Cobalt ions induced morphology control of metal-organic framework-derived indium oxide nanostructures for high performance hydrogen sulfide gas sensors

Real-time gas sensors with high response and selectivity are highly desirable for hydrogen sulfide (H2S) monitoring concentration changes in the environment, especially at the ultra-trace level. Herein, cobalt-doped indium oxide (In2O3) with shorter-length nanorings was synthesized by foreign metal cobalt ions. By controlling the morphology of the material and calcinating the indium-based metal-organic frameworks (In-MOFs), the nanostructures of the obtained materials have a larger specific surface area, which further improves the sensing performance. The sensor prepared with a suitable amount of cobalt doping materials can exhibit the best gas-sensing performance. The Co-doped In2O3 sensor shows a high response to 2 ppm H2S (∼12.6) at 225 °C, low detection limits (100 ppb), and excellent selectivity, which is 5.34 times higher than pure In2O3 at 300 °C. Moreover, the potential growth mechanism speculates that the presence of Cobalt ions leads to a change in material morphology from nanorods to nanorings. This work provides an implementable method for controlling the morphology of the materials, which could facilitate the development of high-performance gas sensors.