Thiol-assisted regulated electronic structure of ultrafine Pd-based catalyst for superior formic acid electrooxidation performances

In order to further boost the electrocatalytic performances of small organic molecule oxidation and maintain the structure stability of Pd-based catalyst during long cycle, a new ligand compound ( i.e . propanethiol) was introduced into the Pd/C anode catalyst to prepared Pd/C-SH catalyst by two main steps of propanethiol adsorbed on Vulcan XC-72 carbon (C-SH) by water bath impregnation method and Pd nanoparticles anchored on the functionalized C-SH support by improved liquid reduction method. Results showed that the Pd nanoparticles with high dispersion in Pd/C-SH catalyst were obtained and their particle size distribution was in the range of 1.6–4.8 nm. Moreover, Pd particle size became smaller with the modification of propanethiol, indicating that propanethiol could facilitate the formation of smaller Pd. Electrochemical measurements showed that the mass activity of Pd/C-SH (1229 mA mg −1 ) was 4.6 times that of Pd/C (267 mA mg −1 ) towards formic acid oxidation. Higher stability (30 times higher than Pd/C) and more faster charge transfer kinetics of oxidation reaction were also recorded for Pd/C-SH catalyst. The enhancement of electrochemical performances of Pd/C-SH catalyst might be related to highly dispersed Pd with reduced particle size, adjusted electronic structure of Pd as well as maintained stable Pd structure and particle size.