Cooperative modulation of Fe2(MoO4)3 microstructure derived from absorbent cotton for enhanced gas-sensing performance

Optimizing microstructure factors of metal oxide sensing materials can be important to improve gas sensor performance. Herein, hierarchically hollow microtubes and microchains of monoclinic Fe-2(MoO4)(3) were prepared by simple immersion-calcination method using absorbent cotton as template. The influences of different calcination temperatures on morphology, particle size, crystallinity and crystal facet were also investigated. In spite of very small specific surface area of 1.64 m(2) g(-1), the hollow microtube calcined at 650 degrees C (FMO-650) presents outstanding gas-sensing performance towards H2S owing to the cooperative modulation of micro-structure multi-parameters, such as morphology, size, single crystalline state and exposed active family of (100) crystal planes. At the optimum working temperature of 170 degrees C, the FMO-650 sensor shows high sensitivity to H2S gas with response time being 7 s, and the detection limit of 0.3 ppm is lower than that of any reported Fe-2(MoO4)(3)-based gas sensors. These results clearly indicate that the strategies for optimizing control of microstructure parameters can significantly improve the sensing performance of metal oxide-based materials. In addition, the gas-sensing mechanism of FMO-650 was also discussed in detail.