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Simple Methods for Producing Graphene Quantum Dots from Coal

Scientists at Rice University have found simple methods to reduce three kinds of coal into graphene quantum dots (GQDs) - microscopic discs of atom-thick graphene oxide that have applications in medical imaging, sensing, electronics, and photovoltaics. The GQDs were derived from bituminous coal, anthracite, and coke, a byproduct of oil refining. In quantum dots, band gaps - which determine how a semiconducting material carries an electric current - are responsible for their fluorescence and can be tuned by changing the dots' size. The new process allows a measure of control over their size, generally from 2 to 20 nanometers, depending on the source of the coal. There are many ways to make GQDs, but most are expensive and produce limited quantities. Last year, Rice University researchers found a way to make GQDs from relatively cheap carbon fiber, but coal promises greater quantities made even cheaper in just one chemical step. The fluorescent particles are water-soluble, and early tests have shown them to be nontoxic.

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Electronic Components Electronics & Computers Energy Green Design & Manufacturing Imaging Materials Medical Nanotechnology Semiconductors & ICs Sensors Solar Power

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    Transcript

    00:00:01 [Music] [Music] what we've done is we've taken coal and we've shown that coal contains what we call graphine Quantum dots and what's amazing is that for 5,000 years people have been burning this material and its price is cheaper than anything on planet Earth we can buy coal for $10 to $60 per ton you can't buy even water for that

    00:00:37 much coal is the cheapest thing that we can buy but locked inside coal are what we have found graphing Quantum dots and not just in Trace Amounts but in 20% yield So 20% of this material turns out to be graphine Quantum dots graphine Quantum dots if we when we extract these look like this looks like a black powder coming from this coal or these graphine Quantum dots but once these are in

    00:01:05 solution these light up and flues that's really an important property the reason that's important is because many times we want fluorescent materials for biological operations for biological assays and the fluorescent Quantum dots are extremely expensive and they're toxic very often but these materials are non-toxic and they flues less just like Quantum dots because they

    00:01:32 actually are quantum dots and it's been locked inside this coal for millions of years and we're able to liberate it just by treating with sulfuric acid and nitric acid and it liberates this from the structure in 20% yield and different types of coal have different types of quantum dots meaning that different types of coal yield Quantum dots that flues at different wavelengths that

    00:01:57 means they're different colors depending on what we want so now we have access from CT to very expensive structures that used to be expensive and so the price is going to come way down and they're all of different colors depending on the source of the coal that we use so this is what's been unlocked from coal [Music]