The mechanisms of HCOOH/HCOO-oxidation on Pt electrodes: Implication from the pH effect and H/D kinetic isotope effect

作者：Wei, Yi; Zuo, Xia Qing; Da He, Zheng; Chen, Wei; Lin, Chu Hong; Cai, Jun; Sartin, Matthew; Chen, Yan-Xia^*

来源：Electrochemistry Communications, 2017, 81: 1-4.

DOI：10.1016/j.elecom.2017.05.012

• Formic acid oxidation
• Pt(111)
• pH effect
• H/D kinetic isotope effect
• Mechanism
• Direct pathway

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 HCOO-/DCOO(-)are ca. 5, 2, and 1 in solutions with pH = 1.1, 3.6, and 13, respectively. These findings reveal that HCOOH ->(HCOOad-)-H-rds + 2H(+) + e is the rate-determining step (RDS) for FOR in acid. With increasing pH, the precursor to be discharged changes from HCOOH to HCOO-, and the latter goes through HCOO-->(HCOOad)-H-rds + 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 pH = pKa and the change in overpotential for the RDS of FOR.

• 出版日期2017-8
• 单位中国科学技术大学