New insight into the gas-sensing properties of nanofiber-assembled and nanosheet-assembled hierarchical MoO3 structures

摘要

We successfully synthesized MoO3 hierarchical structures assembled with nanofibers and nanosheets via a hydrothermal method assisted with hexadecyl trimethyl ammonium bromide (CTAB) and polyvinyl pyrrolidone (PVP), respectively. Then, we characterized the structure and morphology of the as-synthesized samples by X-ray diffraction and scanning electron microscopy. We analyzed the formation process of the two structures and verified the effects of different dimensionality assembly units on their gas-sensing properties through gas sensing experiments. Remarkably, nanosheet-assembled hierarchical MoO3 structures, which possess abundant semi-closed microreaction spaces, exhibited an enhanced gas response. The gas response (the ratio of test voltage in the air to test voltage in the target gas) of a nanosheet-assembled MoO3 based-sensor to 400 ppm ethanol reached 32 at an operating temperature of 300 degrees C. While nanofiber-assembled hierarchical structures showed a shorter response (3.2s) and recovery time (2.4s), which was due to the faster gas and electronic diffusion rate of the nanofibers.