It is challenging to elucidate the mechanism of CO₂ methanation reaction over nickel-based catalysts and precisely tune the kinetics of rate-determining-step. In this work, we propose a strategy to engineer the oxygen vacancies of nickel-based catalysts for enhanced CO₂ methanation. A Y₂O₃-promoted NiO-CeO₂ catalyst is prepared and found to exhibit an outstanding methanation activity that is up to three folds higher than NiO-CeO₂ and six folds higher than NiO-Y₂O₃ at mild reaction temperatures (<300 °C). We demonstrate both theoretically and experimentally that the introduction of Y₂O₃ to CeO₂ greatly facilitates the generation of surface oxygen vacancies during the reaction. Using spectrokinetics analysis, we further revealed that these sites promote the direct dissociation of CO₂, which is kinetically more favorable than the associative route. Thus, it dramatically improved the CO₂ methanation activity. The vacancy engineering strategy will potentially guide the rational design of a broad range of heterogeneous catalysts for CO₂ hydrogenation.

阐明在镍基催化剂上进行CO ₂甲烷化反应的机理并精确调整速率确定步骤的动力学是一项挑战。在这项工作中，我们提出了一种策略来设计镍基催化剂的氧空位以增强CO ₂甲烷化。制备了AY ₂ O ₃促进的NiO-CeO ₂催化剂，发现在适度的反应温度下，其甲烷化活性优异，比NiO-CeO ₂高三倍，比NiO-Y ₂ O ₃高六倍（< 300°C）。我们在理论和实验上都证明了Y ₂ O ₃的引入CeO _2的浓度极大地促进了反应过程中表面氧空位的产生。使用分光动力学分析，我们进一步揭示了这些位点促进了CO ₂的直接离解，这在动力学上比缔合途径更有利。因此，它显着提高了CO _2的甲烷化活性。空缺工程策略可能会指导合理设计各种用于CO ₂加氢的非均相催化剂。