Researchers have long sought a way to turn the growing clouds of carbon dioxide in the atmosphere into usable energy sources, but it’s not easy to copy what plants have spent eons evolving. A new discovery at Lawrence Berkeley National Laboratory (LBNL) could finally lead to the creation of catalysts that make so-called artificial photosynthesis a reality. With this technology, we could potentially vacuum excess carbon dioxide out of the atmosphere and turn it into usable biofuel. Of course, there are still some hurdles to overcome, but aren’t there always?

Most of the fuels that keep our world chugging along are composed of long carbon molecules with mountains of energy locked up in the bonds. The high energy density of petroleum-based fuels has made it very difficult for alternatives like solar and wind-generated electricity to take off. Burning fossil fuels is just very attractive from a financial perspective, but it comes the drawback of dumping tons of carbon into the atmosphere, which acts as a greenhouse gas. Plants use that carbon to sustain themselves through photosynthesis powered by the sun, which is exactly the process we would need to harness to reliably siphon all that excess carbon dioxide out of the atmosphere to use as fuel.

The team at LBNL has identified two factors that could lead to the development of a catalyst capable of capturing and accelerating the break down of carbon dioxide from the air (known as reduction). This is the first step in any artificial photosynthesis system. If you can reduce carbon dioxide, it can be used to create more energy dense fuels with water and solar energy — that’s the actual photosynthesis part, and progress has been made on that front as well.

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To speed the development of such materials, the researchers produced a range of bimetallic nanoparticles composed of gold and copper (seen in the photo at the top of this page). They found the potency of a bimetallic catalyst is affected by the electronic and geometric properties. It’s a similar situation to enzymatic activity in a living cell — the enzyme’s functionality depends on the molecule’s surface composition (electrical) and arrangement of atoms at that surface (geometric). Accounting for both of those in precisely designed nanoparticles makes the process of reducing carbon dioxide much easier.

[Research paper: doi:10.1038/ncomms5948 – “Synergistic geometric and electronic effects for electrochemical reduction of ​carbon dioxide using ​gold-copper bimetallic nanoparticles”]

Working with nanoparticles is also a key part of building an artificial photosynthesis system. By virtue of their size, nanoparticles have extremely high surface-to-volume and surface-to-mass ratios. That makes them particularly effective at catalyzing the reactions in artificial photosynthesis compared to any material designed on a larger scale.

Creating biofuels in the same way plants create sugars would not only offer an amazing wellspring of sustainable energy for humanity, but it could help moderate the levels of carbon dioxide in the atmosphere that almost every scientist on the planet points to as the principal cause of climate change.

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