Back in March, we heard about a breakthrough from MIT: an “artificial leaf” that produces pure oxygen and hydrogen gas, powered entirely by sunlight. The technology was described in yesterday’s edition of Science, and the team has released a video showing one of the devices in action.
I say device, but it’s really more of a material. There are no moving parts and it has no set shape or size. The leaf is semiconducting silicon, coated on one side with a special cobalt catalyst, discovered by the project’s Daniel Nocera in 2008, and on the other with a nickel-molybdenum-zinc alloy. Sunlight creates a current within the silicon, and the catalyst causes water molecules to split into gaseous H2 and O2, which rise off in bubbles from opposite sides of the leaf.
Take a look at the video. It’s not particular exciting, but it gives you an idea of what kind of conversion rate we’re talking about:
The gases could be isolated and stored in a fuel cell, which could provide power later and produce pure water as its exhaust.
Nocera and several other researchers formed a company, Sun Catalytix, to independently research, apply, and market the artificial leaves, and last year raised $9.5 million from Tata and other investors.
The leaf-like form factor is easy to demonstrate on a human scale, but there’s no reason why the “leaves” couldn’t be microscopic or enormous. The different use cases require much research and testing, however, which is likely what Sun Catalytix is working on at present. That and figuring out to do with the extra protons the process generates. They envision banks of these things powering houses and communities and storing the excess in tanks for sale or emergencies. Also worth noting is the fact that the idea of these devices isn’t new in itself, but Nocera’s work seems to have produced a cheap, durable, and mass-producible one. The efficiency of solar energy conversion still needs to be greatly improved, though.
[image credit: Dominick Reuter]