Hydrothermal synthesis and characterization under dynamic conditions of cobalt oxide nanoparticles supported over magnesium oxide nano-plates
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Division
Here, a nano-catalyst comprised of oxidized Co NPs supported on MgO nano-plates was synthesized via a hydrothermal co-precipitation strategy and calcination in O2 and subsequently in H2 at 250 °C. Spectro-microscopy characterization was performed by scanning transmission electron microscopy, electron energy loss spectroscopy and scanning X-ray transmission microscopy. Surface measurements under H2 and H2 + CO atmospheres were obtained by ambient pressure X-ray photoelectron spectroscopy and in situ X-ray absorption spectroscopy in the 225–480 °C range. These measurements at the atomic and microscopic levels demonstrated that the oxidized Co nanoparticles uniformly decorated the MgO nano-plates. The surfaces are enriched with Co, and with a mixture of Co(OH)2 and CoO under H2 and H2 + CO atmospheres. Under a H2 atmosphere, the outermost surfaces were composed of (lattice) O2-, CO32- and OH-. No inorganic carbonates were observed in the bulk. Chemisorbed CO, likely on the oxidized Co surfaces, was observed at the expense of O2- under 300 mTorr H2 + CO (2:1) at 225 °C. Gas phase CO2 was detected under 32 Torr H2 + CO (2:1) at 225 °C upon prolonged reaction time, and was attributed to a surface chemical reaction between O2- and chemisorbed CO. Furthermore, sp3 like carbon species were detected on the otherwise carbon free surface in H2 + CO, which remained on the surface under the subsequent reaction conditions. The formation of sp3 like hydrocarbons was ascribed to a surface catalytic reaction between the chemisorbed CO and OH- as the apparent hydrogen source.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division
- Grant/Contract Number:
- AC02-05CH11231
- OSTI ID:
- 1464133
- Journal Information:
- Dalton Transactions, Vol. 45, Issue 24; Related Information: © 2016 The Royal Society of Chemistry.; ISSN 1477-9226
- Publisher:
- Royal Society of ChemistryCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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