For hydrogen atom the energy of fifth shell is -x, what will be the value of E 3and E9, for li ++
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Answer:
History of biofuel cell
The statement “Perhaps the most refined fuel cell system today is the human body, a mechanism that catalytically burns food (fuel) in an electrolyte to produce energy, some of which is electrical” highlights the connection between living organisms and electricity [1, 2]. With an experiment conducted using frog leg, Biologist Lugi Galvani in 1780’s proved that electrical energy and biology have a close connection to each other [3]. Michael Cresse Potter, a Botany professor also demonstrated that living organisms can generate voltage and deliver current [4].
The term “fuel cell” has been in use for over a century. Despite some uncertainty about who first fabricated one, credits of designing and experimenting with first fuel cells go to both Sir William Grove (1839) and the Swiss scientist Christian F. Shoenbein (1868). In early 19th century, different organisms like bacteria, algae, and yeast were considered for this research. With the advent of space race, considerable attention was given to energy generation from recycled waste which in turn ignited interest in microbial fuel cell research. Later, during the sixties and in the early seventies, fuel cell related research accelerated as a consequence of increase in oil prices and has sustained momentum to date. [5, 6]. The time lines of fuel cell development are shown in the Fig.1.
Figure 1.
The time line of fuel cell development [7]
1.2. Types of fuel cells
Fuel cells could be broadly categorized into abiotic fuel cells of which the fuel cell components do not comprise any biological material and biotic or biological fuel cells which comprises living organisms or biological material (such as enzymes or derivatives). The primary types of abiotic fuel cells grouped according to the electrolyte used are shown in Table 1.
Type Features
Alkaline fuel cells (AFC) Uses KOH as the electrolyte and electro-catalysts such as Ni, Ag and metal oxides
Polymer electrolyte membrane fuel cells
(PEMFC) Uses a proton conductive polymer membrane as the electrolyte and Pt as the catalyst
Phosphoric acid fuel cells (PAFC) Uses concentrated phosphoric acid as the electrolyte and Pt as the catalyst
Molten carbonate fuel cells (MCFC) Has a combination of alkali metals (Li, K, or Na )
Solid oxide fuel cells (SOFC) Uses non-porous metal oxide(s) as the electrolyte
Table 1.
Different types of commonly known inorganic fuel cells [7].
The biological fuel cell (BFC) can be categorized into two main areas:
Microbial fuel cells (MFC)
Enzymatic fuel cells (EFC)
The biological fuel cells (BFC) use enzymes or microorganisms as catalysts. In a microbial fuel cell, the oxidation reactions that are catalyzed by microbes; alternatively, when the catalyst is an enzyme, the cell is called as an enzymatic fuel cell. While both microorganisms and enzymes catalyze oxidative reactions that takes place at the anode, only enzymes (sometime coupled with inorganic catalysts) are used in the cathode. Biological fuel cells utilize organic substrates (such as sugars and alcohols) and operate at mild temperature environments where biological activity is optimal. For example, the catalyst used in a microbial fuel cell could simply be an organism like Baker’s yeast that feed on simple sugars or an advanced species like R. ferrireducens [8-10] that thrive on more complex substrates.
1.3. Different categories of microbial fuel cells
Various types of MFC designs have been developed of which five main categories are common:
Uncoupled bioreactor MFC: a separate compartment where organisms produce the hydrogen (fuel) and that hydrogen is fed into a hydrogen fuel cell.
Integrated bioreactor MFC: hydrogen fuel production and the electricity generation both take place in the same chamber.
MFC with mediated electron transfer: where intermediate molecules shuttle electrons from microbial cells to the electrode.
MFC with direct electron transfer: where electron transfer to the electrode take place without the presence of any mediator molecules.
C6H12O6+Mediator(o) → Product+Mediator(r)
E1
Mediator(r) → Mediator(o)+Electrons
E2