Electrochemical Studies of Pd-Based Anode Catalysts in Alkaline Medium for Direct Glycerol Fuel Cells

This study investigates the most effective electrocatalyst for glycerol oxidation reaction (GOR) in alkaline medium for five synthesized electrocatalysts, Pd, PdNi, PdNiO, PdMn3O4 and PdMn3O4NiO, supported on multi-walled carbon nanotubes (MWCNTs) prepared using the polyol method. The particle size and crystalline size of the electrocatalysts were determined using HR-TEM and XRD techniques, respectively, while EDS was used to determine the elemental composition. XRD showed crystalline sizes ranging from 3.4 to 10.1 nm, while HR-TEM revealed particle sizes within the range of 3.4 and 7.2 nm. The electroactivity, electron kinetics and stability of the electrocatalysts towards glycerol in alkaline medium was evaluated using linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA), respectively, while the electroactive surface area (ECSA) of the electrocatalysts was determined using cyclic voltammetry (CV). The metal oxide-based Pd electrocatalysts PdNiO and PdMn3O4 were the most electrochemically active, while the addition of the second metal oxide to the Pd electrocatalyst PdMn3O4NiO did not show any improvement. This was associated with this electrocatalyst having the highest particle and crystalline sizes.

Characterization of Electrode Performance in Enzymatic Biofuel Cells Using Cyclic Voltammetry and Electrochemical Impedance Spectroscopy

The main objective of this study was to examine the quantitative performance of the electrochemical redox reaction of glucose by glucosidase and oxygen with laccase in a phosphate buffer solution at pH 7.0. The characterization of electrode performance was performed by using electrochemical analysis such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The use of such electrochemical analysis (CV and EIS) enables a better understanding of the redox process, the charge transfer resistance, and, hence, the potential mass transfer among the electrode materials in phosphorus buffer solution. The experimental results show that the maximum power densities of the bioanode and the biocathode electrodes were 800 µA/cm2 and 600 µA/cm2, respectively. Both the bioanode and biocathode show high internal resistance. The occurrence of peak-separation shows an excellent mass-transfer mechanism and better chemical reactivity in the electrode.