Synthesis of Carbon Nanotubes From CO2 Enabled by Fe–Mo Bimetallic Catalysts via Effective CO2 Scavenging
Eunchae Oh , Jaewon Jang , Yoon Kyeung Lee , Junghoon Yang , Byung-Joo Kim , Jungpil Kim
Energy & Environmental Materials ›› 2026, Vol. 9 ›› Issue (4) : e70257
The direct conversion of CO2 into high-quality carbon nanotubes (CNTs) remains a formidable challenge, primarily due to the oxidation of metal catalyst by the oxidative nature of CO2. To overcome this limitation, a tandem catalytic system was implemented, in which CO2 was converted to produce CH4 on Ni catalysts in the primary reactor, and the CNT was synthesized from CH4 on an Fe catalyst in the secondary reactor. Nevertheless, unreacted CO2 was introduced into the secondary reactor, where the Fe catalysts were oxidized and thus failed to produce any solid carbon. To prevent the oxidation of Fe catalysts, a bimetallic Fe–Mo catalyst was employed instead of pure Fe. Mo was partially converted to Mo2C by reacting with unreacted CO2, which effectively suppressed the oxidation of Fe, thereby stabilizing the active Fe phase. This transformation was further corroborated by XPS analysis, where the Mo 3d spectra exhibited an increased Mo2+ peak intensity, whereas the Fe 2p spectra showed a stronger metallic Fe signal, confirming that Mo incorporation inhibited Fe oxidation. However, excessive Mo loading resulted in the formation of multi-walled CNTs instead of single-walled CNTs, as evidenced by the reduced selectivity toward radial breathing modes in the Raman spectra and the broader diameter distribution observed in TEM measurements. These findings underscore the critical role of Mo in preserving Fe activity under oxidizing conditions and highlight the importance of optimizing its content, as an appropriate Mo level enables the selective synthesis of high-quality single-walled CNTs from CO2 via a dual-step tandem process.
catalyst oxidation / CNT / CO2 conversion / Mo2C / tandem process
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2026 The Author(s). Energy & Environmental Materials published by John Wiley & Sons Australia, Ltd on behalf of Zhengzhou University.
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