Mimicking the ingenuity of nature with artificial photosynthesis to create fuels

From the UNIVERSITY OF WÜRZBURG

Three ruthenium atoms linked via specially shaped organic bonds make sure that the photosystem works more efficiently than its predecessors. Graphic: Valentin Kunz & Marcus Schulze

Three ruthenium atoms linked via specially shaped organic bonds make sure that the photosystem works more efficiently than its predecessors. Graphic: Valentin Kunz & Marcus Schulze

Nature shows how to do it: Photosynthesis is a process used by plants to create energy-rich organic compounds, usually in the form of carbohydrates, and oxygen (O2) from carbon dioxide (CO2) and water (H2O) driven by light. If we succeeded in mimicking this process on a large scale, numerous problems of humanity would probably be solved. Artificial photosynthesis could supply the Earth with fuels of high energy density such as hydrogen, methane or methanol while reducing the amount of carbon dioxide in our atmosphere and slowing down climate change.

Developing the necessary efficient catalysts and associated dyes is a focal area of research at the Chair of Professor Frank Würthner at the University of Würzburg’s Institute of Organic Chemistry. Two of Professor Würthner’s doctoral students, Marcus Schulze and Valentin Kunz, have recently reported a partial success in this regard. They present the results of their research work in the current issue of the journal Nature Chemistry.

Improving an artificial photosystem

“In nature, the so-called photosystem II is a central component of the photosynthesis process”, explains Marcus Schulze. It is a protein complex with a catalytically active centre consisting of multiple metal atoms. They have to work together to split water into its two elementary constituents, a process taking place in two spatially separated electrochemical half reactions. It is already possible to mimic these two reactions in the laboratory. But: “Hydrogen production already works quite well. The water oxidation to oxygen, however, needs to be accelerated so that the balance of the individual half reactions matches better,” says Schulze.

Scientists still frequently use the rare noble metal ruthenium as a catalyst for artificial photosynthesis. Basically, the artificial system works with similar efficiency as its natural counterpart. However, the catalyst tends to decompose itself relatively quickly. This is where the chemists of Würzburg leapt to action: “We incorporated the ruthenium atoms into special supramolecular structures which slow down the destruction and enable a kind of ‘self-healing process’,” Valentin Kunz explains.

Two years of lab work

This structure is similar to a ring in which three ruthenium atoms are interconnected using three so-called ligands which are specially shaped organic compounds. Custom-tailored binding sites make sure that the metal centres and ligands fit like key and lock. What sounds comparably easy took two years of non-stop meticulous working in the laboratory. “You successively turn different screws and see what happens,” Kunz describes their approach.

The result is a “cyclic self-composing system of defined individual blocks” as the two chemists explain. Its benefit in “synthetic terms” is its simple structure and ease of production along with the fact that the blocks automatically assemble to form the desired structure without requiring major technical effort. This property makes it better suited for potential applications than previous systems.

The next steps

The chemists are pleased to note that the water oxidation catalyst they developed is also more efficient, although they cannot yet explain why that is so. These explanations might be delivered in the near future by the experts in theoretical chemistry with whom Frank Würthner’s chair is cooperating closely. Roland Mitri, head of the Chair of Theoretical Chemistry at the University of Würzburg, and his co-worker Merle Röhr are already looking for an answer to this question by developing formulas and algorithms.

Even though the system of the two junior scientists is better than its predecessors: “We still have a long way to go until the process is ready for the market,” explains Marcus Schulze. And: “What we are doing is fundamental research,” Valentin Kunz adds. The next steps have already been planned: Firstly, the chemists want to study further changes at the catalyst’s structure and their impact on the function. Secondly, they want to link it to dyes so that the reaction becomes photocatalytic, which means the reaction will work with light.

The joint project Soltech

Marcus Schulze and Valentin Kunz’s research was performed within the scope of the Bavaria-wide joint project Soltech (Solar Technologies Go Hybrid). Launched in 2012, the Free State of Bavaria funds new concepts to convert solar energy into electricity and non-fossil fuels. So-called key labs in the following universities are involved in the project: University of Bayreuth, University Erlangen-Nuremberg, LMU Munich, TU Munich and the University of Würzburg.

The Würzburg key lab is located at the Center for Nanosystems Chemistry founded in 2010 at Professor Frank Würthner’s initiative. His research team has been working on selectively organising small organic molecules to form larger assemblies that absorb sunlight and transport it to electrodes to be converted into electric power. Another goal of the Würzburg key lab is to develop artificial chloroplasts that use light energy to generate fuels similar to a plant cell.

The joint project also includes other participants from Würzburg such as the work groups of Professors Tobias Brixner, Christoph Lambert, Florian Beuerle, Roland Mitri and Todd Marder from chemistry as well as the teams of Vladimir Dyakonov and Jens Pflaum in physics.

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A supramolecular ruthenium macrocycle with high catalytic activity for water oxidation that mechanistically mimics photosystem II; Marcus Schulze, Valentin Kunz, Peter D. Frischmann and Frank Würthner; Nature Chemistry, DOI: 10.1038/NCHEM.2503

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77 thoughts on “Mimicking the ingenuity of nature with artificial photosynthesis to create fuels

  1. ‘Scientists still frequently use the rare noble metal ruthenium as a catalyst for artificial photosynthesis.’

    ‘Secondly, they want to link it to dyes so that the reaction becomes photocatalytic, which means the reaction will work with light.’

    If it’s not working with light now, it’s not photosynthesis.

    • Great. now all we need is for George Soros, to corner the market on Ruthenium.

      Why not try Aluminum or Iron instead of Ruthenium.

      There is plenty of old Iron lying around just catalyzing its merry way into oblivion.

      G

    • Please wake me, when I can fill up with Ruthenium Gas at my local Arco Gas station.

      g

  2. It might surprise these researchers, but plants still need energy to make their organic compounds via photosynthesis. They get this from where? The sun, of course. Plants vary in their energy conversion efficiencies, but the sources I can drag up quickly all suggest the most efficient are less than 10%. PV conversion efficiencies vary as well but most agree they can max out at least 20%. So this artificial photosynthesis is going to solve many of humanities problems? (And ruthenium ain’t cheap!)

    It’s funny how the laws of physics seem to intrude into best laid plans.

    • This is interesting because if we can make in the lab a working sun -> artificial plant -> complex, high energy compound, then we don’t have to do sun -> PV cell-> battery -> lab/farm -> high energy compound

      • There will never be working in the lab based on the solar theory because it is wrong.

        Plasma suns have been created in the lab, every 20 years physicists tell us it will take another 20 years to recreate the sun in a lab, since 1960.

      • Never be a thermonuclear sun lab recreation

        Darn straight there won’t. For the skeenth time, the proton-proton chain contains a weak force-mediated reaction that runs incredibly slowly, even at solar core temperatures and pressures; only the fact that the solar core is also massive allows the Sun to generate enough energy to shine. As far as J/kg goes, you’d be better off with dogs on treadmills.

    • Actually, the most efficient plants for photosynthesis are sugarcane, and they max out at 1%! Most plants, including wheat and potato are around 0.1%.

      So plants waste 99% to 99.9% of incoming solar energy.

    • Buy land; they ain’t making any more of that.

      Funny how that low energy solar flux of about 100 watt per square foot, (tops) gets in the way of making a killing.

      G

      • “MarkW on May 4, 2016 at 1:13 pm
        Every multi-story building is making more land.”

        Yes, Mark, and does’nt WUWT insist 3% of dry surface is inhibited by man.

  3. One can do this — OR — one can learn how to farm [a novel concept and quite boring for the average bureaucrat]. Send me a grant, I’ll review the literature! {sarc for those who need to have such things explained}

    • Spot on, old trout!
      Every time we grow a crop of oats we seed 90kg per hectare with seed that is around 40% C. Last year we harvested 4,000 kg per hectare of oats i.e. 1,600 kg of C.
      To do this 6,400 kg of CO2 was consumed per hectare of crop.
      Our Federal government in OZ does not recognise crops as an element in C sequestration; they only consider pasture.

    • You need 64,000 acres of land in order to be able to farm. That puts the farm house five miles away from the nearest road or neighbor. Seems about far enough.

      g

  4. Interesting approach, but very preliminary. It looks like the major problem is the stability of the catalyst, and I don’t think ruthenium isis very cheap.

  5. Doesn’t the University of Texas at Arlington (UTA) already have such a machine?
    It makes fossil fuels from CO2 an solar energy

  6. Speaking as a chemist, it’s a very nice result with some interesting chemistry to explore.

    It’s not photosynthesis, however, and there’s a huge amount of work in store before anyone figures out whether that molecule or other molecules like it will be useful for energy production. Like fusion, it’s 20 years away.

    • We can already make fuel from sunlight and water since 1954 with the invention of the photovoltaic cell. Just use the electric current from solar cells to initiate electrolysis of water and you’ll get hydrogen fuel.

      • Agree with Mark: Thermonuc is just a funding trough for these useless “academics”. This solar conversion “breakthrough” is another one. Sorry for sounding like a pessimistic but science is becoming field for the PR specialists and shysters :(

  7. If anyone managed to make this cost-effective (which I very much doubt) we would suddenly have a serious co2 scarcity on our hands, putting plant life itsekf at risk. Good job it’s so unlikely!

  8. Past the Popular Science press release, I am sure there is some good chemistry here. People have been looking at Rh complexes (among others) as a mimic for natural photosynthetic systems for a long time. Start with inorganic coordination chemistry, add ligand field theory and molecular orbital theory and start developing inorganic charge-transfer complexes. I can not tell from this press release if they did anything novel or unique, but the chemistry in this area is quite interesting.

  9. “It’s funny how the laws of physics seem to intrude into best laid plans.”

    An all too familiar story to those engineers like myself working on the “bleeding edge” of technology…

    Once the US Congress votes to repeal the laws of physics I have about a hundred really nifty world saving ideas in my files all ready to “give it a whirl”…

    Nice idea, with possible (repeat possible) uses, but, in honesty do these folks really think they can improve on how plants (some aka as weeds) survive ?

    Cheers, KevinK

  10. “Artificial photosynthesis could supply the Earth with fuels of high energy density such as hydrogen, methane or methanol while reducing the amount of carbon dioxide in our atmosphere and slowing down climate change.”

    The above pretty much sums up their idiocy.
    We should mimic photosynthesis cause good…While reducing the amount of carbon dioxide in our atmosphere..cause bad.
    Just what do they think photosynthesis (Plants) is doing naturally?
    Is natural photosynthesis not essential to our living?
    If one is a boon to mankind,how does starving it of fuel with the other compute?

  11. Here in Vermont, from recent digital mapping analysis, we have 78% forest across the landmass. We do carbon sequestration the old fashioned way. Recently, some of our favorite trees have taken CO2, bit of rain, some sun and made maple syrup – gallons and gallons. If they get sluggish with the sap, I tell them stories about Drax.

    Soon we will be storing CO2 in the leaves of potatoes, tomatoes, beans, apples and all manner of fruits and vegetables. The only mining required is to ride behind the tiller while man and machine exhale plant fertilizer. I even have a holder for my carbonated hops …

  12. Failures of Chance
    Barnam and Bailey would have been proud. Except that it is physically impossible for “Nature” to have done it in the first place, based on stochastic processes and the 4 known laws of physics, given the entire age of the universe, and rearranging all the particles in the universe at the maximum rate of inverse Planck time. See William Dembski, The Chance of the Gaps.
    See Evolutionary Informatics for technical papers. William A. Dembski and Robert J. Marks II, “LIFE’S CONSERVATION LAW: Why Darwinian Evolution Cannot Create Biological Information” in Bruce Gordon and William Dembski, editors, THE NATURE OF NATURE (Wilmington, Del.: ISI Books, 2009).

    Darwinism Failing
    The Templeton Foundation is putting $8.7 million to reinvent Darwinism. See Templeton now rebranding Darwin rethink.
    The Royal Society is also seeking new ways forward from Darwinism. Intelligent Design Aside, from Templeton Foundation to the Royal Society, Darwinism Is Under Siege

      • Mark The bigger challenge is how the Origin of Life (OOL) occurs from stochastic processes and the 4 forces.

      • No mystery: genetic variation through mutation, and “natural selection” through…(hmm, they never really got around to explaining that one). Genetic mutation comes from radiation damage, so the argument is that radiation exposure is good (evolutionarily) for our genetic makeup. Natural selection has allowed the greatest range of life we can ever imagine, so, really, there is no “selection.” Everything thrives. It makes so much sense.

        But don’t be a village idiot challenging people to “define ‘Darwinism’.” If you don’t know what it is, look it up. And if you are just throwing a challenge around, make it better than “add two plus two.”

      • I have a degree in biology and have studied evolution. At no time has the word “Darwinism” been used. Your use of “Darwinism” places you outside the scientific community. It is a straw man your tribe has created, which you love to bash. Scientists don’t even know what you are talking about. You are entertaining yourselfs; the scientific community doesn’t even know you exist.

        Bash away; nobody cares.

    • So what are the four known laws of physics; well besides the Optical sine theorem ??

      G

      • george e. smith – Mea culpa. I meant t four forces of physics.
        Strong nuclear, weak nuclear, electromagnetic and gravity.

      • You’re forgiven before the fact; too good a come on to leave be.

        But Coulomb force should come between Strong and Weak.

        Well your alignment is ok too, since Strong and Weak are the two ” Short range ” forces, and Coulomb / Gravity are the two infinite range forces.

        So yes I like your order better; more fundamental.

        I ordered by strength.

        Gosh ! Gravity is just so damn weak; but then it sucks, which is wonderful !

        G

    • It would be cheap on the planet Mercury. But not cheap to transport hither and yon.

  13. Although it is not altogether clear that CO2 is a problem, energy to bring the rest of humanity to a modern living standard definitely is. Fossil is finite, even if we frack our arses off; finite. Even if Thomas Goldman was right, finite.

    Always been a fusion guy, but alternatives are ALWAYS good.

    Wee beasties got photosynthesis going say…2.5 billion years after our planetary dust coalesced into something recognizable.

    Photosynthesis has evolved. “We” have the catalyst RUBISCO that got it going. Other catalysts improved a bit for C4 and CAM.

    Hey, catalysts are good…

    • “Fossil is finite, even if we frack our arses off; finite.”

      Yet not a peep about methane hydrate.

      • “crystal methane” is fossil as well. To be sure, all in fossil energy will last a long time, but ultimately we are going to need something far more serious than bird cuisinarts.

    • Well, for heaven’s sake, EVERYTHING is “finite.” Do you actually believe the sun will shine forever?

      • I believe the sun will shine a couple three billion years more based on it’s apparent status as a main sequence star. Of course, it could explode tomorrow…
        Even if Thomas Gold was right and there is substantial mineral methane, current fuels last maybe a millennium?
        BTW, as the sun expires it will expand and incinerate us. Now THAT will be some global warming.

      • Gymnosperm: Please consider the quantity of radioactive and fissionable elements available in our terrestrial environment (not to mention the interplanetary environment). That will give us energy beyond our ability to forecast…from which we will be able to synthesize hydrocarbons for transportation fuel and chemical feedstock purposes.

  14. This work is also being pursued here in Sweden. One of the scientists that lives a few doors down the hallway from me described how frustrating and tantalizing this field of study is as they see the reactions but it still costs more energy than is output thus far. Perhaps one day there will be success.

    • Perhaps, but it’s rather doubtful and fairly pretentious. Plants are very subtle and smart things that build the “factories” that collect and convert the light into carbohydrates and fats themselves which means they are, overall, easily able to get much more energy output than input.
      Similar problem in attempts to harness fusion energy.

  15. the artificial system works with similar efficiency as its natural counterpart

    So its equally as useless at meeting energy needs then?

  16. Another area of science we dont understand fully.

    I think they are getting a little ahead of themselves and appear at least in text a bit more optimistic than the current status of research should lend to.

    How about keeping schtum until you have some results.

    Before reading this article I had thought we didn’t really understand photosynthesis, and thought we cracked up, then I read and see we are exactly where we are before I read this article.

    Why did these dopes mention climate change. Rubber heads

  17. The idea is to take solar energy and store it as chemical potential energy. You could take a PV cell and use the voltage to split water by electrolysis, getting hydrogen and oxygen. Not very efficient, but neither is this.

    • Well we used to have a stored chemical potential source of original solar energy.

      I think they used to call it …. COAL …

      G

    • Even if you could rely on 100 watts/square meter as an averaged value of insolation, and 30% conversion efficiency, you would still need 33 square kilometers of land for a 1 GW powerplant equivalent. A nuclear powerplant of the same output would probably fit within a city block. Do you have any idea what scale of construction project you are committed to? Or what resources (e.g., silicon) need to be dedicated to such a facility? For what? The whole point of this website is for folks to wake up to the fact that the answer is: Nothing!

  18. Hydrogen production already works quite well. The water oxidation to oxygen, however, needs to be accelerated so that the balance of the individual half reactions matches better

    I don’t get the stoichiometry. How can the 2 parts of the reaction be unbalanced?
    If you split off the hydrogen from a molecule of water, aren’t you left with oxygen?

    • Ruthenium is a catalyst in the sense that it has less than the optimum number of electrons in an atom. It can interact with other elements to temporarily share electrons weakly. The electrons in water are notionally spread out over the entire molecule holding the ruthenium atoms, which takes some energy. This allows two hydrogen atoms to pair off and form a stable molecule. The oxygen molecules can also do the same, but at a much lower rate since more energy is involved. If more than one or maybe two hydrogen atoms form the catalyst molecule can’t absorb energy from molecular collisions to allow an oxygen molecule to form. The heat energy liberated when hydrogen and oxygen burn has to be supplied in order to divide water molecules into separate hydrogen and oxygen molecules. ~285kJ/mole(20 grams). That is relatively quite a lot of energy.

    • You are assuming that the process leads to complete hydrolysis (direct production of O2 and H2). What is more likely is that the process splits a single hydrogen from the water molecule, leaving an OH radical. The hydrogen atoms (present in water as H3O hydronium ions) can collect as H2 or recombine with OH as water. The OH radicals can combine as hydrogen peroxide (H2O2) which can spontaneously decompose into water and O2. The possibility of combination reactions is possibly the source of the inefficiency.

  19. If the ‘environmentalists’ latch on to the idea of photosynthesis fuels, we’ll have a successful lab experiment that can produce ten drops of fuel per minute. Then after100 years we’ll have invasive factory monocultures replacing all natural vegetation on Earth. We’ll have deserts covered with scummy ponds of gene-spliced algae jumping out of the pot and blooming all over the planet. We’ll have things that need to be exposed to sunlight that will cover hundreds of square miles and no one will want to tend it and it’ll all fail miserably at the onset of Winter or some pathogen.

    Or we could have used nuclear energy and put it all in a few buildings, seed the whole chemical process with pure intense UV that blazes day and night. Or dispense with the complexity altogether and use nuclear process heat to get hydrogen from water with ample energy to sequester carbon from the air if that floats anyone’s boat.

    The entire landscape of modern so-called environmentalism has been a ludicrously shabby and clumsily constructed ‘front’ to cover for an irrational fear and dislike of nuclear energy. The whole damned thing.

    If we do manage to achieve mass carbon sequestration from atmosphere,and what a hideously loud sucking sound that would make, better not put ‘renewable energy’ folk in charge of the operation. They’ll be tossing their own children into the hopper to get extra carbon credits.

    I’m becoming a bitter old man.at this young age.

    • “The entire landscape of modern so-called environmentalism has been a ludicrously shabby and clumsily constructed ‘front’ to cover for an irrational fear and dislike of nuclear energy.”

      Bitter is better with when blended with the delicious irony that nuclear energy is the only baseload electric generation technology that emits no carbon dioxide!

  20. Crude oil is such a complex long chain molecule, able to be cracked into all the good things we use. I have always wanted to ask all these clever chemists where these complex chemical chains came from. It would seem that these men wish to duplicate it to make green gas.

    Understanding where all the oil gas came from would be a good first step, or is it how the Russians describe it. Made by a process deep within our world.

    My biggest puzzle is where did all the water on our world come from, that is a lot of Hydrogen and Oxygen and a lot of burning.

  21. We need to work on this as its hard to believe the fossils will last for ever. I’d guess its going to be GM microbes playing a part in the eventual solution.

  22. IIRC the Ruthenium thing was all the vogue about 40 years ago. Low efficiency, short life of the dyes.
    Seems they are re-discovering the wheel. You’d think 40 years of development would come up with something or the idea is a bust.

  23. And: “What we are doing is fundamental research,” Valentin Kunz adds.

    Nothing wrong with fundamental research.

    mp3 ist der Standard für die Codierung von Audiodaten und wurde hauptsächlich am Fraunhofer IIS entwickelt.

    mp3 was developed with states R&D funding.

    YouTube makes money of.

    • That rolls off your tongue like nectar; specially that hauptsachlich (umlaut in zere somewhere) .

      Danke !

      G

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