Transforming CO2 into fuel using solar energy is a very attractive bio-inspired solution to address certain energy and environmental issues. A team of Franco-Chinese scientists recently developed a catalyst model that makes it possible to precisely decipher the mechanisms of CO2 reduction and CO into methanol (Methanol, also known as methyl alcohol, carbinol, etc.). They also demonstrate the unique role played by the topology of the catalyst support (In chemistry, a catalyst is a substance which increases the speed of a chemical reaction;…) on its catalytic efficiency.
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Making carbon dioxide (CO2) a renewable and sustainable source of carbon is a major challenge for scientific research and a major political issue. . Nature has already had this idea since it transforms CO2 and water into glucose using energy (In the common sense, energy refers to everything that allows us to carry out work, make energy, etc.) of the sun via photosynthesis (Photosynthesis (Greek φῶς phōs, light and…): a remarkable form of energy storage. Research (Scientific research refers primarily to all the actions undertaken with a view to… ) is inspired by it to develop photo-electrochemical processes capable of converting CO2 into a wide range of organic molecules with high added value such as formic acid, methane (Methane is a hydrocarbon with the chemical formula CH4. C is the simplest compound of…), methanol or ethanol.
During these processes, the CO2 molecule gradually loses its oxygen atoms which are replaced by hydrogen atoms (Hydrogen is a chemical element with symbol H and atomic number 1.), storing as it passes through energy in the form of chemical bonds. This transformation, called “reduction reaction”, requires energy but also active, selective and durable catalysts to overcome the very high stability of CO bonds and only promote the desired reduction, to methanol for example, among the numerous reactions. possible. A crucial point which significantly slows down the deployment of these very attractive solutions.
In this context, scientists from the Molecular Electrochemistry Laboratory (LEM, CNRS/Université Paris Cité), in collaboration with Chinese teams, have developed a model catalyst with a unique Cobalt (Co) atom with a well-defined coordination structure. defined to study the underlying mechanism of reduction reactions of CO2 but also of CO (carbon monoxide) to methanol. The cobalt molecular complex chosen is cobalt phthalocyanine. In the presence of CO2, the reduction process stops at the formation of CO and the production of methanol is tiny. On the other hand, in the presence of CO alone, the reduction of the latter to methanol takes place selectively and with very good yield.
The use of a cobalt molecular catalyst anchored to the curved surface of carbon nanotubes promotes the selective reduction of CO2 to methanol with high yields. This same reduction is not favored if the catalyst is on a flat surface.
© Marc Robert
Scientists have shown that this mechanism, linked to the too short residence time of CO on the surface of the catalyst in the presence of CO2, could be circumvented by playing on geometry (Geometry is the part of mathematics which studies the figures of the space…) of the catalyst support. Indeed, once anchored to the surface of carbon nanotubes, the constrained and strongly curved arrangement of the catalyst molecules favors interaction (An interaction is an exchange of information, affects or energy between two agents within …) between cobalt atoms and CO molecules. This strong interaction results in a longer residence time which favors the continuation of the carbon monoxide reduction process (Carbon monoxide is one of the oxides of carbon. Its crude formula is written CO and its formula…) into methanol with high yield.
These results were the subject of a double publication in the journals Nature Catalysis and Nature Communications. They should allow the optimization and development of molecular catalysts based on particularly active and selective non-critical metals to produce methanol from CO2 from industrial fumes, or even from less concentrated sources.
In-situ spectroscopic probe of the intrinsic structure feature of single-atom center in electrochemical CO/CO2 reduction to methanol
Xinyi Ren, Jian Zhao, Xuning Li, Junming Shao, Binbin Pan, Aude Salamé, Etienne Boutin, Thomas Groizard, Shifu Wang, Jie Ding, Xiong Zhang, Wen-Yang Huang, Wen-Jing Zeng, Chengyu Liu, Yanguang Li, Sung -Fu Hung, Yanqiang Huang, Marc Robert & Bin Liu.
Nature Communications 2023
Strain enhances the activity of molecular electrocatalysts via carbon nanotube supports
Jianjun Su, Charles B. Musgrave, Yun Song, Libei Huang, Yong Liu, Geng Li, Yinger Xin, Pei Xiong, Molly Meng-Jung Li, Haoran Wu, Minghui Zhu, Hao Ming Chen, Jianyu Zhang, Hanchen Shen, Zhong Tang , Marc Robert, William A. Goddard & Ruquan Ye.
Nature Catalysis 2023
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