Rational H₂ Partial Pressure over Nickel/Ceria Crystal Enables Efficient and Durable Wide‐Temperature‐Zone Air‐Level CO₂ Methanation

On the way to carbon neutrality, directly catalyzing atmospheric CO₂ into high-value chemicals might be an effective approach to mitigate the negative impacts of rising airborne CO₂ concentrations. Here, we pioneer the investigation of the influence of the H₂/CO₂ partial pressure ratio (PPR) on air-level CO₂ methanation. Using Ni/CeO₂ as a case catalyst, increasing H₂/CO₂ PPR significantly improves low-temperature CO₂ conversion and high-temperature CH₄ selectivity, i. e., from 10 of H₂/CO₂ PPR on, CO₂ is completely methanized at 250 °C, and nearly 100 % CH₄ selectivity is achieved at 400 °C. 100-hour stability tests demonstrate the practical application potential of Ni/CeO₂ at 250 °C and 400 °C. In-situ DRIFTS reveal that reinforced formate pathway by increasing H₂/CO₂ PPR is responsible for the high CH₄ yield. In contrast, even though the CO pathway dominated CO₂ conversion on Ni is enhanced by rising H₂/CO₂ PPR, but at a high reaction temperature, the promoted CO desorption still leads to lower CH₄ selectivity. This work offers deep insights into the direct air-level CO₂ resourceization, contributing to the achievement of airborne CO₂ reductions.