I’ve talked about direct solar to hydrogen production several times in the past (see links at the bottom of the page) and Stanford University researchers in Northern California think they may have solved the sticking point in order that this kind of R&D can go forward.
Water is the most abundant resource on Earth and the most abundant hydrogen feedstock as well. And by splitting water into its two elements, hydrogen and oxygen, the hydrogen can be used to power cars or use in stationary fuel cells. The problem lay in using silicon solar chips immersed in water. Silicon tends to quickly corrode because of the oxygen that is separated in the electrolysis process.
But, the Stanford University researchers have discovered that if they coat the photovoltaic silicon electrodes with a small atomic layer of titanium dioxide this will be both transparent to light and will protect the silicon from corrosion.
According to Stanford, “Sunlight travels through the protective titanium dioxide into the photosensitive silicon, which produces a flow of electrons that travels through the electrochemical cell into the water, splitting the hydrogen from the oxygen. The hydrogen gas can be stored and then, when the sun is not shining, the process can be reversed, reuniting hydrogen and oxygen back into water to produce electricity … Yi Wei Chen and Jonathan Prange, the lead doctoral students on the McIntyre-Chidsey team, discovered that the key to the titanium dioxide’s protectiveness is achieving a very thin, yet high quality layer of material. They found that a layer just two nanometers thick was sufficient so long as it was free of the pinholes and cracks that doomed earlier titanium dioxide experiments.
“With their electrodes successfully shielded from corrosion, the researchers revealed yet one more engineering ace in the hole, adding a third layer of ultra-thin iridium, a catalyst, atop the titanium dioxide. Iridium boosts the rate of the splitting reaction and improves performance of the system.”
This system isn’t yet production ready. More research will be needed to fine tune and scale up their system. But, if all goes well, this may just be the breakthrough research we need in order to produce massive amounts of hydrogen renewable with just the aid of the sun.
Direct Solar to Hydrogen Links