Effect of Cu Doping on Synthesis, Composition and Sensor Properties of InO Nanostructures.

Cu-doped InO nanocomposites with copper compositions of 1-3 wt.% are synthesized by a hydrothermal method using water or alcohol as a solvent. Cubic InO is formed when water is used for synthesis, while composites synthesized in alcohol contain rhombohedral InO. This trend is independent of the amount of copper introduced. The Cu ions are shown to be uniformly distributed in the InO nanoparticles without significant destruction of the indium oxide structure. All the composites exhibit a porous structure that depends on the solvent used for the synthesis. The addition of copper to both crystalline forms of indium oxide increases the resistance of the films and reduces the operating temperature. The phase state of indium oxide also affects the conductivity of the composites. There is an increase in sensory response to H and CO with the introduction of Cu into samples with cubic structure, but a reduction in response in samples with the rhombohedral phase of indium oxide.