Adsorption and electro-oxidation of CO on a polycrystalline Pt electrode in acidic solutions were systematically revisited by in situ attenuated-total-reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) in conjunction with related Gram–Schmidt response analysis. CO was either adsorbed in the double-layer region, i.e., 0.45 V (RHE) (denoted as CO@DL) or in the hydrogen underpotential deposition region, i.e., 0.1 V (RHE) (denoted as CO@UPD). The results indicate that the CO@UPD and H2Ofree coexisted structure (or simply costructure) forms only at a sufficiently high global CO coverage (H2Ofree denotes hydrogen-bonding-broken water); In contrast, the CO@DL and H2Ofree costructure forms in an earlier adsorption phase, less dependent on the global CO coverage. The partial oxidation of CO from solution and weakly adsorbed COL at the active sites is suggested to yield a prepeak that occurs with the relaxation of the COad-H2Ofree costructure and the disorganization of the outer water net layers. In the main oxidation process, the oxidation of CO@UPD tends to proceed via the “mean-field approximation” kinetics due to the high COad mobility resulting from the oxidation prepeak. The oxidation process of CO@DL is, however, likely via the “nucleation and growth” kinetics due to the good stability of the local CO@DL and H2Ofree costructured islands. The H2Ofree can be better assigned to the “probe” of the local COad coverage rather than the main oxygenated species for COad oxidation according to the spectral results for both CO@UPD and CO@DL.
"This is due to the strong adsorption of CO on the electrode surface, blocking the electrocatalytic sites from further oxidation of fuel. Consequently, methanol oxidation along with CO adsorption and oxidation on electrocatalysts such as Pt surfaces has been an intensely researched field for several decades            . Many studies have sought to gain enough understanding of this system to find CO-tolerant catalysts or to engineer a Pt surface structure or morphology with a lower propensity toward CO adsorption     . "
[Show abstract][Hide abstract] ABSTRACT: A newly formulated four-component modified Butler-Volmer model has been developed to evaluate global oxidation kinetic parameters for the various types of carbon monoxide adsorbates (COads) on a nanoparticle Pt surface determined by the type of bonding as well as the local structure of the adsorption site. Partial coverages of COads were prepared by potentiostatic adsorption of methanol followed by potentiostatic partial oxidation at various elevated potentials and for various durations. Anodic linear sweep voltammetry was then performed, and the COads oxidation peaks were fitted with the model to analyze the kinetics. According to the model, preferential oxidation with respect to COads bonding and Pt substrate structure can be achieved dependent upon the potential and extent of oxidation. Partial oxidation at 450 mV vs. RHE for 60 min. resulted in a majority population of linearly bonded COads on cubic-packed Pt sites; whereas partial oxidation at 650 mV vs. RHE for 220 sec. resulted in a majority population of bridged-bonded COads on close-packed Pt sites.
[Show abstract][Hide abstract] ABSTRACT: In this work we investigate the electro-oxidation of glycerol reaction on polycrystalline platinum in acidic media. By using in situ FTIR and isotopically labeled glycerol (13CH2OH–12CHOH–13CH2OH) we demonstrate the co-existence of 13CO2 and 12CO2 as products of electro-oxidation. Results indicate that glycerol completely dissociates on Pt surfaces and that both groups contribute to the production of CO2. Moreover, terminal 13CH2OH groups are easier to electro-oxidize than the central group, which is interpreted in terms of a more favorable position of –13CH2OH groups to react with Pt–OHad species.
[Show abstract][Hide abstract] ABSTRACT: The electrochemical reduction of oxygen was studied on multi-walled carbon nanotube-supported palladium nanoparticle (PdNP/MWCNT) modified glassy carbon (GC) electrodes. The catalyst materials were prepared using two different methods and their electrocatalytic activity towards oxygen reduction was explored in both acid and alkaline media using the rotating disk electrode (RDE) method. Cyclic voltammetry was employed for CO stripping experiments and for the determination of real surface area of carbon nanotube–supported Pd nanoparticles. The surface morphology of PdNP/MWCNT nanocomposites was examined by transmission electron microscopy (TEM). Oxygen electroreduction kinetics were compared with those of bulk palladium electrodes. Enhanced electrocatalytic activity of PdNP/MWCNT modified GC electrodes was observed. The Tafel behaviour of oxygen reduction was similar for PdNP/MWCNT and bulk Pd electrodes. The RDE data analysis showed that the reduction of oxygen on the PdNP/MWCNT electrocatalysts studied followed a four-electron pathway.
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