Synthesis of urchin-like In2O3 hollow spheres for selective and quantitative detection of formaldehyde

Abstract

Developing high performance gas sensor for detection of flammable and toxic gases is great significant for environment and health protection. Herein, we reported the selective and quantitative detection of ppb level formaldehyde (HCHO) on a gas sensor based on urchin-like In2O3 hollow spheres (HSs), which were synthesized by calcinating the pre-synthesized urchin-like In(OH)3 HSs at different temperatures. The results of XRD, SEM, TEM and N2 adsorption-desorption analysis indicated that at an optimized calcination temperature of 350 °C, In2O3 HSs with uniform urchin-like morphology and the specific surface area as high as 122.02 m2/g were prepared. At an optimum operating temperature of 140 °C, the sensor fabricated with In2O3-350 showed outstanding gas sensing properties to ppb level HCHO, such as high sensitivity, good selectivity, fast response speed, and low detection limit (50 ppb). Importantly, the In2O3-350 sensor also exhibited a good response linearity within a wide HCHO concentration range from 50 ppb to 10 ppm, demonstrating its potential for quantitative detection of HCHO. These good gas sensing properties of In2O3-350 were contributed to its unique urchin-like hollow structure, small crystallite size, and high specific surface area.