Not to be confused with the Nissan Leaf, Scientists claim to have replicated an artificial leaf ... turning sunlight and water into hydrogen and oxygen, on the cheep (relatively speaking). Debut of the first practical “artificial leaf” Hope it's true. We'll see.
Good stuff; I don't see them saying how the oxygen and hydrogen will be separated though. This may not be necessary for the downstream fuel cell, but having those gases together (at anything more than trace concentrations) is not a safe and stable mixture. The nit I'd pick is that these and similar projects not misuse that word photosynthesis. It has a meaning and it is not the same as photolysis. Making carbohydrates out of CO2 is leaf magic, and it is not being done here.
+1 The abstract says: "... This talk will present the creation of a new catalyst that captures many of the functional elements of photosynthesis and in doing so provides a highly manufacturable and inexpensive method to effect a carbon-neutral and sustainable method for solar storage – solar fuels from water-splitting..." It would be more correct to call this a "leaf-like" device. Agree on the significant for its absence info on how the oxygen and hydrogen are separated and captured. If these have to be compressed for use in a fuel cell, the needed energy would have to come from somewhere -- from the fuel cell? -- reducing the overall system efficiency... inherent conversion losses, diminishing returns, etc. Nonetheless, very cool. FWIW, on a softer, less scientific note: TREES I think that I shall never see A poem lovely as a tree. A tree whose hungry mouth is prest Against the earth's sweet flowing breast; A tree that looks at God all day, And lifts her leafy arms to pray; A tree that may in Summer wear A nest of robins in her hair; Upon whose bosom snow has lain; Who intimately lives with rain. Poems are made by fools like me, But only God can make a tree. Joyce Kilmer (1886-1918) Originally published in Trees and Other Poems, 1914. PC posts by fools like us, Won't correct this little fuss.
I think that I shall never see a billboard lovely as a tree. Perhaps, unless the billboards fall, I'll never see a tree at all. Ogden Nash (1902-1971)
Plants aren't terribly efficient at turning sunlight into human usable energy forms (perhaps because they have a different agenda). Somewhere around 1-4%. Solar panels are already way more efficient for our purposes. I really don't see how it is an 'artificial leaf' any more than a standard solar cell. They are in fact, silicon wafers. The advantage of these is that they produce hydrogen directly? People talk about efficiency of solar cells as though it was the be all and end all. Personally I couldn't care less. What I care about is cost. I have plenty of roof space, and we have plenty of desert. If these can be made cheaply, it could well be a huge advance, if not, they are another in a long line of curiosities.
Corwyn, YES! Let's hijack this thread and talk about photosynthesis instead. Plants' agenda (to the extent I dare speak for them) is to make carbohydrates. Light and water are essential, along with nitrogen and phosphorus (among others) to build the 'magic' molecules. UV light has always been a problem bcause of its ability to break those molecules. After photosynthesis 'caught on' and oxygen accumulated in the atmosphere, more problems from photo-oxidation, but fortunately UV decreased as ozone accumulated in the upper atmosphere. Remember from school those tiny holes in leavs? Stomates. At least 1000 molecules of water blow out those holes, for each CO2 that gets in (swimming upstream in a manner of speaking. That's for water-efficient plants; worse is typical. So, unless the water supply is high and uninterrupted, another problem. There's your drought stress; squeeze those stomates closed and hope for better days ahead. Meanwhile photorespiration keeps happening; a curse of a subset of the magic molecules. Poor little leaves losing the carbon that they worked so hard to collect. It ain't easy being green. 1-4% energy harvest seems darn good to me, and if they ever tire of it, food for us fossil burners won't last long. That's our agenda for plants - eat 'em or eat some animal that did so. Under elevated CO2, plants make new leaves with less stomates. That water loss is a serious matter. If I don't get banned for the hijack, we can discss the C4 photosynthetic pathway. What fun! But sadly, nothing to do with nickel-based catalysts for water photolysis.
The only practical advantage I see is that the gasses are storable. If it's more efficient than hydrolysis driven by electricity from a conventional solar panel, that's great. If not, it's an interesting scientific breakthrough, but that's it. I looked, and all I could find was that nebulous "10 times as efficient as photosynthesis".
Heard coverage of this on NPR, Science Friday. The host interviewed the lead scientist. While the demo unit is about the size of a credit card, a very low-demand household in a developing country would need "units about the size of two doors," ~50 sq.ft. Oxygen and hydrogen are produced on separately on the two sides of the card, so should be easy to collect. Compression of the gases to any appreciable degree would be costly, energy-wise.
I always laugh when developers of new solar power inventors talk about 'remote third world villages'. Like they really think that those will be the first place to utilize cheap solar power, instead of rich $#*#s making solar powered ATVs and jetskis. Yes, it might help the poor eventually, once the rich have gotten all the toys they want.
