Co3O4-ZnO P-N Heterostructure Nanomaterials Film and its Enhanced Photoelectric Response to Visible Lights at Near Room Temperature

In this paper, Co3O4-ZnO nanomaterials with Co3O4 doping mass fractions of 0%, 2.13%, 4.13%, and 6.13% were prepared by sol-gel method. In order to explain and confirm the influence of the incorporation of Co3O4 on the surface morphology and gas sensitivity of ZnO at a relatively low gas concentration, additional studies such as XRD, XPS, SEM, EDS and UV-vis spectroscopy were performed. And its photoelectric response to 100 ppm acetone at near room temperature and visible light irradiation was studied. Due to the formation of P-N heterojunctions, the Co3O4-ZnO heterostructural nanoparticles has a highe response to low concentrations of acetone gas than undoped ZnO nanoparticles even at operating temperatures as low as 30ºC. The addition of Co3O4 improves the sensitivity and selectivity of ZnO thick films. The sensitivity of the 4.13wt% Co3O4-ZnO sample to 100 ppm acetone at a working temperature of 30ºC was 24.36. The light excitation effect was significantly enhanced. Under visible light irradiation, the sensitivity can reach 37.21. In addition, the Co3O4-ZnO P-N heterojunction model was combined with visible light excitation theory to further explore the mechanism of gas sensing reaction.

本文采用溶胶-凝胶法（sol-gel method）制备了Co₃O₄掺杂质量分数分别为0%、2.13%、4.13%及6.13%的Co₃O₄-ZnO纳米材料。为阐释并验证Co₃O₄掺入对ZnO表面形貌与气敏性能在低气体浓度条件下的影响，本研究开展了X射线衍射（XRD）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）、能量色散X射线能谱（EDS）及紫外-可见光谱（UV-vis spectroscopy）等表征测试。同时探究了其在近室温与可见光辐照条件下对100 ppm丙酮的光电响应特性。由于P-N异质结的形成，Co₃O₄-ZnO异质结构纳米颗粒即使在低至30℃的工作温度下，对低浓度丙酮气体的响应性能仍优于未掺杂的纯ZnO纳米颗粒。掺入Co₃O₄可提升ZnO厚膜的气敏灵敏度与选择性。在30℃工作温度下，4.13wt% Co₃O₄-ZnO样品对100 ppm丙酮的气敏灵敏度为24.36；可见光辐照可显著增强光激发效应，此时该样品的灵敏度可达37.21。此外，本研究结合Co₃O₄-ZnO P-N异质结模型与可见光激发理论，进一步剖析了气敏反应的作用机制。