Selective sensing of NH3 by Si-doped α-MoO3 for breath analysis

In situ XRD analysis of the MoOx phase dynamics revealed a thermally induced recrystallization of β-MoO3 at 300-350 °C and optimal annealing at 450 °C for synthesis of highly nanocrystalline α-MoO3. For selective NH3 sensing, however, the optimum SiO2 content was 3 wt% and the operational temperature 400 °C. This sensor showed superior NH3 selectivity toward acetone, NO and CO, and accurately detected breath-relevant NH3 concentrations down to 400 ppb under 90% relative humidity (RH). As a result, a stable and inexpensive sensor for NH3 is presented which has the potential for further development toward a hand-held device for the early-stage diagnosis and monitoring of ESRD.