关键词: Pd基催化剂, Sb修饰, 甲酸电氧化, 浸渍还原法

Abstract: Palladium is considered as an efficient anode catalyst with high catalytic activity for electrooxidation of formic acid. To further improve the catalytic activity and stability, alloying or surface modification with Sb is an effective way. In this work, the well dispersed carbon supported Pd-Sb composite nanocatalysts (Pd-Sb/C) were synthesized by traditional impregnation reduction method with trisodium citrate as the complexing agent, sodium borohydride as the reducing agent. The morphologies of Pd-Sb/C and the effects of molar ratio of Pd to Sb on the electrocatalytic properties of Pd-Sb/C for HCOOH electrooxidation were studied. The XRD and XPS analyses on the as-prepared Pd-Sb/C catalyst revealed that Sb (0) was presented on the Pd surface, and the immature alloying of Pd with Sb was achieved. Cyclic voltammetryic and chronoamperometric studies indicated a volcano-shaped relationship between Sb content and electrocatalytic activity with an optimum molar ratio of Pd:Sb=20:1. Compared with the commercial Pd/C catalyst, the Pd-Sb/C (20:1) presented the highest electrocatalytic activity and best stability. This enhancement may be attributed to the electronic effect and bi-functional effect induced by addition of Sb onto Pd surface, resulting in a weaker adsorption and accelerated oxidative removal of CO poison formed during HCOOH electrooxidation.

Key words: palladium-based catalyst, antimony decoration, formic acid electrooxidation, impregnation reduction