Carbon dioxide (CO2) is society’s ultimate waste product, with billions of tons of the stuff injected into the air every year. But recycling it into valuable fuels and chemicals has always required too much energy to make financial sense. Now, researchers have found two efficient ways to convert CO2 into energy-rich by-products, they reported last week here at a meeting of the American Chemical Society (ACS). If they gain traction, they could help solve another pressing problem: Because both approaches require a steady stream of electrons from a source of electricity, they could siphon up all the ‘lost’ solar and wind energy that can’t currently be stored in electric grids.
To recycle CO2, some researchers are mimicking photosynthesis, harnessing sunlight to convert the molecule into carbohydrates. But these solar fuel reactors often need to run at 1000 °C. Other chemists favor a more traditional approach that would carry out similar reactions, but near room temperature in electrochemical cells that need electricity and special catalysts. The first step in such an electrolytic approach is splitting CO2, a tough, stable molecule, into oxygen and carbon monoxide (CO), a slightly more energy-rich molecule that can form the basis for hydrocarbon fuels like methanol. That process starts with two catalyst-covered electrodes dunked in a beaker of water into which CO2 has been dissolved. The stream of electrons between these electrodes carry out separate reactions that split water and CO2, ultimately generating CO and more water.
Read the original article by Robert Service