Tubular palladium-based catalysts enhancing direct ethanol electrooxidation

Direct ethanol fuel cell (DEFC) has the advantages of high power density, high energy conversion efficiency and environmental friendliness, but its commercialization is restricted by factors such as insufficient activity and low anti-poisoning ability of anode catalyst for incomplete oxidation of ethanol. It is of great significance to design and prepare anode catalyst with high activity and high anti-poisoning ability that can be recycled. In this work, tubular palladium-based (Pd-based) catalysts with abundant lattice defect sites were prepared by simple and reproducible electro-displacement reactions using Cu nanowires as sacrificial template. Pd is the main catalytic element which provides adsorption sites for ethanol oxidation. Ag and Cu introduced facilitates the formation of hydroxyl groups to oxidize toxicity intermediates, and changes the d-band center position of Pd, so as to adjust the adsorption and desorption of ethanol and its intermediates on the Pd surface. At the same time, Au introduced with high potential maintains the stability of the catalyst structure. The tubular structure exposes more active sites, improves the atomic utilization rate and enhances the ability of the catalyst resisting dissolution and aggregation. The series of PdAuAgCu tubular catalysts with outer layer dendrites were prepared by electro-displacement reactions using the mixture (ethylene glycol : ultra-pure water = 3 : 1) as the reaction solvent and fivefold twinned Cu nanowires as sacrificial template. The performance evaluation of ethanol electrocatalytic oxidation showed that the Pd₁₇Au₄₀Ag₁₁Cu₃₂ tubular catalysts were prepared at 120 °C and 10 mM CTAB had excellent overall performance, with a peak mass activity of 6335 mA mg_Pd^-1, which was 9.6 times of Pd/C (JM). The residual current density after the stability test of 3000 s was 249 mA mg_Pd^-1, which was 3.3 times of Pd/C (JM).