This work reports a facile glycerol-assisted solvothermal method for synthesizing hierarchical three-dimensional (3D) wool-ball-like zinc oxide (ZnO) nanostructures and their subsequent modifications with multi-walled carbon nanotubes (MWCNTs) as modifiers for achieving sensitive and selective detection of toxic sulfur dioxide (SO₂) gas. Structurally, the as-synthesized 3D wool-ball-like ZnO is assembled of two-dimensional (2D) plate-like structures, which themselves are arranged by numerous small nanoparticles. Furthermore, in this work we observed an interesting new phenomenon in which when a high concentration of MWCNTs is introduced, many small nanorods grew on the surface of the plate-like structures which assemble the 3D wool-ball-like ZnO nanostructures. When evaluated for SO₂ detection, the ZnO/MWCNTs (10:1) composite (ZnO:MWCNTs = 10:1) shows a high response of 220.8 to 70 ppm of SO₂ gas (approximately three times higher than the response of pure wool-ball-like ZnO) at an optimum operating temperature of 300 °C. Additionally, the composite also displays good stability and selectivity to SO₂ with the response to 50 ppm of SO₂ being 7–14 times higher than the responses to other tested gases at a similar concentration. The excellent sensing performance of the wool-ball-like ZnO/MWCNTs (10:1) composite is mainly attributed to: (i) the formation of p-n heterojunctions at the ZnO/MWCNTs interfaces, which greatly enhance the resistance changes upon exposure to SO₂ gas and (ii) the increased amount of adsorption sites for O₂ and SO₂ gas molecules owing to the larger surface area of the composite and defects sites generated by the functionalization process of MWCNTs.

这项工作报告了一种简便的甘油辅助溶剂热法，用于合成分层的三维（3D）毛球状氧化锌（ZnO）纳米结构及其随后的修饰，以多壁碳纳米管（MWCNT）为修饰剂，以实现敏感和选择性检测有毒的二氧化硫（SO ₂）气体。在结构上，合成后的3D羊毛球状ZnO由二维（2D）板状结构组装而成，这些结构本身由许多小的纳米颗粒排列而成。此外，在这项工作中，我们观察到一个有趣的新现象：当引入高浓度的MWCNT时，许多小的纳米棒在组装3D毛球状ZnO纳米结构的板状结构的表面上生长。评估SO _2时检测发现，ZnO / MWCNTs（10：1）复合材料（ZnO：MWCNTs = 10：1）表现出220.8至70 ppm的SO ₂气体的高响应（大约是纯羊毛球状ZnO的响应的三倍） ）的最佳工作温度为300°C。此外，该复合材料还对SO ₂表现出良好的稳定性和选择性，对50 ppm SO ₂的响应比对其他浓度相同的测试气体的响应高7-14倍。羊毛球状ZnO / MWCNTs（10：1）复合材料的出色传感性能主要归因于：（i）在ZnO / MWCNTs界面处形成p - n异质结，这大大增强了暴露时的电阻变化到SO ₂气体和（ii）由于复合材料的表面积较大以及MWCNTs的官能化过程产生的缺陷部位，导致O ₂和SO ₂气体分子的吸附部位数量增加。