Researchers at Tokyo Metropolitan University have developed groundbreaking technology that converts captured carbon dioxide (CO2) into a potent green fuel.
This marks a significant advancement in carbon capture and utilization, an essential field for combating climate change and achieving carbon neutrality.
The team has designed a new type of electrochemical cell that effectively transforms bicarbonate—a derivative of captured CO2—into formate, a powerful green fuel. This innovation addresses major challenges in reactive carbon capture (RCC) and performs comparably to traditional gas-fed methods, which are often more energy-intensive.
“Carbon capture and utilization to convert atmospheric CO2 into useful chemicals and fuels is essential for achieving a carbon-neutral or negative emission future,” the researchers noted.
Carbon capture technology is recognized globally as a crucial tool for reducing emissions. However, the challenge remains: what to do with the captured CO2? This question has fueled research into converting CO2 into useful substances like formate, which can generate power in fuel cells. Unfortunately, this approach typically requires pure CO2, which is energetically costly.
Reactive carbon capture offers a promising solution. Here, CO2 dissolved in alkaline solutions like bicarbonate can be directly converted into formate ions, bypassing the need for pure CO2 and simplifying the conversion process. Nevertheless, designing an electrochemical cell that efficiently produces formate from bicarbonate without unwanted reactions is complex.
The research team’s innovative electrochemical cell features electrodes made of catalytic materials separated from a polymer electrolyte membrane by a porous membrane made of cellulose ester. In this configuration, hydrogen ions generated at one electrode travel through the electrolyte membrane to react with bicarbonate ions in the porous layer, producing CO2 within the pores. This CO2 is then converted to formate ions at the other electrode.
The results of this design are promising. The new cell achieved an 85% faradaic efficiency at high currents, meaning that 85% of the electrons were converted into formate. The cell also displayed impressive stability, functioning effectively for over 30 hours and achieving a nearly complete conversion of bicarbonate to formate. After water removal, the end product is a solid, crystalline formate fuel ready for use.
The research team hopes that their bicarbonate electrolyzer will become a viable option for society in the quest for a green transformation.