Bi-modified Pd/C catalyst via irreversible adsorption and its catalytic activity for ethanol oxidation in alkaline medium

• Pd-Bi/C catalysts were easily prepared by irreversible adsorption of Bi on Pd/C surface.
• The adsorption of Bi increases the oxygen-containing species obviously on Pd-Bi/C surface.
• Only a little amount of Bi on Pd-Bi/C can play a significant role in ethanol oxidation reaction (EOR).
• Current density of EOR on Pd-Bi/C (20:1) is 2.4 times higher than that on Pd/C.
• Anti-poisoning ability and durability of Pd-Bi/C (20:1) is greatly enhanced.

A facile approach to promote ethanol electro-oxidation on Pd-based catalysts is presented by the modification of Bi on Pd/C catalyst via irreversible adsorption. X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) measurements show that the modification of Bi has no significant effect on the Pd morphology and particle size distribution. Bi(III) and Pd(0) are the dominant forms in Pd-Bi/C catalyst. Electrochemical tests show that the modification of the appropriate amount of Bi on Pd/C catalyst can remarkably enhance activity toward ethanol oxidation reaction (EOR) up to about 2.4 times higher compared to Pd/C catalyst. The Pd-Bi/C (20:1) catalyst exhibits excellent stability and enhances CO tolerance. The enhanced electrochemical performance of Pd-Bi/C catalyst is attributed to the electronic effect and the bifunctional mechanism. The high exchange current density and the low apparent activation energy on Pd-Bi/C (20:1) catalyst reveal its faster kinetics and higher intrinsic activity compared to Pd/C catalyst.

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