[ Instrument R & D of Instrument Network ] Recently, the team of Fang Xiaodong and Meng Gang of the laser center of Anhui Institute of Optics and Fine Mechanics, Institute of Material Science, Chinese Academy of Sciences, made new progress in p-type copper iron gas sensors. Related achievements were published in the international journal Sensors and Actuators B: Chemical with the title "Ultra-sensitive, highly selective H2S gas sensor based on the reversible sulfuration-oxidation reaction on the surface of CuAlO2".
A gas sensor is a converter that converts a certain gas volume fraction into a corresponding electrical signal. The probe head conditioned the gas sample through the gas sensor, usually including filtering out impurities and interfering gas, drying or refrigeration processing instrument display part.
A gas sensor is a device that converts information such as the composition and concentration of gas into information that can be used by people, instruments, computers, etc.! Gas sensors are generally classified as a category of chemical sensors, although this classification is not necessarily scientific.
The development of ultra-miniature gas sensors based on oxide semiconductors to realize the rapid identification and detection of indoor and outdoor atmospheric pollutant molecules has important application prospects. Traditional oxide semiconductors are difficult to be practical because of their broad-spectrum response. The team of Anhui Institute of Optics and Mechanics mainly starts from the design of sensing materials (surface) and the extraction of gas molecular features, and is committed to the development of oxide sensors with identification and detection functions.
P-type copper iron ore (ABO2) is an important class of functional oxides. The rich selection of A and B ions provides sufficient freedom to regulate the exchange of gas molecules and their charge, which is conducive to the design of highly selective gas sensors. Prior to this, deputy researcher Deng Zanhong of the research group has conducted a lot of research work on p-type copper iron ore gas sensors, and developed AgAlO2 and CuScO2 sensors that can work at room temperature, have a high sensitivity to ammonia, and a high selective response. On this basis, Dr. Tong Bin of the research group explored a new CuAlO2 hydrogen sulfide (H2S) gas sensor using a simple sol-gel preparation process.
Hydrogen sulfide, molecular formula is H2S, molecular weight is 34.076, under standard conditions is a flammable acid gas, colorless, smell of rotten eggs at low concentration, sulfur smell at very low concentration, highly toxic (LC50 = 444ppm <500ppm). Its aqueous solution is hydrogen sulfuric acid, which is weaker in acidity and weaker than carbonic acid, but stronger than boric acid. The molecular weight is 34.08, the vapor pressure is 2026.5kPa / 25.5 â„ƒ, the flash point is <-50 â„ƒ, the melting point is -85.5 â„ƒ, the boiling point is -60.4 â„ƒ, and the relative density is (air = 1) 1.19. It is soluble in water, easily soluble in alcohols, petroleum solvents and crude oil. The ignition point is 292 Â° C. Hydrogen sulfide is a flammable and dangerous chemical. It can form an explosive mixture when mixed with air. It can cause a combustion explosion when exposed to fire or high heat. Hydrogen sulfide is an important chemical raw material.
H2S is an acutely toxic gas. Inhalation of a small amount of high concentration (~ 500ppm) H2S can be poisoned in a short period of time. Long-term exposure to low concentration (~ 5-20ppm) H2S can damage the eyes, respiratory system and central nervous system. China's National Occupational Hygiene Standard (GBZ 2.1-2007) stipulates that workplace H2S occupational exposure limits (OELs) are 10 ppm. The CuAlO2 sensor developed by the research group has an electrical response of 4600 to 10ppm H2S at an operating temperature of 160 Â° C and less than 2 to 100ppm NH3, NO2 and various volatile organic molecules, indicating excellent selectivity. In addition, the CuAlO2 sensor also has fast response characteristics. Once the concentration of H2S in the environment is higher than 4ppm, the sensor resistance increases by 3 orders of magnitude in about 1 minute, and an alarm can be issued in time.
Source: Encyclopedia, Hefei Institute of Material Science
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