Xiaogan Li

Novel Nanosized ITO Electrode for Mixed Potential Gas Sensor

The sensing properties of the planar scandia-stabilized zirconia based mixed potential gas sensor coupled with hydrothermally obtained nanosized ITO as an electrode material have been investigated. The planar sensor has shown good sensitivity to low-level of CO concentrations (16-500 ppm) in a lower oxygen ambient (4 vol %) in terms of the high magnitude of the signal and fast response (<5 s). The sensing properties of the planar sensor to CH 4 and other oxidizing gases such as O 2 and NO 2 have also been tested. The results indicate that the sensor could be used to potentially detect the reducing gases such as CO significantly rapidly compared to the oxidizing gases such as O 2 and NO 2 . A possible sensing mechanism of the planar sensor for rapidly detecting CO is also discussed.

Synthesis and characterizations of nanosized tin-doped indium oxide by different soft-chemical routes

Abstract Nanosized tin-doped indium oxide (ITO) with different phase formation and morphologies has been successfully synthesized by two different chemical methods: combustion synthesis from the aqueous tin and indium nitrate solution containing urea as the fuel and hydrothermal treatment of the solution with the urea as the mineralizer. The sub-micrometer ITO nanoclusters with stratified morphology were obtained by calcining the obtained precursor from combustion process at 600°C for one hour. However, by utilizing urea as the mineralizer during hydrothermal treatment, the obtained ITO powders exhibit a composite consisting of spheres and rods after calcining at 600°C for one hour. Both of the processing routes yield a two-phase mixture consisting of rhombohedral and cubic forms of ITO. Supported by ORS scholarship and Institute for Materials Research in Leeds University

Planar Mixed-Potential CO Sensor Utilizing Novel ( Ba0.4La0.6 ) 2In2O5.6 and ITO Interface

The mixed potential sensor coupling La-doped Ba 2 In 2 O 5 (BLIO) and tin-doped indium oxide (ITO) as the electrolyte and sensing electrode, respectively, was investigated to detect the reducing gases such as CO. The fabricated planar ITO‖BLIO‖Pt sensor exhibited a fast response to low-level CO concentrations from ∼100 to ∼400 ppm above 600°C. The sensor signal was not affected by changes of oxygen concentrations from ∼4 to ∼21 vol % and methane (<300 ppm). The advantage of utilizing BLIO as the electrolyte is to have a better chemical compatibility and stability at the interface of the ITO-sensing electrode and BLIO solid electrolyte.

La-Doped Ba2In2O5 Electrolyte: Pechini Synthesis, Microstructure, Electrical Conductivity, and Application for CO Gas Sensing

Dense (Ba1―xLax)2In2O5+x (BLIO) electrolytes with different compositions (x = 0.4, 0.5, 0.6) were fabricated using powders obtained by the Pechini method. The formation of BLIO powders was investigated by using X-ray diffraction and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The calcination temperature and time were optimized. The sintered (Ba1―xLax)2In2O5+x electrolytes showed a relative density greater than ∼97%, and the major phase of three electrolyte compositions was indexed as a cubic perovskite. The electrical conductivity of BLIO ceramics at elevated temperatures in air was measured by ac-impedance spectroscopy. The activation energies for conduction in BLIO were 102 kJ mol―1 between 473 and 666 K and 118 kJ mol―1 between 769 and 873 K, which are comparable to that for 8 mol % yttria-stabilized cubic zirconia. Mixed-potential gas sensors utilizing BLIO-based electrolytes exhibited good sensitivity to different CO concentrations from ∼100 to ∼500 ppm and excellent selectivity to methane at around 873 K.

Non-Equilibrium Potentiometric CO Sensor Using (BaxLa1-x)2In2O5 (0.4<=x<=0.6) Electrolyte

Dense (BaxLa1-x)2In2O5 (BLIO) ceramic electrolytes with different compositions (x=0.4, 0.5, 0.6) were synthesised by Pechini method during which the obtained sintered BLIO electrolytes showed high relative density of ~98% and indicated a pure single cubic phase. The CO sensing properties of as-fabricated planar-type BLIO-based sensors coupled with ITO and Pt as the sensing electrode and reference electrode, respectively was investigated. The sensors showed good sensitivity to different concentrations of CO from 0 to 500ppm and excellent selectivity over low-concentrations of methane (<500ppm). However, the sensors with dense electrolyte indicated more sluggish response compared with the sensors coupled with corresponding porous electrolyte as previously reported. The long-term stability of the sensor for the detection of CO was also investigated which indicated a reasonably stable sensor signal after the initial declination.