Lianjin Chen,Xiaosen Wang,Aimei Zhu,Qiugen Zhang,Qinglin Liu
Direct ethanol fuel cell can convert chemical energy into electric energy directly, and has the advantages of being free from Carnot cycle and being friendly to environment, so it has a broad application prospect. However, the insufficient activity and toxicity resistance of anodic catalysts limit their commercial application, mainly due to the limited adsorption sites and the toxic inactivation of catalysts resulting from the production of toxic intermediates (CO ads ) during the ethanol oxidation reaction (EOR) process. In this study, the Au@PdAg porous hemispherical catalyst assembled by nanotubes was successfully prepared by soft template method and co-reduction method using dioctadecyl dimethyl ammonium chloride (DODAC) as surfactant, and its EOR performance was tested. Au@Pd 1.0 Ag 1.0 has the highest mass current density with a peak value of 4048.8 mA mg Pd − 1 , which is 7.8 times of Pd/C (JM). After 5000 s stability test, the residual current density value is still 863.4 mA mg Pd − 1 . The results showed that the introduction of the oxygenophilic metal Ag was conducive to the formation of OH ads and the oxidation of CO ads . The porous structure of the nanotube assembly facilitates electron transfer and provides more adsorption sites, which makes the catalyst show good electrocatalytic activity and anti-CO poisoning ability.
Graphical Gold@palladium-silver alloy core-shell dendritic nanocrystals with tunable size and elemental composition were fabricated in high purity via seeded growth. Compared to commercial Pd/C catalysts, the current products exhibit enhanced activity and excellent operation stability for electroxidation of ethanol in alkaline media. We report a facile synthesis of Au@PdAg alloy core-shell nanocrystals in dendrite form, having tunable size and composition. In particular, using spherical Au nanoparticles as seeds, the co-reduction of Pd and Ag precursor in growth stage results in the formation of PdAg alloy shells with a dendrite shape. Their size and elemental composition can be tuned by varying the seed amount and feeding ratio in Pd and Ag precursor, respectively, illustrating the versatility of the current synthetic strategy. The size, morphology, and elemental composition of the products have been characterized using a set of techniques, including SEM, TEM, XRD, XPS, HAADF-STEM, and EDX-STEM mapping. When working as electrocatalysts, the current Au@PdAg alloy core-shell nanocrystals supported by carbon black exhibit enhanced activity and excellent operation stability for electroxidation of ethanol as compared to commercial Pd/C. The current work offers a feasible strategy to preparation of multi-metallic core-shell dendritic nanocrystals with controllable size and composition and could find important use in fuel cells and related fields.
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