engleski

Hydrogen Evolution on Nickel Incorporated in Three-dimensional Conducting Polymer Layers

The paper discusses results on the development of nickel/conducting polymer composite layers used as catalysts in the hydrogen evolution reaction (HER). Conducting polymers (CP), polypyrrole (PPY) and polyaniline (PANI), are used as three-dimensional pattering templates (matrices) for electrodeposition of nickel on an inert glassy carbon surface. It is shown that Ni / CP layers offer a significantly higher overall electrocatalytic activity in the HER than Ni electrodeposited on a flat two-dimensional substrate. This is a result of favorable Ni / CP morphology which yields an increase in the active surface area of the catalyst. The overall best catalyst is a Ni / PANI layer formed by incorporation of small amounts of Ni into a thick pre-deposited PANI layer. The resulting porous layer is composed of ca. 3 mm interconnected spherical Ni particles, with an almost complete surface absence of PANI. The increased porosity of the layer is of a great benefit at high HER overpotentials, where accumulation of produced molecular hydrogen inside the catalyst layer is prevented. Due to a lower porosity, all the Ni / PPY catalytic layers studied are susceptible to the surface blockage (hydrogen accumulation) at high overpotentials. However, in the lower overpotential region, a Ni / PPY catalyst formed by incorporating a larger amount of Ni into a thin porous pre-deposited PPY layer offers an electrocatalytic HER activity comparable to the best Ni / PANI catalyst. When PPY and Ni are electrodeposited simultaneously (co-deposition method), a substantial decrease in a diameter of Ni islands, down to 100 nm, and an increase in the island surface density are obtained.

Hydrogen ; Water electrolysis ; Electrocatalysis ; Nickel ; Conducting polymers ; Polypyrrole ; Polyaniline.

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