Anodic Pt dissolution in concentrated trifluoromethanesulfonic acid

We investigated the anodic Pt dissolution in concentrated trifluoromethanesulfonic acid (TFMSA). The dependence of the Pt dissolution rate on the TFMSA concentration was first measured from the weight difference of a Pt-flag electrode before and after successive potential cycles. From this measurement, the Pt dissolution rate in 10 mol dm−3 TFMSA is found to be over 40 times greater than those in 1 and 4 mol dm−3 TFMSA. Next, the anodic Pt dissolution was assessed in 10 mol dm−3 TFMSA by a potential step technique using a Pt dual microelectrode having generator and collector electrodes. The obtained result shows that the anodic Pt dissolution in 10 mol dm−3 TFMSA occurs when the Pt generator electrode potential is stepped from 0.25 to 1.0–2.0 V vs. Ag/Ag2SO4. Furthermore, the absolute steady-state current-based coulomb charges obtained at the generator (|QG|) and collector (|QC|) reflect the anodic Pt dissolution and the reduction of the dissolved Pt, respectively. The magnitude of |QG| and |QC| linearly increase when the generator potential shifts from 1.0 to 2.0 V vs. Ag/Ag2SO4. The absolute ratio, |QC/QG|, also gradually increases according to the shift in the generator electrode potential. These results demonstrate that the anodic Pt dissolution in 10 mol dm−3 TFMSA occurs at ≥1.0 V vs. Ag/Ag2SO4 and that the ratio of the anodic Pt dissolution per total reaction charges increases according to the positive shift of the Pt electrode potential.