Fuel cells, and electrocatalysis

In the past decade, nanomaterials were widely used as eleetrode materials in both electrochemical energy conversion and electrochemical energy storage. For the former, the nanomaterials are served mainly as eatalysts while for the latter, the nanomaterials are used as insertion/extraetion eleetrode materials for lithium ion. This part reviews therefore the major progresses made by Chinese researchers on nanomaterial electrode materials for electrochemical energy storage and conversion, such as lithium ion batteries, lithium-sulfur/oxygen batteries, Na/Mg-ion batteries, fuel cell and electrocatalysis. 

In this paper, we will discuss the thermodynamic principles involved in fuel cells as well as the kinetic aspects of their half cell reactions. In the kinetic considerations, we will also touch, briefly, on the fundamental problem of electrocatalysis. We will then proceed to describe different types of fuel cells and finally present the status of this new electrical generation device. 

Several important energy-related applications, including hydrogen production, fuel cells, and CO2 reduction, have thrust electrocatalysis into the forefront of catalysis research recently. Electrocatalysis involves several physiochemical environmental dfects, which poses substantial challenges for the theoreticians. First, there is the electric potential which can aifect the thermodynamics of the system and the kinetics of the electron transfer reactions. The electrolyte, which is usually aqueous, contains water and ions that can interact directly with a surface and charged/polar adsorbates, and indirectly with the charge in the electrode to form the electrochemical double layer, which sets up an electric field at the interface that further affects interfacial reactivity. 

Two years ago, Advances in Catalysis featured a chapter on chemisorbed intermediates in electrocatalysis. In this issue we follow up with a chapter by Wendt, Rausch, and Borucinski, Advances in Applied Electrocatalysis. The successful commercial application of electrocatalysis requires a detailed, fundamental knowledge of the many catalytic phenomena such as adsorption, diffusion, and superimposition of catalyst micro- and nanostructure on the special requirements of electrode behavior. Considerable understanding of the status and limitations of electrolysis, fuel cells, and electro-organic syntheses has been obtained and provides a sound basis for future developments. 

Electrocatalysis is receiving increasing levels of attention in the computational community due to the recent interest in fuel cells and electrochemical energy conversion technology. The presence of an electrolyte and electric potential substantially complicates modeling efforts of these systems. Simple models to account for these phenomena were developed by Norskov and co-workers, while more sophisticated approaches were developed by Neurock and co-workers.There are other approaches as well, but these two are the ones most often used in the work reviewed here. Other notable approaches include that by Alavi and co-workers , and the Anderson group s approach." ... 

In the field of electrocatalysis the situation seems to be somewhat better as far as the problems of clean surfaces and the existence of chemical effects are concerned. Unfortunately, so far only a few reactions have been studied. Thus, much more systematic fundamental research has to be done. From the results already available one can extract the hope that ion-bombardment will be of future importance for fields involving electrocatalytical reactions such as, for example, hydrogen technology, energy conversion, fuel cells and electrochemical redox reactions. 

Carbon supported Pt and Pt-alloy electrocatalysts form the cornerstone of the current state-of-the-art electrocatalysts for medium and low temperature fuel cells such as phosphoric and proton exchange membrane fuel cells (PEMECs). Electrocatalysis on these nanophase clusters are very different from bulk materials due to unique short-range atomic order and the electronic environment of these cluster interfaces. Studies of these fundamental properties, especially in the context of alloy formation and particle size are, therefore, of great interest. This chapter provides an overview of the structure and electronic nature of these supported... 

SERS may lead to detection techniques and assays with good sensitivity and selectivity. The area of electrocatalysis is continuously expanding. It has great potential in the area of electrochemical energy systems, especially fuel cells and batteries. The fundamental questions on nucleation, electrocrystallization, faceting, energy dissipation in hot metals and redox potential of nanoparticles are some of the issues that will remain the focus of immediate research. 

Modifed electrodes have many potential applications. A primaiy interest has been in the area of electrocatalysis. Here, electrodes capable of reducing oxygen to water have been sought for u.se in fuel cells and batteries. Another potential application is in the production of electrochromic devices that change color on oxidation and reduction. Such devices could be used in displays or smtin win-... 

Once this solid oxide fuel cell anode electrocatalysis becomes mechanistically understood and optimized, it may provide a route for the simultaneous electrochemical synthesis of C2 hydrocarbon species and generation of electrical energy from CH4. 

Sao Paulo, at Sao Carlos, Brazil. He is employed at the University of Sao Paulo since 1981 where actually he is Full Professor of Physical Chemistry (2009) at the Institute of Chemistry of Sao Carlos. He made a post-doctorate at the University of Ottawa, Canada (1988-1990) and was a Visiting Professor at the University of Illinois at Urbana-Champaign, USA (1998-1999). He has published more than 130 articles in international scientific journals. He is author of four book chapters and one book. He had supervised 18 Ph.D. thesis and 21 M.Sc. thesis. He has delivered 87 international conferences. The main research areas are electro-catalysis, fuel cells, and alcohol electro-oxidation. He is the Associate Editor of the journal Electrocatalysis, published by Springer. 

Fabio Terzi is a Researcher at the University of Modena and Reggio EmUia, Italy. He received his Master s Degree in Chemistry in 2001 from the University of Modena and Reggio Emilia. In 2005, he received his PhD degree from the University of Modena and Reggio Emilia, defending a thesis entitled Development and Application of Metal Nanostructured Systems for Electrocatalysis. Fuel Cells and Sensors (supervisor Prof. Renato Seeber). 

Extensive studies of the possibility of increasing the efficiency of hydrogen-oxygen fuel cells and of using other fuels have promoted the formation of a new branch of modern theoretical and applied electrochemistry - electrocatalysis. One of the most interesting achievements in... 

Braunchweig B et al (2013) Electrocatalysis a direct alcohol fuel cell and surface science perspective. Catal Today 202 197-209... 

Mukeijee S, McBreen J. The effect of Ru and Sn additions to Pt on the electrocatalysis of methanol oxidation An in situ XAS investigation. Proceedings of the 2nd international symposium on new materials for fuel cells and modem battery systems. Savadogo O, Roberge PR, editors. Montreal, Canada Ecole Polytechnique de Montreal 1997 548-59. 

These preliminary results are a first demonstration that the shape-selected particles concept may work in a realistic fuel cell environment. Future research will focus on degradation and stability tests of the novel materials as well as their application in other fuel cell types, as for instance direct methanol fuel cells and high-temperature pol)uner electrolyte membrane fuel cells. Moreover, the effect of the surfactant requires special attention, as the surfactant molecules may also influence the electrocatalysis by a ligand effect or an ensemble effect directing the adsorption of reactants to specific surface sites. 

Only recently, carbon nanotubes and graphene attracted increasing attention as catalyst support in fuel cells and other applications due to their favorable properties. Also the use of hierarchical structures, which are obtained by templating [74,75], as well as mesoporous carbons has received a proper share of interest. For the broad application of these more sophisticated carbon structures, however, their cost needs to be significantly reduced. Among these promising carbon-based materials, the use of CNTs as support in electrocatalysis will be described in some detail in the following. 

Lei, H., Atanassova, P., Sun, Y., and Blizanac, B. (2009) State-of-the-art electrocatalysts for direct methanol fuel cells, in Electrocatalysis of Direct Methanol Fuel Cells From Fundamentals to Applications (eds. H. Liu and J. 

Oxidation can also occur at the central metal atom of the phthalocyanine system (2). Mn phthalocyanine, for example, can be produced ia these different oxidation states, depending on the solvent (2,31,32). The carbon atom of the ring system and the central metal atom can be reduced (33), some reversibly, eg, ia vattiag (34—41). Phthalocyanine compounds exhibit favorable catalytic properties which makes them interesting for appHcations ia dehydrogenation, oxidation, electrocatalysis, gas-phase reactions, and fuel cells (qv) (1,2,42—49). 

---