The remaining challenge of WO3-based NO2 sensors correlates with the requirement of elevated temperature above 100 °C, which goes against the practical feasibility for the operation at a room-temperature environment. Here, we demonstrate the potential solution by carrying out the rational incorporation of intriguing curved silicon nanobelts (SiNBs) with WO3 nanoparticles via solution synthesis. The ultrasensitive characteristics emerging from the detection of a wide-range NO2 concentration from 0.3 to 30 ppm without exhibiting obvious saturation are displayed, where the cycling repeatability and long-term stability for NO2 sensing are further justified. The incorporated WO3/SiNB heterostructures trigger the remarkably improved sensing performance for detecting 3 ppm of NO2 gas beyond 2.8 and 1.4 times that of WO3/planar Si and WO3/straight Si nanowires, respectively. This can be attributed to the appearance of uneven carrier distribution in the vicinity of WO3/SiNB heterojunctions as NO2 gases are adsorbed, which causes the substantial reduction of the depletion region and in turn suppresses the surface resistivity. The sensing mechanism is further evidenced by the mediation of gate bias that manipulates the sensing contribution from SiNB sides, which readily validates the synergetic interplay of WO3/SiNB hybrid structures.
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