High-performance and cost-effective NO_2-based gas sensors of metal oxides that operate at room temperature (RT) are of immense importance. A design strategy of a three-dimensional hierarchical nanostructure formed by the combination of two-dimensional (2D) graphitic carbon nitride (g-C₃N₄) nanosheets that are decorated with nickel oxide (NiO) nanosheets (NSs) via a facile hydrothermal method has been investigated here. The as-fabricated nanocomposite (g-C₃N₄/NiO, NiCN) sensor showed high sensing performance toward NO₂ gas with a maximal sensitivity of 25.4 to 50 ppm, fast response time (0.53 s) and quick recovery time (25.06 s). Furthermore, the optimized nanocomposite structure (NiCN-2) showed long-term stability (12 weeks), a low detection limit (10 ppb) and higher selectivity toward NO₂ gas at RT. This exceptional sensing performance of the NiCN-2 sensor toward NO₂ might be attributed to the unique 3D hierarchical structures with a large specific surface area (146.8 m²·g⁻¹), highly porous surface, abundant defect sites, extended internal charge transfer between the p-n heterojunction and high adsorption and transportation rates in the nanocomposite sensor. This study provides a new strategy for the formation of heterostructures between metal oxides and g-C₃N₄ for excellent gas sensitivity and addresses the fabrication of highly potent gas sensors.

在室温（RT）下运行的高性能，经济高效的基于NO ₂的金属氧化物气体传感器至关重要。由二维（2D）石墨化碳氮化物（gC ₃ N ₄）纳米片组合而成的三维分层纳米结构的设计策略，该纳米碳片通过便捷的水热方法装饰有氧化镍（NiO）纳米片（NSs）。在这里进行了调查。制成的纳米复合材料（gC ₃ N ₄ / NiO，NiCN）传感器显示出对NO _2的高感测性能气体的最大灵敏度为25.4至50 ppm，响应时间短（0.53 s），恢复时间短（25.06 s）。此外，优化的纳米复合结构（NiCN-2）表现出长期稳定性（12周），低检测限（10 ppb）和在室温下对NO ₂气体的选择性更高。NiCN-2传感器对NO _2的出色感测性能可能归因于具有大比表面积（146.8 m ² ·g ^-1）的独特3D分层结构），高度多孔的表面，丰富的缺陷部位，pn异质结之间扩展的内部电荷转移以及纳米复合传感器中的高吸附和传输速率。这项研究为在金属氧化物和gC ₃ N ₄之间形成异质结构提供了一种新的策略，以实现出色的气体敏感性，并解决了高效气体传感器的制造问题。