The origins of formic acid electrooxidation on selected surfaces of Pt, Pd, and their alloys with Sn

Radhey ShyamYadav, Medhanie Gebremedhin Gebru, Hanan Teller, Alex Schechter, Haya Kornweitz

Research output: Contribution to journalArticlepeer-review


Bimetallic and trimetallic catalysts enhance the catalytic process of formic acid oxidation (FAO) and its adsorbed CO* main intermediate. A comprehensive study, using DFT calculations and electrochemical experiments, was conducted on a series of five mono-, bi-, and tri-metallic catalysts for FAO: Pt(111), Pd(111), Pt3Sn(111), Pd3Sn(111), and Pt3Pd3Sn2(111), considering both pathways: direct oxidation to CO2 and the indirect pathway involving the oxidation of adsorbed CO*. The results show that H-COOH cleavage is thermodynamically predominant on most of the surfaces except Pd3Sn(111). However, kinetically, O-H bond scissoring is preferred on all of the surfaces. The barriers for O-H and C-H cleavage for Pt(111) and Pt3Pd3Sn2(111) are comparable thus the process is governed by thermodynamics. On Pt(111), C-H cleavage is favored, while on Pt3Pd3Sn2(111), both O-H and C-H cleavage are equally viable due to similar thermodynamic profiles. Additionally, Pt-based alloys promote the indirect mechanism, whereas Pd enhances the direct mechanism. Alloying Pt with Sn and the combined effect of Pt, Pd, and Sn in a trimetallic alloy results in the weakening of the HCOOH adsorption and reduces all the activation barriers. The electrochemical findings support the computational results, demonstrating that Pd(111) exhibits oxidation peaks at a low potential, 0.37 V, (indicating a direct mechanism), while Pt-based catalysts display oxidation peaks at around 0.95 V, indicative of the indirect mechanism. Notably, Pt3Pd3Sn2/C shows the highest overall performance towards FAO, with peak current densities of 225 mA mgPGM−1. Thus, Pt3Pd3Sn2 is the most efficient catalyst, providing the lowest energetic pathways for FAO reaction.

Original languageEnglish
JournalJournal of Materials Chemistry A
StateAccepted/In press - 2024


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