Translated from Japanese. Originally published 4/12/2022.

Article: https://www.newsweekjapan.jp/press-release/2022/04/gsmofmetal-organic-framework.php

GS Alliance succeeds in artificial photosynthesis using quantum dot-metal organic framework (MOF) composite

GS Alliance Co., Ltd. will use the greenhouse gas CO2, water, and solar energy to , succeeded in synthesizing formic acid, which can be used as an intermediate raw material for fuels and chemical substances, by artificial photosynthesis without the need for external electrical energy.

Artificial Photosynthesis Experiment

Global environmental destruction such as global warming, resource depletion, and plastic pollution caused by the population explosion is becoming serious, and it is becoming a catastrophic level that destroys the ecosystem. Under these circumstances, in order to deal with greenhouse gases and energy resource shortages, attention is being paid to artificial photosynthesis, a technology that uses solar energy like plants to produce organic matter from carbon dioxide (CO2) and water. are gathering. CO2 is said to be the cause of global warming, and reducing CO2 is the goal for building a decarbonized, carbon-neutral society.
By using CO2 as a raw material, it is a dream-like technology that creates a new resource energy and simultaneously achieves CO2 reduction. At present, Japanese research and development is one step ahead in the world.


MOFs are a new type of superporous organic-inorganic hybrid materials synthesized from inorganic metal clusters and organic linkers.The structures can be controlled at the molecular level of nanometers, and the surface area is extremely large. It is the most advanced material that has been Due to these excellent features, MOFs are being investigated for various applications such as gas storage, gas separation, metal adsorption, catalysts, drug delivery, water treatment, sensors, electrodes, and filters. Recent research has revealed that MOFs have an excellent ability to recover CO2, and studies have also begun on applying the recovered CO2 to photoreduction, synthesis of chemical substances, in other words, artificial photosynthesis. .
Due to its unique ultramicroporous structure and the advantage that the wavelength range of light absorption can be optimized by synthesis, MOFs are more advantageous than other candidate materials for artificial photosynthesis such as oxides, metal complexes, nitrides, and enzymes. It is also said that The GS Alliance synthesizes such MOFs, and also synthesizes MOFs that are optimal for absorbing CO2 in-house.

Quantum dots, on the other hand, are state-of-the-art materials with ultrafine structures on the single nanoscale (0.5-9 nm) with optical properties that follow quantum chemistry and quantum mechanics. It is said that the number of atoms and molecules per quantum dot is several to several thousand, and they are also called artificial atoms and artificial molecules. When the material reaches this size, due to a physicochemical effect called quantum confinement, the electronic energy levels in the quantum dot are not continuous but separated, and the emission wavelength due to photoexcitation depends on the size of the quantum dot. It will show similar phenomenon. Quantum dots are also being researched and developed as materials that may be suitable for artificial photosynthesis because of their excellent light absorption ability, ability to generate multiple excitons, and large surface area.
However, these quantum dots had problems with durability and water resistance.

GS Alliance synthesizes both MOFs and quantum dots in-house. This time, by combining and optimizing these two cutting-edge materials, the weak points of quantum dots, durability and water resistance, are improved by incorporating them into MOF, resulting in 216 μmol h-1 g-1 cat We succeeded in synthesizing formic acid with a high yield. As the light source, we used an LED light centered around 460 nm. It can be inferred that the photoexcited electrons in the quantum dots are smoothly transported to the metal catalyst of the MOF, resulting in a synergistic effect that improves the catalytic activity.

This time, formic acid made by artificial photosynthesis may contribute to the construction of a hydrogen society. One of the major reasons why the hydrogen society has not spread worldwide is the difficulty of hydrogen storage. Methods such as hydrogen tanks have been used, but hydrogen is the smallest element in the universe, and it is very difficult and expensive to store hydrogen, especially gaseous hydrogen. On that point, although formic acid has the disadvantage of being a strong acid, it is much easier to store than hydrogen because it is a liquid. There is also research and development to directly use formic acid as a fuel for fuel cells instead of hydrogen. Alternatively, hydrogen can be generated in situ from formic acid with a catalyst.
Therefore, the company is currently conducting research and development of artificial photosynthesis with the main purpose of producing formic acid, which is easy to store in every sense, instead of hydrogen.

We will continue to study how to further improve the yield and aim for the practical application of artificial photosynthesis.


Company Profile
Trade name: GS Alliance Co., Ltd. (Fuji Pigment Co., Ltd. Group)
Representative: Dr. Ryohei Mori (Engineering)
Headquarters location: 2-22-11 Obana, Kawanishi City, Hyogo Prefecture 666-0015 Business description: Research and development of cutting-edge technologies in the
environment and energy fields that tackle the challenges of decarbonization and carbon neutrality (United Nations start-up support program UNOPS GIC KOBE adopted in 2020) URL: https://www.gsalliance.co.jp/