Electrocatalytic Performance of Silicotungstic Acid Modified Carbon Supported Pd Catalyst for Oxidation of Fomic Acid

The carbon supported Pd (Pd/C) anodic catalyst in the direct formic acid fuel cell (DFAFC) was prepared with the complex reduction method and the promote action of silicotungstic acid (SiWA) in the electrolyte for the oxidation of formic acid at the Pd/C catalyst was investigated. It was found that SiWA could increase the electrocatalytic activity and stability for the oxidation of formic acid. The promote action is related to the SiWA concentration. When the SiWA concentration is 0.40 g.L-1 the promote action is the largest. However, when the SiWA concentration is higher than 0.40 g.L-1, overfull adsorbed SiWA would cover too much active points of the Pd/C catalyst, leading to a decrease in the promote action of SiWA. In addition, because the adsorption of SiWA on the Pd/C catalyst decreases the adsorption strength of CO on the Pd/C catalyst, SiWA could increase the electrocatalytic stability of the Pd/C catalyst for the oxidation of formic acid and also promote the oxidation of formic acid through the direct route.