Lingfeng Jin

Synthesis, Characterization and Enhanced Sensing Properties of a NiO/ZnO p–n Junctions Sensor for the SF6 Decomposition Byproducts SO2, SO2F2, and SOF2

The detection of partial discharge and analysis of the composition and content of sulfur hexafluoride SF6 gas components are important to evaluate the operating state and insulation level of gas-insulated switchgear (GIS) equipment. This paper reported a novel sensing material made of pure ZnO and NiO-decorated ZnO nanoflowers which were synthesized by a facile and environment friendly hydrothermal process for the detection of SF6 decomposition byproducts. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the structural and morphological properties of the prepared gas-sensitive materials. Planar-type chemical gas sensors were fabricated and their gas sensing performances toward the SF6 decomposition byproducts SO2, SO2F2, and SOF2 were systemically investigated. Interestingly, the sensing behaviors of the fabricated ZnO nanoflowers-based sensor to SO2, SO2F2, and SOF2 gases can be obviously enhanced in terms of lower optimal operating temperature, higher gas response and shorter response-recovery time by introducing NiO. Finally, a possible gas sensing mechanism for the formation of the p–n junctions between NiO and ZnO is proposed to explain the enhanced gas response. All results demonstrate a promising approach to fabricate high-performance gas sensors to detect SF6 decomposition byproducts.

Improved C2H2 sensing properties of Ni doped ZnO nanorods

Abstract Pure and Ni doped ZnO nanorods were successfully synthesised via a simple hydrothermal synthesis method and characterised by X-ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM) and high resolution TEM respectively. Sensing properties were systematically measured towards acetylene gas (C2H2). The Ni doped ZnO gas sensor exhibits excellent gas sensing performances, such as lower working temperature, higher gas response, rapid response and recovery time, than those of pure ZnO gas sensors. All results demonstrate the potential of Ni dopant for improving the gas sensing properties of ZnO gas sensors to C2H2 gas.

Pt-doped SnO 2 nanoflower gas sensor detection characteristic for hydrocarbon gases dissolved in transformer oil

Methane, ethane, ethylene and acetylene are the effective failure characteristic gases for power transformer, which can effectively reflect the electric and overheat faults. Monitoring these gases have a great significance in diagnosis and evaluation the running state of transformer. In this paper, Ptdoped SnO2 nanoflower gas sensor was prepared, then its detection characteristic and response mechanism of hydrocarbon gases had been studied. The results indicated that, as the increasing of specific surface area, compared to the pure SnO2 nanoparticle gas sensor, the Pt-doped SnO2 nanoflower gas sensor has higher sensitivity and faster response characteristic to hydrocarbon gases, and responses versus gas concentration kept a good linearity when the gas concentration between 5 μL/L and 50 μL/L. The role of the dopant of Pt into the SnO2 and the sensing mechanism had also been discussed in this work.

Hydrothermal Synthesis and Responsive Characteristics of Hierarchical Zinc Oxide Nanoflowers to Sulfur Dioxide

Sulfur dioxide, SO2, is one of the most important decomposition byproducts of sulfur hexafluoride, SF6, under partial discharge in GIS apparatus. The sensing performances of semiconductor gas sensors can be improved by morphology tailoring. This paper reported the synthesis method, structural characterization, and SO2 responsive characteristics of hierarchical flower-shaped ZnO nanostructures. Hierarchical ZnO nanoflowers were successfully prepared via a facile and simple hydrothermal method and characterized by X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, respectively. Planar chemical gas sensor was fabricated and its responsive characteristics towards SO2 were systematically performed. The optimum operating temperature of the fabricated sensor was measured to be about 260°C, and the corresponding maximum responses were 16.72 and 26.14 to 30 and 60 ppm of SO2. Its saturated gas concentration was 2000 ppm with a response value of 67.41. Moreover, a quick response and recovery feature (7 s and 8 s versus 80 ppm of SO2) and good stability were also observed. All results indicate that the proposed sensor is a promising candidate for detecting SF6 decomposition byproduct SO2.

Detection of acetylene dissolved in transformer oil using sno 2 /rgo nanocomposite gas sensor

The operation conditions of oil immersed power transform will affect the safety and stability of power system directly. As one of the main fault characteristic gases dissolved in transformer oil, acetylene (C₂H₂) gas can effectively reflect the discharge faults which occur in oil-paper insulation system. Monitoring its content of C₂H₂ gas has a great significance in diagnosis and evaluation the running state of transformer. In this paper, tin oxide (SnO₂) and reduced graphene oxide (rGO) nanocomposite based C₂H₂ gas sensor was developed. The gas sensing material was synthesized by a facile hydrothermal method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscope (TEM). Then, the gas sensing properties of as-synthesized nanomaterials were tested by exposing to different concentration of C₂H₂ gas with a temperature range of 100-300 °C and its gas sensing mechanism of C₂H₂ gas was discussed. The characterization results indicated that the SnO₂ and SnO₂/rGO were succeed synthesized. Under the optimum operating temperature (180 °C) of SnO₂/rGO, it exhibited a low detection limit (1 μL/L), high response (50 ppm, 13.2) and good linearity (1-10 μL/L). The gas sensing mechanism for the better sensing properties to C₂H₂ gas was explained based on superhigh surface areas and heterojunction between SnO₂ and rGO. This results highlight SnO₂/rGO can effective enhance the C2H2 gas sensing properties for monitoring the dissolved C₂H₂ gas in transformer oil with high performances.

Study on gas sensing properties and mechanism of Ag-doped SnO 2 gas sensor to H 2

H2 is one of the main fault characteristic gases dissolved in transformer oil, which can indicate the electric faults, such as high energy discharge, spark discharge and partial discharge, and partial oil overheating phenomenon. Detection the content of H2 has an important significance for transformer diagnosis and state assessment. Gas sensing detection technology is the core of online monitoring device. In this paper, for the detection of dissolved H2, based on the density functional theory and the first-principles, pure and Ag-doped SnO2 models and gas adsorption models were built, and theoretical calculations were conducted. Meanwhile, pure and Ag-doped SnO2 gas sensing materials were synthesized with hydrothermal method. Then SnO2 based gas sensors were fabricated and their gas sensing properties were measured. Finally, its gas sensing mechanism was discussed based on the macro gas sensing properties and micro simulating calculations. The results indicated that, Ag doping can improve the gas sensing properties of SnO2 nanostructures to H2, Ag doping sensor has better effect than pure sensor for H2 detection, such as a lower optimum operating temperature of 340 °C, lower detection limit of 10 µL/L with higher sensitivity. The role of the dopant of Ag into the SnO2 and the sensing mechanism had also been discussed in this work. The experimental results verifies the feasibility and accuracy of study the gas sensing performances of SnO2 based gas sensors using the first-principles calculation based on the density functional theory, further perfecting its gas sensing mechanism of SnO2 based gas sensor and providing us a fresh idea and feasible way to develop different kinds dopant of metal or metal-oxide gas sensors with high performances.