Abstract: The structural and electrocatalytic characteristics of composite materials
based on non-precious metals were studied. Precursors of metallic phase (Ni, Co or
CoNi) and oxide phase (TiO2) were grafted on a carbon substrate (Vulcan XC-72) by
the sol–gel procedure and thermally treated at 250 ºC. Ni and CoNi crystals of 10–20
nm were produced, in contrast the Co and TiO2 were amorphous. The dissimilar
electronic character of the components gives rise to a significant electrocatalytic activity
for the hydrogen evolution reaction (HER), even in the basic series of prepared
materials. Further improvement of the catalysts was achieved by modification of all
three components. Hence, Mo was added into the metallic phase, TiO2 was converted
into the crystalline form and multiwall carbon nanotubes (MWCNTs) were
used instead of carbon particles. The improvement, expressed in terms of the lowering
the hydrogen evolution overpotential at 60 mA cm-2, was the most pronounced
in the Ni-based systems grafted on MWCNTs (120 mV lower HER overpotential)
compared to 60 mV in case of Ni-based systems grafted on crystalline TiO2 (TiO2
prepared at 450 ºC) and of Ni-based systems containing 25 at.% Mo. Nevertheless,
even with the realized enhancement, of all the tested materials, the Co-based systems
remained superior HER catalysts.
Keywords: composite electrocatalysts, hydrogen evolution, electronic interaction,
real surface area
