Gas dependent sensing mechanism in ZnO nanobelt sensor

•ZnO nanobelts exhibit an appreciable response towards H2S and NO.•At room temperature, sensor recovers completely after exposure to NO (1 to 60ppm).•At room temperature, incomplete recovery observed on exposure to higher concentrations of H2S (> 5 ppm).•Complete recovery on exposure to concentrations higher than 5ppm H2S is achieved by heating the sensor films at 250°C.•Incomplete recovery after exposure to higher concentrations of H2S is due to formation of ZnS. Gas sensing properties of ZnO nanobelts synthesized using carbothermal reduction method has been investigated. At room temperature (28°C), the sensor films exhibit an appreciable response towards H2S and NO and response of these two gases were studied as a function of concentration. For NO the sensor films exhibit a complete reversible curve for the concentration range between 1 and 60ppm. However, for H2S a complete recovery was obtained for concentration