Adsorption of Formate on Au(111) in Acid Solution: Relevance for Electro-Oxidation of Formic Acid

作者：Kibler Ludwig A^*; Al Shakran Mohammad

来源：Journal of Physical Chemistry C, 2016, 120(29): 16238-16245.

DOI：10.1021/acs.jpcc.6b02044

The behavior of formic acid on Au(111) in perchloric acid solution at room temperature has been investigated by electrochemical methods and in situ scanning tunneling microscopy (STM) in the potential region negative to surface oxidation. Specific adsorption of formate lifts the reconstruction of the Au(111) surface. Currents for formate adsorption have been separated from those of formic acid oxidation by varying the sweep rate between 0.01 and 50 V s(-1). A 2D phase transition within the formate layer adsorbed on long-range Au(111) terraces gives rise to a characteristic voltammetric needle-peak. Parallel chains of strongly bound formate have been imaged by in situ STM. Steady-state voltammetry at different formic acid concentrations shows a characteristic bell-shaped current maximum and a pronounced current jump related with the adlayer phase transition at more positive potentials. Oxidation kinetics of formic acid strongly depends on formate adsorption, which is determined by the electrode potential, the pH, and the formic acid concentration. Various adsorbates (bidentate and monodentate formate and/or carboxylate) with entirely different reactivity are supposed to play a role in the formic acid oxidation mechanism.

• 出版日期2016-7-28