For realizing high-performance ozone (O3) sensing, hierarchical branch-like In2O3 (B-In2O3) nanomaterials were designed and prepared via a facile co-precipitation method. The unique In2O3 structure consists of abundant nano-rods with the length of ca. 450 nm enabling effective adsorption and diffusion of oxygen and O3 molecules. The sensors based on B-In2O3 showed sensitive O3 sensing performances at a relative low working temperature. The response of B-In2O3 based sensors to 100 ppb of O3 is 44 at 70 °C, which is 4.9-fold higher than the commercial In2O3 (C-In2O3) particles. The limit of O3 detection was as low as 30 ppb. Moreover, the gas sensor exhibited excellent selectivity and device stability. The great sensing behavior is proved to be closely related to the oxygen-chemisorbed ability and large specific surface area of In2O3 materials. Taken together, this work provides a potential sensing platform for highly sensitive and ppb-level O3 detection.

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