Thin-film CoB catalyst templates for the hydrolysis of NaBH4 solution for hydrogen generation

Thin-film CoB alloy catalysts were prepared on Ni-foam substrates using electroless as well as electroplating techniques. Electroless plating was carried out using cobalt (II) sulfate as the source of Co2+, sodium succinate as the complexing agent, and dimethyamine borane as the source of boron as well as the reducing agent. Electroplating was carried out using cobalt (II) sulfate and cobalt (II) chloride as the sources of cobalt, and boric acid as the source of boron. The thin-film CoB/Ni-foam templates were characterized using ICP, XRD and SEM techniques. The normalized B content was in the range of 1.0–1.30 and 0.20–0.60wt.% for electroless and electroplated templates, respectively. The B content is less than that required for stoichiometric alloy formation, which indicates the simultaneous deposition of the Co metal along with CoB alloy. An optimum condition of 0.100ML−1 each of cobalt (II) sulfate heptahydrate Co(SO4)·7H2O, sodium succinate (Na2C4H4O4) and dimethylamine borane (CH3)2NHBH3, at 60°C with the pH value of 4–5 and a plating time of 1h was identified for the preparation of the catalyst templates by electroless plating. Where as, 0.125ML−1 each of cobalt (II) chloride hexahydrate (CoCl2·6H2O), Co(SO4)·7H2O, 0.125ML−1 of boric acid at the current density range of 160–320mAcm−2 and a temperature of 60°C was identified as the optimum condition for the electroplating method. Maximum H2 generation rates of 1.64 and 0.30Lmin−1g−1 of catalyst were obtained with electroless and electroplated thin-film CoB/Ni-foam templates, respectively. The suitability of the electroless plated CoB/Ni-foam catalyst template for extended duration of hydrogen generation from NaBH4 was studied up to 60h. Activation energies of 44.47 and 54.89kJmol−1 were calculated for electroless and electroplated CoB/Ni-foam catalyst templates, respectively.