Development of In2O3-based Sensing Materials for NO2 Detection at Room Temperature

Liu, Yanna

Development of In2O3-based Sensing Materials for NO2 Detection at Room Temperature

dc.contributor.advisor	Du, Ke
dc.contributor.author	Liu, Yanna
dc.contributor.committeemember	Kim, Seongwan
dc.contributor.committeemember	Song, Hua
dc.contributor.committeemember	Hu, Jinguang
dc.contributor.committeemember	De Visscher, Alex Andre Hugo
dc.date	2023-06
dc.date.accessioned	2023-05-05T19:05:59Z
dc.date.available	2023-05-05T19:05:59Z
dc.date.issued	2023-04-24
dc.description.abstract	In2O3-based chemiresistive gas sensors are extendedly employed in detecting and monitoring trace gas pollutants such as nitrogen dioxide (NO2) owing to their benefits of low cost, small size, and long lifespan. However, their applications are also limited by low sensitivity (compared to optical sensors), long response/recovery time, and the requirement of operation under high temperatures (when compared to electrochemical sensors). This study designed and fabricated three new materials to overcome these challenges. The first material is Ag nanoparticles decorated In2O3 microtubes (Ag-In2O3) derived from annealing metal-organic-framework (In-MIL-68) and loading Ag nanoparticles by chemical reduction. When the weight proportion of Ag reached 6%, the materials exhibited superior NO2 sensing performance at room temperature (RT, 20-25oC). The response is up to 60.2 to 1 ppm NO2, about 3.5 times that of the In2O3 sensor. The corresponding response/recovery time declines from 228/381 s (pure In2O3) to 157/90 s (Ag-In2O3). Its detection limit is 162 ppb. The excellent NO2 sensing properties can be attributed to the formation of heterojunction between Ag and In2O3, high surface area, and spill-over effect of Ag. The second material is constructed by MoS2 nanoflakes grown vertically on the surface of In2O3 microtubes. We found that In2O3@MoS2 composite with a 25% mass of MoS2 presents an outstanding sensing performance with a response of 39.4 to 1 ppm NO2 at RT. The response and recovery time are 72 s and 118 s, respectively, and the detection limit is 115.4 ppb. The enhanced NO2 sensing performance may benefit from p-n heterojunction at the MoS2/In2O3 interface, the increased oxygen vacancies, chemisorbed oxygen, and improved specific area and pore size distribution. The third material is synthesized through rational integration of ultrathin 2D g-C3N4 nanosheets and In2O3 nanoparticles by hydrothermal and calcination. The optimized composites demonstrated a high gas response of 325 toward 1 ppm NO2 and a short response/recovery time (115/81 s). Moreover, the prepared composites displayed excellent reproducibility, a low detection limit (18 ppb), and satisfied selectivity to NO2 at RT. The outstanding gas sensing properties might be due to heterojunction, enhanced specific surface, and enriched defects.
dc.identifier.citation	Liu, Y. (2023). Development of In2O3-based sensing materials for NO2 detection at room temperature (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.uri	http://hdl.handle.net/1880/116169
dc.identifier.uri	https://dx.doi.org/10.11575/PRISM/dspace/41014
dc.language.iso	en
dc.publisher.faculty	Schulich School of Engineering
dc.publisher.institution	University of Calgary
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	gas sensor
dc.subject	NO2 sensing
dc.subject	heterojunction
dc.subject	In2O3
dc.subject	room temperature
dc.subject.classification	Engineering--Environmental
dc.subject.classification	Materials Science
dc.title	Development of In2O3-based Sensing Materials for NO2 Detection at Room Temperature
dc.type	doctoral thesis
thesis.degree.discipline	Engineering – Mechanical & Manufacturing
thesis.degree.grantor	University of Calgary
thesis.degree.name	Doctor of Philosophy (PhD)
ucalgary.thesis.accesssetbystudent	I do not require a thesis withhold – my thesis will have open access and can be viewed and downloaded publicly as soon as possible.