CO2 Conversion Tech Uses Visible Light Panels

Tokyo, Japan – Mitsubishi Electric Corp and Science Tokyo reported the development of a technology that converts carbon dioxide into formic acid using visible light and photocatalyst panels.

The technology utilizes polymeric carbon nitride to absorb visible light with wavelengths up to 450 nanometers and convert CO2 into formic acid, the companies stated.

The photocatalyst system is formed and fixed on flat panels rather than dispersed as particles in solution.

The panel structure consists of a titanium oxide layer deposited on a borosilicate glass substrate, with carbon nitride placed on top. Ruthenium complex compounds are absorbed onto the panel as CO2 reduction active sites.

Testing indicated that the panels achieved 85 percent selectivity for formic acid production when exposed to 400-nanometer visible light.

This result compares to 80 percent selectivity observed with conventional dispersed particle methods.

Light-to-formic acid conversion efficiency was measured at 2 percent, similar to the traditional approach.

According to the companies, the panel method eliminates the filtration operations required to separate catalyst particles from reaction solutions.

The immobilization process involves applying a carbon nitride suspension liquid to the titanium oxide layer, followed by heating in electric furnaces at specific temperatures and heating rates determined through testing.

Mitsubishi Electric conducted studies of experimental conditions and evaluated the structure and activity of the immobilized photocatalyst.

Science Tokyo handled design and material selection for multi-layer immobilization and prepared catalyst materials.

The photocatalyst generates formic acid, hydrogen, and carbon monoxide. Formic acid accounted for 85 percent of the total products generated, compared to 80 percent in powder suspension catalyst systems.

Formic acid has the chemical formula HCOOH and remains liquid at room temperature. The research was funded by a Japan Society for the Promotion of Science grant (JP22H05148).

Mitsubishi Electric stated it plans to examine technology to maximize the utilization of electrons generated on organic semiconductor surfaces for formic acid production reactions.

Science Tokyo was established in October 2024 through the merger of Tokyo Medical and Dental University and Tokyo Institute of Technology.