Enhanced electrocatalytic activity of urchin-like Nb2O5 microspheres by synergistic effects with Pd toward electrooxidation of ethylene glycol in an alkaline medium

Abstract Urchin-like niobium oxide (U-Nb2O5) microspheres are obtained using a low-temperature hydrothermal method. The nanosized palladium (Pd) particles loading onto U-Nb2O5 (Pd/U-Nb2O5) microspheres are successfully prepared using a reflux method. X-ray diffraction results imply that the U-Nb2O5 and Pd/U-Nb2O5 microspheres belong to the orthorhombic phase, and Pd loading does not change the crystalline phase. The average size of nanosized Pd particles loaded is 4.25 nm. In addition, the valence states of Pd on the surface of the Pd/U-Nb2O5 microspheres are mainly of a Pd° form. The catalytic activity of the different loading amount Pd/U-Nb2O5 electrocatalysts is carried out in a 0.5 M KOH and 1 M ethylene glycol (EG). When the usage of palladium acetate is 10 mg (the mass ration of Pd to Nb2O5 is 10 %), the Pd/U-Nb2O5 electrocatalyst exhibits high catalytic activity for the electrooxidation of EG in an alkaline medium. The current density of EG electrooxidation on the Pd/U-Nb2O5 modified glassy carbon electrode is higher than that on commercial Pd/C (10 %). Moreover, the Pd/U-Nb2O5 electrocatalyst exhibits strong anti-CO poisoning ability and good stability for EG oxidation in alkaline medium. After 6000 s, the maintained current density on the Pd/U-Nb2O5 electrocatalyst is 12.7 times that on commercial Pd/C. This remarkable performance of the Pd/U-Nb2O5 electrocatalyst is owing to the synergistic effect between Pd and Nb2O5. The calculation results imply that the synergistic effect improves electron transfer.