Bikogiannakis, Alexandros K., Drivas, Charalampos, Lymperi, Andriana, Isaacs, Mark A., Kordouli, Eleana, Katsaounis, Alexandros, Taylor, Martin J. and Kyriakou, Georgios
2026.
Defect - dispersion synergy and single-atom stabilization in Ru/TiO2 catalysts for CO2 hydrogenation.
Chemical Engineering Journal
547
, 180898.
10.1016/j.cej.2026.180898
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Abstract
Carbon dioxide (CO2) hydrogenation represents a central route for sustainable fuel production and carbon recycling, yet its efficiency is critically dependent on the structural and electronic properties of the catalyst. In practical heterogeneous systems prepared by conventional wet-chemical methods, a distribution of active sites, ranging from atomically dispersed species to subnanometric clusters and nanoparticles, typically coexist in the final catalyst. Here, we investigate how support defect engineering governs this distribution in Ru/TiO2 catalysts with varying metal loadings and oxidative pre-treatments. Comprehensive spectroscopic and imaging analyses, including XPS, HR-STEM, and XAS established a clear correlation between Ru structure and catalytic behavior. Critically low Ru loadings (0.2 wt%) induced a transition from metallic nanoparticles to highly dispersed and single atom species, while oxidative pretreatment generated RuO2 like domains. A fraction of isolated Ru atoms persisted, particularly on defect-rich TiO2, where oxygen vacancies act as anchoring sites, improving stability under redox conditions. Catalytic testing revealed that Ru dispersion and oxidation state jointly determine activity and selectivity: extended metallic Ru or oxidized Ru nanoparticles favor complete hydrogenation to CH4, whereas isolated Ru species promote CO formation via the reverse water–gas shift pathway. The coexistence of these Ru configurations is associated with enhanced low temperature activity, while defect engineered supports improve stability against deactivation. Defect engineering of TiO2 provides an effective strategy to stabilize atomically dispersed Ru and to balance nanoparticles and atomic species, offering a versatile strategy to tune CO2 hydrogenation performance and advance the design of Ru based catalysts for sustainable hydrogenation processes.
| Item Type: | Article |
|---|---|
| Date Type: | Publication |
| Status: | Published |
| Schools: | Schools > Physical, Chemical & Environmental Sciences Research Institutes & Centres > Cardiff Catalysis Institute (CCI) |
| Publisher: | Elsevier |
| ISSN: | 1385-8947 |
| Date of First Compliant Deposit: | 24 August 2026 |
| Date of Acceptance: | 17 August 2026 |
| Last Modified: | 02 Sep 2026 10:23 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/189133 |
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