Performance And Mechanism Of QCM Sensor Based On Low-dimensional ZnSn(OH) 6 Modification

Gas sensors are widely applied to many feilds including environmental monitoring, medical diagnostics, industrial and agricultural production, food hygiene, and national defense and public security and so on. Carrying out the low dimension materials surface modification of the QCM sensor has important theoretical and practical significance. In this work, hydrothermal method was used to prepare ZnSn(OH)6(ZHS), the morphology and structure of as-prepared samples were characterized by XRD, SEM, TG/DSC, IR. Meanwhile, phase transformation on ZHS was studied deeply. The humidity and gas sensing properties were also researched by ZHS coated on QCM. As a result, we established logical relationship of "morphology-gas sensing properties." To be more specific, both tgo-Delta Mass and Delta F-Delta R were introduced to identify gas species. The results as follows:(1) ZHS was successfully synthesized by hydrothermal process. It was concluded that the as-product is ZHS While Zn2+:Sn4+:OH- is abovel:l:5. With increasing of OH-concentration, the micro-surface of ZHS tended to be smooth. The orthorhombic ZnSnO3 crystals were successfully synthesized when heated to 160?. However, the fcc-ZnSnO3 crystals were obtained by heat treatment via Muffle furnace.(2) Effect of humidity on the CO gas sensing of ZnSn(OH)6 with rough surface was studied. The models of adsorption/adsorption process were established. In detail, Langmuir model is fit for low humidity and the Bimodal exponential model for high humidity.(3) Compared humidity sensing and gas sensing properties of propous ZHS with different cubic size and adsoption model were studied respectively. It was concluded that humidity sensing belongs to BET model, while CO gas sensing to second order adsorption equation.(4) We researched the sensor selectivity by analysis of QCM testing parameters. The specific curves distributed on 2 d plane were studied by t90-Delta Mass and Delta F-Delta R. This method was used to identify gas species(5) We achieved CO detection of low concentration (ppm) at room temperature. By adding amount of coating on QCM, CO in ppm level was detected at room temperature.