Au/C catalysts promoted with Ni for glycerol electrooxidation in alkaline media

Au/C catalysts promoted by Ni at different Au:Ni atomic ratios (3:1, 2:1, and 1:1) were prepared for glycerol electrooxidation in alkaline media by a polyvinyl alcohol protection method. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, and inductively coupled plasma atomic emission spectroscopy. According to the cyclic voltammogram, Ni enhanced the catalytic activity of gold for glycerol electrooxidation in the alkaline media, although the average particle size of the AuxNiy/C catalysts was slightly larger than that of the Au/C with small cluster formation. The optimum atomic ratio of Au:Ni was found to be 2:1, since the Au2Ni1/C provided the maximum mass current density at approximately 18% higher than did the Au/C. The stability of the Au2Ni1/C also improved, as evidenced by chronoamperometry. These improvements are attributed to the ability of Ni to enhance the OH-adsorbed species on the Au surface, thereby inducing a lower onset potential and helping to remove intermediates from the active site. To reduce cluster formation, the effects of metal sol preparation and metal loading sequence on the catalysts' performance were further studied at this atomic ratio (2:1). Catalysts with preloading of Ni (Au-2/Ni-1/C) were found to provide the highest maximum mass current density with comparable decay rates among all the catalysts tested. [GRAPHICS] .