Zinc oxide nanoparticle incorporated graphene oxide as sensing coating for interferometric optical microfiber for ammonia gas detection

- A simple and reliable ammonia optical fiber sensor is demonstrated using zinc oxide (ZnO) decorated graphene oxide (GO).
- GO-ZnO nanocomposites show additional synergistic effects that are desirable and advantageous for gas sensing.
- The experimental results show a sensitivity of 31 pm/ppm to ammonia from 4 ppm to 140 ppm at room temperature.
- The sensor shows an excellent selectivity to ammonia compared to several possible interfering analytes such as alcohol, methanol, acetone and methylbenzene.

A simple and reliable method by combination of sensing coating and interferometric optical microfiber to detect the concentration of ammonia is reported in this study. The sensor is fabricated by coating the tapered microfiber interferometer (MFI) with zinc oxide nanoparticle incorporated graphene oxide (GO-ZnO). GO-ZnO nanocomposites serving as an electron acceptor trap electrons after ammonia absorption and then change the surface refractive index of the optical microfiber in MFI. Subsequently, the MFI translates the tiny refractive index change into wavelength shift of the transmission spectra. As prepared sensor exhibits a good repeatability and high sensitivity to ammonia with different connections from 4 ppm to 140 ppm at room temperature. The gas sensor response to ammonia has been studied in different moisture level and show reliable operation in low humidity atmosphere. In addition, the gas sensor also displays an excellent selectivity to ammonia compared to several possible interfering volatile organic compounds. This may be attributed to the selective ammonia absorption at the GO-ZnO surface and the additional synergistic effects of GO-ZnO nanocomposites that are desirable and advantageous for gas sensing.