Gas sensors based on heterojunctions have attracted extensive
attention
because of their high sensitivities over monolithic metal oxide. However,
it is difficult to obtain homogeneous and stable heterojunctions by
traditional synthesis methods. Herein, we proposed an in situ oxidation
technique to fabricate WS2/WO3 nanosheets with
p-n heterojunctions in a convenient and controllable manner. Through
this method, the ratio of WS2/WO3 can be effectively
regulated by adjusting the oxidant concentration and oxidation time.
The obtained WS2/WO3 nanosheets were characterized
by scanning electron microscopy (SEM), transmission electron microscopy
(TEM), X-ray photoelectron spectroscopy (XPS), etc. Then, a gas sensor
based on WS2/WO3-4 heterojunctions was constructed
to detect acetone in a wide range of 20–500 ppm. It was also
found that the WS2/WO3-4-based sensor exhibited
excellent repeatability, selectivity, and long-term stability for
acetone determination. The sensitivity of the sensor toward 100 ppm
acetone was 3.5, which was much higher than that of pure WO3. The results indicated that construction of heterojunctions could
be therefore considered as a favorable method for improving the sensitivity
of the prepared gas sensor. Moreover, this work provides a simple
and flexible avenue to synthesize heterojunctions with high structural
homogeneity for applications in various fields.
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