Hydrogen Evolution Revolution

Conventional wisdom has it that there are three ways out of our dependence on fossil fuels. One, we use renewables; two, we crack the nuclear fusion problem; and three, we start using hydrogen instead of petroleum/oil. Each of these routes has their advantages and disadvantages and the reality is that we’ll probably end up using a mixture of all three. Renewables (barring tidal) are unpredictable and unreliable but are relatively cheap and most parts of the world have access to a renewable resource. Fusion as yet doesn’t work and when it does building the reactors will be expensive, but when we do crack it it will be a source of reliable and almost infinite power. If we start building internal combustion engines that burn hydrogen instead of petrol then the only thing that will come out of the exhaust pipe is water, but we don’t yet have a way of cheaply producing hydrogen on an industrial scale to make it affordable to the public.

Progress has been made, however, on that last problem. Researchers from the University of Wisconsin and the King Abdullah University of Science and Technology claim to have made a catalyst that produces hydrogen almost as well as the existing best catalyst but at a fraction of the cost. To produce hydrogen isn’t difficult, there are several potential methods the most straightforward of which, put very simply, is to pass electricity through water to split the hydrogen and oxygen in a molecule of water. On its own it is rather a slow and inefficient process that requires the water to be heated to a very high degree, about 2500 of them, but there are catalysts that can speed it up. Unfortunately these catalysts tend to be made from noble metals like gold, platinum and iridium; all of which are prohibitively expensive and not all that abundant if you need it on a worldwide, industrial scale.

The new paper in Nature Materials, then, is exciting because it details the creation of a new catalyst that doesn’t use any expensive, fancy pants noble metals. They took the known catalyst cobalt disulphide and tried to ‘tune the hydrogen adsorption free energy’ (no, I don’t know what that means either). Basically they swapped out one of the sulphides with other elements to see how it would affect its performance. They found that if you swap one sulphide with a phosphorous then you get an enzyme that works nearly as efficiently as the current gold standard platinum-based catalyst. Plus, the cost of such an enzyme would be negligible; sulphur and phosphorous are common as muck and even cobalt is three orders of magnitude cheaper than platinum.

Although this is potentially a very exciting development we should bear in mind that this has so far only been tested in the lab. We don’t know yet how scalable and practical using this new catalyst will prove to be but with a little luck, and a lot of hard work, we might be a step closer to a clean, green way of sustaining our increasingly power-hungry civilisation.

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