Electrocatalytic behavior of amino compound oxidation on NiCo catalyst and energy conversion

Abstract

Carbon-supported Ni and NiCo catalysts have been prepared for amino compound electrooxidation. Their electrocatalytic behaviors toward 8 kinds of amino acids (glycine, alanine, histidine, methionine, proline, serine, tyrosine, and cysteine) were investigated via electrochemical methods and in situ Raman spectroscopy. The Ni and NiCo catalysts demonstrated catalytic activity for amino acid electrooxidation, and the current densities differ according to the R side chain group. Compared to Ni/C, NiCo/C is superior in terms of onset potential and anodic current density. Electrochemical in situ Raman characterization indicated that Ni_xCo_1–xOOH was generated above the onset potential. The amino compounds were electrooxidized after the onset potential by the Ni_xCo_1–xOOH active species. However, the anodic current of cysteine was observed at a more negative potential than the onset potential, caused by the electrooxidation of sulfur in the R side chain. A direct alkaline fuel cell was fabricated with glycine as the fuel. The fuel cell with NiCo/C anode catalyst achieved a maximum power density of 3.0 mW cm⁻² at 60 °C, 1.5 times higher than that of the fuel cell with the Ni/C anode catalyst.