Square-wave pulse electrodeposition of gold nanoparticles for ethanol electrooxidation

Abstract

Gold nanoparticles (AuNPs) were synthesized as an electrocatalyst using a square-wave pulse deposition technique. By adjusting the applied upper potentials, we were able to control the size and distribution of the Au NPs. Analysis using the X-ray photoelectron spectroscopy technique confirmed the formation of metallic-phase Au particles on the fluorine-doped tin oxide (FTO) coated glass. Morphological studies show that at an upper potential of 0.00 V, fine particles were uniformly dispersed on the FTO substrate. With increasing potential, the particles underwent growth and coalescence, forming short chain-like structures. At potentials exceeding 0.25 V, the particle number decreased, and larger spherical particles were obtained, particularly at 1.00 V. Electrochemical impedance spectroscopy measurements exhibited low charge transfer resistance for the Au NPs synthesized at 0.25 V, producing high catalytic activity for the ethanol electrooxidation. The Au NPs electrocatalyst electrodeposited at low potential also shows a high poisoning resistance as indicated by the low j_b/j_f ratio value that resulted in catalytic stability as indicated by a slow current decay from the chronoamperometry measurements. The results contribute to the advancement of efficient and stable Au NPs electrocatalysts, particularly in ethanol electrooxidation.