Bionic leaf or artificial leaf absorbs carbon dioxide in the atmosphere to produce fuel and release oxygen in the process, imitating the natural process of photosynthesis.
Researchers like Biswajit Bhattacharyya working at the Indian Institute of Science (IISc), Bengaluru, Karnataka have developed a Bionic leaf or Artificial leaf that absorbs carbon dioxide in the atmosphere to produce fuel and release oxygen in the process, imitating the natural process of photosynthesis. The development is being viewed as the latest approach in tackling global warming and climate change while keeping the atmospheric carbon dioxide levels under control.
They claim this to be a method to achieve two targets simultaneously (1) It provides a source of renewable energy, (2) while significantly reducing the carbon dioxide in the atmosphere, as well as releasing oxygen back in the atmosphere.
What is a leaf? A leaf is one of the expanded, usually green organs borne by the stem of a plant or tree.
Photosynthesis is the process through which plants generate their food. Plants absorb the light from our Sun with a green pigment called chlorophyll. In this process carbon dioxide is converted into organic compounds, more specifically sugars, through the energy coming from sunlight. Human beings exploit that energy when they eat plants, or when they eat animals that have eaten plants, or when they burn either plants or substances ultimately derived from plants: firewood, coal, oil, natural gas.
Bionic leaf is efficient
IISc’s scientists from the Chemistry department consider their bionic leaf it to be “100 times more efficient” than a natural leaf in absorbing carbon dioxide. In their words,” It is composed of “completely biocompatible, earth abundant, inexpensive elements”. In the words of Shri Bhattacharyya, the first author of the paper, “Although several attempts have been made worldwide to replicate photosynthesis, the bionic leaf or Quantum leaf developed at IISc is the most efficient device using sunlight to convert carbon dioxide (CO2) to oxygen.”
“This is the most energyefficient method to convert carbon dioxide into fuel and oxygen using only sunlight. While most plants convert less than one per cent of the available solar energy into chemical energy, the material developed by us can convert about 20 per cent of the incident solar energy into chemical energy in the form of fuel and oxygen,” He further added.
In the words of Dr
Anshu Pandey, Associate Professor, “Quantum dots — semiconducting nanocrystals — made of specific materials, act as catalyst to convert CO2 into formic acid, that can be used as fuel. “It was made of cheap elements allowing adaptation of the technology in an industrial scale, without providing further details. The efficiency observed by us is a major jump over available methods and is close to the maximum efficiency that can possibly be achieved artificially,” he further added.
Photosynthesis is the process through which plants generate their food. In this process carbon dioxide is converted into organic compounds, more specifically sugars, through the energy coming from sunlight. The process is carried out by Green leaves of plants, which store energy from the sun. Human beings exploit that energy when they eat plants, or when they eat animals that have eaten plants, or when they burn either plants or substances ultimately derived from
The Scientists have been exploring different catalysts to force CO2 reduction, but so far such reactions have been inefficient and rely on expensive precious metals such as silver. What they needed was a new family of catalysts chemicals with extraordinary properties.
plants: firewood, coal, oil, natural gas.
The pioneering work on bionic leaves was carried out by Dr Daniel George Nocera, an American chemist, working at
Harvard University. In
2011, Dr Nocera, announced a cheap, playing-card-size coatedsilicon sheet that, when placed in a glass of tap water and exposed to sunlight, split the water into hydrogen and oxygen. The gas could easily be collected and either burned or used to power a fuel cell. He called the device an “artificial leaf,” and claimed that artificial leaves could one day enable people everywhere to live without being connected to any power grid.
The process could be described more precisely as solar-powered electrolysis of water: using energy from the sun to split water into hydrogen and oxygen. Scientists led by Dr Amin Salehi-Khojin, Assistant Professor at the University of Illinois at Chicago, USA, have now developed "artificial leaves" - solar cells that cheaply and efficiently convert atmospheric carbon dioxide directly into usable hydrocarbon fuel using sunlight.
Artificial leaf delivers syngas
A solar farm of such "artificial leaves" could remove significant amounts of carbon from the atmosphere and produce energy-dense fuel efficiently. The new solar cell is not photovoltaic. It is photosynthetic. In the words of Dr Amin SalehiKhojin, “Instead of burning fossil fuels like coal or crude oil to produce energy as well as greenhouse gases like carbon dioxide , we can now reverse the process and convert atmospheric carbon dioxide into fuel using sunlight."
“While leaves in plants produce fuel in the form of sugar, our artificial leaf delivers syngas, or synthesis gas, a mixture of hydrogen gas and carbon monoxide, which can be burned directly, or converted into diesel or other hydrocarbon fuels. If we could convert CO2 in the air into fuel at a cost comparable to a liter of petrol or diesel it would render fossil fuels obsolete.” He further added.
Chemical reactions that convert CO2 into flammable forms of carbon like carbon monoxide are called reduction reactions, the opposite of oxidation or combustion. The Scientists have been exploring different catalysts to force CO2 reduction, but so far such reactions have been inefficient and rely on expensive precious metals such as silver. What they needed was a new family of catalysts -chemicals with extraordinary properties.
They focused on a family of nano-structured compounds called transition metal dichalcogenides - or TMDCs - as catalysts, putting them together them with an unconventional liquid as the electrolyte inside a twocompartment, threeelectrode electrochemical cell.
The best of several catalysts they studied turned out to be nano flake tungsten diselenide. "The new catalyst is more active; more able to break carbon dioxide's chemical bonds," said Mohammad Asadi, postdoctoral researcher at University of Illinois at Chicago, a member of Dr Amin Salehi-Khojin’s, team. In fact, the new catalyst is 1,000 times faster than noble-metal catalysts like silver, gold or platinumand about 20 times cheaper.
The artificial leaf consists of two silicon photovoltaic cells of 18 square centimeters to harvest light. When light of 100 watts per square meter – about the average intensity reaching the Earth's surface – energises the cell, hydrogen and carbon monoxide gas bubble up from the cathode, while free oxygen and hydrogen ions are produced at the anode. Further work is in progress. Research on similar lines is being carried out at number of universities in the US and Germany. It is felt that research on similar lines should be taken up more vigorously in India and that too immediately.
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