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This research explores the glycerol electrooxidation reaction (GEOR) on a platinum electrode, with a special emphasis on the role of the chemical properties of the anion present in the electrolyte composition. Essential knowledge of the mechanism and dynamics of glycerol electrooxidation is obtained through comprehensive studies that involve in situ FTIR measurements and the analysis of electrochemically oscillatory responses. This study focuses on the complex interplay between anion adsorption strength and the GEOR, focusing on the differences in CO adsorption coverage, which is the main strongly adsorbed intermediate. The anion adsorption strength, with the order HClO4 < H2SO4 < H3PO4, affects significantly not only the CO coverage on the platinum surface but also the overall glycerol electrooxidation rate. The observed differences in the electroactivity are attributed to competitive adsorption phenomena, in which specific coordinated ions have greater adsorption capabilities than perchlorate ions. These findings highlight the critical relevance of designing and optimizing electrocatalysts for glycerol electrooxidation and related processes with careful consideration of the electrolyte composition, notably the anion.

Korovaichuk A, Makarova J, Makarov VA, Benito N, Herreras O. Minor contribution of principal excitatory pathways to hippocampal LFPs in the anesthetized rat: A combined independent component and current source density study. J Neurophysiol 104: 484-497, 2010. First published May 12, 2010; doi:10.1152/jn.00297.2010. Analysis of local field potentials (LFPs) helps understand the function of the converging neuronal populations that produce the mixed synaptic activity in principal cells. Recently, using independent component analysis (ICA), we resolved ongoing hippocampal activity into several major contributions of stratified LFP-generators. Here, using pathway-specific LFP reconstruction, we isolated LFP-generators that describe the activity of Schaffer-CA1 and Perforant-Dentate excitatory inputs in the anesthetized rat. First, we applied ICA and current source density analysis to LFPs evoked by electrical subthreshold stimulation of the pathways. The results showed that pathway specific activity is selectively captured by individual components or LFP-generators. Each generator matches the known distribution of axonal terminal fields in the hippocampus and recovers the specific time course of their activation. Second, we use sparse weak electrical stimulation to prime ongoing LFPs with activity of a known origin. Decomposition of ongoing LFPs yields a few significant LFP-generators with distinct spatiotemporal characteristics for the Schaffer and Perforant inputs. Both pathways convey an irregular temporal pattern in bouts of population activity of varying amplitude. Importantly, the contribution of Schaffer and Perforant inputs to the power of raw LFPs in the hippocampus is minor (7 and 5%, respectively). The results support the hypothesis on a sparse population code used by excitatory populations in the entorhino-hippocampal system, and they validate the separation of LFP-generators as a powerful tool to explore the computational function of neuronal circuits in rea, Spanish Ministry of Education and Science, Comunidad Autónoma de Madrid, Depto. de Análisis Matemático y Matemática Aplicada, Fac. de Ciencias Matemáticas, TRUE, pub

In the present paper, the influence of electrogenerated (110) defects in the methanol oxidation reaction (MOR) on a Pt(111) electrode has been studied. It is shown that methanol oxidation is favored at the defected surfaces as evidenced by the displacement of the onset potential to lower values and the increase of the peak current density. The currents obtained by transient curves at short times (0.015 – 0.5 s) at 0.50 V vs RHE demonstrate the faster formation of strongly adsorbed species on disordered surfaces when compared to Pt(111). On the other hand, for long-term transient currents (600 s), the surface with a higher surface density of (110) defects presented the best activity among all ones studied. Galvanostatic results showed that potential oscillations emerged only on disordered surfaces. The large induction time up to the beginning of the oscillations as well as the lower frequency registered on these surfaces demonstrates the enhancement of CO formation on defects. This point is confirmed by in situ FTIR experiments. From the results obtained by using electrochemical techniques, it was possible to infer that the dehydration rate constant (kdh) and the rate constant for CO oxidation (kCO) are affected by the number of (110) defects, which give rise to kCO and kdh values higher than those obtained for Pt(111).

In the present paper, we have studied the influence of (bi)sulfate anion (0.1 and 0.5 M) on the electro-oxidation of glycerol on basal Pt(hkl) and stepped surfaces belonging to the series of Pt(S)[n(1 1 1) × (1 1 1)]. Cyclic voltammograms and derivative voltammetry pointed out that the catalytic activity decreases for Pt(1 1 1) and Pt(1 1 0) and, to a minor extent, for stepped surfaces in 0.5 mol/L H2SO4. Chronoamperometric curves demonstrated that above 0.60 V (vs RHE), for both concentrations (0.1 and 0.5 mol/L H2SO4), stepped surfaces and Pt(1 1 0) showed greater ability to catalyze the glycerol electro-oxidation in comparison with Pt(1 1 1). Potential oscillations were mapped along with slow galvanodynamic sweeps and studied at constant current. For Pt(1 1 1), no oscillations were found in the galvanodynamic regime, however, under the galvanostatic regime, period 1 oscillations were observed after a long induction period. The oscillations showed a very similar profile for stepped surfaces, even for the Pt(3 3 2) surface, which has a high density of (1 1 0) steps. Pattern changes were observed only for Pt(1 1 0) compared to other surfaces. Therefore, we conclude that (1 1 0) step sites influence the oscillatory behavior, thus the insertion of the steps favors the path of formation of inactive species, which compete for the same catalytic sites in a given potential region. The extinction of the mechanism oscillatory occurs differently due to the intrinsic characteristics of each surface electrode for the formation of (hydro)oxides.