Carbon supported PdM (M = Fe, Co) electrocatalysts for formic acid oxidation. Influence of the Fe and Co precursors

Pd and PdM (M = Fe or Co) nanostructured electrocatalysts were synthesized by the impregnation method and supported on carbon black Vulcan XC-72R for the formic acid oxidation reaction, FAOR, in acid medium. Nitrates or chlorides were used as Fe and Co precursors to study the counter ion role on the physicochemical features and electrochemical performance of the electrocatalysts. TEM analysis showed that PdM was deposited on the carbon material with a particle size around 2-3 nm. From XRD, peaks associated with the fcc palladium planes were observed along with evidence of PdM alloy formation, particularly when the nitrate salts were used as metal precursors. Furthermore, XPS analyses indicated that nitrates promote the metal oxide formation to a greater extent than chlorides, mainly for Pd. PdCo electrocatalyst obtained from nitrates exhibited the highest performance for FAOR with a steady state current density of 451 and 313 mu A cm(-2) at 200 and 400 mV respectively, which is in both cases, 3 times larger than that developed for a commercial Pd/C catalyst. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.