Zinc oxide-copper sulfide semiconductor nano-heterostructure for low-level electrochemical detection of 4-nitrotoluene

•Hydrothermal and microwave assisted synthesis of ZnO-CuS nano-heterostructure (NHS).•Nanocomposite consist of CuS nanoparticles adhered on 2-D ZnO nanosheets.•Electrochemical detection of 4-nitrotoluene with ZnO-CuS NHS/Au sensor.•1.87 µA (µM)−1 cm2 sensitivity, 0.769 to 38 µM LDR, and LOD of 77.5 nM.•ZnO-CuS NHS/Au sensor exhibited good sensing activity in real water. 4-nitrotoluene (4-NT) is an extensively used chemical, and a highly hazardous water contaminant. Exploring new materials for development of efficient 4-NT sensors is extremely important. Hence, this work reports the development of novel ZnO-CuS nano-heterostructure (NHS) using cost-effective and easy synthesis procedure. The well-characterized ZnO-CuS NHS were utilized for the fabrication of ZnO-CuS NHS/gold (Au) sensor for 4-NT detection using voltammetric techniques (CV and DPV). The ZnO-CuS NHS 2 (ZnO:CuS = 2:1)/Au sensor offered significant electrical response for 4-NT reduction in neutral pH samples. ZnO-CuS NHS 2/Au electrode demonstrated linear response in 0.769–38.00 µM detection range, a nanomolar detection limit of 77.5 nM, and good sensitivity of 1.87 µA (µM)−1 cm2. Moreover, reusable, reproducible and selective sensing performance was shown by the ZnO-CuS NHS 2/Au sensor, and the sensing efficiency was validated in real samples as well. The synergy between the n-type ZnO and p-type CuS, resulted in amelioration of the electrocatalytic activity of the NHS, as compared to individual ZnO and CuS nanostructures. Phytotoxicity and biocompatibility studies assured the low-toxicity of ZnO-CuS NHS 2. ZnO-CuS NHS 2/Au sensor had an easy and rapid development procedure, and provided substantially low detection limit for 4-NT compared with many previously developed 4-NT sensors. Herein devised efficient ZnO-CuS NHS 2/Au electrochemical sensor for 4-NT detection is cost-efficient with the prospective of being scaled-up for point-of-care sensors required for monitoring 4-NT from environmental samples. [Display omitted]