Adsorption effect of NO 2 on ZnO (100 nm) nanowires, leading towards reduced reverse leakage current and voltage enhancement

Here, we report the adsorption effect of NO2 on ZnO (100 nm) nanowires. We have studied the effect of adsorbed NO2 molecules on ZnO nanowire-based energy harvester for an exposure time of 1, 2, 3, 4, 5 and 6 h in a sealed chamber at 50 ppm which yielded piezoelectric voltage of 543.6 mV, 834.6 mV, 1.071 V, 1.78 V, 1.969 V and 2.835 V, respectively. We have thoroughly investigated the behaviour of ZnO nanowires in the presence of NO2 and observed a maximum output piezoelectric voltage of 2.835 V with a power density 158.2 mW cm−2. This is the first time that ZnO-based piezoelectric energy harvester is being used for the voltage enhancement in the presence of NO2. We have used vertically integrated nanowire generator (VING) structure. X-ray diffraction pattern revealed the growth orientation of ZnO nanowires were along the c-axis from the substrate. ZnO nanowires were grown on indium tin oxide-coated polyethylene terephthalate substrates via a hydrothermal route. Surface morphology has been examined by scanning electron microscopy images and diameter of ZnO nanowires was found to be around 100 nm. Piezoelectric voltage has been generated by the VING by applying minute external force of ~50 nN. Periodic output voltage peaks were being measured by picoscope 5204.