The development of WO3-based gas sensors for analysis of acetone in exhaled breath is significant for noninvasive diagnosis of diabetes. A series of Fe-doped hexagonal and monoclinic WO3 phase−junction (Fe−h/m−WO3) sensors were synthesized by the hydrothermal calcination method, and the influences of operating temperature and light irradiation on the response were studied. Under light emitting diode (LED) illumination, Fe−h/m−WO3 exhibited higher responses to acetone than those of the undoped WO3-based sensors at an operating temperature of 260 °C with 90% relative humidity, and good linearity between response and acetone concentration (0.5 to 2.5 ppm) was achieved under the 90% relative humidity condition. Meanwhile, the optimal Fe−h/m−WO3 sensor exhibited high selectivity and stability for a duration of three months. The excellent sensing performance of Fe−h/m−WO3 was attributed to the formation of phase−junction and Fe doping, and these were beneficial for the separation of photon−generated carriers and oxygen adsorption on the WO3 surface, promoting the generation of superoxide radicals, which was demonstrated by electron paramagnetic resonance and photocurrent tests. Additionally, the Fe−doped WO3 phase−junction sample also showed good photocatalytic performance for rhodamine B degradation. This study may provide some insights into rational design of new types of gas sensors and offer an alternative for noninvasive diagnosis of diabetes.

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Due to the impact of climate change, the development of low-carbon economy and building a low carbon city has become one of the optimal mode of urban development in the future. This paper first describes the related concepts of low-carbon cities, introduces the status of the development of low carbon cities in Shandong Province, identify the favorable conditions and unfavorable factors of the development of low carbon cities in Shandong Province, and finally put forward countermeasures and suggestions. This article points out that Shandong Province should improve the low - carbon policies and systems, build a legal system, increase low-carbon capital investment, develop the carbon trading markets, adjust industrial structure, promote energy conservation etc, then realize the healthy development of low-carbon city.

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