Scientists achieve direct electrocatalytic reduction of CO2, raising hopes for smart carbon capture

Chemists at Tokyo Tech propose an innovative way to achieve carbon capture using a rhenium-based electrocatalytic system that is capable of reducing low-concentration CO₂ (even 1%) with high selectivity and durability, which is a new potential technology to enable direct utilization of CO₂ in exhaust gases from heavy industries.

The CO₂ reduction reaction takes place in the cathodic chamber shown on the right.

Scientists are closer to finding effective ways to reduce CO₂ levels — a vital part of responding to climate change and energy efficiency challenges.

A study led by Osamu Ishitani of the Department of Chemistry, Tokyo Tech now demonstrates the advantages of applying electrocatalysis¹ to capture low-concentration CO₂.

In their study published in Chemical Science, Ishitani and colleagues including Hiromu Kumagai and Tetsuya Nishikawa drew on decades of work on honing the capabilities of a rhenium-based catalyst, and demonstrated its ability to reduce low-concentration CO₂ in the presence of a chemical called triethanolamine (TEOA).

Compared to many previous studies that have focused on reducing pure CO₂, few have explored how to improve direct capture of low-concentration CO₂ — a topic that warrants further investigation, considering that plants harness low concentrations of CO₂ (about 400ppm, that is 0.04% of the atmosphere) and exhaust gases from heavy industries typically contain low levels of CO₂ (around 3–13%).

By avoiding the need for additional energy-consuming condensation processes, their strategy, if scaled up, could provide a more viable, environmentally friendly solution to CO₂ capture in many settings.

In a series of experiments (see Figure 1) to assess electrocatalytic activity, the researchers found that at a CO₂ concentration of 1%, the rhenium-based catalyst showed very high selectivity (94%) towards carbon monoxide (CO) formation (see Figure 2).

Electrocatalytic reduction of low-concentration CO₂ was achieved using a rhenium-based complex with high CO₂-capturing ability.

A likely reason behind the high performance, the researchers say, is the efficient insertion of CO₂ into the rhenium–oxygen bond.

The researchers aim to continue systematically investigating promising strategies to help reduce real-world CO₂ levels.

The present study was supported by a CREST (Core Research for Evolutional Science and Technology) program on Molecular Technology backed by the Japan Science and Technology Agency (JST).

The paper has been selected as part of the 2018 ChemSci Pick of the Week Collection and a news story are posted on News & events of Royal Society of Chemistry.

Reference

Authors :	Hiromu Kumagai, Tetsuya Nishikawa, Hiroki Koizumi, Taiki Yatsu, Go Sahara, Yasuomi Yamazaki*, Yusuke Tamaki and Osamu Ishitani
Title of original paper :	Electrocatalytic Reduction of Low Concentration CO2.
Journal :	Chemical Science (2018)
DOI :	10.1039/C8SC04124E
Affiliations :	Department of Chemistry, School of Science, Tokyo Institute of Technology *Present address: Faculty of Science and Technology, Department of Materials and Life Science, Seikei University

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