One of the primary drivers of climate change, CO2 emissions, have reached over 35 million tons worldwide. With global annual temperatures still rising, reducing CO2 emissions has become a necessity. To turn this necessity into an opportunity, researchers have been working to find ways to capture the CO2, thereby reducing emissions and then converting that CO2 into valuable chemicals and fuels.
One of the difficulties in working with CO2 is that it is very thermodynamically stable. To overcome this, additional energy and a strong catalyst are needed to drive the reaction. A research group at China University of Petroleum (East China) has been investigating the use of carbon-based catalysts in the conversion process. They have designed several different very effective synthesis strategies using these catalysts in the catalytic conversion of CO2.
A review of their work was published in Carbon Future on September 10.
"In this review, we summarized the development strategy of catalysts by carbon species assisting method in our research group, which can be applied for CO2 thermochemical and electrochemical hydrogenation. This review aims to inspire new ideas for CO2 hydrogenation through the design of carbon-based catalysts," said Mingbo Wu, a professor at the College of New Energy, State Key Laboratory of Heavy Oil Processing at the China University of Petroleum (East China) and lead author of the paper.
The researchers chose to focus on carbon species because their physical and chemical properties make them good candidates as catalysts, they can be relatively inexpensive and are very stable. Carbon-based catalysts can also play various roles in the preparation and process of CO2 catalytic conversion. They can be used to modify the structure of catalyst, as supports of catalyst, as electronic regulators of catalyst and as the bulk catalysts.
CO2 conversion occurs via CO2 hydrogenation, the addition of hydrogen atoms to the CO2 and removing its oxygen atoms. This is accomplished using either the energy from electrocatalysis, which uses electricity to drive the process, or thermocatalysis, which uses heat to drive the process. In order to avoid increasing the amount of pollutants and green-house gases, Wu's team recommends using green renewable energy as the energy source wherever possible.
Wu's team has designed and researched several different catalyst strategies. An example of one of these strategies is the electrocatalysis reduction of CO2 via a carbon-based catalytic material.
In essence, CO2 is converted to HCOO, formate, which is a nontoxic, easy to transport and very promising green fuel. The difficulty in designing these strategies lies in building a process that is both efficient and stable, hence the importance of the design of the process and the type of catalyst used. The researchers carried out the conversion using carburized iridium oxide nanorods, a metallic oxide. The process they designed uses the carbon species' ability to modulate the electronic structure of metals, thus enhancing the activity of catalysts and selectivity of formate, said Wenhang Wang, a researcher from the School of Chemistry and Chemical Engineering at Liaocheng University and first author of the paper.
"We will always be committed to the development and application of carbon-based catalysts. With the development on the design concept of the catalyst and characterization technology, we strongly believe that a clear roadmap of the utilization of carbon materials for catalysts is drawn and the breakthrough in this field will be witnessed in the near future," Wu said.
Other contributors include Wenhang Wang from the Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry and Chemical Engineering, Liaocheng University, China and the College of New Energy, State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao, China; Yang Wang and Hui Ning from the College of New Energy, State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao, China; and Xiangjin Kong from the Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry and Chemical Engineering, Liaocheng University, China.
This work was supported by the National Key Research and Development Program of China, the National Natural Science Foundation of China and the Taishan Scholar Project.
About Carbon Future
Carbon Future is an open access, peer-reviewed and international interdisciplinary journal, published by Tsinghua University Press and exclusively available via SciOpen. Carbon Future reports carbon-related materials and processes, including catalysis, energy conversion and storage, as well as low carbon emission process and engineering. Carbon Future will publish Research Articles, Reviews, Minireviews, Highlights, Perspectives, and News and Views from all aspects concerned with carbon. Carbon Future will publish articles that focus on, but not limited to, the following areas: carbon-related or -derived materials, carbon-related catalysis and fundamentals, low carbon-related energy conversion and storage, low carbon emission chemical processes.
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