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2 results on '"CaFe2O4"'

1. Visible Light-Driven p-Type Semiconductor Gas Sensors Based on CaFe2O4 Nanoparticles

Author

Qomaruddin, Olga Casals, Andris Šutka, Tony Granz, Andreas Waag, Hutomo Suryo Wasisto, Joan Daniel Prades, and Cristian Fàbrega

Subjects
calcium iron oxides, cafe2o4, led, metal oxides (mox), p-type gas sensors, room temperature, visible light activation, Chemical technology, TP1-1185
Abstract

In this work, we present conductometric gas sensors based on p-type calcium iron oxide (CaFe2O4) nanoparticles. CaFe2O4 is a metal oxide (MOx) with a bandgap around 1.9 eV making it a suitable candidate for visible light-activated gas sensors. Our gas sensors were tested under a reducing gas (i.e., ethanol) by illuminating them with different light-emitting diode (LED) wavelengths (i.e., 465−640 nm). Regardless of their inferior response compared to the thermally activated counterparts, the developed sensors have shown their ability to detect ethanol down to 100 ppm in a reversible way and solely with the energy provided by an LED. The highest response was reached using a blue LED (465 nm) activation. Despite some responses found even in dark conditions, it was demonstrated that upon illumination the recovery after the ethanol exposure was improved, showing that the energy provided by the LEDs is sufficient to activate the desorption process between the ethanol and the CaFe2O4 surface.

Published
2020
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2. Preparation and Optical Properties of PVDF-CaFe2O4 Polymer Nanocomposite Films

Author

Sultan Alhassan, Majed Alshammari, Khulaif Alshammari, Turki Alotaibi, Alhulw H. Alshammari, Yasir Fawaz, Taha Abdel Mohaymen Taha, and Mohamed Henini

Subjects
nanocomposites, PVDF polymer, CaFe2O4, Polymers and Plastics, General Chemistry
Abstract

In this work, a synthesis technique for highly homogeneous PVDF-CaFe2O4 polymer films direct from solution was developed. The structural characterizations were conducted using XRD, FTIR, and ESEM experimental techniques. The XRD characteristic peaks of CaFe2O4 nanoparticles revealed a polycrystalline structure. The average crystallite size for CaFe2O4 was calculated to be 17.0 nm. ESEM micrographs of PVDF nanocomposites containing 0.0, 0.25, 0.75, and 1.0 wt% of CaFe2O4 showed smooth surface topography. The direct Edir and indirect Eind band gap energies for the PVDF-CaFe2O4 nanocomposites were decreased with the additions of 0.0–1.0 wt% CaFe2O4. In addition, the refractive index (n0) increased from 3.38 to 10.36, and energy gaps (Eg) decreased from 5.50 to 4.95 eV. The nonlinear refractive index (n2) for the PVDF-CaFe2O4 nanocomposites was improved with the addition of CaFe2O4 nanoparticles, exceeding those reported in the literature for PVC, PVA, and PMMA nanocomposites. Therefore, the PVDF-CaFe2O4 nanocomposites are expected to take the lead in optoelectronic applications because of their unusual optical properties.

Published
2023
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