Atmosphere-sensitive photoluminescence of Co_xFe_3−xO₄metal oxide nanoparticles

Abstract

CoxFe3−xO4 (0.4 < x < 2.5) nanoparticles show a broad green emission induced by surface OH-groups with a lower stability regarding UV-photoinduced dehydroxylation on Fe-rich (x ≤ 1.6) nanoparticles.

Monitoring Catalytic 2-Propanol Oxidation over Co3O4 Nanowires via In Situ Photoluminescence Spectroscopy

“…A broad green emission was observed in studies of metal oxides such as Al 2 O 3 or Co x Fe 3−x O 4 as well and assigned to OH groups bound to the catalyst's surface. 24,32,33 TPO experiments in a gas phase reactor coupled with a micro gas chromatograph show water formation upon heating in the gas flow and thereby verify a decrease in surface coverage with water/OH groups up to a temperature of ∼200 °C (Figure S2). Above this temperature the water content in the gas flow hardly changes.…”

“…An optical spectroscopy tool, which has so far hardly been used for in situ investigations of catalytic gas phase processes (only a few studies on photocatalysis exist , ), is photoluminescence (PL) spectroscopy. With PL spectroscopy, electronic transitions of metal oxide catalysts, , active surface sites, , or molecules at the metal oxide gas phase interface , can be excited and detected. PL spectroscopy shows a high sensitivity to smallest concentrations, even for fluorescent molecules with low quantum yields .…”