Selective Functionalized Pt nanoparticles on WS2 by Atomic Layer Deposition for Enhancing Recovery and Responsivity of NO2 Gas Sensor

Abstract

The need for gas sensing of trace amounts of NO2, which could cause damage to human respiratory system, has attracted great interest for environmental monitoring and health protection. Especially, two-dimensional transition metal dichalcogenides (2D TMDCs) based gas sensors have shown outstanding gas sensing properties even at room temperature owing to its high surface-to-volume ratio. However, 2D TMDCs based gas sensors have several issues such as poor recovery rate due to chemisorbed gas molecules (NO2) at defects such as dangling bonds or grain boundaries (GBs) and low response. [1] In order to solve this problem, functionalization of 2D TMD surface has been widely studied using noble metals such as Pt, Pd, Au.[2] Among them, Pt nanoparticles (Pt NPs) is known to be effective materials for enhancing the NO2 sensing properties due to its greater electronic or chemical sensitization effect than that of other noble metal NPs. [3] For synthesis of Pt NPs, conventional methods such as PVD and hydrothermal method could attribute to agglomeration of NPs which could lead to incomplete recovery and formation of undesirable current path of sensor. So, in this study, we selectively functionalized Pt NPs on defects of tungsten disulfide (WS2) using atomic layer deposition (ALD) which could easily control distribution of NP. The Pt functionalized WS2 gas sensor showed 6 times higher response and higher recovery rate (~93.2%) than those of pristine WS2 based gas sensor, respectively.