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<p>Oxygen vacancies are often considered the active sites for CO<sub>2</sub> conversion, but their engineering to enhance activity and stability has been scarcely investigated, especially at high reaction tempeture (≥600 °C) or under severe stressing conditions (i.e., in presence of H<sub>2</sub>S). We demonstrate that oxygen vacancies in defective MgO nanocrystals (less than 20 nanometres) can be significantly promoted by the addition of atomically dispersed Ce atoms anchored at these defective MgO sites. These catalysts combine high performance in CO<sub>2</sub> conversion with exceptional stability even in the presence of 300 ppm H<sub>2</sub>S. For a loading &lt;2 wt%, the Ce atoms are exclusively present as isolated species coordinated to oxygen-defective sites of MgO nanocrystals. These Ce single atoms promote the formation of these defects and facilitate the adsorption of CO<sub>2</sub>, enhancing the activation of H<sub>2</sub> molecules, but do not play a role alone as single-atom catalysts. Extensive mechanistic studies, chemical kinetics and theoretical modelling prove that the single-atom-assisted oxygen vacancies (SA-O<sub>v</sub>) enables the high catalytic performance and stability, thereby opening new avenues for catalyst design.</p>

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Single Ce atom-assisted oxygen vacancies as active and stable sites for CO2 conversion

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月15日

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  • Shiyan Li,
  • Na Li,
  • Tian Qin,
  • Zhanglong Guo,
  • Yuan Lyu,
  • Riguang Zhang,
  • Xi Liu,
  • Liwei Chen,
  • Siglinda Perathoner,
  • Gabriele Centi,
  • Yuefeng Liu

摘要

Oxygen vacancies are often considered the active sites for CO2 conversion, but their engineering to enhance activity and stability has been scarcely investigated, especially at high reaction tempeture (≥600 °C) or under severe stressing conditions (i.e., in presence of H2S). We demonstrate that oxygen vacancies in defective MgO nanocrystals (less than 20 nanometres) can be significantly promoted by the addition of atomically dispersed Ce atoms anchored at these defective MgO sites. These catalysts combine high performance in CO2 conversion with exceptional stability even in the presence of 300 ppm H2S. For a loading <2 wt%, the Ce atoms are exclusively present as isolated species coordinated to oxygen-defective sites of MgO nanocrystals. These Ce single atoms promote the formation of these defects and facilitate the adsorption of CO2, enhancing the activation of H2 molecules, but do not play a role alone as single-atom catalysts. Extensive mechanistic studies, chemical kinetics and theoretical modelling prove that the single-atom-assisted oxygen vacancies (SA-Ov) enables the high catalytic performance and stability, thereby opening new avenues for catalyst design.