Oxygen vacancies in Ru/TiO2 - drivers of low-temperature CO2 methanation assessed by multimodal operando spectroscopy

Sebastian Cisneros; Ali Abdel-Mageed; Jawaher Mosrati; Stephan Bartling; Nils Rockstroh; Hanan Atia; Hayder Abed; Jabor Rabeah; Angelika Brückner

doi:10.1016/j.isci.2022.103886

Oxygen vacancies in Ru/TiO₂ - drivers of low-temperature CO₂ methanation assessed by multimodal operando spectroscopy

iScience. 2022 Feb 8;25(3):103886. doi: 10.1016/j.isci.2022.103886. eCollection 2022 Mar 18.

Authors

Sebastian Cisneros¹, Ali Abdel-Mageed^{1

2}, Jawaher Mosrati^{1

3}, Stephan Bartling¹, Nils Rockstroh¹, Hanan Atia¹, Hayder Abed¹, Jabor Rabeah¹, Angelika Brückner^{1

4}

Affiliations

¹ Leibniz-Institut für Katalyse, Albert-Einstein-Str. 29A, 18059 Rostock, Germany.
² Department of Chemistry, Faculty of Science, Cairo University, Giza 12613, Egypt.
³ Laboratoire de chimie des matériaux et catalyse, Département de chimie, Faculté des sciences de Tunis, Université de Tunis el Manar, Tunis 1092, Tunisie.
⁴ Department Life, Light and Matter, University of Rostock, Albert-Einstein-Str. 25, 18059 Rostock, Germany.

Abstract

Hydrogenation of CO₂ is very attractive for transforming this greenhouse gas into valuable high energy density compounds. In this work, we developed a highly active and stable Ru/TiO₂ catalyst for CO₂ methanation prepared by a solgel method that revealed much higher activity in methanation of CO₂ (ca. 4-14 times higher turnover frequencies at 140-210°C) than state-of-the-art Ru/TiO₂ catalysts and a control sample prepared by wetness impregnation. This is attributed to a high concentration of O-vacancies, inherent to the solgel methodology, which play a dual role for 1) activation of CO₂ and 2) transfer of electrons to interfacial Ru sites as evident from operando DRIFTS and in situ EPR investigations. These results suggest that charge transfer from O-vacancies to interfacial Ru sites and subsequent electron donation from filled metal d-orbitals to antibonding orbitals of adsorbed CO are decisive factors in boosting the CO₂ methanation activity.

Keywords: Catalysis; Chemistry; Inorganic chemistry.