Technology

From autumn leaves to high-tech electronics

 By Benjamin Plackett

Most people probably think of New England when it comes to inspiring fall foliage, but Northeastern China is a worthy rival

Around this time of year, the pine, phoenix and persimmon trees that typify the region will begin to shed their leaves and with the seasonal change comes economic opportunity.
But unlike Massachusetts where the leaf-loving-tourists provide the autumnal income boost, in Manchuria the leaves are a source of fuel. The locals will collect and burn them in the colder months ahead as a cheap energy solution, but this intensifies an already worrying air pollution problem.
This could all be about to change though. A new study by researchers from the Qilu University of Technology, published in the Journal of Renewable and Sustainable Energy, has come up with an alternative.
The scientists have discovered a new technique to convert the leaves into a porous carbon material that can be used to manufacture high-tech electronics.
The hope is that local leaf collectors would now sell the leaves to be used in this new process and instead buy a cleaner fuel source for winter and pocket the difference.
First the leaves are dried and ground up. This substance is then heated to 220 degrees Celsius for 12 hours. This produces a powder made up of tiny spheres made of carbon, which are then treated with potassium hydroxide and again heated at ever increasing temperatures until the furnace reaches 800 degrees Celsius.
The end result is a black carbon powder with tiny pores carved into the surface of the micro-beads by the chemical treatment, which gives the substance extraordinary electrical properties — creating what is known as a supercapacitor.

Schematic diagram for the synthesis of functional carbon from dead leaves and the supercapacitor based measurements (researchgate.net)

Supercapacitors can recharge batteries much faster than ordinary capacitors, making them attractive for large tech companies.
But it’s not just leaves that hold the potential to help us charge up our laptops and smartphones at lightening speed. The researchers also successfully tested pine wood and food waste with their technique.
Air pollution is so bad in China that it is reported 4,000 people die every day from diseases that could be prevented by cleaner air — that accounts for approximately one in six premature deaths in the country. So the need couldn’t be greater for Chinese workers to sell their leaves to the tech giants of this world instead of burning them and adding to their health woes.

READ MORE: Energy leaves for a cleaner future by Amanda Saint

about the author
Benjamin Plackett
I’m a journalist based in London. I report on all things science, tech, and health for a number of different publications. My work has been published by The Daily Dot, Inside Science and CNN among others. I earned my M.A. in Journalism at New York University and my B.Sci in Biology from Imperial College, London.