Palladium–Tin Alloyed Catalysts for the Ethanol Oxidation Reaction in an Alkaline Medium

Abstract

In this paper, we present a study of a series of carbon-supported Pd−Sn binary alloyed catalysts prepared through a modified Polyol method as anode electrocatalysts for direct ethanol fuel cell reactions in an alkaline medium. Transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and aberration-corrected scanning transmission electron microscopy equipped with electron energy loss spectroscopy were used to characterize the Pd−Sn/C catalysts, where homogeneous Pd−Sn alloys were determined to be present with the surface Sn being partially oxidized. Among various Pd−Sn catalysts, Pd 86 Sn 14 /C catalysts showed much enhanced current densities in cyclic voltammetric and chronoamperometric measurements, compared to commercial Pd/C (Johnson Matthey). The overall rate law of ethanol oxidation reaction for both Pd 86 Sn 14 /C and commercial Pd/C were also determined, which clearly showed that Pd 86 Sn 14 /C was more favorable in high ethanol concentration and/or high pH environment. Density functional theory calculations also confirmed Pd−Sn alloy structures would result in lower reaction energies for the dehydrogenation of ethanol, compared to the pure Pd crystal.

Palladium Nanoparticles Anchored on Anatase Titanium Dioxide‐Black Phosphorus Hybrids with Heterointerfaces: Highly Electroactive and Durable Catalysts for Ethanol Electrooxidation

“…A lower Tafel slope is generally considered to indicate fast charge-transfer kinetics because of the rapid transport of active species and rapid electron transmission of the EOR on a catalyst. [55,56] The lowest Tafel slope was found for the Pd/ATN-BP-30% catalyst, indicating that among the Pd-based catalysts tested, its charge-transfer kinetics in the alkaline medium were the fastest. This result can be explained by the contribution of the ATN-BP support to the generation of oxygenated species (e.g., OH ad ) for accelerating the oxidation of the reaction intermediates adsorbed on the Pd sites, in accordance with increase in ECSA CO .…”

Activity Enhancement of Tetrahexahedral Pd Nanocrystals by Bi Decoration towards Ethanol Electrooxidation in Alkaline Media

“…3a), there are several noticeable changes such as a broader but less well-defined hydrogen adsorption/desorption current peak, a significantly narrower double layer region but with higher current, and a less significant but broader current peak associated to surface oxygen-containing (e.g., hydroxyl) species formation/stripping processes. Nevertheless, compared with a polycrystalline Pd/C catalyst [31], a more pronounced current peak for surface hydroxyl adsorption/formation was observed for the THH Pd NCs, indicating a stronger interaction between Pd and hydroxyl groups due to the stepped facets being present on the THH Pd NCs. The latter phenomenon is consistent with that observed in the acidic medium (Fig.…”

“…Teng and co-workers [31] also reported a series of carbon supported Pd-Sn nanocrystals for ethanol electrooxidation where an enhancement in the activity was attributed to the bifunctional effect of the alloy where Sn or SnO x has stronger interactions with hydroxyl group whilst Pd has excellent properties in the adsorption and dissociation of ethanol. The Pd-Sn alloy structure would result in lower reaction energies for the dehydrogenation of ethanol compared to the pure Pd crystals [31]. A novel Pt-PbO x NC catalyst has been synthesized by Sun's group via a simple wet chemistry method without using surfactants, organometallic precursors or high temperatures [32].…”

“…Recently, Adzic et al [28][29][30] developed multifunctional ternary PtRhSnO 2 and PtIrRh electrocatalysts, which are highly effective in the splitting of C-C bond in ethanol at room temperature and able to oxidize ethanol to CO 2 at low overpotentials [28][29][30]. Teng and co-workers [31] also reported a series of carbon supported Pd-Sn nanocrystals for ethanol electrooxidation where an enhancement in the activity was attributed to the bifunctional effect of the alloy where Sn or SnO x has stronger interactions with hydroxyl group whilst Pd has excellent properties in the adsorption and dissociation of ethanol. The Pd-Sn alloy structure would result in lower reaction energies for the dehydrogenation of ethanol compared to the pure Pd crystals [31].…”

Palladium Supported on 3D Graphene as an Active Catalyst for Alcohols Electrooxidation

“…These advantages enable to use relatively cheaper nonprecious materials for both anodes and cathodes 9 have been reviewed by Antolini et al 8 The higher activity of Pd and Pd-based catalysts in alkaline media for alcohols electrooxidation reaction in comparison to platinum (Pt) is well-established and reviewed by several research groups. [10][11][12][13][14][15][16][17][18][19][20][21][22][23] In order to better utilize the Pd nanoparticles, supported and nanostructured catalysts should be used. The support should meet certain requirements such as a high surface area, excellent electrical conductivity, and provide good contact to the metal nanoparticles.…”