6–10 Jul 2026
University of the Western Cape
Africa/Johannesburg timezone
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CuO/Fe2O3 p-n heterostructures with Ag-functionalization for improved p-xylene and toluene sensing performance

7 Jul 2026, 15:40
20m
Lecture Hall GH1 (University of the Western Cape)

Lecture Hall GH1

University of the Western Cape

Oral Presentation Track A - Physics of Condensed Matter and Materials Physics of Condensed Matter and Materials

Speaker

Vuyani Sifunda (University of limpopo)

Description

Tremendous effort has been invested in the fabrication of nanomaterials for gas detection of volatile organic compounds (VOCs), such as acetone, methanol, ethanol, benzene, and toluene. These VOCs act as important medical biomarkers for various diseases, such as diabetes, lung cancer, asthma, and halitosis. In this study, pristine and Ag-loaded CuO/Fe2O3 p-n heterostructures were synthesized using a hydrothermal method. The structural, morphological, and optical properties were analysed. Powder X-ray diffraction patterns showing peaks from 30 to 75 for Cupric oxide (CuO) and 20 to 65 for Hematite (α-Fe2O3) confirmed the formation of a heterostructure. Surface analysis revealed a porous morphology consisting of irregular particles and cube-like structures, which is beneficial for gas diffusion. Optical studies demonstrated a reduction in the optical bandgap as the Ag-loading concentration increased on the CuO/Fe2O3 p-n heterostructures. From the gas-sensing perspective, when incorporating 0.75 wt% and 2 wt% of Ag, the CuO/Fe2O3 p-n heterostructure sensor displayed superior responses of 7.3 and 7.6 to 100 ppm C7H8 and C8H10, respectively. The superior sensing characteristic is attributed to the combined effects of p-n heterojunction barrier modulation and Ag-induced enhancement of oxygen adsorption and activation. The findings highlight the vital roles of noble-metal functionalization and heterostructure engineering in designing next-generation gas sensors.

Keywords: p-n heterojunction, volatile organic compounds (VOCs), next-generation gas sensors.

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Authors

David Motaung (University of the Free State) Hendrik Swart (University of the Free State) Katlego Morulane (University of Free State) R.E. Kroon (Department of Physics, University of the Free State) Vuyani Sifunda (University of limpopo)

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