Preparation Of Ga-based Semiconductor Materials And Their Gas Sensing Properties

As one of the most important factor which affect the people's quality of life,the indoor air quality has received great aby harmful gases,suspended particles,microbes,etc.Among them,the volatile gases like ttention.Usually,indoor air quality can be affected formaldehyde and benzene not only seriously threaten the human health but also difficult to detect due to their colorless and tasteless nature.Thus,exploring a highly efficient and cost-effective method to detect sub ppm level formaldehyde is exigent.Compared with current available methods such as liquid chromatograph,colorimetry,gas chromatograph and photo ionization detectors,gas sensor based on metal oxide semiconductors has attracted considerable attention by combining the advantages of low cost,rapid and sensitive detection.As a typical p-type semiconductor,gallium has been widely used in gas monitoring and detecting.However,there are some problems of the gallium-based gas detector restrict their wide application.For instance,the working temperature is too high and the gas sensing properties such as selectivity and stability are unsatisfactory.Which reminding us that we still require further work on metal oxide semiconductor gas sensor.1)In this work,we successfully fabricated the Ga-In bimetallic nanofibers(Ga1.4Ino.6O3)through the electrospinning method and doped different contents of iridium oxide into the Gai.4In0.6O3 nanofibers for optimizing formaldehyde sensing properties of pure GIO nanofibers.The IrO2-loaded porous GIO nanofibers exhibit an excellent sensing performance such as high sensitivity,good stability and excellent selectivity.What's more,the IrO2-loaded GIO nanofibers also have the low detection limit(60 ppb)that satisfied in application.It is obvious that both the iridium and the the 1D porous structure with high surface volume ratio evidently enhanced the performance of gas sensor.2)In this paper,high-performance toluene and xylene detection has been realized by a sensor based on novel p-p heterojunction NiO-NiGa2O4 nanospheres.Construction of optimized p-p heterojunctions,which resulting from the rationally controlling of the NiGa2O4 content in NiO-NiGa2O4,leads to significantly promoted sensing properties for toluene and xylene detection.It is found that the sensor based on 50%NiO-NiGa2O4 exhibits the best sensing performances.Its highest response(Rg/Ra ?12.7 to toluene;Rg/Ra = 16.3 to xylene)is almost 10 times higher than that of the pure NiO(Rg/Ra<2)to 100 ppm toluene and xylene at 230°C.More importantly,the sensor exhibits superior selectively for detection of the methyl benzene even against more reactive interfering gases/vapors,such as formaldehyde and ethanol.The p-p oxide heterojunction suggests a promising sensing material for toluene and xylene detection with high response,excellent selectivity,good stability and rapid response/recover time.