Development of 2D CuO based chemiresistive sensors for detecting binary mixture of volatile organic compounds and investigation of the adsorption kinetics via Eley-Rideal mechanism

[Display omitted] •Two dimensional CuO nanomaterial was synthesized using a surfactant assisted hydrothermal method.•CuO nanoflakes based sensor was exhaustively tested for the five volatile organic compounds (VOCs) and their ten combinations of binary mixtures with three different concentrations of each VOC in the mixture.•An interesting observation was made regarding binary mixtures of VOCs: the sensor responses to these mixtures were approximately the sum of the responses to the individual VOCs in the mixture.•To comprehend the sensing mechanism of binary mixtures of VOCs, gas adsorption kinetics were investigated through the Eley-Rideal mechanism. The findings indicate that the kinetics of binary VOC mixtures align with the principles of the Eley-Rideal mechanism.•Detecting VOCs in binary mixtures is a crucial task. This was achieved by extracting features from the sensor data and employing the random forest machine learning algorithm for both data classification and quantification. Detection of mixture of volatile organic compounds (VOCs) and prediction of the individual components present in it plays a significant role in various applications arching from health care to environmental monitoring. In this research, CuO nanoflakes of thickness ∼ 35 nm, and direct and indirect bandgaps of 1.8 and 1.3 eV, respectively, were synthesized hydrothermally. Chemiresistive sensors fabricated using the CuO nanoflakes were tested for individual gases and all combinations of binary mixtures of five VOCs namely acetone, acetonitrile, isopropanol, methanol, and toluene at 300 °C which was found to be the optimum temperature of operation for all the five VOCs. The response of CuO was found to range from 58–140 %, 35–95 %, 23–98 %, 17–50 %, and 5–30 % for 25–75 ppm of toluene, methanol, isopropanol, acetonitrile, and acetone respectively. The response was found to be an addition of the responses of CuO to the two individual VOCs when the sensing layer was exposed to the mixture of two at 300 ℃. The adsorption kinetics of the metal oxide for mixture of gases is explained using the Eley-Rideal mechanism. Also, the random forest (RF) algorithm was employed to identify the individual VOCs and their respective concentrations just by taking inputs from the response transients of CuO nanoflakes to the binary mixtures of VOCs and was found to exhibit 93.8 % accuracy.