The effect of the alkali metal cation on the electrocatalytic oxidation of formate on platinum

Abstract

Non-covalent interactions between hydrated alkali metal cations and adsorbed oxygenated species on platinum might considerably inhibit some electrocatalytic reactions. We report in this communication the effect exerted by electrolyte alkali metal cations on the electro-oxidation of formate ions on platinum. The system was investigated by means of cyclic voltammetry and chronoamperometry in the presence of an electrolyte containing Li⁺, Na⁺, or K⁺. As already observed for other systems, the general activity towards the electro-oxidation of formate ions was found to increase in the sequence Li⁺ < Na⁺ < K⁺. In addition, we observed that the inhibition caused by smaller cations has a peculiar potential dependence because of the multi-peaked current profile of the electro-oxidation of formate on platinum. In this respect, we have also identified a new effect caused by cation inhibition at intermediate potentials, namely a peak splitting towards the use of smaller cations. Results are discussed in connection with mechanistic aspects of this model system

High Order Cyclic Voltammograms During Electrooxidation of Ethanol Catalyzed by Gold

“…30 Nakamura et al 34 observed, by infrared spectroscopy, the same OH adsorption rate at potentials below 1.30 V on Au(111) surface regardless the cation, however X-ray diffraction reveled a protective effect against surface roughening at high potentials, this protection being more effective in the presence of Li + than Cs + .…”

“…Catalytic effects caused by the interactions between cations and O(H) x adsorbed species were recently reported in literature [27][28][29][30][31][32] for several fuel cell reactions. In general, small cations, like Li + and Na + , strongly interact with adsorbed O(H) x,ad , causing the stabilization of these species.…”

“…On Pt, the interactions occur from the first stages of O(H) x adsorption, reflecting in the onset potential, peak current and product distribution 28,30,31,35 of the reactions catalyzed by this surface. On the other hand, the presence of cations on Au does not change the onset nor the peak current, but increasing the cation charge density, the Au surface becomes less susceptible to roughening/relaxation effects as observed in all-S cycles.…”

“…Interesting, on gold surfaces, the adsorption of hydroxyl ion, as well the initial oxide layer, are weakly influenced by cations producing no apparent changes in the catalysis of oxygen reduction 33 or alcohol oxidation reactions. 30,32,34 We performed experiments replacing Na + ions by Li + or K + and analyzed the response during EER. Figure 5 shows the effect of an alkali cation on CV for ethanol electrooxidation.…”

Reações oscilatórias e a temperatura: dos efeitos em escala <i>bulk</i> ao monitoramento local

“…117 Para os picos correspondentes à adsorção de hidrogênio nos terraços, os autores usaram duas funções hiperbólicas inversas, e para os picos correspondentes a adsorção competitiva de H + /OH -nos degraus, os autores usaram uma função gaussiana. A deconvolução de picos sobrepostos na voltametria da platina em meio básico foi uma ferramenta usada também em [118] para estudar o impacto de cátions nas assinaturas voltamétricas. Os autores recorreram a uma função gaussiana única para inferir sobre as diferenças qualitativas nos voltamogramas obtidos na presença de diferentes eletrólitos básicos.…”