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Scientists Achieve Perfect Efficiency For Water-Splitting Half-Reaction (phys.org)
Dthief writes: Splitting water is a two-step process, and in a new study, researchers have performed one of these steps (reduction) with 100% efficiency. The results shatter the previous record of 60% for hydrogen production with visible light, and emphasize that future research should focus on the other step (oxidation) in order to realize practical overall water splitting. The main application of splitting water into its components of oxygen and hydrogen is that the hydrogen can then be used to deliver energy to fuel cells for powering vehicles and electronic devices. The process involves exposing the water to a mass of platinum-tipped nanorods, with visible light driving the reaction.
The 100% efficiency refers to the photon-to-hydrogen conversion efficiency, and it means that virtually all of the photons that reach the photocatalyst generate an electron, and every two electrons produce one H2 molecule. At 100% yield, the half-reaction produces about 100 H2 molecules per second (or one every 10 milliseconds) on each nanorod, and a typical sample contains about 600 trillion nanorods.
Whether using pure O2 in an engine make sense depends on where the engine is used. For a fixed installation it could make sense to use pure oxygen but for something like a vehicle I'd recommend against it - unless you think that vehicle accidents need to become more spectacular.
I do agree, though, that it makes more sense to store the O2 than to vent it. There are plenty of uses for bottles of pure O2.
USE HOT GRITS WITH STATUE OF NATALIE PORTMAN (NAKED AND PETRIFIED)
This is not a solar energy 'scheme'. It is a more efficient method to produce hydrogen for fuel cells. I too am a fan of nuclear, properly done, but solar energy and solar processes have their place in a good energy mix.
Silence is a state of mime.
They are not splitting water at all. They are just encouraging individual H atoms (H+ ions, or basically protons) to combine into H2 molecules.
Normally, even pure water has a whole lot of individual H+ ions floating around in it, and the same number of OH- ions. Those H+ don't combine into H2 because that would require extra electrons, which are stuck in the OH- ions. That's why you can create H2 using an electric current which delivers the missing electrons so the H can pair up. (This doesn't work very efficiently in pure water, but a bit of catalyst helps a lot.)
Acidic solutions have more H+ (along with negative ions from the acid, like for example HSO4-), basic solutions have less H+ (and more OH-)
Apparently the researchers are using a basic solution (high pH, lots of OH- and less H+), and then using photons to liberate electrons from the OH- to allow H+ to combine into H2.
This works best in a basic solution because the problem is not so much the number of H+, but rather the number of OH- ions that can be persuaded to give up an electron by nudging them with a photon. In an acidic solution, most of the eligible electrons are stuck in the negative ions from the acid which are much more possessive of their electrons.
The big novelty is apparently that they can get the OH- to give electrons to the H+ and let them combine into H2, rather than combining back into H2O.
The engine is the oxidation part. It outputs water, not O2.
The process described in the arcticle would happen in an industrial complex of some sort.
Apparently the researchers are using a basic solution (high pH, lots of OH- and less H+), and then using photons to liberate electrons from the OH- to allow H+ to combine into H2.
That would leave you with uncharged hydroxyl radicals with an unpaired electron, so I don't think that's what they're doing. They are only talking about the reduction half reaction (2 H+ + 2e- --> H2). There has to be an oxidation half reaction. You're proposing (OH- --> OH + e-), but they're talking about splitting water, ie : 2 H2O --> O2 + 4 H+ + 4e-
I suspect they need the high pH to let the H2 diffuse away.
Solar power is a distraction from energy production schemes that actually work.
Solar power is the root of all energy production schemes that actually work. With maybe an exception for nuclear. It's the only energy input into our otherwise closed system. Oil and coal are both sequestered solar power, while wind and hydro are both driven by solar power converted to heat.