First-principles prediction of Ni-MoO3 as selective and sensitive sensor for detecting CO over CH4, H2, H2O, NH3, H2S gases

Developing sensitive gas sensor is essential for preventing carbon monoxide poisoning. Current experiments demonstrated excellent performance of Ni-MoO₃ as gas sensor, however, atomic-scale sensing mechanism that is critical for developing novel gas sensor is not explored. In this study, adsorption and electronic properties of CH₄, H₂, CO, H₂O, NH₃, H₂S gases on Ni-doped MoO₃ are calculated by first-principles. The CO/Ni-MoO₃ system presents the greatest energy of adsorption, the most significant changes in the band gap, and the largest differential charge density, together with the smallest adsorption distance, indicating an intense interaction and chemisorption between CO and Ni-MoO₃. Upon the CO adsorption, density of state for Ni-MoO₃ descends to a lower energy level, and the increasing in DOS near Fermi level results in a substantial alteration in conductivity. It can be deduced that the Ni-MoO₃ system exhibits sensitive and selective detection toward CO gas.