E-Locus - Institutional Repository of the University of Crete

Home Collections Type of Work Post-graduate theses

Post-graduate theses

Current Record: 8 of 6684

[Add to Basket]

Identifier

000465933

Title

Cs2AgBiBr6 perovskites & 2D material conjugations for gas sensing applications

Alternative Title

Cs2AgBiBr6 περοβσκίτες & σύζευξη με δισδιάστατα υλικά για εφαρμογή σε ανίχνευση

Author

Συσκάκη, Μαρία

Thesis advisor

Στρατάκης, Εμμανουήλ

Reviewer

Κιοσέογλου, Γεώργιος
Ρεμεδιάκης, Ιωάννης

Abstract

Gas sensors are devices capable of detecting the presence and concentration of various gases, playing a crucial role in applications such as air-quality monitoring, public safety, agriculture, and medical diagnosis. The most common sensing materials are metal oxide semiconductors, which have low-cost production and high sensitivity, albeit necessitate high temperatures or other external stimuli to operate. Therefore, there is need to develop new sensing materials that can overcome this limitation, while maintaining or offering better sensing performance. An alternative and promising candidate material for gas sensing is the group of all-inorganic metal halide perovskites, having the general formula ABX3, where A is an organic or inorganic cation, B is a metal cation, and X is a halide anion. They have exhibited the ability to detect gases (O3 and H2) at very low concentrations (a few ppb), featuring fast response times (few hundreds of seconds) without the demand of external triggering. However, challenges persist, including environmental instability and toxicity of lead, commonly utilized as the metal cation. Taking into account the aforementioned properties and needs, this project aimed to fabricate lead-free double halide perovskite gas sensing elements (Cs2AgBiBr6) in the form of nano- or micro-crystals, employing a straightforward and room-temperature ligand-free precipitation method. Furthermore, the perovskites were conjugated with 2D graphene-based materials and Transition Metal Dichalcogenides (TMDs) to enhance their conductivity and their sensing ability. Diverse synthesis methods and characterization techniques were used to optimize the fabrication process and understand the sensing mechanisms of those novel materials. Cs2AgBiBr6 nanocrystals found to be capable of detecting low O3 concentrations down to 50 ppb, having response and recovery times around 1 minute.

Language

English

Subject

Gas detection

Graphene

Lead-free prerovskites

Metal halide perovskites

Nanomaterials

Ozon gas

Reduced graphene oxide

Όζον

Αμόλυβδοι περοβσκίτες