Ab-initio density functional theory study of a WO₃ NH₃-sensing mechanism

WO₃ bulk and various surfaces are studied by an ab-initio density functional theory technique. The band structures and electronic density states of WO₃ bulk are investigated. The surface energies of different WO₃ surfaces are compared and then the (002) surface with minimum energy is computed for its NH₃ sensing mechanism which explains the results in the experiments. Three adsorption sites are considered. According to the comparisons of the energy and the charge change between before and after adsorption in the optimal adsorption site O_1c, the NH₃ sensing mechanism is obtained.