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Resolving the Effect of Oxygen Vacancies on Co Nanostructures Using Soft XAS/X-PEEM

Qiu, Chengwu; Odarchenko, Yaroslav; Meng, Qingwei; Xu, Shaojun; Lezcano-Gonzalez, Ines; Olalde-Velasco, Paul; Maccherozzi, Francesco; ... Beale, Andrew M; + view all (2022) Resolving the Effect of Oxygen Vacancies on Co Nanostructures Using Soft XAS/X-PEEM. ACS Catalysis pp. 9125-9134. 10.1021/acscatal.2c00611. Green open access

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Abstract

Improving both the extent of metallic Co nanoparticle (Co NP) formation and their stability is necessary to ensure good catalytic performance, particularly for Fischer–Tropsch synthesis (FTS). Here, we observe how the presence of surface oxygen vacancies (Ovac) on TiO2 can readily reduce individual Co3O4 NPs directly into CoO/Co0 in the freshly prepared sample by using a combination of X-ray photoemission electron microscopy (X-PEEM) coupled with soft X-ray absorption spectroscopy. The Ovac are particularly good at reducing the edge of the NPs as opposed to their center, leading to smaller particles being more reduced than larger ones. We then show how further reduction (and Ovac consumption) is achieved during heating in H2/syngas (H2 + CO) and reveal that Ovac also prevents total reoxidation of Co NPs in syngas, particularly the smallest (∼8 nm) particles, thus maintaining the presence of metallic Co, potentially improving catalyst performance.

Type: Article
Title: Resolving the Effect of Oxygen Vacancies on Co Nanostructures Using Soft XAS/X-PEEM
Open access status: An open access version is available from UCL Discovery
DOI: 10.1021/acscatal.2c00611
Publisher version: https://doi.org/10.1021/acscatal.2c00611
Language: English
Additional information: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/)
Keywords: oxygen vacancies; TiO2; cobalt; metal-support interaction; nanoparticle size; XAS/X-PEEM
UCL classification: UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL
URI: https://discovery.ucl.ac.uk/id/eprint/10152661
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