MXene hybrid nanoparticle sensor for gas detection

Details

Supervisors

Hermans, Sophie ; Hackens, Benoît

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil en chimie et science des matériaux, à finalité spécialisée

Abstract

enThis thesis presents the development of a room-temperature chemiresistive gas sensor based on a hybrid material composed of molybdenum disulfide nanoparticles/nanoplatelets (MoS2) and two-dimensional Ti3C2Tx MXene. The work addresses the need for scalable, energyefficient gas sensing solutions and leverages the synergistic properties of hybrid materials to enhance sensitivity and selectivity. Two synthesis strategies were employed to prepare the MoS2/MXene hybrids of various weight proportions: (i) intimate physical mixing of the individual components, and (ii) in-situ hydrothermal growth of MoS2 in the presence of MXene. The resulting hybrids were then deposited onto interdigitated electrode (IDE) electrode substrates via drop-casting to fabricate the chemiresistive gas sensor. Gas sensing tests were conducted using ammonia (NH3) and hydrogen sulphide (H2S) under varying conditions of gas concentration and humidity. All the developed hybrids showed a strong ptype response to ammonia under gas exposure correlating with the physicochemical properties of the respective materials. The best performing sample in terms of response magnitude and recovery times was the hydrothermal hybrid with a 5:1 ratio between MoS2 and MXene. It showed a response of 9.61% to 100ppm of ammonia, with a response and recovery time of 16 and 21 minutes, respectively. The limit of detection was calculated to be between 3.27 and 3.52 ppm. Additionally, humidity tests revealed that the sensor response to ammonia increased in the presence of humidity. The enhanced performance was attributed to the growth of defectrich nanoplatelets of MoS2 on the high surface area MXenes producing a hybrid that combined the highly active adsorption sites of MoS2 and MXenes with the conductive properties of MXenes as well the formation of heterojunctions between these materials which further enhanced the overall response. Furthermore, pristine MoS2 and MXene showed no gas sensing response, which further corroborates the synergistic effect of the hybrid resulting in a more effective material. A performance comparison between the intimate mixing and hydrothermal hybrids showed that the in-situ growth of the MoS2 on the MXenes is more beneficial for the synthesis of the final hybrid as it results in a more homogeneous material with more heterojunctions resulting in better charge transfer dynamics and performance. This work further adds to the existing, but very limited, literature on MoS2/MXene composites for gas sensing while also providing insights into the influence of the synthesis route on the gas sensing performance.