Artificial photosynthesis

Idemitsu Kosan Co.,Ltd.

Outline

Artificial photosynthesis is a technology for artificially producing useful substances from CO2 and water, just as plants use sunlight to make sugar and the like from CO2 and water.
We are working on technologies to generate useful substances such as synthesis gas (H2 and CO) and hydrocarbons from CO2 and water using renewable energy such as sunlight.
So far, we have successfully synthesized hydrocarbons such as methane directly from CO2 and water using a gas diffusion electrode using a proprietary catalyst.
In the past, there were many systems in which CO2 was once dissolved in water to react, but this is the technology which is characterized by adopting a gas diffusion electrode that can directly react CO2 as a gas.
In the artificial photosynthesis technology using this gas diffusion electrode, development is underway to further enhance the CO2 treatment capacity by improving the performance, reducing the cost, and extending the life of the electrode catalyst.
By promoting research on artificial photosynthesis using such gas diffusion electrodes and establishing technology to efficiently produce useful substances such as synthesis gas and hydrocarbons from CO2 by 2030, sustainable CO2 reuse Contribute to the realization of a possible society.

Description

1. Background to this research
As a method to reduce CO2 emissions, technology to convert CO2 into useful substances such as hydrocarbons using renewable energy is expected to be realized.However, CO2 is physically stable and is converted to hydrocarbons, etc. It is difficult to do.

In recent years, Japan has been leading the world in research on converting CO2 into useful substances using artificial photosynthesis technology using sunlight as an energy source, but many research institutions have converted CO2 once dissolved in water until now.
In this method, the supply amount of CO2 as a raw material is limited by the solubility in water, and there is a problem that it is difficult to increase the processing capacity.

2. Features and achievements of this research and development
Using gas diffusion electrodes used in fuel cells to artificial photosynthesis, we succeeded in obtaining hydrocarbons by directly reducing gaseous CO2.
The electrode that reacts with CO2 uses a gas diffusion electrode that uses a proprietary catalyst, and the photoanode uses a stacked structure of a semiconductor photocatalyst and a CIS thin-film solar cell manufactured by Solar Frontier KK. We succeeded in synthesizing methane with solar energy conversion efficiency of 0.61% and ethylene with 0.1% under simulated sunlight irradiation.

That is, the conversion efficiency of solar energy into hydrocarbons was 0.71%, which could be increased to the same level as photosynthesis of plants in nature.
This technology can directly increase the processing capacity because it can directly use gaseous CO2, which is advantageous for practical use. On the other hand, solar power alone limits operation during the daytime and is affected by the weather. We are developing technology to realize a system that can be operated continuously for a long time by using external power derived from renewable energy.
3. Future technology development goals and schedule
We are conducting research on artificial photosynthesis using this gas diffusion electrode, and by 2030 we will establish a technology to produce useful materials such as synthesis gas and hydrocarbons from CO2 with high efficiency, thereby achieving sustainable CO2 recycling. Contribute to the realization of a possible society.

As a technological development, we will promote higher performance, lower cost, and longer life of the electrode catalyst, etc. to increase the CO2 processing capacity and reduce the cost of the system for mounting.