Hybrid Two -Dimensional Materials and metal Oxides for Resistive Gas Sensors

Publication:
Hybrid Two -Dimensional Materials and metal Oxides for Resistive Gas Sensors

dc.contributor.advisor	Kumar, Mahesh
dc.creator.researcher	Kumar, Sumit
dc.date.accessioned	2026-03-23T07:19:55Z
dc.date.available	2026-03-23T07:19:55Z
dc.date.awarded	2025-06-05
dc.date.issued	2025-06-05
dc.date.registered	2020-09-01
dc.description.abstract	The advancement of resistive gas sensors with enhanced sensitivity, selectivity, and stability is pivotal for applications in environmental monitoring, industrial safety, and healthcare. This research investigates the design and fabrication of hybrid nanomaterials by the integration of two-dimensional (2D) materials, metal oxide semiconductors, high-entropy alloy (HEA) quasicrystal nanosheets, and carbon nanotubes. The synergistic interaction through these components is designed to enhance gas adsorption, charge transfer, and overall sensor performance, opening the way for enhanced gas sensing technologies. 2D materials are known for their high surface area and tunable electronic properties, offering suitable for sensing applications. However, their sensitivity and selectivity can be limited in its pristine form. To address this, the integration of HEA quasicrystal nanosheets with 2D materials to form heterostructures that provide the unique properties of both components. Quasicrystal nanosheets, composed of multi-metallic principal elements, exhibit high structural stability and catalytic activity, which can enhance gas adsorption and charge transfer processes. The quasicrystalline nature of these nanosheets introduces aperiodic order, potentially creating a high density of active sites for gas interactions. This integration aims to improve the sensitivity and selectivity of the sensors by facilitating stronger and more specific gas-surface interactions. We report a highly sensitive and selective nitrogen dioxide (NO2) sensor using a hybrid nanocomposite of two-dimensional (2D) Al70Co10Fe5Ni10Cu5 quasicrystal (QC) nanosheets and MoS2 nanoflakes. The Al70Co10Fe5Ni10Cu5/MoS2 heterostructure enhances the sensor's performance, showing a gas-sensing response (ΔR/Ra %) of ∼66%, approximately 2.27 times than MoS2 alone at 100 ppm NO2 and 100°C. Additionally, we explore the gas-sensing properties of 2D QC nanosheets integrated on 1T and 2H mixed phase WS2 nanoflakes, which exhibit a 2.33 times higher response (ΔR/Ra% = 52%) for 20 ppm NO2 at 125°C compared to bare WS2. The enhanced performance is attributed to increased active sites for NO2 adsorption, as explained by density functional theory (DFT), which shows that 2D QCs provide higher adsorption energy and improved Fermi level alignment, significantly boosting the sensor's sensitivity. This work provides valuable insights for designing efficient NO2 gas sensors. Metal oxides are widely used in gas sensors due to their semiconducting properties and chemical stability. However, their performance at room temperature is often suboptimal. To enhance their sensing capabilities, incorporate quasicrystal nanosheets and carbon nanotubes to form a heterostructure. These carbon nanotubes provide sufficient electrical conductivity and large surface areas, facilitating efficient charge transport and gas diffusion. We report the development of highly sensitive and selective gas sensors for NO2 and H2S detection using low-cost, scalable fabrication techniques. For NO2 detection, a hybrid sensor combining two-dimensional (2D) quasicrystal (QC) Al70Co10Fe5Ni10Cu5 nanosheets with α-Fe2O3 nanoparticles exhibited a sensitivity of 32% for 1 ppm NO2 at 150°C, 3.5 times higher than bare α-Fe2O3. The enhanced performance is attributed to nano heterojunction formation between 2D QC and α-Fe2O3, improving charge ransport and signal strength. DFT calculations confirm these findings, showing improved adsorption and charge transfer. For H2S detection, a sensor based on multiwalled carbon nanotubes (MWCNTs) and copper oxide (CuO) particles demonstrated a 73% response to 10 ppm H2S at 50°C, 1.6 times higher than bare CuO sensors. The MWCNT@CuO interface forms a p–p heterojunction, enhancing sensitivity by modifying the band structure and increasing chemisorbed oxygen content. These sensors offer high performance, low power consumption, and excellent selectivity, providing promising solutions for gas sensing applications. For hydrogen (H₂) sensing, AlMnPdPtAu QC nanosheets were integrated with CNTs via a cost-effective screen-printing method, sensor with outstanding sensitivity (103% at 1 ppm and 130.4% at 100 ppm), rapid response/recovery (19 s/81 s), and room-temperature operation. Structural and spectroscopic investigations, supported by DFT calculations, revealed dissociative H₂ adsorption, spillover mechanisms, and strong electronic coupling at the QC@CNT interface, driven by Mn site interaction and Bader charge transfer. This research finding suggests that these hybrid structures can enhance gas sensing performance, paving the way for the development of next-generation sensors with potential applications in environmental monitoring and industrial safety.
dc.description.statementofresponsibility	Mahesh Kumar
dc.format.extent	xxiii, 165p.
dc.identifier.accession	TP00226
dc.identifier.citation	Kumar, Mahesh (2020).Hybrid Two -Dimensional Materials and metal Oxides for Resistive Gas Sensors (Doctor's thesis).Indian Institute of Technology, Jodhpur
dc.identifier.uri	https://ir.iitj.ac.in/handle/123456789/271
dc.language.iso	en
dc.publisher	Indian Institute of Technology, Jodhpur
dc.publisher.department	Electrical Engineering
dc.publisher.place	Jodhpur
dc.title	Hybrid Two -Dimensional Materials and metal Oxides for Resistive Gas Sensors
dc.type	Thesis
dspace.entity.type	Publication