Activity screening of Pt-CeO2 gradient films prepared by bipolar electrochemistry for electrooxidation reactions.

Glassy carbon electrodes were modified with a CeO2 film and Pt nanoparticles (Pt-CeO2) for electrocatalysis. Interestingly, the oxidation of benzyl alcohol was significantly enhanced when Pt-CeO2 films were prepared by the simultaneous electrodeposition of the two materials, indicating a significant synergistic electrocatalytic activity. Subsequently, bipolar electrochemistry was employed to prepare Pt-CeO2 gradient films. Scanning electrochemical microscopy (SECM) was employed for studying local electrochemical properties at liquid/solid interfaces. SECM allowed mapping the local electrochemical performance of the Pt-CeO2 gradient films for benzyl alcohol oxidation, showing that the reaction rate is proportional to the local Pt-CeO2 surface coverage. Therefore, Pt-CeO2 deposits with different densities along the bipolar electrode offer tunable catalytic performances for benzyl alcohol oxidation. This allows identifying in a fast and straightforward way the optimal conditions for electrocatalytic processes in a more general sense because the approach, illustrated here with one specific reaction, can be easily generalized to other catalytically active surfaces.