Kinetic evaluation of the formic acid electrooxidation on steady state on palladium using a flow cell

MONTERO, MARÍA A.; G.C. LUQUE; A.C. CHIALVO; DE CHIALVO, MARÍA R. GENNERO

JOURNAL OF ELECTROANALYTICAL CHEMISTRY - (Print)

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2021

1572-6657

The HCOOH electrooxidation reaction (FAO) is studied on palladium in a 0.5 M HCOOH +0.5 M H2SO4 solution. The steady state current - potential curve is measured in the potentialregion 0.1 < E (vs. RHE) / V < 0.6 by chronoamperometry. Open circuit potential transient isalso recorded as well as potentiodynamic sweeps at 0.01 V s-1. The absence of adsorbed CO isconfirmed by voltammetric stripping, in agreement with published spectroscopicmeasurements. On this basis, a kinetic mechanism is proposed, involving adsorbed hydrogenand formate as reaction intermediates, which can also describe the spontaneous HCOOHdehydrogenation reaction at open circuit. The mechanism involves two reaction pathways.One where current is generated entirely by the oxidation of Had, which explains theelectrocatalytic activity of palladium at low potentials. The other pathway, which prevails athigh potentials, includes the electrooxidation of both, Had and HCOOad, reactionintermediates. The corresponding theoretical expression for the current density - potentialdependence on steady state is derived, which accurately correlates the experimental results.