Investigation of Inverse Nickel Supported Zirconia with Nano-Bulk Interfaces for CO₂ Hydrogenation by DFT...

The catalytic hydrogenation of carbon dioxide (CO₂) to methane (CH₄) represents a significant strategy for sustainable energy conversion, offering a potential solution for greenhouse gas utilization through the production of synthetic natural gas. However, this thermochemical process is confronted with numerous challenges that require further investigation. Guided by theoretical calculations, which revealed the potential superiority of the inverse-structured ZrO₂/Ni catalyst for CO₂ hydrogenation to CH₄, we synthesized both inverse ZrO₂/Ni and conventional Ni/ZrO₂ catalysts via the sol-gel method to experimentally validate these predictions. Consequently, inverse ZrO₂/Ni obtained a CO₂ conversion of 90.9% at 270 °C, while the Ni/ZrO₂ sample exhibited only 62.3% of CO₂ conversion. DFT calculations and the CO₂-TPD results demonstrated that the ZrO₂/Ni configuration exhibited stronger CO₂ adsorption capabilities. The XPS analysis further revealed a higher concentration of oxygen vacancies over the ZrO₂/Ni sample relative to that of the Ni/ZrO₂ catalyst, potentially accounting for its enhanced catalytic performance. Finally, both in situ DRIFTS measurements and DFT computational results consistently supported the formate pathway mechanism for the NiZr catalytic system.