Nickel cysteine complexes as anodic electrocatalysts for fuel cells

Compared to platinum, nickel is an inexpensive catalyst that can oxidize methanol in alkaline media. There is a desire to increase nickel loading during electrodeposition for improved performance. In this paper, a nickel cysteine complex (NiCys) is used as the precursor for electrodeposition on glassy carbon electrode surfaces. After optimization of cysteine concentration, the surface concentration of NiOOH on NiCys electrodes characterized by cyclic voltammetry in 0.1 M NaOH can reach 1.28 (± 0.32) × 10−7 mol/cm2. The large amount of NiOOH on NiCys electrodes provide 5 times the methanol oxidation current compared to Ni electrodes prepared without cysteine as demonstrated by chronoamperometry at 0.7 V vs. Hg/HgO. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy have been applied to examine surface morphologies and structures of NiCys and Ni electrodes. The analysis reveals that cysteine adjusts the solubility of Ni(OH)2 in 0.1 M NaOH, so more uniform and smaller size nanoparticles are electrodeposited on electrode surfaces compared to Ni electrodes.