New catalyst improves conversion of CO2 to syngas
30 July 2014
Researchers from the University of Illinois at Chicago (UIC) have identified molybdenum disulfide as a promising cost-effective substitute for noble metal catalysts for the electrochemical reduction of carbon dioxide. A paper on their work is published in the journal Nature Communications.
While noble metals such as gold and silver are able to reduce carbon dioxide at moderate rates and low overpotentials, their cost is a challenge to the development of inexpensive systems with an efficient CO2 reduction capability. Amin Salehi-Khojin, UIC professor of mechanical and industrial engineering, and his colleagues developed a novel two-step catalytic process for CO2reduction that uses molybdenum disulfide and an ionic liquid. The new catalyst improves efficiency and lowers cost.
The discovery is a big step toward industrialization, said Mohammad Asadi, UIC graduate student and co-first author on the paper.
With this catalyst, we can directly reduce carbon dioxide to syngas without the need for a secondary, expensive gasification process.—Mohammad Asadi
In other chemical-reduction systems, the only reaction product is carbon monoxide. The new catalyst produces syngas, a mixture of carbon monoxide plus hydrogen.
The high density of loosely bound, energetic d-electrons in molybdenum disulfide facilitates charge transfer, driving the reduction of the carbon dioxide, said Salehi-Khojin, principal investigator on the study. The catalyst produces a very stable reaction that can go on for hours, he said.
In noble metal catalysts like silver and gold, catalytic activity is determined by the crystal structure of the metal, but with molybdenum disulfide, the catalytic activity is on the edges. Fine-tuning of the edge structures is relatively simple. We can easily grow the molybdenum disulfide with the edges vertically aligned to offer better catalytic performance.—Amirhossein Behranginia, co-author
In comparison with other two-dimensional materials such as graphene, there is no need to play with the chemistry of molybdenum disulfide, or insert any host materials to get catalytic activity, noted Bijandra Kumar, UIC post-doctoral fellow and co-first author of the paper.
The proportion of carbon monoxide to hydrogen in the syngas produced in the reaction can also be easily manipulated using the new catalyst, said Salehi-Khojin.
The study was supported by UIC’s Chancellor Innovation Fund; by the American Chemical Society Petroleum Research Fund grant #53062-ND6; and the Herbert E. Paaren Graduate Fellowship. This work was carried out in part in the Frederick Seitz Materials Research Laboratory Central Facilities, University of Illinois.
Mohammad Asadi, Bijandra Kumar, Amirhossein Behranginia, Brian A. Rosen, Artem Baskin, Nikita Repnin, Davide Pisasale, Patrick Phillips, Wei Zhu, Richard Haasch, Robert F. Klie, Petr Král, Jeremiah Abiade & Amin Salehi-Khojin (2014) “Robust carbon dioxide reduction on molybdenum disulphide edges,” Nature Communications 5, Article number: 4470 doi: 10.1038/ncomms5470
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