Lighting the path to recycling carbon dioxide

• Semiconductive photocatalysts that effectively soak up solar energy might help reduce the energy called for to drive a bioelectrochemical procedure that transforms CO2 emissions into valuable chemicals, KAUST scientists have revealed.

Recycling CO2 can simultaneously minimize carbon discharges right into the atmosphere while producing beneficial chemicals as well as gas, discusses Bin Bian, a Ph.D. student in Pascal Saikaly's laboratory, who led the research study. "Microbial electrosynthesis (MES), coupled with a renewable resource supply, could be one such modern technology," Bian states.

MES exploits the capacity of some microbes to occupy CO2 and also convert it into chemicals, such as acetate. In nature, chemolithoautotroph germs metabolize minerals as a resource of power in a procedure that involves the shuttling of electrons.

This ability can be made use of to transform CO2 right into value-added products if the microbes are supplied with a stream of electrons as well as protons from anodic water splitting in an electrochemical cell (see photo).

In their latest work, instead of concentrate on the CO2-to-acetate action, the group dealt with decreasing the power input for molecular oxygen (O2) production at the anode, a reaction that maintains the total cell in equilibrium. "In MES systems, the process that takes in the most energy is believed to be the oxygen development response (OER)," Bian describes.

Researchers have utilized light-capturing anode materials, such as titanium dioxide, that harness energy from sunshine to help drive the OER. In their existing work, the team examined an encouraging option for the photoanode, the light-harvesting product, bismuth vanadate.

Bismuth vanadate taken in energy from a much wider range of the solar range than titanium dioxide, making the whole MES cell much more effective, the team showed. "We got solar-to-acetate conversion effectiveness of 1.65 percent, which is the highest reported until now," Saikaly says.

"This effectiveness is around eight times greater than the 0.2 percent performance of worldwide all-natural photosynthesis, which is nature's solar-powered process for converting CO2 into energy-rich particles," Bian notes.

So far the group has maintained the microbe biocatalysts provided with a consistent stream of electrons and CO2 to maintain their growth. "The following step for us is to evaluate our system under real sunshine and keep track of the strength of the biocatalysts under an intermittent renewable energy source," Saikaly states.