S-doped wse2@polyaniline heterojunction: Electronic structure modulation and interfacial synergistic effects drive ultrasensitive ammonia gas sensing at room temperature

The development of highly efficient room-temperature ammonia (NH 3 ) sensors is crucial for industrial production and environmental monitoring. However, existing materials generally face critical challenges, including insufficient sensitivity, humidity susceptibility, and limited charge-transfer efficiency. In this study, a synergistic strategy combining electronic structure modulation with heterointerface engineering was employed to fabricate a 2D/1D heterojunction sensing material composed of S-doped WSe 2 @polyaniline (PANI). The electronic band structure was optimized by substituting S atoms into Se sites within the WSe 2 lattice, and in situ oxidative polymerization was used to achieve vertical growth of PANI nanorods on the surface of S-WSe 2 , which significantly enhanced the gas-sensing performance of the composite. The S-WSe 2 @PANI sensor exhibited a remarkable response of 505.75 % to 100 ppm NH 3 at 25 °C and 45 % relative humidity (RH), representing 7.44-fold and 5.32-fold increases compared with pure WSe 2 and PANI sensors, respectively. The sensor also demonstrated an ultra-low theoretical detection limit of 170.31 ppb and excellent moisture resistance (with a response of 857.63 % to 100 ppm NH 3 at 80 % RH). Density functional theory (DFT) calculations revealed that the S-WSe 2 @PANI heterostructure possessed stronger NH 3 adsorption capability, while the work-function difference at the PANI/S-WSe 2 interface effectively promoted charge transfer. This study integrates electronic structure regulation and morphological synergy design strategies to establish an innovative paradigm for high-performance room-temperature NH 3 sensors with substantial potential for application in complex environmental monitoring scenarios.