Comparative Evaluation of Chemically and Green-Synthesized Silica-Modified CeO₂ Nanostructures for Time-Dependent Room-Temperature Ammonia Sensing

Danish Majeed; Syeda Sarah Zehra Zaidi; Syed Muhammad Mohsin; Muhammad Sajid Ali Asghar; Asad A. Zaidi

doi:10.36561/ING.30.10

Authors

Danish Majeed NED University of Engineering and Technology, Pakistán https://orcid.org/0009-0006-1005-8443
Syeda Sarah Zehra Zaidi NED University of Engineering and Technology, Pakistán https://orcid.org/0009-0005-1762-6530
Syed Muhammad Mohsin NED University of Engineering and Technology, Pakistán https://orcid.org/0009-0006-0799-7925
Muhammad Sajid Ali Asghar NED University of Engineering and Technology, Pakistán https://orcid.org/0000-0002-4551-1299
Asad A. Zaidi Islamic University of Madinah, Arabia Saudita https://orcid.org/0000-0001-5457-5684

DOI:

https://doi.org/10.36561/ING.30.10

Keywords:

Silica nanoparticles, Green synthesis, Cerium oxide, Chemiresistive ammonia sensor, Room-temperature gas sensing

Abstract

Silica nanoparticles were synthesized via two distinct routes – a conventional chemical process and a sustainable green approach using sugarcane bagasse – and incorporated into cerium oxide (CeO₂) nanostructures for comparative evaluation as room-temperature ammonia (NH₃) gas sensors. The chemical route yielded silica by precipitating sodium silicate, whereas the green route extracted bio-silica from agricultural waste (sugarcane bagasse). Both silica types were integrated with CeO₂ through a precipitation/coating method to form silica–modified CeO₂ composite nanoparticles, which were fabricated into chemiresistive sensor devices. Structural characterization by scanning electron microscopy (SEM) revealed an elongated, rod-like CeO₂ morphology distributed in a silica-rich matrix, and energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of Si, Ce, and O, indicating successful composite formation. Gas sensing tests demonstrated that all sensors responded to NH₃ at room temperature, with an initial rapid decrease in resistance upon NH₃ exposure. The gas response (defined as change in resistance ratio) reached over 600% within seconds of exposure for fresh sensors and progressively increased with continued exposure up to 10 min. After 15 min of continuous NH₃, however, the sensor response became negative (~–11%), suggesting surface saturation or irreversible adsorption of NH₃ on the active sites. These results suggest that sugarcane bagasse-derived silica can produce NH₃ response trends broadly comparable to chemically synthesized silica under the present experimental conditions. However, a full statistical comparison using multiple devices is still required to confirm equivalent performance. The incorporation of green-sourced silica thus provides an environmentally friendly pathway to high-performance, room-temperature gas sensors, though calibration and long-term stability tests are needed for further development.

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