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    09 Nov '12 21:431 edit
    http://physicsworld.com/cws/article/news/2012/nov/09/nanocrystals-produce-hydrogen-using-sunlight
    “...
    Nanocrystals produce hydrogen using sunlight
    Nov 9, 2012 1 comment

    Artificial photosynthesis in action
    Researchers in the US have made hydrogen fuel using just sunlight, nanocrystals and a cheap nickel catalyst. The new artificial photosynthesis process is the first of its kind to continually produce fuel for several weeks without slowing down. As a result it could be important for green-energy applications and also for certain industrial processes such as those for producing ammonia.
    During photosynthesis, plants harness solar radiation and convert it into energy. Most artificial photosynthesis systems try to mimic this natural process by exploiting light-absorbing dye molecules called chromophores to split water into hydrogen and oxygen. The hydrogen is produced in the reductive side of the reaction and the oxygen in the oxidative side. These so-called half-reactions are part of the process that converts light into energy, but the problem is that such technologies are inefficient and short-lived because the Sun's rays damage and destroy the light-absorbing dyes in just a few hours.
    Now, a team of researchers led by Todd Krauss, Patrick Holland and Richard Eisenberg at the University of Rochester has developed a new photochemical hydrogen-generating system made of cadmium–selenide (CdSe) quantum dots, nickel salt catalysts and ascorbic acid (vitamin C). The system lasts for several weeks rather than just hours and, in water, has an efficiency of 36% for converting solar power into energy. If the surrounding solution is a mix of water and ethanol, this efficiency increases to 66%. Such high values have never yet been observed for such all-solution-based systems. The only snag is that the vitamin C (which acts as an electron donor) gets used up and regularly needs to be replenished during each hydrogen production cycle.

    How it works
    The CdSe quantum dots absorb two photons of light and transfer two electrons to the nickel catalyst. The two remaining protons combine to produce a hydrogen molecule, explains Krauss. "Our work is different from most other previous research in that the catalyst is formed in situ from the quantum-dot ligands," he says. "Most other solution-based systems produce hydrogen for just hours, or at most a day, because the chromophores degrade, so our long-lived system is rather unusual."
    The researchers say that their catalyst–nanocrystal pairs are better than previous artificial photosynthesis nanoparticle systems because they are more stable to sunlight, but admit that they do not yet know why this is the case.
    "This new system will also certainly help us better understand the reductive side of artificial photosynthesis – something that may one day help lead to more effective and efficient water splitting," adds Krauss, "Our work is an important step in that direction."

    Making ammonia
    According to the team, such a clean source of hydrogen could not only find applications in green energy, but also in industry, for example in the Haber process for producing ammonia.
    The Rochester team is now looking at other nanoparticle systems to try out. "We are also investigating other less-expensive catalysts and hope to find a way to replace the sacrificial vitamin C molecule with electrons, say from a circuit. Such experiments could be the next step towards a true artificial photosynthesis system, but we are still a far cry from that since we have only performed half of the full reaction," says Krauss.

    ...”

    If a practical artificial way of converting solar energy into chemical energy (in the form of hydrogen in this case) with up to at least 66% energy efficiency really can be made ( as I think the above implies ) then that would make it much more efficient than nature's photosynthesis which can convert solar energy into chemical energy (usually in the form of sugar in this case) with a pathetic maximum theoretical energy efficiency of only about 11% ( see http://en.wikipedia.org/wiki/Photosynthetic_efficiency ) and in practice is always much less than this! ( mostly between 3% and 6% ) so, if I am reading this right, it should be possible to make such artificial photosynthesis at least 6-fold more efficient than nature's photosynthesis!
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    11 Nov '12 18:16
    Originally posted by humy
    http://physicsworld.com/cws/article/news/2012/nov/09/nanocrystals-produce-hydrogen-using-sunlight
    “...
    Nanocrystals produce hydrogen using sunlight
    Nov 9, 2012 1 comment

    [b]Artificial photosynthesis in action

    Researchers in the US have made hydrogen fuel using just sunlight, nanocrystals and a cheap nickel catalyst. The new artificial photosynthesis ...[text shortened]... photosynthesis at least 6-fold more efficient than nature's photosynthesis![/b]
    why must you berate the natural process which has led to the development of the technology?
  3. Joined
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    11 Nov '12 19:329 edits
    Originally posted by robbie carrobie
    why must you berate the natural process which has led to the development of the technology?
    I didn't. I said what I said with enthusiasm rather than anger and I am not complaining about anything here.
    I said natures photosynthesis has “...a pathetic maximum theoretical energy efficiency of only about 11% ...” which I believe is merely stating a fact for 11% is surely pretty unimpressive compared to what can at least in theory can be achieved artificially whichever way you look at it.
    Obviously I am not angry that nature's theoretical maximum is 11% ( that would be like being angry that all the deserts are dry ) nor am I angry about anything else here but rather I am very pleased that our best is much more than 11%.
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    11 Nov '12 21:02
    Originally posted by humy
    I didn't. I said what I said with enthusiasm rather than anger and I am not complaining about anything here.
    I said natures photosynthesis has “...a pathetic maximum theoretical energy efficiency of only about 11% ...” which I believe is merely stating a fact for 11% is surely pretty unimpressive compared to what can at least in theory can be achieved artifici ...[text shortened]... ut anything else here but rather I am very pleased that our best is much more than 11%.
    well, ok, but the technologies that have been developed from an emulation of nature is
    astounding.
  5. Subscribersonhouse
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    11 Nov '12 23:39
    Originally posted by robbie carrobie
    well, ok, but the technologies that have been developed from an emulation of nature is
    astounding.
    We learn from nature all the time. But like he said, we have photocells more efficient than plants converting directly to electricity. He is saying in the natural world 89% of the sun's energy is wasted.

    The big problem with H2 is what to do with it once we have it. You can't just make a big gas bag and drive off with it, you would have a car 15 feet long and a bag on top 50 feet high....

    You can't just compress the gas, it would add double the weight to the car.

    The so far best idea is to sequester the gas in a solid, a hydride that has a huge surface area inside that holds on to the gas till it is heated to some temperature, hopefully only a couple hundred degrees, that alone is another problem.

    If we ever get H2 to live in a reasonable hydride and give us say, 400 km range, then we have something. All that science is going on in parallel however.
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    12 Nov '12 01:20
    Originally posted by robbie carrobie
    well, ok, but the technologies that have been developed from an emulation of nature is
    astounding.
    Nobody is saying that our scientists are better than god, by god.
  7. Subscribersonhouse
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    12 Nov '12 02:33
    Originally posted by joe beyser
    Nobody is saying that our scientists are better than god, by god.
    Not YET anyway🙂
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    12 Nov '12 09:046 edits
    Originally posted by joe beyser
    Nobody is saying that our scientists are better than god, by god.
    Oh wait, he was speaking of God? I should have guessed. I was wondering what his problem was.
    Why would his perfect god make something so imperfect that we can better it by far? I guess that was his problem.
    Of course, this is not a problem for evolution for evolution does not predict perfection but predicts imperfection -which is exactly what we see.

    I am guessing that part of his problem was he thought I was criticizing a God! How can I criticize what doesn't exist?
    But, if I was criticizing anything, I was not criticizing God/gods but evolution for making an imperfect outcome even though such imperfect outcomes is exactly what we should expect from evolution.
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    12 Nov '12 18:32
    Originally posted by joe beyser
    Nobody is saying that our scientists are better than god, by god.
    No, actually I am perfectly happy saying that today's scientists are better than the Christian imaginary god.
  10. Standard memberforkedknight
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    12 Nov '12 23:37
    Originally posted by googlefudge
    No, actually I am perfectly happy saying that today's scientists are better than the Christian imaginary god.
    There's no need to troll Christians in the science forum.
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    13 Nov '12 12:30
    Originally posted by forkedknight
    There's no need to troll Christians in the science forum.
    I wasn't trolling anyone.

    I was simply pointing out that joe was wrong.
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    13 Nov '12 17:211 edit
    Originally posted by sonhouse
    You can't just compress the gas, it would add double the weight to the car.
    I don't see whats wrong with electric cars. I am yet to see any convincing evidence that the whole hydrogen car is nothing more than smoke and mirrors by the powers that be to delay the coming of the electric car. Of course I am not saying hydrogen by photosynthesis would not be very useful - just not for driving cars.
  13. Subscribersonhouse
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    13 Nov '12 17:32
    Originally posted by twhitehead
    I don't see whats wrong with electric cars. I am yet to see any convincing evidence that the whole hydrogen car is nothing more than smoke and mirrors by the powers that be to delay the coming of the electric car. Of course I am not saying hydrogen by photosynthesis would not be very useful - just not for driving cars.
    If they get the storage density down to the point where H2 gives about the same driving range as petrol cars, you can use H2 in a fuel cell, the latest ones are getting very efficient at converting the energy of H2 into electricity, then you can use H2 to power electric vehicles as well.

    It is obvious electric cars would be much more reliable than petrol/diesel cars.
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    13 Nov '12 17:35
    Originally posted by googlefudge
    I wasn't trolling anyone.

    I was simply pointing out that joe was wrong.
    You were wrong about me being wrong as I was only pointing out that nobody was making any statement about god. Just funning robbie.
  15. Subscribersonhouse
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    13 Nov '12 20:36
    Originally posted by forkedknight
    There's no need to troll Christians in the science forum.
    Is that from that book "For whom the bell trolls"?
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