Hydrogen production, by splitting water, enables the conversion of renewable energy into a carbon free, energy-dense sustainable fuel. It is set to increase by at least a factor of 10 by 2050, and has the potential to play a crucial role in decarbonising transport, industry and heating. However, only 4% of hydrogen produced today is from renewable sources; it is mainly produced by steam reforming fossil fuels, producing copious amounts of CO2.

Proton exchange membrane (PEM) electrolysers constitute the ideal means of splitting water into oxygen and hydrogen. They are highly amenable to coupling to renewable electricity sources, such as wind or solar, which are intermittent. Alternatively, PEM photoelectrolysers could allow the direct splitting of water by combining the functionality of a solar cell and an electrolyser in a single monolithic device.

However, current PEM electrolyser and photoelectrolyser technologies are unsustainable: they require copious amounts of iridium-based oxides to catalyse oxygen evolution at the anode. Iridium is one of the scarcest elements; hence, if we are to scale up PEM electrolyser technology to a level where it will make a global impact, i.e. the terawatt level, we need to increase the catalytic activity (essentially the power stored per gram of iridium) by a factor of ~25. Moreover, iridium oxides slowly corrode during use, limiting the lifetime of PEM electrolysers. An alternative solution, could be to substitute iridium for more abundant elements; some non-precious metal oxides, such as those based on manganese exhibit some short lived activity spanning the course of a few hours, but still fall far short of the performance of iridium.

Regardless of whether we use iridium based catalysts or non precious metal alternatives, they need to be more active and stable under the acidic conditions employed in PEM electrolysers to enable large scale hydrogen production. In H2terascale, we will address this challenge by establishing the fundamental factors controlling iridium and manganese oxide catalysts under oxygen evolution reaction conditions.

We have brought together a transdisciplinary team, led by scientists at Imperial College and Swansea, with the support of (i) three UK companies, BP, Johnson Matthey and ITM Power (ii) an European company, HPNow (ii) the UK's National Physical Laboratory and (iii) an overseas institutions, Helmholtz Institute Erlangen Nürnberg.

We will couple advanced operando spectroscopy techniques to benchmark performance tests of a large number of different catalyst materials produced using state of the art thin film deposition technology. We will elucidate the intricate relationship between catalyst structure, composition and functionality. We will establish the design rules for more active more stable catalysts, paving the way for terawatt scale hydrogen production.