Mingjia Bai,Chaoyang Li,Xiaojun Zhao,Qingji Wang,Qinhe Pan
ZnO is a wide band gap semiconductor metal oxide that not only has excellent electrical properties but also shows excellent gas-sensitive properties and is a promising material for the development of NO2sensors. However, the current ZnO-based gas sensors usually operate at high temperatures, which greatly increases the energy consumption of the sensors and is not conducive to practical applications. Therefore, there is a need to improve the gas sensitivity and practicality of ZnO-based gas sensors. In this study, three-dimensional sheet-flower ZnO was successfully synthesized at 60 °C by a simple water bath method and modulated by different malic acid concentrations. The phase formation, surface morphology, and elemental composition of the prepared samples were studied by various characterization techniques. The gas sensor based on sheet-flower ZnO has a high response value to NO2without any modification. The optimal operating temperature is 125 °C, and the response value to 1 ppm NO2is 125. At the same time, the sensor also has a lower detection limit (100 ppb), good selectivity, and good stability, showing excellent sensing performance. In the future, water bath-based methods are expected to prepare other metal oxide materials with unique structures.
Rhombohedral MnCO 3 nanoparticles were successfully grown on nickel foam via a facile and one-pot water-bath means, wherein the hydrolyzation of urea supplied alkali and carbonate ions. The structure and morphology of the nanocomposites were investigated by XRD, FIB/SEM and elemental mapping. Microscopic investigations revealed MnCO 3 particles with mean sizes that varied from 110-255 nm. EDS mapping showed a homogeneous distribution of manganese, carbon and oxygen. The electrochemical properties of the produced composites were estimated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurements using 6 M KOH as the electrolyte. The resulting electrodes displayed maximum specific capacitance (163.7 F g -1 at 0.5 A g -1 ), respectable rate capability, and excellent long-term cycling life (91% retention after 1000 cycles). In addition, this manuscript offers us a simple and rapid strategy for the fabrication of electrode materials for use as energy storage devices.
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