S, N Co-Doped Carbon Dot-Functionalized WO3Nanostructures for NO2and H2S Detection

Abstract

This paper reports the synthesis of a S, N co-doped carbon dot (C-dot)-functionalized WO3(C(S, N)-WO3) nanostructure via a hydrothermal method, which exhibits ultrasensitivity for NO2at the ppb level and H2S at the ppm level along with remarkable selectivity. The WO3morphology is optimized by varying the pH (1.5-3.5) of the solution. Characterization results reveal that the surface morphology at pH 3 is superior for producing uniform nanoneedle nanostructures with high sensitivity toward NO2and H2S. To further enhance the sensitivity and selectivity of WO3nanoneedles, the effect of mixing of C-dots into WO3is investigated systematically. The optimized weight of C-dots in the C(S, N)-WO3composite is 10 mg, which exhibits sensitivity values of 2.2 to 250 ppb for NO2and 29.5 to 100 ppm for H2S. The C(S, N)-WO3composite material shows the highest sensitivity at an optimum substrate temperature of 150 °C, without an obvious influence of humidity up to 50% relative humidity. The limit of detection of the composite sensor is 250 ppb NO2along with excellent repeatability and good long-Term stability. © 2022 American Chemical Society. All rights reserved.