Designing of three-dimensional hierarchical Co₃O₄@g-C₃N₄ nanostructure with highest surface area for sensitive detection of NO₂ gas at room temperature

The increasing demand for advance gas-sensing materials to monitor the NO₂ gas in environment at low-temperature has gain immense attention. So for this-purpose, in the present research-work, we have fabricated the three dimensional (3D) hierarchical nanostructure by the reaction of two dimensional (2D) Co₃O₄ nanosheets (NSs) with 2D g-C₃N₄ nanosheets (Co₃O₄@g-C₃N₄), via a simple hydrothermal synthetic method. The prepared hybrid nanostructure CNCO−2 sensor exhibited extensive sensing performances with excellent sensing response, fast response-recovery time of (29.4, 0.53s and 22.7 s) towards 50 ppm NO₂ gas at RT. The sensor manifest lowest limit of detection (0.01 ppm or 10-ppb), with outstanding recycling capacity of (10-cycles) having almost same response and recovery time. Further, the sensor also shows prominent stability and reproducibility of (10-weeks), with superior selectivity towards NO₂ gas as compared to other interfering gases. Thus, these impressive sensing properties of CNCO-2 sensor might be related to its 3D hierarchical structure with strong heterojunction layers by layers morphology, large surface area, powerful p-n synergism and exposed active sites, which not only helps in the large adsorption of gas molecules, but also facilitate in rich electron mobility across the hybrid nanostructure. This research work will open a new window to strengthen the effect of hetero-structure formation between Co₃O₄ and g-C₃N₄ NSs, for effective NO₂ gas sensing in future.