Ni/CeO₂ is considered as a potentially efficient catalyst for CO₂ methanation. Herein, all possible reaction pathways of CO₂ methanation were investigated by the first-principles calculations based on density functional theory to uncover the intrinsic reaction mechanism over Ni/CeO₂ catalyst. Theoretical analysis results indicate that the strong metal-support interaction between Ni nanoparticle and CeO₂ support is closely associated with the transfer and accumulation of electrons towards the interface. Ni nanocluster on Ni/CeO₂ catalyst is the most active adsorption and activation site of CO₂ molecule. CO₂ methanation over Ni/CeO₂ catalyst is mainly governed by the RWGS + CO-hydro pathway, rather than the pathways of formate formation and direct CO bond cleavage. The main reaction channel of CO₂ methanation is CO₂* → HOCO* → CO* → HCO* → H₂CO* → CH₂* → CH₃* → CH₄*. H-assisted CO bond breakage of H₂CO* plays a critical role in CO₂ methanation, and is the rate-limiting step of RWGS + CO-hydro pathway. The optimal pathway and rate-limiting step of CO₂ methanation are altered in the presence of CeO₂. A complete reaction network is proposed for further understanding the molecular-level reduction mechanism of CO₂ hydrogenation to methane on Ni/CeO₂ catalyst.

Ni / CeO ₂被认为是用于CO ₂甲烷化的潜在有效催化剂。在此，通过基于密度泛函理论的第一性原理计算，研究了所有可能的CO ₂甲烷化反应途径，以揭示Ni / CeO ₂催化剂的内在反应机理。理论分析结果表明，Ni纳米颗粒与CeO ₂载体之间的强金属-载体相互作用与电子向界面的转移和积累密切相关。Ni / CeO ₂催化剂上的Ni纳米簇是CO ₂分子最活跃的吸附和活化位点。Ni / CeO上的CO ₂甲烷化₂催化剂主要由RWGS + CO-氢途径控制，而不是甲酸形成和直接C O键裂解的途径。CO ₂甲烷化的主要反应通道为CO ₂ *→HOCO *→CO *→HCO *→H ₂ CO *→CH ₂ *→CH ₃ *→CH ₄ *。H ₂ CO *的H辅助C O键断裂在CO ₂甲烷化中起关键作用，并且是RWGS + CO-水途径的限速步骤。CeO ₂的存在改变了CO ₂甲烷化的最佳途径和限速步骤。为了进一步理解Ni / CeO ₂催化剂上CO ₂加氢成甲烷的分子级还原机理，提出了一个完整的反应网络。