Gas Sensing with Nano-Indium Oxides (In₂O₃) Prepared via Continuous Hydrothermal Flow Synthesis

Abstract

A rapid, clean, and continuous hydrothermal route to the synthesis of ca. 14 nm indium oxide (In(2)O(3)) nanoparticles using a superheated water flow at 400 °C and 24.1 MPa as a crystallizing medium and reagent is described. Powder X-ray diffraction (XRD) of the particles revealed that they were highly crystalline despite their very short time under hydrothermal flow conditions. Gas sensing substrates were prepared from an In(2)O(3) suspension via drop-coating, and their gas sensing properties were tested for response to butane, ethanol, CO, ammonia, and NO(2) gases. The sensors showed excellent selectivity toward ethanol, giving a response of 18-20 ppm.

Effect of tantalum doping on the structural and optical properties of RF magnetron sputtered indium oxide thin films

“…Indium oxide is an n-type semiconductor with band gap energy 3.5-3.75 eV [2] and usually possesses a cubic bixbyite structure with lattice parameter a¼ b¼c ¼10.118 Å. It can have a rhombohedral structure also which is stable only at high pressures and high temperatures [3,4].In 2 O 3 finds potential applications in liquid crystal displays [5], optoelectronic devices [6], flat panel displays [7], transparent electrodes for heterojunction solar cells [8], gas sensors [9,10], organic light emitting diodes [11]etc.…”

Nanocube In2O3@RGO heterostructure based gas sensor for acetone and formaldehyde detection

“…But it indicates high level of ketone in the blood (ketosis) in insulin-dependent diabetes if its concentration exceeds 1.8 ppm in living places. 7 On the other hand, formaldehyde (HCHO), the most abandoned airborne carbonyl chemical which is extensively used in the decoration of wood furnitures in daily-life and industrial manufacturing processes, is recognized as one of the most serious pollutants in the indoor environment and causes headache, coryza, sick house syndromes, nausea, childhood asthma and even lung cancer. 8,9 Therefore, for the safety point of view fast, accurate and rapid monitoring of these health hazardous and environmental pollutant gases from the public places with an effective and convenient method are of signi-cant practical importance.…”

Highly active and porous single-crystal In2O3 nanosheet for NOx gas sensor with excellent response at room temperature

“…47,48 The ideal structure is considered to be single crystal, because such gas sensing materials can exhibit high electron conductivities, and have abundant interfacial active sites and excellent stability. 49,50 When the porous coupled with single crystallinity provides for the ease of gas diffusion and more active sites for the formation of reactive oxygen species. 51 Then the oxygen species are benet to the gas sensing performance.…”