Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA9300, South Africa; DST/CSIR National Centre for Nano-structured Materials, Council for Scientific Industrial Research, Pretoria ZA0001, South Africa.
Department of Physics and Engineering, University of Zululand, Kwa-Dlangezwa, 3886, South Africa.
J Colloid Interface Sci. 2020 Feb 15;560:755-768. doi: 10.1016/j.jcis.2019.10.036. Epub 2019 Oct 13.
Development of room-temperature operating gas sensors, utilizing p-type CuO nanoplatelets for air quality monitoring with excellent response, high sensitivity and good reliability, is highly desirable. Therefore, in this work, we investigated both the influence of synthesis reaction temperature and time on the sensitivity, selectivity, and response of CuO nanoplatelets prepared through the hydrothermal synthetic method, in the presence of NaOH as base, without the support of any surfactant. The gas sensing findings revealed that the CuO nanoplatelets NO sensitivity and selectivity can be controlled and tuned by adjusting the synthesis reaction temperature and time, while maintaining the morphology. The CuO-based sensors revealed a remarkable response of 14.5 to 20 ppm NO, with a sensitivity of 0.47 ppm at room temperature. A decrease in sensing performance was observed at higher operating temperatures. The findings affirmed that such sensor response/sensitivity is not dependent on the specific surface area and is relatively interrelated to the adsorption sites, the average crystallite size, and low charge carrier concentration, giving rise to a more pronounced change in CuO sensor resistance. The influence of relative humidity (RH) was also investigated to have an understanding of the sensor performance in real testing conditions. Additionally, the stability analyses to four cycles of different humidity percentages and gas concentration-related repeatability conditions were carried out, and the sensor revealed a slight drifting when increasing the number of testing cycles.
开发可在室温下工作的气体传感器，利用 p 型 CuO 纳米板来监测空气质量，具有出色的响应、高灵敏度和良好的可靠性，这是非常理想的。因此，在这项工作中，我们研究了水热合成法在没有任何表面活性剂的情况下，以 NaOH 为碱，合成反应温度和时间对 CuO 纳米板的灵敏度、选择性和响应的影响。气体传感结果表明，通过调整合成反应温度和时间，可以控制和调节 CuO 纳米板的 NO 灵敏度和选择性，同时保持其形态。基于 CuO 的传感器对 20ppm 以下的 NO 表现出显著的响应，在室温下的灵敏度为 0.47ppm。在更高的工作温度下，传感性能下降。研究结果证实，这种传感器的响应/灵敏度不依赖于比表面积，而是与吸附位、平均晶粒尺寸和低载流子浓度相对相关，导致 CuO 传感器电阻发生更明显的变化。还研究了相对湿度 (RH) 的影响，以了解传感器在实际测试条件下的性能。此外，对不同湿度百分比和与气体浓度相关的重复性条件下的四个循环的稳定性进行了分析，当增加测试循环次数时，传感器显示出轻微的漂移。
