کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
185936 459605 2014 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The effect of pH on the electrocatalytic oxidation of formic acid/formate on platinum: A mechanistic study by surface-enhanced infrared spectroscopy coupled with cyclic voltammetry
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
The effect of pH on the electrocatalytic oxidation of formic acid/formate on platinum: A mechanistic study by surface-enhanced infrared spectroscopy coupled with cyclic voltammetry
چکیده انگلیسی

The electrocatalytic oxidation of formic acid (HCOOH) and formate (HCOO−) to CO2 on platinum has been studied over a wide range of pH (0–12) by surface-enhanced infrared absorption spectroscopy (SEIRAS) coupled with cyclic voltammetry. The peak current of HCOOH/HCOO− oxidation exhibits a volcano-shaped pH dependence peaked at a pH close to the pKa of HCOOH (3.75). The experimental result is reasonably explained by a simple kinetic model that HCOO− oxidation is the dominant reaction route over the whole pH range. HCOOH is oxidized after being converted to HCOO− via the acid-base equilibrium. The ascending part of the volcano plot at pH < 4 is ascribed mostly to the increase of the molar ratio of HCOO−, while the descending part at pH > 4 is ascribed to the suppression of HCOO− oxidation by adsorbed OH or oxidation of the electrode surface. In acidic media, HCOOH is adsorbed on the electrode as formate with a bridge-bonded configuration. The bridge-bonded adsorbed formate is stable and suppresses HCOO− oxidation by blocking active site. However, the suppression is not fatal because bridge-bonded adsorbed formate enhances the oxidation of HCOO− at high potential by suppressing the adsorption of OH or surface oxidation. The complex cyclic voltammograms for HCOOH/HCOO− oxidation also can be well interpreted in terms of the simple kinetic model. The experimental results presented here serve as a generic example illustrating the importance of pH variations in catalytic proton-coupled electron transfer reactions.

Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Electrochimica Acta - Volume 129, 20 May 2014, Pages 127–136
نویسندگان
, , , , ,