domain. Detailed discussion on carbon-based nanomaterials like cellulose starch, glucose, carbon nanoparticles, nanographene, carbon nanotubes and carbon nanofibers are presented. Finally, a separate section on carbon-based nanomaterials is presented.
Chapter 8 discusses different types of biofuel cells with special emphasis on glucose-based biofuel cell. Advantages of using glucose oxidase as a natural enzyme-catalyst in these cells are described. Prevention of loss of efficiency at high temperatures due to denaturation of enzymes using polyols is discussed.
Chapter 9 summarizes the basic working principles of various configurations of photoelectrochemical fuel cells that suit different applications and their performance. Several promising applications are also discussed including wastewater treatment, power generation, fuel production, and a wide range of contaminant degradation.
Chapter 10 focuses on various engineering architectures for biofuel cells. It explores the attractiveness of biofuel cells as energy sources. Various routes for design and fabrication of these cells, material options available, relevant characterization techniques, perspectives and future challenges are discussed.
Chapter 11 discusses the history and classification of biofuel cells and biochemical reactions. The classification of biofuel cells comprises bio-electro chemicals producing whole organisms, producing hydrogen gas, etc. Additionally, various commercial applications of biofuel cells are discussed in detail.
Chapter 12 addresses the development and experimental progress of oxygen reduction reactions cathode catalyst for biofuel cells applications. Classification, mechanism, activity and performance of oxygen reduction reaction cathode catalyst are discussed in details. Additionally, various aspects concerning their electrochemical activity and their limitations in terms of technological applications are highlighted in this chapter.
Chapter 13 starts with an introduction for working mechanisms of fuel cells, biofuel cells, and the microbial desalination cell. A major focus is given to explore various configurations of desalination cells designed so far. The chapter concludes with a discussion on the factors affecting the performance and efficiency of desalination cells.
Chapter 14 discusses the types, designs, working principles, applications of biofuel cells and conventional fuel cells. It explains in detail about the types of various fuel cell and biofuel cells such as molten carbonate, proton exchange membrane, direct methanol, solid oxide, alkaline, phosphoric acid fuel cells, microbial, enzymatic, glucose, photochemical and flexible biofuel cells as well as their advantages, limitations, and applications.
Chapter 15 deliberates on different classes of biofuel cells with a focus on wearable biofuel cells, fuel used and bioelectricity generation outlining possible bioelectronic applications. The issues, challenges and scalability of biofuel cells are discussed and addressed through a proposed sustainable solution roadmap.
Chapter 16 discusses different types of anodes that are currently being utilized in biofuel cells. The main idea of this chapter is to deliver information related to recent advancements in the field of anode materials, along with their capability to improve the overall performance of biofuel cells.
Chapter 17 discusses the emerging alternative sources of renewable energy in the form of biofuel cells. The fundamental concepts, and types of biofuel cells and their applications are explained. The prospects of biofuel cells as substitutes of conventional technologies and their potentialities in novel applications are presented.
1
Bioelectrocatalysis for Biofuel Cells
Casanova-Moreno Jannu1, Arjona Noé2 and Cercado Bibiana2*
1CONACYT-Centro de Investigación y Desarrollo Tecnológico en Electroquímica S.C., Pedro Escobedo, Mexico
2Centro de Investigación y Desarrollo Tecnológico en Electroquímica S.C., Pedro Escobedo, Mexico
Abstract
Bioelectrocatalysis is the acceleration of reactions that occur on an electrode via a biological component, be it an enzyme, a cellular organelle or a whole cell. Enzymatic reactions on the anode are mainly the oxidation of saccharides and alcohols, while the oxidative metabolism of bacteria is exploited for removal of short-chain organic acids. In the cathode, the main enzyme-controlled reaction is the reduction of dioxygen, while microbial catalysis tends to obtain hydrogen and methane-like energy vectors. One of the challenges in bioelectrocatalysis is the preparation of electrodes. The techniques for immobilization of enzymes and organelles include the use of polymers and composites and the naturallyoccurring adhesion of bacteria to the solid material forming a biofilm on the electrode. Given the importance of the support material, numerous efforts have been directed to modifying materials that improve the adhesion of enzymes and bacteria, as well as electron transfer. The control of electron transfer is performed by the modification of the pH in the medium, the use of mediators, and the application of a potential difference in an electrolytic cell. The applications of electrochemical cells in bioelectrocatalytic operation include energy conversion, enzymatic sensors and gaseous fuel production in microbial bioelectrochemical systems.
Keywords: Bioelectrocatalysis, biofuel cell, enzymatic electrocatalysis, microbial electrocatalysis
1.1 Introduction: Generalities of the Bioelectrocatalysis
Electrochemical catalysis or electrocatalysis is used to describe charge transfer-based reactions occurring on an electrode. This term was employed for first time in 1936 by Santos and Schimickler [1]. The electrocatalysis is focused on increasing the reaction rate of an electrochemical process (oxidation/reduction), involving a dissociative chemisorption or a reaction step on an electrode surface and thus, the electrocatalysis depends on the ad/desorption of reactants and products, and on the formation of an electrochemical double layer. An electrocatalytic cycle is composed of three stages: 1) mass transport of electroactive species from bulk to the interface, 2) the electrocatalytic reaction, and 3) transport of products to bulk. Additionally, stage 2 involves the adsorption of reactants, the electron transfer, and the desorption of products. Consequently, the art of electrocatalysis consists of identifying the barriers of an electrochemical reaction to adjust the properties of the electrochemical interface (electrode and/or solution) with the aim of remove or at least, decrease the energy barriers (activation energies).
The practical role of electrocatalysis implies the science of designing the electrochemical interface properties. Hence, the morphological and electronic properties of the electrocatalyst, together with the electrolyte characteristics, become important to analyze. On the other hand, the activation energy of electrocatalytic reactions also depends on the electrode potential, thus enabling a fine control of the reactions. Consequently, electrocatalysis focuses on minimizing electrode overpotential, and increasing the reaction rate via the decrease of activation energies for a specific reaction.
The relation between electrocatalysis and microorganisms was presented in 1910 when a yeast was used as catalyst in a fuel cell. In the 60s microbial fuel cells (MFC) were used to exploit human waste from spacecraft, and only about 40 years later, the MFCs gained worldwide attention due to the use