Electro-oxidation of methanol and glucose on preferentially oriented platinum surfaces: the role of oscillatory kinetics

Most electrocatalytic reactions strongly depend on the surface structure. Among the strategies available to modify the electrode structures, cathodic corrosion has proven to be a powerful tool for electrochemical metal etching, leading to preferentially oriented surfaces. In the present work, we treated platinum surfaces with cathodic corrosion leading to preferably oriented (100) structures and tested the obtained electrodes towards the electro-oxidation of methanol and glucose. The surfaces were initially characterized by bismuth and germanium adsorption, and the original surface was modified is the way that the Pt(100) domains change from 20 to 43%, while the Pt(110) ones change from 71 to 36%. For the electro-oxidation of methanol, an activity decreases after corrosion was observed. The electro-oxidation of glucose is found to be more sensitive and a new current peak appears in the voltammogram. Under galvanostatic control, at lower methanol concentration only small amplitude oscillations are observed, at higher concentration, large amplitude oscillations with a quiescent period, both before and after corrosion prevail. For glucose, both before and after corrosion, mixed-mode oscillations are observed, but the morphology is affected by the surface structure: before corrosion, the system stays longer at higher potentials than after corrosion. In summary, we show that oscillations are even more sensitive to surface modifications induced by cathodic corrosion, results are discussed in connection with mechanistic aspects.