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MCI

MAST CARBON INTERNATIONAL LTD
Country: United Kingdom
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25 Projects, page 1 of 5
  • Funder: UKRI Project Code: EP/G00434X/2
    Funder Contribution: 429,910 GBP

    Laccase is a protein excreted by white-rot fungi that works as well or better than precious metals at catalysing the reduction of oxygen to water. This chemical reaction is central to almost all low-temperature fuel cells that work in air.Fuel cells are devices that convert chemical energy from a fuel like methanol or hydrogen directly and efficiently into electrical energy. In contrast, when fuel is burned in a generator, the fuel's chemical energy is converted into thermal energy (hot gases) and mechanical energy (moving pistons) before it becomes electrical energy. Each energy conversion step has losses from heat loss and friction and from inescapable inefficiencies governed by the laws of thermodynamics; fuel cells, on the other hand, can have greater efficiencies by bypassing these intermediate stages.In most fuel cells the oxygen reduction reaction takes place on the surface of particles of expensive precious metals (usually platinum). Laccase catalyses the same reaction using only four copper atoms per enzyme molecule. Laccase catalysis is more energetically efficient, nearly as rapid, and more selective against catalyst-killing gaseous impurities.There are two key problems with using laccase in fuel cells. The first is stability: enzymes are complex and often fragile biological polymers that need to be properly oriented to work in a fuel cell. However, I have developed a technique that extends the working lifetime of laccase in a fuel cell from hours to several months. The second is the amount of electric current that is generated from a given area or volume. The platinum surface can host thousands of reactions at once while the each laccase molecule can only react one oxygen molecule at a time. To compensate for this, I am proposing introducing laccase into porous, three-dimensional electrode materials, essentially taking laccase from working on a open plain and moving it to a multi-storey office complex. For laccase to function as efficiently as possible, it needs to have its reaction needs met: a good supply of oxygen (fast gas diffusion), a constant concentration of hydrogen ions (buffered pH), and a well-connected electrical supply. Designing and building this infrastructure requires a thorough understanding of the interactions between the enzyme's surface and the surface to which it is attached and careful control of how material flows through the pores. Extending the surfaces into the third dimension lets us make more compact power sources that are suitable, for example, for small electronics like portable music players and mobile phones.Most of the surface area of porous materials is on the inside of the structure and probing an interior surface is always a challenge. I will use small gaseous molecules explore the interior, high-energy beams of metal ions to cut open the structure, high-resolution electron microscopy to examine it, and electronic and spectroscopic methods that can interrogate the interaction between the enzyme and a surface.This work is supported by an active, ongoing collaboration with experts in fungal biology. They are currently working on understanding the molecular biology behind laccase, first to mass produce the enzyme, followed by genetic engineering to change laccase's catalytic behaviour, selectivity and surface interactions.In addition to portable fuel cells that work at ambient temperatures, we may also discover more efficient, less expensive catalysts and learn how enzymes are able to carry out the oxygen reduction reaction with copper, a common metal from the first row of the transition metals, rather than platinum, a rare and expensive metal from the third row.

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  • Funder: EC Project Code: 230676
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  • Funder: UKRI Project Code: EP/D038588/1
    Funder Contribution: 507,060 GBP

    Electrochemistry is widely used in the world around us from batteries of different types both large and small, through the industrial processes used to make chlorine and sodium hydroxide and methods to deposit metals for decorative effects and to make microchips, to the portable devices used several times a day by diabetics to measure their blood glucose. Electrochemical reactions occur at surfaces and one of their great advantages is that the voltage applied to the electrode is used directly to drive the chemical reaction and the current that flows is a direct measure of the speed of the reaction. In many cases the challenge is to design the surface of the electrode to carry out a particular chemical reaction so that we can exploit these advantages. At bare metal, or carbon, surfaces reactions occur by the transfer of electrons one at a time. As a result in many reactions that we would like to carry out unstable intermediates are formed which then undergo further reactions that lead to fouling of the electrode surface and the production of undesirable side products. A way to overcome this problem is to modify the electrode surface by attaching molecules which act as intermediates or mediators in the overall reaction. The reaction at the electrode surface then occurs by first transferring the electrons one at a time to (or from) the mediator attached to the electrode surface. Then, in a second step these mediators react with molecules in solution, thus catalysing the reaction that we wish to carry out at the electrode. The big advantage of this approach is that, in principle, we can select the molecules we choose to attach to the surface of the electrode so that they exchange electrons rapidly with the electrode and react selectively with the molecules in solution - we can design the electrode surface for the reaction we want. The challenge is to find the right molecules and the right way to attach them to the electrode surface. For the last 20 years or so efforts to do this have used inspired guesswork to pick one or two molecules to try and then prepared electrode surfaces with these molecules attached. In this project we will tackle this problem in a much more effective way. We will synthesise hundreds or thousands of related, but each slightly different, molecules on electrode surfaces and then screen these to find the best for the particular reactions we are interested in. To do this we will develop new ways of preparing the electrode surfaces and new ways to screen the surfaces for activity. We have chosen three particular reactions for our study. The first is the oxidation of NADH, a common coenzyme. There are hundreds of enzymes in nature which use NADH. If we can find good electrodes for the oxidation of NADH we can then use these different enzymes to make sensors and in fuel cells. In particular a good modified electrode for NADH oxidation could be important in developing better sensors to allow diabetics to measure their blood glucose. The second reaction is the oxidation of ascorbate (vitamin C). Ascorbate is an important possible interference when trying to oxidise NADH because ascorbate is present in blood and many biological samples. Therefore for the NADH electrodes we want to find modified surfaces at which NADH reacts much better than ascorbate. On the other hand ascorbate is also important in its own right as we need to be able to measure its concentration in drinks and foodstuffs so we will also be looking for modified electrodes which are very good for ascorbate oxidation. The final target is dopamine, a molecule involved in signalling between neurones in the brain. Many of the molecules which catalyse the reaction of NADH also catalyse the oxidation of dopamine. We will screen the different molecules we produce to see if any are especially good for the detection of dopamine so that we can produce minute electrodes that can be used to measure dopamine in studies of the brain.

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  • Funder: EC Project Code: 256868
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  • Funder: UKRI Project Code: EP/G00434X/1
    Funder Contribution: 926,104 GBP

    Laccase is a protein excreted by white-rot fungi that works as well or better than precious metals at catalysing the reduction of oxygen to water. This chemical reaction is central to almost all low-temperature fuel cells that work in air.Fuel cells are devices that convert chemical energy from a fuel like methanol or hydrogen directly and efficiently into electrical energy. In contrast, when fuel is burned in a generator, the fuel's chemical energy is converted into thermal energy (hot gases) and mechanical energy (moving pistons) before it becomes electrical energy. Each energy conversion step has losses from heat loss and friction and from inescapable inefficiencies governed by the laws of thermodynamics; fuel cells, on the other hand, can have greater efficiencies by bypassing these intermediate stages.In most fuel cells the oxygen reduction reaction takes place on the surface of particles of expensive precious metals (usually platinum). Laccase catalyses the same reaction using only four copper atoms per enzyme molecule. Laccase catalysis is more energetically efficient, nearly as rapid, and more selective against catalyst-killing gaseous impurities.There are two key problems with using laccase in fuel cells. The first is stability: enzymes are complex and often fragile biological polymers that need to be properly oriented to work in a fuel cell. However, I have developed a technique that extends the working lifetime of laccase in a fuel cell from hours to several months. The second is the amount of electric current that is generated from a given area or volume. The platinum surface can host thousands of reactions at once while the each laccase molecule can only react one oxygen molecule at a time. To compensate for this, I am proposing introducing laccase into porous, three-dimensional electrode materials, essentially taking laccase from working on a open plain and moving it to a multi-storey office complex. For laccase to function as efficiently as possible, it needs to have its reaction needs met: a good supply of oxygen (fast gas diffusion), a constant concentration of hydrogen ions (buffered pH), and a well-connected electrical supply. Designing and building this infrastructure requires a thorough understanding of the interactions between the enzyme's surface and the surface to which it is attached and careful control of how material flows through the pores. Extending the surfaces into the third dimension lets us make more compact power sources that are suitable, for example, for small electronics like portable music players and mobile phones.Most of the surface area of porous materials is on the inside of the structure and probing an interior surface is always a challenge. I will use small gaseous molecules explore the interior, high-energy beams of metal ions to cut open the structure, high-resolution electron microscopy to examine it, and electronic and spectroscopic methods that can interrogate the interaction between the enzyme and a surface.This work is supported by an active, ongoing collaboration with experts in fungal biology. They are currently working on understanding the molecular biology behind laccase, first to mass produce the enzyme, followed by genetic engineering to change laccase's catalytic behaviour, selectivity and surface interactions.In addition to portable fuel cells that work at ambient temperatures, we may also discover more efficient, less expensive catalysts and learn how enzymes are able to carry out the oxygen reduction reaction with copper, a common metal from the first row of the transition metals, rather than platinum, a rare and expensive metal from the third row.

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