Oxygen vacancy engineering in hollow confined Ni/CeO2 nanofibers for steering intermediates in CO2 methanation

Uniformly dispersed and confined hm-Ni/CeO 2 catalysts were synthesized for CO 2 hydrogenation. • The hm-Ni/CeO 2 outperforms its mesoporous counterpart, reaching 84.56% CO 2 conversion at 325 °C with good stability. • The hm-Ni/CeO 2 possesses abundant oxygen vacancies and a higher Ni distribution. • In-situ DRIFTS and DFT studies confirmed that the enhanced methanation performance originates from oxygen vacancies promoting the formate pathway. Confined structure catalysts are widely dedicated to boosting catalytic activity and stability , while controlling their micro-environment and intermediate species remains a challenge. Herein, mesoporous (m-Ni/CeO 2 ) and hollow mesoporous (hm-Ni/CeO 2 ) catalysts were prepared via electrospinning and evaluated for CO 2 hydrogenation to methane. The hm-Ni/CeO 2 catalyst exhibits superior performance, achieving 84.56% CO 2 conversion at 325 °C, along with enhanced low-temperature activity compared to the m-Ni/CeO 2 catalyst. Characterizations revealed that the hm-Ni/CeO 2 catalyst possesses a higher oxygen vacancies and improved Ni dispersion, thereby enhancing metal-support interaction. Furthermore, synchrotron radiation and in-situ DRIFTS confirmed that the hm-Ni/CeO 2 catalyst facilitates the formation of bridging bidentate formate intermediates, which are more favorable for CH 4 production. Finally, DFT verified the predominance of the formate pathway and revealed that oxygen vacancies substantially enhance the reactivity of CO 2 methanation. This work not only develops a novel synthetic strategy for confined porous catalysts but also provides fundamental insights into the role of oxygen vacancies in CO 2 hydrogenation. Download: Download high-res image (203KB) Download: Download full-size image