Highly sensitive room-temperture NO2 gas sensor based on Bi2S3 nanorods

Bismuth sulfide (Bi 2 S 3 ) is known for its remarkable sensitivity and stability, making it as an ideal material for gas sensor. Here, we present a highly sensitive room-temperature NO 2 gas sensor by controlling the Bi 2 S 3 nanorods morphology through hot injection method with varying Bi/S ratios (Bi/S = 1, Bi/S = 2, Bi/S = 4). The as-synthesized samples were subsequently spin-coated onto ceramic substrates to fabricate chemo-resistive gas sensors. TEM and XPS analyses revealed that with the increasing Bi/S ratio in the precursors leading to the nanorods aspect ratios enhancing and the generation of S vacancies facilitating. As a result, Bi 2 S 3 nanorods with a Bi/S ratio of 4 exhibited higher carrier mobility and provided more accessible sites for gas molecules. The optimal sensor (Bi/S = 4) showed an impressive response of 12.2 for 10 ppm NO 2 , which is 4 times higher than the device of Bi/S = 1. It also demonstrated a fast response/recovery time of 39 s/696 s and a lower detection limit down to 120 ppb. These findings highlight the excellent gas sensitivity performance of Bi 2 S 3 nanorods at room temperature and their potential for the development of energy-efficient and cost-effective gas sensors.