Two-dimensional HfTe2 monolayer treated by dispersed single Pt atom for hazardous gas Detection: A First-principles study

Developing sensing materials with high response and selectivity to hazardous gases is crucial in industry, environmental area, and human life safety. In this work, the adsorption and sensing behavior of pristine and single Pt atom doped HfTe2 monolayer to six different hazardous gases (NO2, NO, CO, SO2, H2S, and NH3) were proposed theoretically. The adsorption configurations, adsorption energies, electron transfers, and the ratio of long-range interactions were compared. To discuss the response and desorption process, the work function, occupation function, and desorption time were investigated. It is found that, for pristine HfTe2, the ratio of long-range interactions is larger than 0.5 for most of hazardous gases except NO, but after the introduction of Pt, the adsorption energies increase while the ratio of long-range interactions decrease for all six hazardous gases. This phenomenon is ascribed to the conspicuous enhancement of the chemical and short-range interactions between adsorbed gas molecule and Pt atom. In addition, Pt-HfTe2 has high selectivity to CO at room temperature to about 400 K, and if CO is absent, Pt-HfTe2 shows high selectivity to NO2 at room temperature. The response of Pt-HfTe2 depends on the change of the work function. This study explored the theoretical sensing behavior of single Pt doped HfTe2 as work function-based gas sensor toward different molecules.