Abstract
Sodium tetrahydroborate (NaBH4) was used as a fuel source for hydrogen-oxygen fuel cell. The oxalic acid, Ag+, Cu2+ and Ni (2+) accelerates the hydrogen (H-2 gas) evolution from the self-hydrolysis of NaBH4 at 30 degrees C. Kinetics of H-2 gas generation was evaluated as a function of catalyst, NaBH4, sodium hydroxide concentrations at different temperatures. Hydrolysis NaBH4 follows first-, and fractional-order kinetics with [BH4-], and [H+] respectively. The hydrolysis of NaBH4 decreases with increasing [NaOH] at 30 degrees C. The metal ions (Ag+, Cu2+, and Ni2+) catalyzed the evolution of H-2 gas and hydrolysis followed zero-order kinetics with respect to the metal ions. Hydrolysis of NaBH4 was catalyzed by metal ions and hydrogen ions simultaneously. The activation parameters were calculated and found to be activation energy = 54.9, 59.7, 62.7 kJ/mol, enthalpy of activation = 52.4, 57.5, 60.2 kJ/mol and entropy of activation = -62.2, -48.2, -49.6 J/K/mol for Ag+, Cu2+ and Ni2+ respectively. The catalytic activity of depends on the reduction potential of metal ions; Ag+ (0.799 V) > Cu-2(+) (0.341 V) > Ni-2(+) (-0.257). (C) 2021 The Author(s). Published by Elsevier B.V. on behalf of King Saud University.