Ultrafast NH3 Sensing Properties of WO3@CoWO4 Heterojunction Nanofibres at Room Temperature

Highly selective detection, quick response times (<5 s), and superior response (|Rn – Ra|/Ra = 1.17) to NH3 gas, particularly at room temperature (RT), are still enormous challenges in gas sensor applications. In this paper, a rational design and facile synthesis for a NH3 sensor have been proposed. Massage ball-like WO3@CoWO4 (Co-W) nanofibres (NFs) were prepared by a facile one-step synthesis utilising an electrospinning approach, followed by appropriate calcination. A Co-W NF sensor with a Co-to-W atomic ratio of 3 : 10 (Co-W-3), which consisted of nano-sized WO3 protrusions (10–15 nm) on submicrometre-sized single crystal CoWO4 particles (100–150 nm) exhibited excellent gas-sensing properties at RT due to the single crystal CoWO4–CoWO4 homojunction structure and distinct massage ball-like WO3–CoWO4 heterojunction. The approach developed in this work will be important for the low-cost and large-scale production of a Co-W-3 ultrafast sensing material with highly promising applications in gas sensors.