Nitrogen-Doped Carbon Dots Induced Enhancement in CO 2 Sensing Response From ZnO-Porous Silicon Hybrid Structure

• Published in: Frontiers in chemistry Vol. 8; p. 291
• Main Authors: Ramos-Ramón, Jesús A, Bogireddy, Naveen K R, Giles Vieyra, Jorge Arturo, Karthik, Tangirala V K, Agarwal, Vivechana
• Format: Journal Article
• Language: English
• Published: Switzerland 2020
• Subjects: gas sensing; luminescence; porous silicon; carbon quantum dots; zinc oxide
• ISSN: 2296-2646; 2296-2646

In this study, we report a simple method for the fabrication of carbon dots sensitized zinc oxide-porous silicon (ZnO-pSi) hybrid structures for carbon dioxide (CO
) sensing. A micro-/nanostructured layer of ZnO is formed over electrochemically prepared pSi substrates using a simple chemical precipitation method. The hybrid structure was structurally and optically characterized using scanning electron microscopy, X-ray diffraction, fluorescence, and cathodoluminescence after the incorporation of hydrothermally prepared nitrogen-doped carbon dots (NCDs) by drop casting. With respect to the control sample, although all the devices show an enhancement in the sensing response in the presence of NCDs, the optimal concentration shows an increase of ~37% at an operating temperature of 200°C and a response time <30 s. The increment in the CO
-sensing response, upon the addition of NCDs, is attributed to an increase in CO
-oxygen species reactions on the ZnO surface due to an increment in the free electron density at the metal-semiconductor-type junction of NCD clusters and ZnO micro-/nanorods. A significant increase in the sensing response (~24%) at low operating temperature (100°C) opens the possibility of developing very large-scale integrable (VLSI), low operational cost gas sensors with easy fabrication methods and low-cost materials.