Renewable resources of energy are needed to battle the ever-increasing emanation of C dioxide, which is the dominant nursery gas responsible for planetary heating. Sugar based fuel cells promise an environmentally friendly alternate to fossil fuels. Here I report experimental consequences on the public presentation of a simple sugar/hydrogen peroxide fuel cell. For glucose, fructose sucrose and maltose, I measured the unfastened circuit electromotive force, the short circuit current, the voltage/current relationship, and the electric power as a map of clip. For glucose and fructose the fuel cells started working after a hold clip of 65 min and 9 min, severally. The malt sugar and sucrose fuel cells ne’er developed important electromotive forces nor currents. For glucose and fructose the unfastened circuit electromotive force was 0.84V. The short circuit current was for glucose 7.4mA and for fructose 6.3mA. Glucose delivered twice the maximum power ( 3mW ) than fruit sugar. I report on the possible chemical reactions and discourse the deductions and compare them with the experimental consequences. My consequences show that a glucose/hydrogen peroxide fuel cell has the best public presentation and that sugar based fuel cells are assuring campaigners for environmentally friendly energy bringing systems.
Word Count: 188
An Probe of the Sugar / Hydrogen Peroxide Fuel Cell
Analysiss of a sugar and H peroxide
Table of Contentss:
1.1 Information on the fuels used in the fuel Cell:
1.16 Hydrogen Peroxide
2.0 Materials and Method
2.11 Chemicals Required
2.12 Supplies Required
2.23 pheumatic trough
3.0 Consequences and Discussion
3.13 Sucrose & A ; Maltose
3.2 Chemical reactions at the Cathode
3.3 Chemical reactions at the Anode?
3.3 Glucose/Hydrogen Peroxide Fuel Cell
3.32 electromotive force against current
3.33 exponential decay
3.35 pheumatic trough
3.4 Fructose/Hydrogen Peroxide Fuel Cell
3.42 electromotive force against current
3.43 exponential decay
5.1 Error minimisation
5.2 Possible Mistakes
Carbon Dioxide from firing fossil fuels has been by and large indentified as the taking cause for planetary heating. Renewable, carbon impersonal, resources of energy can supply a solution. Many different engineerings have been proposed and many challenges remain. One such engineering is based on fuel cells. These are devices that make usage of an electrochemical reaction in order to bring forth electricity from fuels. These can be gaseous, liquid, or solid. Gaseous fuel cells, like the well cognize H fuel cell, require sophisticated constructions for the gases to spread. In the instance of liquid fuels and liquid negatron accepters much simpler fuel cell constructions can be used. A conventional of a fuel cell is shown in Fig. 1.
Figure: Schematic of a liquid based fuel cell. The current I flows from the cathode to the anode ; the cell generates a electromotive force V across the external circuit ; positive ions flow through the ion permeable membrane. The fuel cell produces a electrical power
W = IA·V.
Typical fuel cells require proton exchange membranes that separate the anode and cathode compartments from each other. This prevents the direct reaction of the fuels at the Pt electrodes. 2 Simpler designs with glass filters are possible for some fuel cells such as the one used here.
Some liquid fuel cells can be powered by sugar as a fuel. Sugar has the advantage that it is produced in big sums from sugar cane, sugar Beta vulgaris, maize, and fruits, and is therefore to the full renewable. One engineering uses sugar and H peroxide, while others make usage of bacteriums or enzymes.
In this probe I consider a fuel cell that makes usage of different sugars solved in K hydrated oxide as fuel and H peroxide solved in K hydrated oxide as an negatron acceptor. The rule of the design is similar to the 1 proposed by Blume and is described in item subsequently. I investigated the sugars maltose, glucose, sucrose, and fructose. For each sugar I measured the unfastened circuit electromotive force, the short circuit current, the voltage/current relationship, and the electric power as a map of clip.
In order to reply the inquiry, how different sugars consequence the public presentation of a sugar/hydrogen peroxide fuel cell, I set myself the following chief aims:
Design an experimental apparatus that allows the quantitative probe utilizing a digital information acquisition system.
Describe the different chemical reactions.
Measure the unfastened circuit electromotive force and the short circuit current.
Determine the current/voltage features ( I-V curve ) .
Measure the power as a map of current and electromotive force.
Identify restricting factors and betterments.
1.1 Information on the fuels used in the Fuel Cell:
Before I start with the experiment, I would wish to analyze the substances used and to possibly see, which substances should hold a good energy end product. Sugars are saccharides, which are organic molecules dwelling of H, C and O. They are produced by workss through photosynthesis. Sugars constitute a chief ingredient in the metamorphosis of workss and mammals. They can be classified into monosaccharoses, disaccharides, oligosaccharides, and polyoses. A monosaccarharid is a simple sugar, composed of hydroxyl groups. Monosaccharid molecules are either called triose, tetrose, pentose, or hexose, depending on how many C atoms they have ( hexose means 6 atoms, pentose 5, tetrose 4, etc. ) . Disaccharides are two monosaccharoses covalently linked together. Oligosaccharides are ironss of more than two monosaccharoses. Long ironss of covalently linked monosaccharoses or disaccharides are called polyoses. In this probe I considered merely mono- and disaccharides as simple sugars are more reactive.
Monosaccharides can be divided into two groups aldoses like glucose, which have a aldehyde functional group at one terminal and ketoses like fruit sugar which have a ketone group ( at one terminal ) . Monosaccharides have a stereoisomerism. For illustration, as shown in Fig. 2. , glucose has two stereo isomers. The isomerism refers to the chiral C farthest from the aldehyde group. The two stereo isomers are designated D-Glucose or L-Glucose. D is the most of course happening isomer.
Figure: The isomers of glucose.
Monosacharides that are either pentoses and hexoses can cylize. Here the ketone or aldehyde funcitonal group reacts with the hydroxil group of the chiral C ( or anomeric C ) farthest from the ketone or aldehyde functional group. Cylization normally occures when the monosaccharoses is in an aqueous solution. The cyclization of D-Glucose is shown below:
1.12 Glucose ( C6H12O6 ) :
Glucose is a monosaccharide saccharide. As mentioned before Glucose has two isomers D- and L-Glucose. The molecular construction can be seen above.
Glucose can be obtained by hydrolysis of vegetable starches of any sort, such as malt sugar, sucrose, lactose, animal starch and cellulose. But it is normally manufactured from cornflour.
1.13 Fructose ( C6H12O6 ) :
Like Glucose, Fructose is besides a monosaccharide saccharide. Like Glucose it has two isomers D and L. The molecular construction and the cyclization of Fructose is shown below.
Fructose is produce by manner of a procedure that converts about half of the glucose in maize sirup into fructose. The procedure uses an isomerase enzyme.
1.14 Sucrose ( C12H22O11 ) :
Sucrose is most normally known as sugar. It is a disaccharide saccharide Composed of the two monosaccharoses I±-D-Glucose and I?-D-Fructose. It can be extracted from either Beta vulgariss or sugar cane. About 70 % off all saccharose is extracted from sugar cane, the other 30 % are extracted from sugar Beta vulgaris.
1.15 Maltose ( C12H22O11 ) :
Maltose is a disaccharide saccharide produced through either hydrolysis of a polyose like amylum or utilize the enzyme diastase on amylum or any polyose.
1.16 Hydrogen Peroxide ( H2O2 ) :
Hydrogen Peroxide ( 33 % ) is clear colorless liquid which is a strong oxidant, that with contact with other stuffs may do fire and causes Burnss to the eyes, tegument, and respiratory piece of land. If the Hydrogen Peroxide is uncontaminated it usually decomposes easy to let go of O. It should be kept in the dark and in a closed but vented container. This prevents vaporization and taint. The solution should be kept cold it as if it is heated is decomposes violently and fast. The is recommended to revolve the stock to maintain the concentration.
The Fuel Cell:
The schematic of the fuel cell above shows the which substances are were in the fuel cell. The design follows the suggestions by Blumes.
On the left side, at the anode, the sugar ( either Glucose, Fructose, Sucrose, or Maltose ) is added with a K hydroxide solution. On the right, at the cathode, are the substances H peroxide and K hydrated oxide are used.
Now I will the possible reactions that can go on at the cathode and the anode.
Chemical reactions at the Anode:
At the anode ( left side ) the substances K hydrated oxide and a sugar ( Glucose, Fructose, Sucrose, or Maltose ) is present. But before we go into item with each separate chemical expression. I would wish to explicate the reactions in general footings. Any sugar that forms an aldehyde or a ketone in an alkalic solution, is called a reduction sugar. A reduction sugar is fundamentally a sugar that act as a reduction agent. A sugar can merely be oxidized if it can readily exchange between the additive signifier ( acyclic signifier ) and pealing signifier. The additive signifier allows the aldehyde or ketone functional groups to go “ free ” . These groups so readily oxidise. In order for the sugars to hold a additive signifier, the anomeric C has to be “ free ” , intending that the bond between the anomeric C and the O can be opened. Glucose and Fructose can are cut downing sugars since they can readily exchange between at that place additive and ring signifier.
The oxidization of Glucose: Below is the chemical expression for the oxidization of glucose, the expression is shortened with R, as merely the aldehyde group is of import for this reaction. This expression is greatly simplified, there are many complex oxidizations and rearrangements of the decomposition merchandises of Glucose.
ox: R-CHO ( aq ) + 3OH I… ( aq ) a†’ R-COO I… ( aq ) + 2H2O + 2e I…
The oxidization of Fructose: One would believe that fruit sugar is non a reduction sugar, due to the responsiveness of the ketone fructional group, but in fact Fructose can isomerize into an aldose Since the aldehyde group reacts the chemical expression is precisely the same as with glucose.
ox: R-CHO ( aq ) + 3OH I… ( aq ) a†’ R-COO I… ( aq ) + 2H2O + 2e I…
Not all diassachrairdes can readily undergo oxidization. Sucrose is non a reduction sugar because it does non hold a additive signifier, because the anomeric C is non free. Maltose, on the other manus, is a cut downing sugar because one of the anomeric Cs of the two Glucose molecules it is composed of, is free, leting one of the Glucose molecules to open.
The oxidization of Maltose: Since this reaction besides merely involves the aldhyde group it is the same as the oxidizations of Glucose and Fructose.
ox: R-CHO ( aq ) + 3OH I… ( aq ) a†’ R-COO I… ( aq ) + 2H2O + 2e I…
Chemical reactions at the cathode:
At the cathode ( right side ) the substances H peroxide and K hydrated oxide are present. A big assortment of reactions could be taking topographic point at the cathode:
First a H peroxide decomposes in to H2O and O gas general. This reaction is non dependent on electrical power of K hydrated oxide. It merely needs adequate energy in order to respond. :
( 1 )
2 H2O2 ( aq ) a†’ 2H2O ( cubic decimeter ) + O2 ( g )
The O produced from the decomposition of H peroxide so can respond with the H2O nowadays and negatrons provided by the oxidization of the sugars at the anode:
( 2 )
O2 + 2H2O + 4e I… a†’ 4OH I… ( aq )
The hydrated oxide molecules provided K hydrated oxide reacts with the H peroxide:
( 3 )
H2O2 ( aq ) + OH I… ( aq ) a†’ HO2 I… ( aq ) + H2O
The reaction above can be seen as an intermediate measure as the merchandises respond further. The HO2 I… can undergo two different energies, one of them bring forthing electrical energy and the other necessitating it:
First the reaction that produces electrical energy:
( 4 )
HO2 I… ( aq ) + OH I… ( aq ) a†’ O2 + H2O + 2e I…
Now the reaction the requires electrical energy most likely derived from the oxidization of Glucose.
( 5 )
HO2 I… ( aq ) + H2O + 2e I… a†’ 3OH I… ( aq )
Function of the Pt electrodes:
The Pt electrodes besides have an consequence on reactions that take topographic point in the Fuel Cell. Harmonizing to the paper “ Energy denseness of a methanol/hydrogen peroxide fuel cell ” which describes the usage of Pt as a accelerator in a methanol/hydrogen peroxide fuel cell, it states that Pt contact actions reaction 1 more favourably, decomposition reaction of H peroxide. This causes a small useable electrical current. On the other manus the paper states that a big figure of H peroxide molecules undergo reaction 5 and that leads to a useable current, stable current.
Evaluation of the possible reactions:
The bulk of the reactions that will go on at the cathode will most probably be the decomposition of H peroxide ( reaction ( 1 ) ) . But the undermentioned reaction ( 2 ) with O will most probably non go on that frequently due to the fact that the gaseous O will get away the solution really fast. Reaction ( 3 ) and the undermentioned reaction ( 5 ) are of great importance due to the fact that reaction ( 3 ) produces the reactants needed for reaction ( 5 ) , and that reaction ( 5 ) requires 2 negatrons the exact sum of negatrons that is produced at the anode.
Above is a visual image of the reactions taking topographic point in the Fuel Cell. Reaction ( 2 ) was left out because most of the O will most likely escape the fuel cell before responding.
I hypothesize that the sugars Glucose, Fructose, and Maltose will bring forth electrical power, and the sugar Sucrose will non.
2.0 Materials and Method:
2.11 Chemicals Used:
-Hydrogen peroxide concentration 33 % produced by VWR, BHD Prolabo
-Hydrochloric Acid concentration 33 %
-Potassium Hydroxide concentration 25 %
-D-Glucose produced by AppliChem GmbH in 2004
-D-Fructose produced by Merck KGaA in 2000
-Sucrose produced by Merck KGaA in 1990
-Maltose produced by Merck KGaA in 1981
2.12 Supplies Needed:
-U-tube with glass filter provided by
-2 electrolytically plated Pt electrodes provided by the FKG
-variable resistance from 1-100 ohm provided by the Max-Plank Institute for Self-Organization and Dynamics produced by
-digital informations acquisition system provided by… .produced by
– Senors used… ..
-4 25ml graduated cylinders provided by… .produced by
-1 100ml graduated cylinder provided by… .produced by
The chemicals: glucose, fructose, sucrose, maltose, and H peroxide where provided by the school ( Felix Klein Gymnasium ) and used as received. The chemicals, hydrochloric acid K hydrated oxide was provided by the school but in its solid province so the base had to be produced with de-ionized H2O.
Before anything can be done, the U-tube has to be cleaned with nitrohydrochloric acid ( 1 portion concentrated azotic acid and 3 parts concentrated hydrochloric acid ) because the glass filter perchance has some heavy metals that could respond with the H peroxide, and they should be removed.
The original method was provided by the beginning ( Prof. Blume ) but I changed the and adapted the process to suit my experiments.
Schematic of Experiment:
Puting up the Fuel Cell:
The Fuel Cell should be set up harmonizing to the conventional above. The U-Tube with the electrodes attached, as shown in the conventional, will as the Fuel Cell. Depending on the which value is being measured the apparatus of the experiment will be somewhat different. The basic apparatus of the fuel cell will remain the same.
The solution incorporating 10 milliliter of H peroxide ( w=33 % ) and 40 milliliter K hydrated oxide ( w=25 % ) needs to be cold when the experiment starts because it decomposes at room temperature. These solutions should be kept in a icebox.
The other solution incorporating 5 g of sugar and 40 g of K hydrated oxide, should be instantly assorted before the experiment takes topographic point because one time assorted, the sugar starts responding with the K hydrated oxide.
Once both solutions are prepared 25 milliliter of each solution and set one it in its corresponding side of the U-tube. The H peroxide solution goes at the cathode and the sugar solution goes to the anode.
Conventional for Voltage Measurement:
Here one can see the circuit apparatus for the measuring of the electromotive force.
Conventional for Current/Voltage Measurement with a decennary Resistor:
( Schematic )
This conventional is really similar to the conventional for electromotive force measuring it merely adds one more circuit for the opposition and current measuring.
Once the fuel cell is running with its maximal electromotive force, the opposition is so changed every 10 seconds and the electromotive force and current magnitude is measured.
For no affair which sugar was used, there were many bubbles produced at the cathode. Over clip the bubble production lessenings.
When the solution of anode compartment for Fructose is assorted, it turn xanthous.
For Fructose, and Glucose, the solution at the anode becomes xanthous, the solution of the Fructose has a darker yellow than the Glucose.
Very few bubbles are produced at the anode
The Maltose Fuel Cell merely produces are electromotive force of 0.036V and the Sucrose Fuel Cell merely 0.02V
It takes clip before the Fuel Cells of Fructose and Glucose produce a high electromotive force.
When the electrodes are shaken the electrical energy additions greatly.
Fig. ( 1 )
Fig. ( 2 )
Here you can clearly see that the electromotive force is negative and so all of a sudden increases at around 1,500 seconds or about 25 proceedingss after the start of the experiment.
Fig. ( 3 )
Fig ( 4 )
Here you can clearly see that the electromotive force is negative and so all of a sudden increases at around 270 seconds.
Changing the opposition of the Glucose Fuel Cell from 100 to 0 and its effects on the current and electromotive force:
Fig. ( 5 )
Changing the opposition of the Glucose Fuel Cell from eternity to 0 and its effects on the current and electromotive force: note at 660 seconds I did a error of puting the things:
Fig. ( 6 )
Current in Relation to the power of the Glucose Fuel Cell:
Fig. ( 7 )
Voltage in Relation to the power of the Glucose Fuel Cell:
Fig. ( 8 )
Current in Relation to the power of the Fructose Fuel Cell:
Fig. ( 9 )
Voltage in Relation to the power of the Fructose Fuel Cell:
Fig. ( 10 )
Fig. ( 11 )
As one can see in fig. ( # ) the electromotive force against current, with a variable opposition, have striking similarities, particularly at the electromotive force of 0.4 V and below both lines follow the same curve. It appears that glucose has a higher current at low electromotive forces. They might hold been the same if is the lengths and between the different oppositions where the same.
Fig. ( 12 )
Above there is a visual image of the electromotive forces produced by the different sugars in the fuel cell. Glucose and Fructose have a minimum difference in electromotive force but the sugars Maltose and Sucrose clearly are non to be used in this fuel cell as the electromotive force they produce is about nil.
Fig. ( 13 )
Above is a saloon graph of the currents produced at a opposition of 0 from glucose and fruit sugar. It is clearly seen that glucose produces 0.0011 As more than fructose.
3.32 plotting electromotive force against current
3.33 exponential decay Fig ( #
The above graph show a electromotive force of
3.4 Fructose/Hydrogen Peroxide Fuel Cell:
3.42 U/V fig.
3.43 diffusion fig.
3.5 Discussion of Datas: Fig. ( # )
Analysis and Evaluation:
My hypothesizes about the energy production of Glucose, and Fructose, is true. But Maltose did non bring forth a high electromotive force. This is unusual as Maltose is a cut downing sugar. It is possible that the Maltose was contaminated in some manner, as it is 28 old ages old.
What is really interesting is that both Fructose and Glucose had a “ negative ” electromotive force before they increase. The term “ negative ” electromotive force means that the electromotive force was really higher at the cathode so at the anode. The lone account for this is that the H peroxide is responding and bring forthing electricity as shown with reaction 4. The ground why it takes 65 proceedingss for Glucose and Fructose merely 8 proceedingss and 45 seconds to bring forth a high electromotive force, might be that the Fructose solution for the anode compartment already turned xanthous before the experiment even started. This shows that the fructose already started responding and break uping, likely doing more reactive than the Glucose. It is stated by the Blume Website the xanthous colour comes from the many complex oxidizations and rearrangements of the decomposition merchandises of the sugars. Possibly the It is really interesting electromotive forces all of a sudden increase. The electromotive force of the Glucose FC increases about like an asymptote. It is as if a switch was merely thrown. Fructose bit by bit increases in comparing to Glucose.
It was observed that there where many bubbles at the cathode electrode, this shows that a great trade of the Hydrogen Peroxide reacts to bring forth O. Some of the O was most likely reduced.
The observation that the electromotive force increases when the electrodes are shacked shows that the Fuel Cell needs a propellor of some sort in order to travel the solution in the Fuel Cell. This will leting more reactants to clash with each other.
In order to compare the energy production of the Fuel Cells, one needs to compare, electrical current denseness
I have demonstrated that electrical power produced from a fuel cell utilizing H peroxide as an oxidizing agent and the sugar, Glucose or Fructose, as a reduction agent. Both sugars produce about the same sum of energy but one of the sugars seems to be more dependable than the other. For all three tests, Fructose systematically starts bring forthing power merely under 10 proceedingss after the fuel cell was “ activated ” . Unfortunately the clip it takes for Glucose tostart bring forthing really irregular, sometimes 25 proceedingss after “ activation ” or 102 proceedingss after “ activation ” .
As described above the sugar/hydrogen peroxide fuel cell would bring forth a greater electromotive force and electrical power if the Fuel cell had a propellor in order to blend the reactants
5.1 Error minimisation
I did everything in my power to maintain mistakes to a lower limit. Some of the things that I did where:
-cleaning the contacts of the overseas telegrams with emery paper which had corroded over clip.
-I used all of the same lab equipment so that the experimental consequences would non alter from different experiments because of the used of different lab equipment.
5.2 Possible mistakes:
Some of the chemicals where really old and kept in really old containers. The oldest container was at least 28 old ages old and held maltose ( mention ) and containers have notice on them that the containers become poruse after 5 old ages because the light and should be replaced. This was non done. Measurement mistake might hold lead to little differences in the experiments. For illustration, the concentrations of the substances might hold been somewhat different. Little temperature differences between the different experiments, might hold besides lead to some differences in the rate of the reaction ( the experiments where done on different yearss ) . Since the experiments were done at different times on different yearss the overseas telegrams might hold corroded doing a little difference in the conduction of the overseas telegrams. Of class the mistakes caused by the equipment are changeless and do non impact the experiments.