Highly selective and sensitive detection of methyl mercaptan by heterostructural CdS/(Sr0.6Bi0.305)2Bi2O7 chemiresistor

Abstract

Methyl mercaptan (MM) is one kind of volatile sulfur compound (VSC) with odor and properties (inflammable, highly toxic, and corrosive) similar to H₂S; therefore, the highly sensitive and selective monitoring of ambient MM by chemiresistors is strongly essential, but it remains a challenge owing to its relatively weak reducibility/response in comparison with H₂S. In this study, a novel chemiresistor composed of hexahedral particles SBO-loaded CdS nanoparticles has been prepared via a facile chemical precipitation method for the super-sensitive and highly-selective recognition of MM. The heterostructural CdS/SBO (0.05%) chemiresistor exhibited an extremely high response (114.7) to 100 ppm MM at a relatively low operating temperature (100 °C) and was about 36- and 9-fold higher than pure SBO and CdS chemiresistor, respectively. Various characterizations suggested that the sulfurization–desulfurization reaction, the abundant oxygen vacancies, and the generation of n–n heterojunctions at the interface promote the redox reaction of surface-active substances, thereby, boosting the outstanding MM response characteristics. In addition, the heterostructural chemiresistor possesses good selectivity, weak humidity interference, a lower limit of detection (LoD) of 82 ppb, and long-term stability (∼6% decline of response after 120 days), which promises practical applications in air quality (odor) monitoring.