Synthesis and study of reduced graphene oxide substituted Bismuth oxide composite towards humidity sensors

Abstract

This study investigates the characteristics and performance of a composite material comprising bismuth oxide (Bi₂O₃) and reduced graphene oxide (rGO) at varying concentrations. The diffraction pattern for un-substituted α-Bi2O3 nanoparticles (NPs) showed major reflections corresponding to rGO crystal faces, with calculated lattice parameters of a = 5.849 Å, b = 8.166 Å, and c = 7.510 Å. The substitution of α-Bi2O3 with rGO preserved the crystalline phase, and the material’s porosity increased with higher rGO concentrations, as verified by XRD and humidity testing. Notably, at a composition of 20% rGO (Bi 0.2), the composite demonstrated a significant reduction in resistance from 11 to 98% relative humidity (RH), showing an exponential decrease. The response time of the sensor was recorded at 9 s, with a recovery time of 12 s. The material exhibited exceptional humidity sensitivity, especially at higher rGO concentrations, making it highly suitable for humidity sensing applications. Furthermore, the sensor demonstrated high stability over a 60-day period, maintaining consistent performance. These findings highlight the potential of the Bi2O3-rGO composite for robust and reliable sensor applications under varying environmental conditions.