Adsorption of SO2 and NO2 molecule on intrinsic and Pd-doped HfSe2 monolayer: A first-principles study

HfSe2 monolayer with high electron mobility and chemical activity is a good candidate for gas sensing application. Pd-doping with high catalytic performance would effectively enhance the adsorbing and sensing behaviors of HfSe2 monolayer upon target gas molecules. In this work, we using first-principles theory investigated the adsorption performance of intrinsic and Pd-doped HfSe2 (Pd-HfSe2) monolayer upon two toxic gases (NO2 and SO2), to explore their possible application as gas sensors. Our results indicate that Pd-HfSe2 monolayer has desirable adsorption performance upon NO2 molecule compared with SO2 molecule, with higher adsorption energy and charge-transfer, which leads to more sensitive electrical response for NO2 detection. Moreover, the good desorption behavior of Pd-HfSe2 monolayer upon NO2 molecules allows its recycle use as a resistance-type NO2 gas sensors. Thus, we suggest the exploration of Pd-HfSe2 as a novel sensing material for NO2 detection, which would provide some guidance for experimentalists to further investigate its sensing behavior upon NO2. Our work would be meaningful to propose novel sensing materials from the theoretical manner.