In2O3/g-C3N4/Au ternary heterojunction-integrated surface plasmonic and charge-separated effects for room-temperature ultrasensitive NO2 detection

• Published in: Sensors and actuators. B, Chemical Chemical, 2022-11, Vol.371, p.132448, Article 132448
• Main Authors: Han, Chaohan, Li, Xiaowei, Liu, Jie, Dong, Haipeng, Cheng, Wanying, Liu, Yu, Xin, Jiayu, Li, Xinghua, Shao, Changlu, Liu, Yichun
• Format: Article
• Language: English
• Subjects: Carbon nitride; Carrier recombination; Electromagnetic absorption; Gas sensors; Gold; Heterojunctions; In2O3/g-C3N4/Au; Indium oxides; Light; LSPR; Metal oxides; Nanofibers; Nanoparticles; Nitrogen dioxide; NO2; Room temperature; Sensors; Visible-light activated
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2022.132448

Light-activated gas sensors based on semiconducting metal oxides (SMOs) hold great promise for next-generation gas sensing application, due to their unique superiority including room-temperature operation, intrinsic safety, and simple device structure. However, poor visible-light absorption and fast carrier recombination of SMOs sensing film are two main barriers that seriously restrict their sensing performance of light-activated gas sensors. Herein, a visible-light activated gas sensor based on Au nanoparticles modified In2O3/g-C3N4 heterojunction nanofibers is developed. Excellent sensing response (Rg/Ra = 17.2 to 1 ppm NO2, where Ra and Rg represent the resistance of sensors when exposed to air or target gas) and fast response/recovery kinetics at room temperature are obtained, which is markedly better than the sensors based on pristine In2O3 nanofibers and In2O3/g-C3N4 nanofibers. Through the discussion and estimation of experimental results, the improved gas sensing properties of In2O3/g-C3N4/Au-based sensors are speculated to be related to the enhanced visible light utilization benefiting from localized surface plasmon resonance (LSPR) effect of Au nanoparticles, and the efficient separation of photo-generated carriers enabled by heterojunctions between In2O3, Au, and g-C3N4 components. The current work will provide a universal strategy to develop high-performance light-activated gas sensor and a deep understanding about the sensing principle of this novel type of gas sensor. [Display omitted] •The built-in electric field of In2O3/g-C3N4 heterojunctions could effectively separate the photogenerated carries.•The LSPR effect of Au nanoparticles extends the visible-light absorption range of sensing materials.•The Schottky junctions formed on the interface of Au and SMOs could increase the separation of photogenerated carries.•The Au nanoparticles could promote the chemical adsorption of NO2 molecules on the sensing materials.