Boosting the acetone gas sensing of WS2–ZnO nanosheets by codecoration of Pt/Pd nanoparticles

WS2-based gas sensors are used for detection of toxic gases at low temperatures due to their high surface area, weak interlayer van der Waals force, and high electrical conductivity. However, in their pristine form, they exhibit poor selectivity. Herein, to increase the selectivity of WS2 sensors, ZnO shells (10-50) nm were fabricated on WS2 nanosheets (NSs) using atomic layer deposition. The sensor with a ZnO shell thickness of 10 nm displayed an improved gas response under 4.2 V applied voltage in the self-heating condition. Next, Au, Pt, Pd, and Pt/Pd nanoparticles (NPs) were decorated on WS2–ZnO (10 nm) NSs, and the Pt/Pd decorated WS2–ZnO (10 nm) NSs exhibited the highest response of 13.77 to 10 ppm acetone under the fixed applied voltage of 4.2 V. The enhanced output was related to the catalytic nature of the Pt and Pd noble metals, formation of WS2–ZnO heterojunctions, and Pt/ZnO and Pd–ZnO Schottky barriers. This study illustrates the promising role of bimetallic Pt/Pd decorations in enhancing the performance of resistive gas sensor.