Carrageenan Asissted Synthesis of Palladium Nanoflowers and Their Electrocatalytic Activity toward Ethanol

Palladium (Pd) nanoflowers with tunable thorns were prepared by a facile and rapid route with the assistance of carrageenan. The superior nature of well-dispersed Pd nanoflowers has been disclosed by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy measurements. The growth of thorns of Pd nanostructures was first stimulated with the continuous introduction of l-ascorbic acid in the synthesis system and then reached a maximum length of about 132 nm, followed by a slight decrease in concentration. Electrochemical data showed that Pd nanoflowers with the longest thorns exhibited the highest catalytic current density of 1160 mA/mg, optimized tolerance to the poisoning, and the lowest onset potential while others showed a better cycle stability with a catalytic activity maintenance of above 96% after 300 cycles. It is suggested that the structure of thin thorns of Pd nanoflowers should be easier to damage than thick thorns during the electrocatalysis of ethanol. The relationship between Pd nanoflowers and properties as well as the key factors to form the nanoflower structure were discussed based on the experimental data.