Electrocatalytic Activities of Nickel-phosphorous Composite Coating Reinforced with Codeposited Graphite Carbon for Hydrogen Evolution Reaction in Alkaline Solution

Nickel-phosphorus-codeposited graphite carbon (Ni-P-C-g) materials have been studied by means of electrochemical and microstructural techniques. Steady-state polarization Tafel curves showed that the Ni-P-C electrodes were active toward the HER. The activity of the Ni-P-C-g materials was depended on the electrode composition and the best activity was obtained on Ni83P12C5 electrode (eta(250) = -242.4 +/- 2.1 mV), which was subjected to annealing at 400 degrees C in argon atmosphere. EIS measurements revealed that the electrodes were active and the source of the activity was originated mainly from improvement in electronic structure of the catalyst, and partially from increase in the surface roughness caused by the heat treatment process mentioned above. Furthermore, the Volmer-Heyrovsky mechanism was determined for the HER and the latter was the rate-determining step.