Catalysing the world of artificial photosynthesis

Harnessing the light of the sun has long been a dream of scientists around the world. Now research at the University of Liverpool is pushing the boundaries of new materials to recreate the natural magic of photosynthesis, not just in the lab, but at the industrial scales needed to dramatically reduce demand for fossil fuels.

One way to meet global and national renewable energy needs is utilising solar energy to convert waste products back to useful fuels, which could be compatible with existing fuel storage and distribution networks. The double win is that CO2 can be used in the process, yielding useful ‘feedstock’ chemicals for industry such as methanol and urea, which can be used as fertiliser, whilst consuming an unwanted greenhouse gas.

The limiting factor is the efficiency of the catalysts that speed up the reactions to a useful speed. Researchers at the University’s Stephenson Institute for Renewable Energy (SIRE) are innovating with new catalysts and probing their fundamental mechanisms to transform energy generation, storage and transmission.

Postdoctoral early-career researcher Dr Gaia Neri at SIRE says the work is challenging when finding a catalyst capable of selectively making one specific product, as opposed to several unwanted by-products. “We have two approaches. We make new catalysts, but a better understanding of how they work will make them more scalable for large scale industrial fuel production.”

Building on high-quality research

The group she works in has already scored notable successes. A 2016 paper explains how a new nickel catalyst is highly selective for CO2, increasing efficiency and reducing unwanted by-products. It also works at high acidity, which is unusual and useful because industrial catalysts required for this artificial photosynthesis need to work under a robust range of conditions.

More high impact work has been detailed in a 2017 paper where, for the first time, the physics of a molybdenum catalyst was seen at the molecular level on the surface of the electrode. This was revealed by novel use of a cutting-edge form of spectroscopy (vibrational sum-frequency generation spectroscopy), coordinated with advanced facilities and expertise across the University of Liverpool. “It’s a dynamic surface,” Neri explains. “Now we’ve seen how it starts to work, and continues to work.”

Working in partnership

The technique can now be used for other catalysts and so engages with the wider community, and Neri’s work involves considerable collaboration with the project’s academic partners, including Cardiff University and Imperial College London. She works with industrial partners too, who give guidance and useful input on what is involved in terms of industrial scale up.

As an early-career researcher, Neri finds the mix of chemistry, physics and materials at the Institute and in the city of Liverpool itself an exciting and inspiring blend. “Liverpool is great!” she says. “You learn so much because it’s such a stimulating, environment. I am really growing as a researcher.”

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