The electrochemical behaviors of methanol and benzyl alcohol on boron-doped diamond (BDD) electrode are examined with cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The cyclic voltammograms results suggest that the reactivity of the benzyl alcohol is more efficient than that of the methanol. The EIS technique has demonstrated that the charge-transfer resistance (RCT) of oxidation reaction of methanol is larger than that of benzyl alcohol when the potential of the background solution is less than 0.90 V. The reaction kinetics are studied by linear scan voltammetry at various concentrations of the organic compounds (e.g. methanol and benzyl alcohol), various pHs and temperatures. The Tafel slopes and activation energies have indicated that the adsorptions of their organic molecules on the BDD electrodes are the rate-determining steps at low potential range (1.20 to 1.40 V).
Photodeposition of platinum metal on one face of a polyaniline-Nafion composite membrane has been made in aqueous solution containing chloroplatinate and ascorbic acid as a hole scavenger to prepare a catalyst layer for O2 electrode in a polymer electrolyte fuel cell. Fluorescent X-ray analysis of the Pt -deposited composite has revealed gradation of Pt amount is built in direction of membrane thickness by choosing conditions of membrane preparation and irradiation. Two types of membrane-electrode assemblies are fabricated using the Pt-deposited composite membrane; the Pt-deposited face is attached to polyelectrolyte of Nafion membrane or an O2 gas electrode. The former fuel cell exhibits higher performance than the latter one, indicating that diffusibility of H+ in the catalyst layer tends to determine the cell performance. Changes in the cell performance caused by changing Pt amount allow to confirm that Pt amount is certainly gradated in the composite membrane.
Ti1–xVxO2 was prepared by a sol-gel method. The structure, composition, surface area, and specific capacitance (μF cm−2) was characterized by X-ray diffraction, field-emission scanning electron microscopy, energy dispersive X-ray analysis, N2 adsorption/desorption measurements, and cyclic voltammetry. These analyses suggested that high specific capacitance could be attained with rutile type Ti1–xVxO2 with high vanadium content. A maximum specific capacitance of 330μF cm−2 at 1mVs−1 was achieved, which is almost 1. 5 times larger than that of nanocrystalline ruthenium oxide.
Amorphous bismuth oxide (Bi2O3) films have been grown on indium tin oxide (ITO) coating glass substrate by means of electrodeposition. Deposited Bi2O3 films were characterized by structure, morphology, optical properties, and ultimate analysis. X-ray diffraction (XRD) measurements revealed that Bi2O3 amorphous films were grown below 45℃ and above 3 mA cm－2. X-ray photoelectron spectroscopy (XPS) spectra showed that the amorphous films contained potassium descended from supporting electrolyte of KOH. These results suggested that the Bi2O3 films were maintained amorphous phase by inclusion of potassium acted as modified oxide. Refractive index of the Bi2O3 amorphous film grown at 45℃ and 3 mA cm－2 was 1.86, and infrared penetrability of that film was 93%.
As a cathode material of hybrid supercapacitors, a 5-carboxy cyclic indole trimer (5-carboxyCIT) was characterized in a non-aqueous electrolyte, lithium tetrafluoroborate salt in the mixture of ethylene carbonate and dimethylcarbonate (LiBF4/EC+DMC). The 5-carboxyCIT electrode showed three redox couples, where charge transfer occurs with Li+ desorption/adsorption at carboxyl functional group (E0,＝0.19 V vs. Ag/Ag+), BF4− doping/undoping (E0’＝0.48V vs. Ag/Ag+), and Li+ undoping/doping (E0,＝0.96 V vs. Ag/Ag+). Specific capacity of the 5-carboxyCIT was 78 Ah kg−1 (234 Fg−1) at scan rate of 10mV s−1, which is comparable to the capacity in a 4 M H2SO4 aqueous electrolyte (86 Ah kg−1). After potential cycling of 50,000 cycles, the electrode in the LiBF4/EC+DMC electrolyte maintained 70% (55 Ah kg−1) of initial capacity