AWO₄ (A= Zn, Ni) metal tungstates gas sensors: A review

Nowadays, due to extensive emission of toxic gases into our environment, gas sensors are extensively used for the detection of various gases mainly to increase our safety. AWO₄ (A = Zn, Ni) are semiconductor materials with relatively low-cost and abundant, and have stability and good electrical properties. So far, no review paper has been devoted to gas sensing properties of AWO₄ (A = Zn, Ni) gas sensors and they are subject of present review paper. We have paid attention to different aspects of these materials as gas sensors. They are being used in pristine form for the detection of various gases. Furthermore, decoration with noble metals is a popular strategy to enhance their sensing properties. Doping is another feasible route, and finally composite making is widely used to boost their sensing features. We have discussed the sensing mechanism of these sensors in detail. We believe that ZnWO₄ and NiWO₄ gas sensors are very promising materials for sensing purposes thanks to their unique electrical characteristics.