Volatile organic compound sensing devices based on hollow ZnO heterostructures/p-type semiconductors

Author(s)

Tarcísio Micheli Perfecto

• Document type: Doctoral Thesis
• Press: São José do Rio Preto. 2022-05-24.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências Letras e Ciências Exatas. São José do Rio Preto
• Defense date: 2022-05-19
• Advisor: Diogo Paschoalini Volanti

Abstract

Developing a material to detect volatile organic compounds (VOC) is no longer a challenge, despite its great interest. The difficulty is linked to the developing of a material that does not suffer from interferences, such as humidity, other gases or volatiles present in the analyzes. In this sense, this work focuses on developing zinc oxide (ZnO) hollow spheres and modifying them in a new way with nickel (II) sulfide nanosheets (NiS), a material barely studied in the literature, to increase selectivity detection of butanone and reduce the negative effect caused by humidity, in addition to developing a miniaturized device for coupling this sensor. The ZnO hollow sphere (H-ZnO) was synthesized via a microwave-assisted solvothermal method followed by calcination. The NiS-H-ZnO heterostructures were produced by the deposition of NiS nanosheets on H-ZnO using thioacetamide and nickel (II) acetate tetrahydrate as NiS precursors. Under dry conditions, pure H-ZnO presents the best sensing response of 705.3 to 100 ppm of butanone followed by the 5%-NiS-H-ZnO heterostructure with a response of 123.8. However, the selectivity of 5%-NiS-H-ZnO improves and reaches a value of 12.9, which is more than four times higher than the selectivity of pure H-ZnO (3.1). Furthermore, the performance under humidity atmospheres shows that NiS heterostructures suffer less effect of the humidity. The responses to 100 ppm of butanone under 55% of relative humidity were 40.2 and 23.7 for 5%-NiS-H-ZnO and pure H-ZnO, respectively. Therefore, the developed butanone sensor demonstrated excellent response, selectivity, and a promising possibility for its practical use in detection devices in real humidity conditions. Thus, a miniaturized prototype was developed, based on a microcomputer (Raspberry Pi 4), for the use of this sensor in the practical application of butanone detection. (AU)

• FAPESP's process: 18/00033-0 - Sensing devices of volatile organic compounds based on ZnO hollow/p-type semiconductors heterostructures
• Grantee: Tarcísio Micheli Perfecto
• Support Opportunities: Scholarships in Brazil - Doctorate