کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6469626 | 1423976 | 2017 | 4 صفحه PDF | دانلود رایگان |
- The H/D KIE factor for HCOOH/DCOOH or HCOO-/HCOO- is ca. 5, 2 and 1 in solutions with pHÂ =Â 1.1, 3.6 and 13, respectively.
- HCOOHârdsCOOadâ+2H++e is the RDS for FOR in acid, with increase of pH the RDS goes through HCOOâârdsHCOOad+e.
- The origin of the pH dependent FOR activity is pH induced opposite change of reactant concentration and overpotential for the RDS.
The pH effect and the H/D kinetic isotope effect (KIE) for the oxidation of formic acid/formate anions (FOR) on Pt(111) have been studied. The pH-dependent FOR activity displays a volcano shape with a maximum at a pH close to the pKa of HCOOH. The H/D KIE factors for HCOOH/DCOOH or HCOOâ/DCOOâ are ca. 5, 2, and 1 in solutions with pHÂ =Â 1.1, 3.6, and 13, respectively. These findings reveal that HCOOHârdsCOOadâ+2H++e is the rate-determining step (RDS) for FOR in acid. With increasing pH, the precursor to be discharged changes from HCOOH to HCOOâ, and the latter goes through HCOOâârdsHCOOad+e as the RDS. The origin of the appearance of the volcano-type pH dependent FOR activity is pH-induced change from excess HCOOH to excess HCOO- at pHÂ =Â pKa and the change in overpotential for the RDS of FOR.
Journal: Electrochemistry Communications - Volume 81, August 2017, Pages 1-4