Abstract
This paper focuses on the oxidative regeneration of the electroactivity of sulfur-poisoned polycrystalline Pt (poly-Pt) electrode and Pt nanoparticles-modified glassy carbon (nano-Pt/GC) electrode in O-2-saturated 0.1 M HClO4. Recovery of the electroactivity is examined using oxygen reduction reaction (ORR) as a probing reaction. Recovery of the poisoned electrodes is attempted by applying several potential cycles in the range of 0.06 similar to 1.06 V (reversible hydrogen electrode, RHE) for avoiding the dissolution of platinum when the potential is excursed to higher positive values. The recovery of the poisoned electrodes is significantly affected by the dissolved oxygen, i.e., the recovery is more effective under O-2 atmosphere than under N-2 atmosphere. Moreover, the recovery performance of the nano-Pt/GC electrode is more considerable than that of the poly-Pt electrode. The easier recovery of the former electrode is attributed to the relative small ratio of Pt(100) facet as revealed from the facet-dependent voltammetric behavior for the oxidation of formic acid at the Pt electrode in HClO4 solution and from the X-ray diffraction spectrum of the nano-Pt/GC electrode. Interestingly, controlling the potential range for recovery and the number of potential cycles was found to lead to a remarkable electrocatalytic activity of the electrodes for the ORR. A plausible explanation for the obtained results is given in view of the voltammetric measurements.