High-sensitivity formaldehyde gas sensor based on cobalt and indium co-doped ZnO hierarchical microspheres

A zinc oxide gas sensor modified with cobalt and indium produced a response of 265.1 to 100 ppm of formaldehyde at 120 °C, according to a study in the Journal of Materials Science . The response was approximately 18 times greater than that of pure zinc oxide hierarchical microspheres. The sensor also had a reported response time of 6 seconds and a recovery time of 2 seconds.

Formaldehyde is described in the study as a hazardous indoor pollutant that can cause serious health threats during prolonged exposure. The researchers developed the sensor to address the need for rapid and accurate detection of the gas. Their work focused on a sensing material made from zinc oxide hierarchical microspheres co-doped with cobalt and indium through a hydrothermal method.

They systematically investigated how this combination affected the microspheres’ morphological architecture and their formaldehyde gas-sensing behavior. At a formaldehyde concentration of 100 ppm and an operating temperature of 120 °C, the co-doped zinc oxide hierarchical microspheres generated a response value of 265.1. That value was about 18 times the response obtained from the pure zinc oxide hierarchical microspheres used for comparison.

These results were obtained under the experiment’s reported test conditions, which included a 100 ppm formaldehyde concentration and a temperature of 120 °C. The researchers also evaluated repeatability, selectivity and long-term stability, describing the sensor as performing well in all three respects. The available study summary does not provide numerical results for these properties, the gases used to assess selectivity, or the duration of the stability testing.

It also reports that the gas-sensing mechanism of the cobalt- and indium-co-doped zinc oxide was investigated, but the summary does not specify the individual chemical steps or charge-transport processes involved. The demonstrated advance is therefore the measured combination of high response, rapid response and recovery, repeatability, selectivity and stability for the engineered sensing material under the study’s laboratory conditions.

Subject of Research: Cobalt- and indium-co-doped zinc oxide hierarchical microspheres for formaldehyde gas sensing

Article Title: High-sensitivity formaldehyde gas sensor based on cobalt and indium co-doped ZnO hierarchical microspheres

Article References: Yu, T., Liu, X., Wang, C., Duan, Y., Zhou, H., Zheng, J., Fu, Q., Zhao, H., Tao, H., Ma, Z., Li, Z., Chen, Z., & Tu, Y. (2026). High-sensitivity formaldehyde gas sensor based on cobalt and indium co-doped ZnO hierarchical microspheres. Journal of Materials Science, 61(40), 30858-30874. https://doi.org/10.1007/s10853-026-13668-x

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13668-x

Keywords: formaldehyde, gas sensor, zinc oxide, cobalt, indium, hierarchical microspheres, nanocomposites, hydrothermal synthesis, materials science, High-sensitivity, sensor, based