Improvement of catalytic performance of AuAg/C catalysts prepared by galvanic displacement technique for glycerol electrooxidation in alkaline medium

摘要

The activity and stability of AuAg/C electrocatalysts prepared by a galvanic displacement between Au3+ and Ag on carbon were investigated. First, Ag/C was prepared by citrate reduction in alkaline and used as the displaced material. The addition of Au3+ into the Ag/C resulted in smaller fragments of AuAg nanoparticles. These AuAg/C catalysts were prepared at four Au loadings ranging from 5 to 30%wt Au. Upon interaction with glycerol, the catalyst surface became an Au-rich surface, thereby activating the catalysts. The promotion effects of Ag, such as negative shifts of both an onset potential and a potential at maximum current density, were observed on the catalysts with low Au content but not on those with high Au content. The AuAg/C catalysts with low Au content were more active than the Au/C one despite the very much larger size of the metal particles on the AuAg/C catalysts. The most active catalysts were 5%AuAg/C and 10%AuAg/C, providing much higher mass normalized current densities in electrolytes containing 0.1 and 1 M glycerol, respectively. The final current density of 10%AuAg/C after 60 min in 1 M glycerol electrolyte was 445 mA mg(Au) (-1), which was about 9 times higher than that of Au/C. A synergistic effect between Au and Ag improved the stability of the AuAg/C catalysts.