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The development of energy conversion systems with high efficiency, low cost and stability is vital to meet the challenges derived from global warming due to greenhouse gas emissions from the combustion of conventional systems and to reduce the dependence on fossil fuels. More efficient and novel nanostructured materials, with lower cost than conventional ones, are required in this field to meet the requirements posed by new technologies in terms of performance and durability. The overall objective of the present work is the development of cost-effective nanostructured cathode catalysts, not containing Platinum (Pt-free), for polymer electrolyte fuel cells. Ketjenblack (KB) supported Pd and Pd4Co1 alloy electrocatalysts have been synthesized and characterized in a direct methanol fuel cell (DMFC), fed by different methanol concentrations, to evaluate their performance, tolerance to methanol permeated through the polymer electrolyte membrane and durability.

Sviluppo di componenti innovativi e nuove configurazioni di cella per batterie metallo-aria Sviluppo di batterie Fe-aria operanti a bassa temperatura

Metodologie di diagnostica sulle batterie a Litio-ione

The CO2Chem project is focused on the development of a cost-effective and one-step conversion of CO2 and water to high energy density fuels, such as methanol. The co-electrolysis reactor should be able to use the surplus of energy produced by renewable power sources which are characterised by intermittent behaviour. The aim is to achieve a one-step conversion of CO2 and water to alcohols in a device capable to operate under dynamic conditions. In the second period (M4-M7), the activity was addressed to study an electrochemical reactor in the presence of alkaline electrolytes and specifically to use an anion exchange membrane and non noble metal electro-catalysts.

The CO2Chem project deals with a cost-effective and one-step conversion of CO2 and water to high energy density fuels, such as methanol. The project regards the development of a co-electrolysis reactor using the surplus of energy associated to the intermittent behaviour of renewable power sources. The aim is to achieve a one-step conversion of CO2 and water in methanol in a device capable to operate under dynamic conditions. In the first 3 months of the project, the reactor was consisting of solid protonic electrolyte and catalysts for tuning the co-electrolysis of CO2 and water. The process was investigated at low temperature (30-95°C) to evaluate the possibility of direct coupling with renewable power sources. The objective was to achieve a voltage efficiency better than 80% and good characteristics for coupling with renewable power sources. The aim was to developing, prototyping and demonstrating this novel technology in an electrochemical reactor of 5 cm2 as proof of concept.

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are very important processes in different energy conversion devices such as fuel cells, electrolysers, unitized reversible fuel cells and metal-air batteries. In particular, in the latter two systems, both reactions occur on the same electrode during the charge and discharge processes. Such an electrode is called "bi-functional" oxygen electrode and should contain good electro-catalysts for both the oxidation and reduction reactions of oxygen. Furthermore, this electrode should be chemically stable over the wide range of potentials experienced during both processes. Although noble metal catalysts have proved to be effective as oxygen-electrode [1], the high costs and limited reserves in the world hinder their practical application. Recently developed perovskites have shown better activities for OER in alkaline medium of the catalysts based on noble metals. The ORR is the limiting step for this class of non-noble-metals [2-4]. In the present work, a perovskite, namely La0.6Sr0.4Fe0.8Co0.2O3 (LSFCO) was mixed with a carbon material and investigated for operation as both oxygen reduction (ORR) and oxygen evolution (OER) catalyst. The catalyst was investigated in half-cell by using a three-electrode configuration, in alkaline solution at ambient temperature, and compared to a Pd/C catalyst. LSFCO was less active for the ORR, while the performance for the OER was better compared to Pd. In order to get information on the stability, oxygen evolution polarizations were carried out up to 2 V vs. RHE. This may be considered an accelerated stress test since a high electrochemical potential promotes electrocatalyst degradation. The LSFCO-based catalyst showed a more stable behaviour compared to the noble metal catalyst.

Electrocatalysts for the oxygen reduction and/or the oxygen evolution reactions play a key role determining the performance of energy conversion/storage devices, such as fuel cells, electrolysers, regenerative fuel cells or, recently, metal-air batteries [1, 2]. In particular, the life and cost of these devices are directly related to the durability of the catalysts [3, 4]. The high potentials reached, particularly during the oxygen evolution, limit the use of carbonaceous materials as catalysts' supports [2]. The corrosion of the carbon support is one of the main issues affecting the catalyst durability, given that carbon is unstable under such conditions [5]. Thus, highly stable catalysts are required. Titanium suboxides are recognized for their high stability under harsh electrochemical conditions [6, 7]. They were successfully used as a support for iridium oxide in PEM-electrolysers [8]. In the present work, titanium oxides have been studied as Pd-catalysts' supports for their use towards the oxygen reduction and the oxygen evolution reactions (ORR/OER) in alkaline media. In previous works, Pd/C catalysts have been proved to be efficient bifunctional materials for ORR/OER [9,10]. Nevertheless the stability of these materials was not optimal. For this reason, titanium based materials were selected as support with the aim of improving the durability of catalysts towards these reactions (ORR and OER). Pd nanoparticles were supported on titanium-based materials by a sulphite complex route. Catalysts were characterized by means of X-ray diffraction, transmission electron microscopy and N 2 adsorption. Polarization curves were performed in a half-cell system in alkaline solution (KOH) studying the behavior of catalysts for both reactions: the oxygen reduction reaction and the oxygen evolution reaction. All catalysts were compared to a Pd/C catalyst made in-house by using Vulcan as support. Pd on Vulcan proved to be more performing than Pd supported on the titanium-based materials for both reactions. This was ascribed to the better metallic dispersion of Pd particles on the carbon support, favouring a higher surface area and, thus, a higher activity. Catalysts were submitted to several stress tests (ST) in order to analyze the stability of the catalysts, evaluating the activity before and after the ST. Pd supported on the titanium-based materials presented a higher activity after ST than Pd/C.

Supply of scale-up membranes for large area MEAs used in stack testing

This bilateral project between Italy (CNR-ITAE) and Canada-Quebec (INRS-EMT) entitled 'Development of nanostructured catalysts for the conversion of chemical energy into electrical energy in fuel cells' (Sviluppo di catalizzatori nanostrutturati per la conversione di energia chimica in elettrica mediante celle a combustibile) deals with low cost, highly efficient and stable systems for the conversion of energy. The general objective of this activity is the development of new low cost nanostructured catalysts based on noble metal-free formulations for low temperature fuel cells. Replacing platinum-based catalysts with a more abundant material would greatly improve the outlook for the widespread development of fuel cells, i.e. a new technology for the direct conversion of energy with high efficiency. The new formulations must simulate the catalytic behavior of platinum. Catalysts based on nanostructured oxides of Ta and Zr have been characterized in terms of structural and chemical properties as well as electrochemical behavior. The main objective remains to modulate the chemical characteristics and surface in order to obtain electronic properties similar to Pt to ensure similar yields.

Batteries are the key components of the electric vehicles (EVs) and at the same time their most expensive parts. Lithium ion batteries are currently considered as the best option for transportation to be used in plug-in hybrid and full EVs [1]. However, to fully implement EVs in the market, a new generation of battery system will be required providing higher energy density, lower cost and use of abundant and safe materials [2]. In this regard, one of the main fields being explored for a possible breakthrough is metal-air batteries. This devices generate electricity through a redox reaction between a metal (such as Li, Zn, Al, Mg, Na or Fe) and oxygen in air [3]. In comparison to Li, metals such as Zn, Mg, Fe, etc, are much more abundant, present lower costs and are more environmentally safe [1-6]. Among them, the iron-based system is one of the most promising given that combines the high energy density typical of this type of batteries with other specific aspects like reversibility of the iron electrochemistry, simple cell design (no need of membrane), use of abundant low cost manufacturing materials and safety [5, 7]. In this system, the air electrode is a key component. Molecular oxygen takes electrons from the counter metal electrode to complete the electrochemical reaction generating electrical energy, being necessary not only a good performance but a proper stability. In the present work several Pd-based catalysts have been studied for both the Oxygen Reduction Reaction (ORR), taking place in the discharge process of the battery, and the Oxygen Evolution Reaction, taking place during charging. Pd-nanoparticles (3-7 nm) were supported on several supports by means of a sulphite complex route: (i) carbonaceous supports such as Vulcan-XC-72-R (from Cabot) and (ii) non-carbonaceous supports, Ti-suboxides. The electrochemical behavior of these catalysts for both ORR and OER was investigated in half-cell configuration in an alkaline solution (6M KOH) at room temperature. Stability tests were carried out in order to properly select the most appropriate catalyst to be used in a complete cell.

Cathode catalysts for Direct Methanol fuel cells (DMFCs) must have high catalytic activity for the Oxygen Reduction Re-action (ORR), lower cost than the benchmark Pt catalyst and high tolerance to methanol that permeates from the anode side to the cathode side through the membrane. 30% Pd/Ketjenblack (Pd/KB), 30% Pd/Vulcan (Pd/Vul) and 30% Pd/Titanium suboxides (Pd/TinO2n-1) have been synthesized and characterized, in terms of ORR, to evaluate their activity for direct methanol fuel cell (DMFC) applications. By comparing Pd electrocatalysts with commercial 30% Pt/C, it can be noted that Pt/C, as it is known, is the more active electro-catalyst when an ideal acidic electrolyte is considered. Pd/KB is the most active electro-catalyst in acidic environment, when methanol crossover is taken into account.

Data-set on stack assembling and testing including specific performance, durability and accelerated test results

Novel preparation routes regarding the development of cost-effective metal or oxide dispersed nanocatalysts as well as innovative formulations were the object of this WP, together with the development and optimization of nanomaterials for manufacturing an appropriate composite iron-carbon electrode, Fe/C.

Lithium-ion technology presents several disadvantages that hinder the mass introduction of electric vehicles. In this regard, novel approaches and chemistries have been developed with the aim of improving the current features. Among these new technologies, metal-air batteries are receiving especial interest, given that they are capable of very high theoretical energy densities. Iron-air batteries belong to the category of metal-air batteries, in which the anode or negative electrode is formed by a metal and the cathode or positive electrode is a porous air breathing composite material. Having only one reactant contained inside the cell, metal-air batteries permit much more compact and lighter designs and therefore, they are capable of very high energy densities. In the case of iron-air batteries, the cells are composed by an iron negative electrode, a bifunctional air positive electrode and an aqueous potassium hydroxide (KOH) electrolyte. As both the positive and negative electrodes are immersed in the same electrolyte, there are no separating membranes required [1, 2]. The iron oxidation is a surface reaction, and so it is prone to passivation. This issue can be addressed by increasing the electrochemical specific surface of the iron anode, by means of the use of carbon nanomaterials with a porous nanostructure that maximizes the usability of the electrode [3-6]. In the present work, iron oxide has been synthesized by a new methodology based on the Adam's fusion method, usually employed for the production of fine noble metal oxide powders [7]. This method is based on the oxidation of metal precursors in a molten nitrate melt. The so-obtained iron oxide was mixed with different amounts of carbon and tested in a half-cell system with a 6M KOH solution as electrolyte.

Carbon gels are porous materials with a reticular structure formed by interconnected spherical carbon nanoparticles. The versatility of their properties in terms of structure, form and texture favours their application in many fields: catalysis, energy conversion and storage, etc. Among the different types of carbon gels existing, carbon xerogels (CXG) have been widely used, given their low-cost production and good properties (high surface area, mesoporosity, high purity, etc). In this work, CXGs properties were modified varying the synthesis conditions: resorcinol to sodium carbonate molar ratio (CXG-RC-n, with n= 50 ; 800 or 1050). CXGs were physico-chemically characterized and tested as counter electrode in dye sensitized solar cells. Performance was assessed by voltamperometric polarization and impedance measurements under AM 1.5 illumination.These materials showed good perspectives to replace Pt counter electrodes in dye sensitized solar cells.

Direct methanol fuel cells (DMFCs) are an attractive alternative to batteries for portable applications and auxiliary power units mainly due to the high energy density of methanol and the high energy efficiency that characterize low temperature fuel cells. One of the main drawbacks of DMFCs based on acidic polymer electrolyte is the need of platinum group metals to obtain practical performances at low temperature. One attractive idea is to substitute the cathodic Pt/C catalyst by highly performing non-platinum group metal catalysts based on M-N-C (where M=transition metal) structures. In the present work, we have carried out a performance analysis of Fe-N-C-based catalysts in a single DMFC, demonstrating good perspectives for their application in cost-effective DMFCs based on acidic polymer electrolytes.

Final report including an evaluation of the cost-effectiveness of the newly developed components

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Full data set on MEA performance and stability. Scaled-up MEAs of suitable active area for final stack assembling

Publishable Report

The development of energy conversion systems with high efficiency, low cost and stability is vital to meet the challenges derived from global warming due to greenhouse gas emissions from the combustion of conventional systems and to reduce the dependence on fossil fuels. More efficient novel nanostructured materials and with lower cost than conventional ones are required in the research in this area to meet the requirements posed by new technologies in terms of performance and durability. The overall objective of the present activity is the development of new nanostructured catalysts at low cost, not containing precious metals, for fuel cells at low temperature. This collaboration aims to combine the scientific expertise developed on the new generation of catalysts by the Canadian group with those of integration in electrochemical devices of the Italian group. A second objective is to train young researchers through their involvement in other ongoing projects under the Seventh Framework Programme of the European Community and projects in the region of Quebec.

D3.9 Optimized carbon and non-carbon based supported catalyst

Nanomaterials for cell components.

D3.8 Optmized FeC composites and additives