalyst of 1 g at optimum composition were 8.39 wt% and 0.93 L/min·g (deposited catalyst), respectively. The bath composition was found to have a great effect on the Co–P/Ni foam catalyst properties and coating bath stability.

► Electroless deposited Co–P/Ni foam catalyst for flow-type hydrogen generator. ► We investigate the effect of bath composition on the catalyst properties. ► The effect of NH2CH2COOH/CoCl2 was larger than that of NaH2PO2/CoCl2. ► The bath composition considerably affects the coating bath stability. ► As the amount of solute increases, the coating bath undergoes self-decomposition.