“…Transition-metal oxides such as ZnO, , SnO 2 , , WO 3 , , TiO 2 , , In 2 O 3 , and CeO 2 have many possible applications in catalysis, , batteries, and sensors , thanks to their stability, economic production, and compatibility with modern electronics. WO 3 , in particular, is very promising because of its unique physical properties and wide range of applications. ,, As a gas sensor, WO 3 has great potential for air detection and respiratory-disease monitoring, and its sensor-performance depends on changes in the surface resistance of adsorbed gas molecules.…”