Heterogeneously assisted oxidation of adsorbates from carbonmonoxide, methanol and ethanol by hydrogen peroxide solutions on platinum electrodes in sulphuric acid

Abstract

The influence of hydrogen peroxide on the adsorption and oxidation of carbon monoxide, methanol and ethanol adlayers on porous Pt electrodes were studied in 2 M sulphuric acid solution by means of cyclic voltammetry and differential electrochemical mass spectrometry (DEMS). The oxidation of adsorbed species is observed at electrode potentials far less negative than those required for electrochemical adsorbate oxidation. The oxidation by H 2 O 2 is dependent on its concentration in solution, as well as on the adsorbates and their coverages. In all cases the isolated adlayers are oxidised by dissolved H 2 O 2 . However, the presence of H 2 O 2 during adsorption partially inhibits adlayer formation from CH 3 OH and C 2 H 5 OH, but avoids almost completely the adsorption of carbon monoxide. The removal of the residues from the surface by dissolved hydrogen peroxide probably occurs through O ad species formed during the heterogeneous decomposition reaction of H 2 O 2 on Pt.

Cathode Platinum Degradation in Membrane Electrode Assembly Studied Using a Solid-State Electrochemical Cell

“…In the case of H 2 O 2 addition, the results are shown in Figure B. The shape of the cyclic voltammogram is the same as that measured at the Pt electrode in an electrolytic solution containing H 2 O 2 . Also, a successive potential sweep does not change the voltammogram shape.…”

Prepararação e caracterização de eletrocatalisadores PT - terras raras/ C para células a combustível do tipo PEMFC

“…Durante seu funcionamento ocorrem reações de oxidação direta do álcool. No entanto, os produtos de reações intermediárias provocam o envenenamento da Pt por CO, que promove uma significativa diminuição na densidade de corrente e potência da célula (WU, WANG, WANG, 2002;ANTOLINI et al, 2005;CHEN et al, 2006;RODRIGUEZ et al, 2006;WANG, HUANG, YEH, 2007 (PAULUS, 2002). (HITMI et al, 1994;APPLEBY & FOULKES, 1999;FUJIWARA, FRIEDRICH, STIMMING, 1999;OLIVEIRA NETO et al, 1999;OLIVEIRA NETO et al, 2002).…”