Carbon emissions and rising temperatures are global crises that need no introduction. Not surprisingly, countries all over the world are looking into energy conservation and alternative fuels. And closer home in Bengaluru, a team of scholars in the Indian Institute of Science (IISc) may have achieved a breakthrough.
A team led by Biswajit Bhattacharyya, a fifth year PhD scholar at IISc, has made an artificial ‘leaf’ which can not only replicate photosynthesis in a more efficient manner than actual leaves, but use carbon dioxide from the atmosphere to make bio fuel.
Their paper on the same authored by Biswajit (28) and six others was published in the American Chemical Society Journal on June 1 and the patent was also granted. “It feels great to have contributed to this,” says Biswajit.
A snapshot of the published paper
How the ‘leaf’ was made
It all began two years ago when Biswajit and his team, under the supervision of Professor Anshu Pandey, were looking for a substance that could absorb sunlight better.
“What the naturally green leaves do is that because they already have chlorophyll, they only absorb the blue and red rays from the sun. The green rays, which are present in more quantity in sunlight, remain unutilised. So, we were searching for a material which could absorb the green rays as well,” Biswajit says.
In that process, they found that copper aluminium sulphate and zinc sulphide, which are otherwise wide band gap semiconductors, became low band gap semiconductors when combined. Simply put, the lower the band gap, the better conductivity a substance will have.
How the ‘leaf’ works
“Basically, for photosynthesis or the process of plants taking in carbon dioxide to produce oxygen and glucose. For this process to happen, a high energy photon, electron and sunlight are needed. The electron needs to have a lot of kinetic energy,” Biswajit explains.
The semiconductor they made by combining copper aluminium sulphate and zinc sulphide fulfilled the requirements to convert sunlight into energy, which is how they decided to try and replicate photosynthesis.
In the process, they also found that this quantum leaf had a much better rate of energy conversation compared to natural leaves – 20% as compared to 0.4-0.5% in photosynthesis.
The team then harnessed this capacity to produce a sulphate format bio fuel which not only allows for 100% combustion but whose carbon dioxide emissions can be recycled by the quantum leaves.
The application of the ‘leaf’
Biswajit explains that they called it a leaf because the material’s microstructure closely resembled that of an actual leaf and because it could replicate photosynthesis.
Microstructure of the artificial 'leaf'
That being said, the application of this technology will require these artificial ‘leaves’ to be used in bulk – for instance, to produce 50-100 gm of fuel, 1027 leaves would be required.
That being said, he does see immense potential in the technology, given that the world is searching for environment friendly and renewable alternatives to fossil fuels. “It will also help in reducing the carbon footprint,” Biswajit says.