Spontaneously Bi decorated carbon supported Pd nanoparticles for formic acid electro-oxidation

• Published in: Electrochimica acta 2013-09, Vol.107, p.562-568
• Main Authors: Bauskar, Akshay S., Rice, Cynthia A.
• Format: Article
• Language: English
• Subjects: Adatom adsorption; Adsorption; Bismuth; Carbon; Decoration; Electrocatalysis; Formic acid; Formic acid electro-oxidation; Fuel cells; Nanoparticles; Palladium; Stability; Surface chemistry
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2013.06.042

•Selective decoration of Bi onto commercial Pd/C is carried out by a simple gas controlled surface potential modulation technique.•Bi decorated Pd/C catalyst exhibits higher and sustained formic acid oxidation activity presumably via the electronic effect.•Shielding of Pd atoms by Bi increases long term stability.•Formic acid electro-oxidation current increased by 121% at 0.2V vs. RHE. The activity and stability of carbon supported palladium (Pd/C) nanoparticles decorated with a submonolayer of bismuth (Bi) for formic acid (FA) electro-oxidation was investigated herein. The FA electro-oxidation activity enhancement of Bi decorated Pd/C was evaluated electrochemically using a rotating disk electrode configuration by linear sweep voltammetric and chronoamperometric measurements. Commercial Pd/C was decorated by irreversible adsorption of Bi via a simple gas controlled surface potential modulation technique, and the coverage of Bi adatoms as measured by cyclic voltammetry was controlled in the range of 30–87%. An optimal Bi coverage was observed to be 40%, resulting in a favorable decrease in the FA onset potential by greater than 0.1V and increase in electro-oxidation current density from 0.25mAcm−2SA to 0.55mAcm−2SA at 0.2V vs. RHE, compared to commercial Pd/C. The results indicate that Bi decorated Pd nanoparticles have excellent properties for the electro-oxidation of FA, i.e. high electro-catalytic activity and excellent stability, due to sustained promotion of dehydrogenation pathway attributed to the electronic effect, thereby promoting FA adsorption in the CH-down orientation. Based on no significant shifting in the CO stripping peak position, minimal impact of Bi on the PdCO bond strength is observed. Chronoamperometry results show much better long-term electro-catalytic activity for Bi decorated Pd nanoparticles attributed to shielding of surface Pd atoms by Bi and reducing Pd dissolution.