Ni and Ni-Mo hydrogen evolution electrocatalysts electrodeposited in a polyaniline matrix

Electrocatalytic activity of Ni and NiMo electrodeposited in a three-dimensional polyaniline (PANI) matrix was investigated in the hydrogen evolution reaction (HER). By using PANI an increase in surface roughness of the metallic catalytic layers could be obtained, ultimately yielding an increased overall electrocatalytic activity in the HER. It was demonstrated that alloying Ni with Mo results in an increased electrocatalytic activity in the HER when compared to pure Ni. This is due to an improved intrinsic activity of the material, which was explained on the basis of the modification of the electron density in the d-shell upon alloying Ni with Mo. An improvement of the NiMo/PANI catalysts' intrinsic properties was also demonstrated by a significant decrease in activation energy in the HER when compared to the Ni/PANI layer. By using DC linear polarization and AC electrochemical impedance spectroscopy techniques the mechanism and kinetics of the HER on the investigated catalysts was determined. (c) 2005 Elsevier B.V. All rights reserved.