Synthesis and application of biogenic gold nanomaterials with {1 0 0} facets for crude glycerol electro-oxidation

Abstract

In this work, gold nanomaterials were obtained using aqueous extracts of black carrots varying the molar ratio between the extract and the gold precursor salt (1:10, 1:5 and 2:5). Additionally, Au nanoparticles were obtained by the Turkevich method as reference material (Au Turkevich). Transmission electron micrographs indicated that a 1:5 ratio allowed to obtain a mixture of gold shapes like triangular, plate, rod, wire, and hemispherical shapes. The electrocatalytic evaluation for 0.5 M glycerol electro-oxidation indicated that Au (1:5) displayed higher current density (298.26 vs. 230.25 mA mg−1), and a more negative onset potential (ΔE = 150 mV) than Au Turkevich. In addition, Au (1:5) displayed higher current density during the electro-oxidation of 1 M crude glycerol (466.91 vs. 244.73 mA mg−1) with a similar potential difference. The improvement in activity and durability presented by Au (1:5) was attributed to the abundance of {1 0 0} facets as was determined by X-ray diffraction and HR-TEM.