Facile preparation of N-S co-doped graphene quantum dots (GQDs) from graphite waste for efficient humidity sensing

Abstract

In this work, graphene quantum dots (GQDs) were prepared from Graphitic waste. The resulting GQDs were evaluated for the potential application for resistive humidity sensors. The resistive humidity sensors were fabricated on the pre-patterned interdigital ITO electrodes using the three different concentrations (2.5, 5.0, and 10 mg) of GQDs in DMF. The GQDs films were deposited using the spin coating technique. The GQDs (10 mg/ml) based impedance sensors showed good sensitivity and lowered hysteresis as compared to the other ratios (2.5 and 5 mg) of the GQDs. The maximum calculated hysteresis of the GQDs (10 mg) based humidity sensor is around 2.2 % at 30%RH, and the minimum calculated hysteresis of the GQDs (10 mg/ml) based humidity sensor is approximately 0.79 % at 60 %RH. The response and recovery time found to be 15 s and 55 s, respectively. The interesting humidity-dependent resistive properties of these prepared GQDs make them promising for potential application in humidity sensing.