NI-AL POWDER ELECTROCATALYST FOR HYDROGEN EVOLUTION - EFFECT OF HEAT-TREATMENT ON MORPHOLOGY, COMPOSITION, AND KINETICS

Electrocatalytic activity toward the hydrogen evolution reaction in alkaline media was studied on three types of electrodes: (i) pressed Ni + Al powders; (ii) same as i but heated at 400-degrees-C; (iii) same as i but heated at 700-degrees-C; followed by leaching aluminum in alkaline solution. Steady-state polarization and ac impedance spectroscopy were used to determine the electrode activities. A dramatic increase in activity occurs after heating N1 + Al powders above the Al melting point, which is connected with the diffusion of Al into Ni and formation of new phases. The hydrogen evolution reaction proceeds through the Volmer-Heyrovsky mechanism and the main factor influencing the activity is the roughness factor.