Single-atom nickel sites on a vibration-responsive material boosted CO₂-to-CO conversion under ultrasonic vibration

Osaka, Japan - Researchers at The University of Osaka have developed a catalyst that uses vibrational energy to convert carbon dioxide (CO₂) into carbon monoxide (CO), an important industrial feedstock. The work demonstrates a new piezocatalytic route for CO₂ conversion under mild conditions—at low temperature and ambient pressure, offering a potential path toward future low-energy carbon recycling technologies.

CO₂ emissions are a major driver of global warming, and technologies that convert CO₂ from a waste product into a useful carbon resource are becoming increasingly important for achieving carbon neutrality. CO is a useful product of CO₂ reduction, but conventional production methods require high temperatures and substantial energy input. A promising alternative is to use catalysts that harness mechanical energy, such as vibration, to drive chemical reactions under mild conditions, although their efficiency and product selectivity for CO₂ conversion have remained limited.

The research team designed a catalyst based on barium titanate (BaTiO₃), a piezoelectric material that generates electric charges under mechanical stimulation. By depositing nitrogen-doped carbon containing atomically dispersed nickel on BaTiO₃ nanocubes, the researchers created a material that efficiently reduced CO₂ to CO under ultrasonic vibration at room temperature and ambient pressure.

In five hours of sonication, the new catalyst produced 377 mmol g⁻¹ of CO, compared with 123 mmol g⁻¹ for pristine BaTiO₃, corresponding to a 3.1-fold improvement. No H₂, CH₄, or HCOOH were detected as carbon-reduction products under the tested conditions, indicating almost 100% selectivity for CO among the detected carbon products.

The study also clarified why the catalyst performed so well. The nitrogen-doped carbon helped promote charge separation and transfer, while the isolated nickel single-atom sites acted as highly active centers for CO₂ reduction. Structural analysis showed that the nickel atoms were atomically dispersed in a Ni-N₄ configuration within the carbon layer. The catalyst also remained stable over repeated cycles, suggesting that the nickel sites were firmly anchored during operation.

The work provides a new design strategy for combining piezoelectric materials with single-atom catalytic sites, opening a possible path toward sustainable CO₂ conversion using underutilized mechanical energy. Dr. Yoshifumi Kondo, senior author of the study, commented, “Establishing technologies to recycle industrially emitted CO₂ is essential for achieving carbon neutrality. In this work, we clarified part of the design guideline for reaction-active sites in piezocatalytic CO₂ reduction. Going forward, we hope to develop new low-energy CO₂ conversion methods that make use of underutilized energy, such as mechanical vibration and waste heat.”

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The article, “Ni single-atom doped N-doped carbon deposited on BaTiO₃ for efficient piezocatalytic CO₂ reduction,” was published in Journal of Materials Chemistry A at DOI: https://doi.org/10.1039/D5TA09053A

About The University of Osaka
The University of Osaka was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan's leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world. Now, The University of Osaka is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation.
Website: https://resou.osaka-u.ac.jp/en