Facile Solution-Processed Deposition of Bi₂S₃ Nanostructures for a Highly Sensitive and Selective Room-Temperature NO₂ Sensor

In this work, we present an approach for utilizing pristine Bi 2 S 3 as a sensing material for the detection of NO 2 gas at room temperature. Spanish oyster-like hierarchical Bi 2 S 3 nanostructures, with a diameter of 832 nm and a Brunauer–Emmett–Teller (BET) surface area of 20.56 m 2 /g, were grown using the [Bi{S 2 P(O(Pr) 2 ) 3 }] complex via an optimized, one-step, low-temperature, and in situ solvothermal process. In contrast, the spin-coating method resulted in impurities even after the annealing step. X-ray diffraction (XRD), Raman, selected area diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM) analyses confirmed the orthorhombic bismuthinite phase of the Bi 2 S 3 nanostructures, with a calculated band gap of 2.82 eV. The Bi 2 S 3 -based sensor exhibited exceptional sensitivity and selectivity toward NO 2, surpassing other gases such as CO 2, NH 3, H 2 S, and C 2 H 6 O at room temperature. Specifically, the sensor demonstrated a high response of 39.4%, rapid response/recovery times (14/257 s), excellent repeatability, and stability (30 days) under 100 ppm of NO 2 exposure. The enhanced performance at room temperature is attributed to the competitive adsorption of NO 2 on the hierarchical structure of Bi 2 S 3, facilitating increased gas adsorption and charge transfer.