Highly Reliable Dimethyl Disulfide Chemiresistive Gas Sensor Based on Vacancy-Engineered MoO 3 Nanobelts for Complex Odor Monitoring and Field Testing

Dimethyl disulfide (DMDS) is an odorous sulfur-containing volatile organic compound primarily emitted from sewage treatment plants. However, most metal-oxide-based DMDS gas sensors have been limited to parts-per-million-level performance despite the fact that DMDS can cause severe health concerns and produce an unpleasant smell even at ppb-level concentrations. Previous studies have primarily focused on enhancing the DMDS gas response via vacancy engineering without addressing the gas reliability. Here, we explored a MoO₃-based DMDS gas sensor and the correlation between detection performance and vacancy concentration through an oxygen annealing process. As the annealing temperature increased, the DMDS gas response decreased, whereas the baseline resistance remained stable. Additionally, the sensor exhibited a 34-fold improvement in gas repeatability and a 20% faster recovery time compared to nonannealed MoO₃. This can be attributed to the reduced number of bound gas molecules on the vacancies. We finally conducted an odorous gas sensing test collected at a sewage treatment plant for the first time. We achieved a clear gas response, closely matching values obtained from standard gas cylinders with identical concentrations. This study provides insight into the design of metal-oxide-based gas sensors for constructing a practical odor monitoring system.