Evaluation of Pt Alloys as Electrocatalysts for Oxalic Acid Oxidation: A Combined Experimental and Computational Study

Abstract

In this study we combined experimental approaches and density functional theory to evaluate novel platinum-based materials as electrocatalysts for oxalic acid oxidation. Several Pt alloys, PtSn (1:1), PtSn (19:1), PtRu (1:4), PtRuSn (5:4:1), and PtRhSn (3:1:4), were synthetized using sacrificial support method and tested for oxidation of oxalic acid at pH 4. It was shown that PtSn (1:1) and PtRu (1:4) have higher mass activity relative to Pt. These two materials along with Pt and one of the least active alloys, PtSn (19:1), were further analyzed for the oxidation of oxalic acid at different pHs. The results show that all samples tested followed an identical trend of decreased onset potential with increased pH and increased catalytic activity with decreased pH. Density functional theory was further utilized to gain a fundamental knowledge about the mechanism of oxalic acid oxidation on Pt, PtSn (1:1), and PtRu (1:4). The results of the calculations along with the experimentally observed dependence of generated currents on the oxalic acid concentration indicate that the mechanism of oxalic acid oxidation on Pt proceeds without the participation of surface oxidizing species, while on Pt alloys it involves their participation.

Novel Hybrid Catalyst for the Oxidation of Organic Acids: Pd Nanoparticles Supported on Mn‐N‐3D‐Graphene Nanosheets

“…The atomically dispersed metal atoms coordinated with nitrogen and/or carbon were proposed to be the active sites in similar Fe‐ containing catalysts . In addition, a similar approach was used previously by us to study the oxidation of oxalic acid on Pt alloys and Mn−N‐C catalyst derived from Mn and Aminoantipyrine …”

“…This is best illustrated in the case of the oxalic acid, where the hybrid Pd/Mn−N‐3D‐GNS catalyst is characterized with low onset potential due to the presence of Pd nanoparticles and higher currents than the ones measured for any of the components separately. This is most likely due to comparably high activity of both Mn−N‐C sites and metallic Pd for oxalate oxidation . In the case of the mesoxalic acid, the hybrid catalyst demonstrates only slightly lower currents than the intrinsically most active Mn−N‐3D‐GNS catalyst, however, the presence of Pd decreases the onset potential as compared to Mn−N‐3D‐GNS for almost 60 mV.…”

“…This allows for comparison between Pd/Mn−N‐3D‐GNS, Pd/3D‐GNS, and Mn−N‐3D‐GNS. Onset potentials were determined quantitatively by taking 10 times the standard deviation of the capacitive current as shown in our previous work . Onset potentials are given relative to a Ag/AgCl reference electrode unless otherwise stated.…”