NTP-enhanced lattice oxygen activation in Ce-Co catalysts for low-temperature soot combustion

Soot emitted from diesel exhaust is the primary contributor to haze formation and elevated PM_2.5 levels. Catalytic diesel particulate filters (CDPF) are considered the most economical and feasible post-treatment technique for controlling soot elimination. During cold starts of diesel engines, exhaust temperatures remain low (100-200 °C), resulting in a substantial increase in pollutant emissions. However, currently available catalysts cannot reduce the ignition temperature below the exhaust temperature, because few catalysts can continuously provide sufficient amounts of reactive oxygen species at such low temperatures. Therefore, it is imperative to develop an effective low-temperature soot oxidation catalytic technology with a low energy demand and cost. NTP can enable the activation of surface-catalyzed reactions via high-energy electrons (1-10 eV) under mild conditions, overcoming the limitations of traditional thermal catalysis. Furthermore, it has the advantage of being able to generate various active oxygen species (e.g., O atoms, O₃, O^–, O₂^–, and OH radicals). Consequently, NTP may serve as a viable strategy to activate metal-oxygen bonds, thereby enhancing the reactivity of lattice oxygen in redox reactions.

Recently, a research team led by Prof. Zhen Zhao from China University of Petroleum (Beijing) and Shenyang Normal University, China fabricated Co-doped CeO₂ catalysts (Ce_1–xCo_xO_2-δ) and integrated the catalysts into NTP for catalytic soot combustion. This study confirms the dominant role of lattice oxygen in catalytic soot combustion over NTP-Ce_0.8Co_0.2O_2-δ at low temperatures. The results were published in Chinese Journal of Catalysis (DOI: 10.1016/S1872-2067(25)64775-9).

Ce_1-xCo_xO_2-δ catalysts with asymmetric Ce-O-Co structures were successfully prepared via a facile heteroatomic doping strategy. At 200 °C and 4.3 W (discharge power, P_dis), NTP-Ce_0.8Co_0.2O_2-δ achieved 96.9% soot conversion (X_C), 99.0% CO₂ selectivity (S(CO₂)), and a maximum energy conversion efficiency (E_max) of 14.7 g kWh^–1. Compared with previously reported results, NTP-Ce_0.8Co_0.2O_2–δ exhibits the highest S(CO₂) and E_max values. Remarkably, even without heating, X_C, E_max, and S(CO₂) reached 92.1%, 6.1 g kWh^–1, and 97.5%, respectively, at 6.3 W (P_dis). The results of characterization and theoretical calculation demonstrated that Co dopes into the CeO₂ crystal lattice and forms an asymmetric Ce–O–Co structure, making oxygen “easy come, easy go”, thereby enabling the rapid combustion of soot over NTP-Ce_0.8Co_0.2O_2-δ. This study highlights the great potential of NTP for activating lattice oxygen and provides valuable insights into the design of efficient NTP-adapted catalysts for oxidation reactions.

About the journal

Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top six journals in Applied Chemistry with a current SCI impact factor of 17.7. The Editors-in-Chief are Profs. Can Li and Tao Zhang.

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