MoS₂-PdS₂ Heterostructure for NO₂ Sensing under Ambient Conditions: An Experimental and Computational Study

Area of Science:

• Materials Science
• Nanotechnology
• Environmental Science

Background:

• Effective gas sensors are crucial for environmental protection, especially for detecting harmful gases like nitrogen dioxide (NO2) at room temperature (RT).
• Detecting trace amounts of NO2 at RT remains a significant challenge.
• Van der Waals (vdW) junctions of 2D materials offer unique properties for advanced sensing applications.

Purpose of the Study:

• To develop an efficient NO2 gas sensor operating at room temperature (RT).
• To investigate the sensing performance of a MoS2/PdS2 vdW heterojunction for NO2 detection.
• To explore the underlying mechanisms enhancing sensor performance.

Main Methods:

• Fabrication of a MoS2/PdS2 vdW heterojunction.
• Characterization of the heterojunction's electrical conductivity and NO2 sensing properties at RT (30 °C).
• Density Functional Theory (DFT) calculations to analyze NO2 adsorption and charge transfer.

Main Results:

• The MoS2/PdS2 heterojunction exhibited significantly enhanced conductivity compared to pristine materials.
• The sensor demonstrated a remarkable relative response (∼25%) to 20 ppm NO2 at RT, surpassing individual MoS2 (∼12%) and PdS2 (∼7%) sensors.
• A low limit of detection (LOD) of 1.4 ppb, good response/recovery times, and excellent stability were achieved.

Conclusions:

• The MoS2/PdS2 vdW heterojunction is a highly effective platform for room-temperature NO2 gas sensing.
• DFT calculations confirmed that the p-p junction facilitates favorable NO2 adsorption and charge transfer, boosting sensor performance.
• This work provides a promising framework for developing advanced 2D vdW heterojunction-based gas sensors.