In this paper, the different valent metal-cations (Zn, In and Zr) doped porous CoO nanostructures were synthesized through the pyrolysis of ZIF-67 metal–organic framework (MOF). The influence of the different valence and doping content of metal-cations on the morphology, microstructures and gas-sensing performance of CoO sensors is discussed in detail. The Zr-doped CoO nanostructures present the higher specific surface area for the smaller average grain size, and the toluene gas-sensing performance of CoO nanostructures is significantly improved with the high-valent Zr-doping. The high valence Zr-doping greatly improves the toluene gas-sensing properties, which CoZrO sensor exhibits the highest response value of 94.58 to 100 ppm toluene gas (3.8-fold of CoO sensor). The donor Zr-doping to p-type CoO nanostructures optimizes the hole distribution and further affects Fermi level. Combining with the more oxygen adsorption from the high specific surface area, the resistance in air greatly decreases and resistance in toluene gas increases.

中文翻译：

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ZIF-67 MOF 衍生的高价金属阳离子掺杂 Co3O4 纳米结构的高度增强的甲苯气敏行为

本文通过 ZIF-67 金属有机骨架（MOF）的热解合成了不同价位金属阳离子（Zn、In 和 Zr）掺杂的多孔 CoO 纳米结构。详细讨论了金属阳离子的不同价态和掺杂含量对CoO传感器的形貌、微观结构和气敏性能的影响。 Zr掺杂的CoO纳米结构具有较小的平均晶粒尺寸和较高的比表面积，并且高价Zr掺杂显着提高了CoO纳米结构的甲苯气敏性能。高价Zr掺杂极大地提高了甲苯气敏性能，CoZrO传感器对94.58至100 ppm甲苯气体表现出最高响应值（是CoO传感器的3.8倍）。 p型CoO纳米结构的施主Zr掺杂优化了空穴分布并进一步影响费米能级。结合高比表面积带来的更多氧气吸附，空气中的阻力大大降低，甲苯气体中的阻力增加。