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A tiny, golden way to curb carbon emissions

Image: File photo of a coal power plant
New technology that involves gold nanoparticles can more efficiently convert the greenhouse gas carbon dioxide emitted from power plants into fuel.Nick Simonite / AP

Once – or if – we decide to seriously fight climate change, there will be riches to be found in technologies that turn the greenhouse gas carbon dioxide into something useful, such as fuel. One such method may truly be golden, according to new research.

The story starts with another metal – copper, the stuff of pennies. It is well known as one of the few metals that can turn carbon dioxide into fuels such as methane and methanol.

When fashioned into an electrode and stimulated with a voltage, the copper serves as a catalyst. Bubble CO2 over it and an electrochemical reaction converts the gas into another molecule.

“The problem is that it can convert into a number of molecules, some of them desirable like methane or methanol, and some that are not so desirable like carbon monoxide,” Kimberly Hamad-Schifferli, a mechanical and biological engineer at MIT, told me Thursday.

The undesirable carbon monoxide is produced when the copper has been oxidized – the same process that turns pennies green. Hamad-Schifferli and her colleagues went searching for a way to slow, or prevent, copper from oxidizing so it could keep converting carbon dioxide into the useful fuels.

Image: Image of copper and gold nanoparticles.
Researchers have combined gold nanoparticles (in light red) with copper nanoparticles (in light green) to form hybrid nanoparticles (dark red), which they turned into powder (foreground) to catalyze carbon dioxide reduction.Zhichuan Xu / MIT

To do this, they mixed itsy bitsy particles of gold in with copper particles. 

“Gold by itself,” she explained, “doesn’t oxidize.”

That’s why, for example, a gold wedding band doesn't change color.

“We thought, well, OK, let’s throw in a little bit of gold and maybe it will slow this oxidation,” she said. “And we found that if you put in just a little bit of gold, it does prevent this oxidation.”

What’s more, by using itsy bitsy particles, measured on the nanoscale, the team was able to increase the efficiency of the conversion. That’s because when you make something smaller, the surface to volume ratio goes up, Hamad-Schifferli said. 

In other words, the use of tiny bits of gold in this process helps slow down the oxidation of copper and the process consumes less energy.

The team’s long-term goal is to incorporate this technology into a reactor that could, for example, be fit to a coal-fired power plant that would capture and convert the carbon dioxide emissions into more fuel. This, in turn, would curb the plant’s overall greenhouse gas emissions. 

How much of a dent in greenhouse gas emissions the technology could make isn’t yet known, though it could be significant. 

"I don't think we can make it emissions free," Hamad-Schifferli said. "That would be a tall order for this ... but now we have a potential for factories to turn their waste into something useful and maybe that could have a financial benefit."

Of course, gold isn't exactly cheap. However, it is less expensive, for example, than platinum currently used in fuel cell technology. So when – or if – power plants have to start doing something about all the carbon dioxide they produce, this technology may truly be a golden opportunity.

“It is a tradeoff,” Hamad-Schifferli said. “You are putting this more expensive metal in there, but if you can increase the lifetime of your reactor, or require less energy to convert the CO2 to methane, that is a benefit.”

Findings are to be published in Chemical Communications .

John Roach is a contributing writer for To learn more about him, check out his website  and follow him on Twitter . For more of our Future of Technology  series, watch the featured video below.