E. Modica

Influence of flow field design on the performance of a direct methanol fuel cell

Serpentine (SFF) and interdigitated (IFF) flow fields were investigated with regard to their use in a direct methanol fuel cell (DMFC). The DMFC equipped with SFFs showed lower methanol cross-over, higher fuel utilisation and slightly larger voltage efficiency at low current densities. IFFs enhanced mass transport and membrane humidification allowing to achieve high power densities of 450 and 290 mW cm−2 in the presence of oxygen and air feed, respectively, at 130°C. A fuel efficiency of 90% was obtained with the IFFs in the presence of 1 M methanol feed at 130°C and a current load of 500 mA cm−2.

Investigation of direct methanol fuel cells based on unsupported Pt-Ru anode catalysts with different chemical properties

The structure, chemistry and morphology of commercial unsupported Pt–RuOx and in-house prepared Pt–Ru catalysts were analysed. The catalytic activity of these materials towards electro-oxidation of methanol in solid-polymer-electrolyte direct methanol fuel cells have been investigated at 130°C. The in-house prepared unsupported Pt–Ru catalyst showed higher performance with lower activation control and mass polarisation losses in relation to the Pt–RuOx catalyst. An enhancement of mass-transport properties was obtained in the presence of interdigitated flow-fields. Maximum power densities of about 0.45 and 0.29 W cm−2 in the presence of oxygen and air-feed, respectively, were obtained at 130°C. Methanol cross-over rates and fuel efficiency were determined under various conditions.

Investigation of unsupported Pt–Ru catalysts for high temperature methanol electro-oxidation

Abstract Two unsupported Pt–Ru catalysts, varying in the nature and content of RuOx species, were investigated for methanol electro-oxidation in a solid polymer electrolyte fuel cell at high temperature. The catalyst containing a lower amount of ruthenium oxide showed higher catalytic activity and lower mass transport limitations. A physicochemical investigation was carried out to support the interpretation of electrochemical results. Pt–Ru alloy appears more active than Pt–RuOx in the chemisorption of labile-bonded oxygenated species, which promote the oxidation of the methanolic residues adsorbed on the catalyst surface.

Investigation of the activity and stability of Pd-based catalysts towards the oxygen reduction (ORR) and evolution reactions (OER) in iron–air batteries

Pd-based catalysts supported on commercial carbon supports (Ketjenblack and Vulcan) have been studied for both the ORR and the OER. Pd proved to be a suitable bi-functional catalyst for the ORR and the OER, with Vulcan as the carbon support providing the highest stability during accelerated degradation tests.

Ageing effects of electrodes in ceramic fuel cells

Abstract A physico-chemical characterization of aged electrodes of a 150 W solid oxide fuel cell (SOFC) tubular stack is presented. X-ray diffraction and electron microscopy analyses showed that significant chemical and morphological changes occurred in both anodic and cathodic components after 3000 h operation. Depletion of ceria at the anode side with operation time caused a change in selectivity of the methane oxidation reaction, leading to a significant increase of the deep oxidation products in the catalytic step preceding the electrochemical reaction. This determined both OCV drop and performance decay. Moreover, prolonged operation resulted in a narrowing of the three-phase reaction zones at the electrode-electrolyte interface.

Natural pyrite-based electrodes for photoelectrochemical applications

Abstract The screen printing technique has been used for the manufacturing of photoelectrodes based on natural pyrite. Materials have been investigated by X-ray diffraction, energy dispersive X-ray analysis and scanning electron microscopy. Information on the electrochemical reactivity of the surface has been obtained by cyclic voltammetry in alkaline solution. Photoactive anodes in polyiodide electrolyte based photoelectrochemical cells have been obtained upon thermal activation of electrodes in air. These results have been interpreted on the basis of the formation of a heterostructure composed of FeS 2 and Fe 2 O 3 phases.