Pd functionalized MoS2 hierarchical spherical for detection of NO2: A combined experimental and theoretical study

Since nitrogen dioxide (NO 2 ) is an air pollutant that can seriously harm human health, developing high-performance gas sensors capable of efficiently detecting nitrogen dioxide at room temperature is of great significance for environmental monitoring and health protection. In this work, we synthesized hierarchical spherical MoS 2 with a high specific surface area via a hydrothermal method and uniformly loaded Pd nanoparticles onto its surface through an in-situ reduction strategy, successfully constructing a Pd/MoS 2 composite material. Characterization techniques including SEM, TEM，XPS confirmed the successful loading of Pd nanoparticles and the electronic interaction between Pd and MoS 2 . Experimental results demonstrate that the 1% Pd/MoS 2 composite exhibits optimal sensing performance toward NO 2 at room temperature: a high response value (Rg/Ra) of 9.33 toward 10 ppm NO 2 , along with excellent selectivity, repeatability, and long-term stability. Density Functional Theory (DFT) calculations further elucidated the enhancement mechanism: the introduction of Pd significantly increased the adsorption energy of NO 2 on the material surface (from −0.253 eV to −1.41 eV), thereby greatly improving the sensor's sensitivity and response kinetics. This research provides an effective material design strategy and theoretical foundation for developing high-performance, low-power-consumption room-temperature NO 2 gas sensors.