Novel highly active carbon supported ternary PdNiBi nanoparticles as anode catalyst for the alkaline direct ethanol fuel cell

Abstract

The study focuses on the influence of Ni and Bi on alkaline ethanol oxidation reaction (EOR) activities, stabilities and structure characteristics of carbon supported Pd-based nanocatalysts (Pd/C, Pd 60 Ni 40 /C, Pd 60 Bi 40 /C, Pd 60 Ni 20 Bi 20 /C) by cyclic voltammetry/chronoamperometry using rotating disk electrode and various physico-chemical methods such as X-ray powder diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy coupled with energy dispersive X-ray spectroscopy and inductively coupled plasma optical emission spectrometry. Nickel generates more adsorbed OH on the Pd catalyst surface than Bi and promotes the oxidation of adsorbed ethanol species. This results in a low onset potential toward ethanol oxidation with high current density. The presence of Bi facilitates high tolerance toward various reaction intermediates resulting from the incomplete ethanol oxidation, but might also initiate the agglomeration of Pd nanoparticles. The novel Pd 60 Ni 20 Bi 20 /C nanocatalyst displays exceptional byproduct tolerance, but only satisfying catalytic activity toward ethanol oxidation in an alkaline medium. Therefore, the EOR performance of the novel carbon supported ternary Pd x Ni y Bi z anode catalyst with various atomic variations (Pd 70 Ni 25 Bi 5 /C, Pd 70 Ni 20 Bi 10 /C, Pd 80 Ni 10 Bi 10 /C and Pd 40 Ni 20 Bi 40 /C) using the common instant reduction synthesis method was further optimized for the alkaline direct ethanol fuel cell. The carbon supported Pd:Ni:Bi nanocatalyst with atomic ratio of 70:20:10 displays outstanding catalytic activity for the alkaline EOR compared to the other Pd x Ni y Bi z /C nanocatalysts as well as to the benchmarks Pd/C, Pd 60 Ni 40 /C and Pd 60 Bi 40 /C. The synergy and the optimal content in consideration of the oxide species of Pd, Ni and Bi are crucial for the EOR kinetic enhancement in alkaline medium.

Alkaline Ethanol Oxidation Reaction on Carbon Supported Ternary PdNiBi Nanocatalyst using Modified Instant Reduction Synthesis Method

“…Opening the potential window further to 1.5 V (Fig. S10a) reveals the oxidation of Ni(OH) 2 to NiOOH in the positive scan and subsequent reduction of NiOOH to Ni(OH) 2 in the negative scan for all three catalysts, indicating the presence of Ni(OH) 2 on the surface of the catalysts that is consistent with the XPS analysis [28]. Ni redox is more pronounced on Pd 85 Ni 10 Bi 5 /C (II) and Pd 85 Ni 10 Bi 5 /C (III) relative to Pd 85 Ni 10 Bi 5 /C (I) catalyst, which is likely due to the lower overall concentration of Ni on these samples as measured by XPS (Tables S14-S17).…”

“…6a) are suppressed for the ternary catalysts relative to commercial Pd/C. This suppression is due to the presence of bismuth, which lowers the degree of H insertion into the Pd crystal structure due to modified electronic properties as shown previously [23,28,34]. The characteristic peak at 0.9 V in CV of the forward scan (Fig.…”

“…In both cases, the nanoparticles are significantly more evenly dispersed on the carbon support, which we attribute in part to the inert N 2 atmosphere used in synthesis. Synthesis of the Pd 85 Ni 10 Bi 5 /C (I) under ambient atmosphere most likely results in the formation of various undesired oxide species, which easily tend to agglomerate with metal ions on the carbon support material [28]. Improved dispersion of Pd 85 Ni 10 Bi 5 /C (II) and Pd 85 Ni 10 Bi 5 /C (III) is likely also driven by improved solubility of the precursor salt PdCl 2 due to the substitution of HCl for the NaCl used to synthesize Pd 85 Ni 10 Bi 5 /C (I) .…”

“…The characteristic peak at 0.9 V in CV of the forward scan (Fig. 6a) is attributed to the oxidation of Bi(OH) 3 in the presence of KOH to form Bi 2 O 3 [24,28,34]. Opening the potential window further to 1.5 V (Fig.…”

Morphology‐Controllable Synthesis and Growth Mechanism of 3D‐Hierarchical Pd/SnO2/Ni Foam (NF) as the Cathode for Al‐H2O2 Semi‐Fuel Cell

“…As a semiconductor material, tin dioxide has been widely used inelectrode materials, because of its advantages of high electron mobility, low cost and good chemicalproperties, such as PEM fuel cell and direct ethanol fuel cell . Our recent study also shows that the Pd/SnO 2 /NF electrode had the considerable catalytic activity and stability for H 2 O 2 electroreduction in alkaline electrolyte .…”