Reading Reaction Journal #5

Porous carbon nanofibre arrays can be made using crab shells as a template

From crab shell to fuel cell

09 April 2010
Crab shells provide a cheap and convenient template to make high performance carbon electrodes for energy storage and conversion, say Chinese scientists.
Carbon materials have many potential applications, including as electrodes in supercapacitors and fuel cells. The pore structure is known to affect their physicochemical properties and is normally controlled by using a porous hard template such as zeolite or silica. But the process usually involves using hydrofluoric acid to remove the templates, which can be complex and costly.
A research group from Fudan University, led by Yong-Yao Xia, has demonstrated that crab shell has a well aligned porous structure at the microscopic level. Exploiting this unique structure, they have generated porous carbon nanofibre arrays by combining the hard crab shell template with an established soft templating method. 'Biological templates are generally abundant, renewable, inexpensive and environmentally benign compared to artificial templates,' explains Xia.
After burning the crab shell in air, the porous template mainly consists of calcium carbonate. Adding a soft copolymer template and resol precursor forms the carbon framework. Heating under nitrogen gas removes the soft template and the hard template can be dissolved in hydrochloric acid.
'The crab shell hard template is not only easy to remove but also hierarchically porous,' says Rui Zhang, an expert in porous carbon materials at the Shanghai Institute of Technology. The templated carbon nanofibre arrays retain this hierarchical porosity, forming pores of three sizes. The largest result from the packing of nanofibres, the medium pores from voids between the nanofibres and the carbon nanofibres themselves contain the smallest pores.
The pore structure is suitable for charge storage by ion adsorption/desorption as an electrode material for supercapacitors or platinum/palladium catalyst loading for fuel cell applications, says Xia. Aided by the large surface area and complex structure, Xia' material shows excellent results in both cases.
Xia's team is now using crab shell to template other porous materials as well as investigating alternative shellfish templates.






References
Wise, E. (2010, April 09). From crab shell to fuel cell. Chemistry World, Retrieved May 03, 2010, from http://www.rsc.org/Publishing/ChemTech/Volume/2010/05/from_crab_shell.asp

Vocabulary
Template: a shape made of metal, plastic, or paper which is used to make copies or to guide someone in cutting something
Fuel: a substance such as oil or gas that is used to provide heat or power, usually by being burned
Aligned: to put (two or more things) into a straight line
Hydrofluoric acid: an acid containing hydrogen and chlorine
Copolymer: a polymer consisting of two or more different monomers, polymer: a chemical substance consisting of large molecules made from many smaller and simpler molecules
Precursor: something which happened or existed before another thing, especially if it either developed into it or had an influence on it
Nitrogen: a gas with no colour or taste which forms about 78% of the Earth's atmosphere and is a part of all things which live
Adsorption: The process by which molecules of a substance, such as a gas or a liquid, collect on the surface of another substance, such as a solid. The molecules are attracted to the surface but do not enter the solid's minute spaces as in absorption. Some drinking water filters consist of carbon cartridges that adsorb contaminants.
Platinum: a valuable metal that is silver in color, does not react easily with other elements, and is used in jewelry and in industry
Ion: an atom that has a positive or negative electrical charge as the result of adding or taking away an electron
Nanofibre: A kind of fibre, but it is so small that you cannot see with your eyes

Summary
Chinese scientists have found a way, which uses crab shells to supply a cheap and easy template, to make high performance carbon electrodes for save and switch. Carbon materials have many important submissions. However, if the process requires the use of hydrofluoric acid to remove the templates, it is very expensive and hard. Because the pore structure will affect their physicochemical properties, they will look for another method to complete this research. Eventually, a research group from Fudan University, led by Yon Yaoxia, proved that crab shells have well aligned porous structure at the microscopic level. The crab shell is a kind of biological templates, so it is a renewable, inexpensive and environmentally material. After the crab shell burns in the air, the mainly thing is calcium carbonate. After special processing, it can be dissolved in hydrochloric acid. Rui Zhang says, “the crab shell hard template is not only easy to remove but also hierarchically porous.” The moldboard carbon will become pores of three sizes. Xia says: The pore structure is not only suitable for charge save by ion adsorption as electrode material for supercapcitors but also suitable for platinum catalyst loading for cell submissions. Now Xia’s team uses crab shells to template other porous materials.

Reaction
This article talks about scientists using biological materials to replace the materials, which is costly and difficult to achieve. Indeed, in the world, the resources have become less and less. Although the biological materials are renewable, if people overuse the materials from nature, it is also cannot renew. This article introduces how to get energy from crab shells for human beings and it also introduces how to use inexpensive and environmental materials to develop new energy. That is a benefit for human beings, but it is not good for the natural balance. Do the scientists think about whether will they overuse the crab shells, what will happen next? Right, we cannot see the crab. I have to say that crab shell being able to transform to a fuel cell is a miracle. It can change the resource configuration. Before we used a fuel cell from chemicals which wastes a lot of materials and cannot get the expected results, but now they use biological materials, which can release more energy than chemicals. At the end, I hope scientists can look for some materials without animals. Fortunately, the scientists are looking for other materials to replace the crab shells, for example, shellfish templates. However, I come out with the same question about new materials in my mind.

Reading Reaction Journal #4

Editorial: Smoking kills

Carcinogens in cigarette smoke hang around indoors like a bad smell - we know that. What we didn't realize until now is that nicotine residues absorbed on indoor surfaces (carpets, wallpaper etc) react with gases in the air to produce even more cancer-causing carcinogens.

© THINKSTOCK PHOTOS

According to the World Health Organization, tobacco is the second major cause of death in the world. It is responsible for the death of one in 10 adults, killing 5.4 million people annually. Furthermore, if current patterns continue, smoking is predicted to kill 8 million people per year by 2030.

So what is the significance of this new discovery? Desorption of carcinogenic tobacco-specific nitrosamines or TSNAs (originating from cigarette smoke) from indoor surfaces, a process coined 'third-hand smoke', was already known to be an additional source of exposure to these toxins. The new research has shown, for the first time, that nicotine residues absorbed on surfaces can react with atmospheric species, such as nitrous acid - providing another source of TSNAs.

Children in smoking households are of particular concern, because they interact very differently with their surroundings to adults: touching and licking surfaces and fabrics. It has been estimated that their exposure to third-hand smoke could be up to 20 times higher than adults. The new findings make the situation for these children look even bleaker.

In light of this discovery and its potential impact in children, is there something that could or should be done differently? During the last decade, governments around the globe have made the fight against smoking one of their main public health priorities. The EU has tackled the issue of smoking prevention and cessation from many different fronts. A series of schemes, such as 'Help - for a life without tobacco', designed to raise awareness and educate the public in the dangers of smoking have been run. All tobacco advertising and sponsorship on television has been banned since 1991, and in 2005 this was extended to cover other forms of media. More importantly, legislation has been implemented to limit exposure to second-hand smoke in public places and the workplace.

These measures are working, but can we go a step further to protect the public against this newly found threat? This would mean regulating what people do in private. Governments can protect people in public places, but they haven't got the mechanisms to protect those exposed in the home or in the car. Surely that would be intrusive, impossible to police and simply completely unrealistic. So to the question 'can we implement smoking bans at home?' I'm afraid my answer is no.

Instead we must continue to work at reducing the human impact of smoking through educating people, raising awareness, offering support mechanisms to those who'd like to quit smoking and finding novel ways to discourage those who are thinking of taking it up. Slowly but surely we must succeed in eradicating a problem that continues to plague the developed world and will certainly become a serious concern in the developing world in the coming decades.

References
Seijo, B. C. (2010). Editorial: Smoking kills. Chemistry World, Retrieved April 26, 2010, from http://www.rsc.org/chemistryworld/Issues/2010/March/Editorial.asp

Vocabulary
Carcinogens: a substance that can cause cancer (= a serious illness that causes tissues and cells to grow too quickly)
Nicotine: a poisonous chemical found in tobacco
Residues: something that is left after the main part is no longer present
Toxins: a poisonous substance, esp. one that is produced by bacteria and causes disease
Interact: to communicate with or react to each other
Bleak: (esp. of a place or the weather) cold and not welcoming
Cessation: the ending of a condition or the stopping of an activity
Banned: to forbid (someone) from doing something or (something) from being done
Legislation: a law or set of laws that is being created
Mechanisms: a way of doing something, esp. one that is planned or part of a system
Eradicating: to get rid of or destroy (something) completely
Intrusive: If something or someone is intrusive, they become involved in things which should be private.


Summary
We know that carcinogens in cigarette smoke have a bad smell, but we don’t know nicotine is absorbed on indoor surfaces, and it will make more cancer-causing carcinogens with gases. The World Health Organization announced that tobacco is the second major cause of death in the world. Every year 5.4 million people will be killed by one in ten adults, who smoke cigarettes. The author thinks it kill 8 million people per year by 2030 if current patterns keep on. There is a process coined 'third-hand smoke’; we know it to be an additional source of exposure to these toxins, which are nitrosamines or TSNAs, and will react with atmospheric species. Children in smoking households could have up to 20 times higher could than to touch 'third-hand smoke’ because they always touch and lick surfaces. Because of this discovery, a lot of governments have tackled the issue of smoking prevention and cessation from many different fronts. They also use some rule to limit exposure to second-hand smoke in public places and the workplace. The author says “they haven’t got the mechanisms to protect those exposed in the home or in the air”, so it still is a problem. He hopes people can teach their children not to touch cigarettes, and he suggests that government may set some support mechanisms to make quitting smoking an institution. If we don’t solve this problem, it will become a serious concern in the developing world in the coming decades.
Reaction
This article talks about how a few cigarettes can make people to die. Some smoke can be absorbed by indoor surfaces, which is a big problem because the smoke which has lots of carcinogens can make children who never smoke cigarettes should die. When we cast light on the discovery and its potential impact on children, people should pay attention to the children. However, the governments cannot stop the problem from spreading all over the world, and there are even some governments which set some policy to deal with 'third-hand smoke’ or ‘second-hand smoke’, consequently, there is no influence on smoking people. Smoking is not only no good for people who smoke, but also it is not good for people who live with them. This article lets me know that 'third-hand smoke’ or ‘second-hand smoke’s harm is more than that of people who smoke cigarettes. I think the schools have duty to teach students the smoke is not good; at the same time, in the home, parents need to tell them again. To solve the smoke problem is not easy, and no matter how much scientists research how to cure cancer, why are they still not successful? Because people produce the cancer in their body by themselves, scientists just can find few ways to cure nature cancer (which just happens a in the cell in the nature ways). If human beings want live a long time on the earth, we need a loving life, which is not to harm you or even to harm others.