Activating and modifying the basal planes of MoS2 for superior NO2 sensing at room temperature

The gas sensing performance of two-dimensional (2D) materials is greatly hindered by their inactive basal planes. In this work, a hierarchical MoS2 material with a 2D-in-3D architecture has been synthesized by a facile hydrothermal method with subsequent high temperature annealing in argon atmosphere and Zn doping for NO2 gas sensing application. High temperature annealing makes MoS2 material generate a large number of S-vacancy defects and resulting in strong interlayer coupling and spin-orbit coupling effects. It is found that the hierarchical MoS2 annealed at 700 and 850 °C exhibited extremely high gas sensing performance at room temperature in terms of sensitivity, response and recovery speeds, selectivity and stability. The introduction of transition metal Zn element further improves the gas sensing performance of the MoS2 material. After Zn doping, the MoS2 annealed at 850 °C reached an unprecedented gas response of 1405% to 100 ppm NO2 with a detection limit of 8.1 ppb. The relevant gas sensing mechanism is discussed in depth. This work opens up a simple and highly efficient way for activating and modifying the basal planes of MoS2 with robust architecture.