Copper-indium oxide: A faster and colder way to reduce our carbon footprint

With climate change worsening, there is a need for technologies capable of capturing and using the CO’s atmosphere.₂ (carbon dioxide) and reduce our carbon footprint. Interior of renewable energy, CO₂E-fuel based has emerged as a promising technology that seeks to convert atmospheric CO₂ into clean fuel. The process involves the production of synthetic gas or syngas (a mixture of hydrogen and carbon monoxide (CO)). With the assistance of the water-gas transfer reorganization (RWGS), CO₂ broken down to the CO required for syngas. While promising in terms of conversion efficiency, the RWGS response calls for high temperatures (> 700 ° C) to prevail, while at the same time generating unwanted byproducts.

To address these problems, scientists developed a chemically modified volatile version of the CO-modified RWGS reaction₂ to CO in a two-step mode. First, metal oxide, used as an oxygen storage material, is depleted by hydrogen. After that, it is re-oxidized by CO₂, extracting CO. This method is free of undesirable byproducts, simplifies gas separation, and can be enabled at lower temperatures depending on the selected oxide. As a result, scientists have been looking for oxide products that exhibit high levels of oxidation reduction without the need for high temperatures.

In a recent study published in Chemical Science, scientists from Waseda University and ENEOS Corporation in Japan have revealed that the novel indium oxide was modified with copper (Cu – In₂O.₃) exhibits modern CO₂ conversion rate of 10 mmolh^-1g^-1 at very moderate temperatures (400-500 ° C), making it a disadvantage among oxygen storage materials required for CO at low temperatures₂ turn. To better understand this behavior, the team studied the structural properties of Cu-In oxide along with the kinetics involved in the chemical reaction of RWGS.

The scientists performed X-ray-based analyzes and found that the sample initially contained parental material, Cu2In₂O.₅, which was initially reduced by hydrogen to form a Cu-In alloy and indium oxide (In₂O.₃) and then oxidized by CO₂ to the result of Cu – In₂O.₃ and X-ray data showed CO. that it was oxidized and reduced during the reaction, giving the main news to scientists. “The X-ray measurements made it clear that the chemically curved RWGS reaction is based on the reduction and oxidation of Indium which leads to the formation and oxidation of the Cu-In alloy,” says Professor Yasushi Sekine of University Waseda, who led the study.

The genetic studies provided further insight into the reaction. The reduction step showed that Cu was responsible for the reduction of indium oxide at low temperature, while the oxidation step showed that the surface of Cu-In alloy maintained a highly reduced state while its mostly oxidation. This allowed the oxidation to occur twice as fast as other oxygen. The team attributed this strange oxidation behavior to the rapid migration of negatively charged oxygen ions from the surface of a Cu-In alloy to its bulk, which helped to produce a selective mass of oxide.

The results, as expected, have inspired scientists about the future prospects for copper-indium oxygen. “Given the current situation with carbon emissions and global warming, a high-performance carbon dioxide conversion process is highly desirable. While reacting RWGS with a chemical loop works to good with many oxides, our novel Cu-In-oxide here shows significantly higher performance than any of them.We hope this will make a significant contribution to reducing our carbon footprint and driving Man towards a more sustainable future ”, Sekine concluded.

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Authors: Jun-Ichiro Makiura (1), Takuma Higo (1), Yutaro Kurosawa (1), Kota Murakami (1), Shuhei Ogo (1), Hideaki Tsuneki (1), Yasushi Hashimoto (1), Yasushi Sato (2) )), and Yasushi Sekine (1)

Title of original paper: Rapid Oxide ion migration in bulk Cu-In-oxide and its use for efficient CO₂ turn at lower temperatures

Iris: Chemical Science

DOI: 10.1039 / d0sc05340f

(1) Department of Applied Chemistry, Waseda University

(2) ENEOS

Located in the heart of Tokyo, Waseda University is a leading private research university that has recently been dedicated to academic excellence, innovative research, and civic engagement at local and global levels since 1882. It is the number one University in Japan in international activities. , including the number of international students, with the widest range of degree programs taught entirely in English. To learn more about Waseda University, visit https: //www.waseda.jp /top /en