Direct Methanol Fuel Cell – Alternative Materials and Catalyst Preparation

Preparation and comparative evaluation of PVC/PbO and PVC/PbO/graphite based conductive nanocomposites

Two series, A and B, of PVC based nanocomposite polymer membranes (nCPMs) were prepared using PbO only and PbO/graphite mixture as a filler by solution casting method. Seven samples with varying compositions (5–35%) of filler particles were prepared for each series and were compared by thickness measurements, porosity, water uptake, swelling degree, ionic conductivity, ion exchange capacity (IEC), membrane potential and transport number. The maximum values for these characteristics were observed as 0.402 mm, 0.77, 141.3%, 0.11, 0.0033 Scm−1, 8.6 milli-eq.g−1, 0.19 V and 0.01391 for series-A composites whereas that of 0.367 mm, 0.83, 63.4%, 0.019, 0.00981 Scm−1, 5.21 milli-eq.g−1, 0.13 V and 0.0108 for series-B nCPMs respectively. The SEM images of membranes showed greater voids produced in the series-B compared to series-A composites. The maximum Ionic conductivity, IEC, membrane potential and transport number were observed for membrane with 25% PbO/graphite, 20% PbO and 35% PbO particles respectively.

A State-of-Art on the Development of Nafion-Based Membrane for Performance Improvement in Direct Methanol Fuel Cells

Nafion, a perfluorosulfonic acid proton exchange membrane (PEM), has been widely used in direct methanol fuel cells (DMFCs) to serve as a proton carrier, methanol barrier, and separator for the anode and cathode. A significant drawback of Nafion in DMFC applications is the high anode-to-cathode methanol fuel permeability that results in over 40% fuel waste. Therefore, the development of a new membrane with lower permeability while retaining the high proton conductivity and other inherent properties of Nafion is greatly desired. In light of these considerations, this paper discusses the research findings on developing Nafion-based membranes for DMFC. Several aspects of the DMFC membrane are also presented, including functional requirements, transport mechanisms, and preparation strategies. More importantly, the effect of the various modification approaches on the performance of the Nafion membrane is highlighted. These include the incorporation of inorganic fillers, carbon nanomaterials, ionic liquids, polymers, or other techniques. The feasibility of these membranes for DMFC applications is discussed critically in terms of transport phenomena-related characteristics such as proton conductivity and methanol permeability. Moreover, the current challenges and future prospects of Nafion-based membranes for DMFC are presented. This paper will serve as a resource for the DMFC research community, with the goal of improving the cost-effectiveness and performance of DMFC membranes.

Methanol, Ethanol, and Formic Acid Oxidation on New Platinum-Containing Catalysts

Electrooxidation of methanol, ethanol, and formic acid was studied on three platinum-containing electrocatalysts: PtCu/C, Pt/(SnO2/C), and Pt/C, Pt content being about 20 wt%. In all reactions, the integral specific activity of the catalysts, estimated from the results of cyclic voltammetry, grows in the Pt/C < Pt/(SnO2/C) < PtCu/C row. The influence of the reagent nature subjected to electrooxidation is manifested both in the difference of the absolute rate values of the corresponding reactions, decreasing in the order CH3OH > HCOOH > C2H5OH, and in the different ratio of these rates on different catalysts and at different potentials. Pt/(SnO2/C) catalyst containing SnO2 nanoparticles is the most active among the studied catalysts in methanol and formic acid electrooxidation reactions under potentiostatic conditions at the E = 0.60 V. Moreover, in formic acid electrooxidation reaction it is significantly superior to even the PtRu/C commercial catalyst. The reasons for the positive influence of Cu atoms and SnO2 nanoparticles on the catalytic activity of platinum are presumably associated with different effects: Interaction of the d-orbitals of copper and platinum atoms in bimetallic nanoparticles and implementation of the bifunctional catalysis mechanism on the adjacent platinum and tin dioxide nanoparticles.

Chemically reduced graphene oxide–P25–Au nanocomposite materials and their photoelectrocatalytic and photocatalytic applications

CRGO–P25–Au NCMs were prepared through a one-pot chemical reduction method. Photoelectrocatalytic oxidation of methanol with high photocurrent and photocatalytic reduction of Cr(vi) ions to Cr(iii) ions were demonstrated.

Photoelectrocatalytic performance of a titania-keggin type polyoxometalate-gold nanocomposite modified electrode in methanol oxidation

Aminosilicate sol-gel supported titania-keggin type polyoxometalate-gold nanocomposite materials (APS/(P25-PTA-Au)NCM) (APS, (3-aminopropyl)triethoxysilane; P25, Degussa-TiO2; PTA, Na3PW12O40·xH2O) were prepared by a simple chemical reduction method and characterized by diffuse reflectance spectroscopy, photoluminescence, x-ray diffraction, transmission electron microscopy and energy-dispersive x-ray analysis. The as-prepared APS/(P25-PTA-Au)NCM was used to fabricate the photoelectrode for a photoelectrochemical cell. The photoelectrocatalytic activity of the APS/(P25-PTA-Au)NCM modified photoelectrode in methanol oxidation was investigated. The APS/(P25-PTA-Au)NCM modified photoelectrode showed a higher photocurrent for methanol oxidation than control photoelectrodes. The modification of titania using PTA and Au nanoparticles significantly boosted the photoelectrocatalytic performance by a synergistic effect and thus improved the interfacial charge transfer processes. The presence of Au nanoparticles enhances the interfacial electron transfer process. The APS silicate sol-gel matrix acts as a very good support material for the preparation of the nanocomposite material and for preparation of the chemically modified electrode. This newly fabricated APS/(P25-PTA-Au)NCM modified photoelectrode could be a promising candidate for photoelectrochemical cells.