Professor Ho-Jin Son’s research team develops CO2 conversion technology using solar light
 Paper published in the international journal in the field of chemistry, ACS Catalysis

 
▲ From the left, Department of Advanced Materials Chemistry Professor Ho-Jin Son, Ha-Yeon Cheong (Researcher, Co-author), Sunghan Choi (Researcher, Co-author) 

Professor Ho-Jin Son’s research team of the Department of Advanced Materials Chemistry, College of Science and Technology, has developed a technology that can convert CO2 into synthetic fuel using the red light from solar energy.

CO2, identified as the biggest cause of global warming, does not easily convert to other materials, for it is very stable. In order to overcome the environmental problems caused by CO2, research on technology development is being developed.

However, the present technology is at a level that decomposes CO2 by injecting expensive electric and thermal energy making it difficult to use it widely. CO2 conversion through artificial photosynthesis has limitations in that the catalytic efficiency is low and the conversion reaction is not stable.

The research team developed a photocatalyst for CO2 conversion by applying high efficiency solar capture technology. Thru this, and with the CO2 converting into carbon monoxide intermediates, usable synthetic fuels are created. The research team used chlorophyll-like porphyrin* dyes, which capture light when plants conduct photosynthesis. Porphyrins are easily decomposed when they are exposed to sunlight for a long time, but oxide semiconductors are bonded together to dramatically improve light stability. The conversion efficiency improved by 10-20 times compared to the photocatalyst composed only of porphyrin, and the catalytic reaction continued in the long-term continuous process for more than four days.

* Porphyrin: A compound found in plant chlorophyll, used in various fields such as solar cells.

In particular, from amongst visible light, porphyrin can also absorb red light with long wavelengths and low energy. Red light, which is not used in photovoltaic power generation and had been discarded, can be used to collect light energy and induce the CO2 reduction reaction stably. 

Professor Son explained the significance of the research, “The photocatalyst developed in the future can be applied to large-capacity CO2 conversion and is expected to make a great contribution to the development of the environmental industry in response to climate change”.

The research was conducted with the support of the Ministry of Education‧National Research Foundation’s University Leading Technology Licensing Offices (TLO) Support Program, Individual Basic Science & Engineering Research Program, and the Ministry of Science & ICT‧National Research Foundation’s Technology Development Program to Solve Climate Changes. The research results were published in the January 9 edition of the international chemistry journal, ACS Catalysis.
- Title of the Article: Development of Lower-Energy Photosensitizer for Photocatalytic CO2 Reduction: Modification of Porphyrin Dye in Hybrid Catalyst System
- Authors: Professor Ho-Jin Son (Corresponding Author, Korea University), Ha-Yeon Cheong (Co-author, Korea University), Sung-Han Choi (Co-author, Korea University)

Terminology
1. ACS Catalysis
  ○ The most authoritative journal in the field of chemical catalysts. It has an impact factor of 10.614 based on the evaluation criteria of the academic indicator evaluation agency, Thomson JCR.

2. CO2
  ○ CO2 is the Industrial waste resulting from the unrestricted use of carbon resources across the industry throughout the industrial revolution period. This material is very stable and is difficult to convert without an external energy supply.

3. Artificial photosynthesis
  ○ The natural world uses solar energy to convert CO2 into energy materials with high efficiency and selectivity. This process is called artificial photosynthesis.

4. Hybrid photocatalyst
  ○ It is composed of organic and inorganic materials, and it is an organized nanomaterial that maximizes the advantages of each characteristic.

5. Ternary system
  ○ It is a technology that collects three different components into one and induces a synergy effect by organically connecting each component. 

6. Fischer-Tropsch synthesis reaction
  ○ As a reaction for directly synthesizing high value-added hydrocarbons from synthetic gas, it is advantageous in that alcohols, such as methanol and ethanol, can be obtained in addition to hydrocarbons that have various carbon number distributions

Figure Description

Figure 1: High-efficient, long-life CO2 reduction through a chemically encapsulated Ternary System (Porphyrin-Titanium-Re-catalyzed) Hybrid Catalyst with Porphyrin Dyes. The overall low photostability of conventional homogeneous porphyrin-based photocatalysts had the problem of initially degrading the catalyst efficiency. However, by using chemical encapsulation and low energy light, the porphyrin dye was made to operate stably in the photocatalyst system. The durability was maintained for over 100 hours, and the photocatalytic efficiency showed a TON value of more than 1000.