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Our insatiable appetite for energy has got us into a mess, with the burning of fossil fuels releasing greenhouse gases that are heating the atmosphere. It is enough to make you envious of plants, which produce their own energy – through photosynthesis – in a way that actually uses up the greenhouse gas carbon dioxide. If we could learn to mimic this trick on a grand scale, it would enable us to effectively liquefy sunlight to create a clean, green fuel.

Unfortunately, photosynthesis is a tough chemical reaction to copy. It involves many processes, including capturing sunlight, splitting apart water molecules to yield protons, and joining these protons with carbon atoms from CO₂ to ultimately produce fuel in the form of sugars. In nature, these jobs are performed by proteins that have had hundreds of millions of years to evolve – and they still only manage to turn energy from sunlight into fuel with an efficiency of 1 per cent at best.

A decade ago, chemist . That is just one part of recreating photosynthesis, however, and progress has since stuttered.

Then people started to realise that instead of recreating photosynthesis from scratch, we could combine the best bits of chemistry and biology in a bionic leaf. Such leaves typically employ materials that efficiently absorb sunlight as well as natural proteins that excel at stitching together fuel molecules. A team led by . , a chemical that can be used in fuel cells, with almost 1 per cent efficiency – on a par with what nature can achieve.

Nocera has embraced a similar approach. In 2016, he unveiled a system in which his water-splitting catalysts produced protons and electrons and fed these to bioengineered bacteria. The set-up could . “We did a complete artificial photosynthesis that’s 10 to 100 times better than nature,” says Nocera.

This is one great challenge that chemists have more or less solved, then. “It’s not a chemistry problem, necessarily, any more,” says Nocera. “It’s not even a technology problem.” For him, the reason we aren’t all running our cars on fuel from bionic leaves has more to do with a lack of will to build the necessary infrastructure.