Pd CeO ndash C also possesses a very

In Fig. 6 the CV curves of BYL-719 electrooxidation on Pd/CeO2–C catalysts with different CeO2 contents in an aqueous solution containing 1.0 mol L−1 KOH and 20.0 mmol L−1 glucose with a potential scanning rate of 50 mV s−1 at 36.5 °C, are depicted. In the forward potential scanning, the oxidation peak at about 0.02 V for all the catalysts can be attributed to either the oxidation of glucose on the surface of the catalyst or the further oxidation of adsorbed species at more positive potential, which is an indicator of the activity of the catalysts. The higher current density is, the better catalysts are. Obviously, the CeO2 content in the Pd/CeO2–C catalysts has a considerable effect on the electrocatalytic activity for glucose oxidation. Its corresponding effect can be distinctly observed in Fig. 6B. With the increase of CeO2 content until the Pd:CeO2 molar ratio is 3, the current density increases from 4.4 mA cm−2 on Pd/C to 5.7 mA cm−2 on Pd/CeO2–C-3, which is even higher than birds on Pd-based binary catalysts [17], [18], [19] and [30]. While a further increase of the CeO2 content in the Pd/CeO2–C catalysts leads to the decrease of the current density, and even worse than that on Pd/C. The above volcano behavior with Pd/CeO2–C-3 at the summit could be understood as follows. The performance enhancement is attributed to the decreased Pd particles size as CeO2 is introduced as proved by XRD results and the synergistic of CeO2 to remove the adsorbed intermediate products as oxygen storage materials [31] and [32]. While, the excessive amount of CeO2 results in the decayed current density because of both the decrease of the electrical conductivity and partial blockage of the Pd active sites.