Low-Dimensional Hybrid Halide Heterostructures for X-ray Detection, Multifield Energy Transduction and Photoelectrocatalysis

Gupta, Shresth (2026) Low-Dimensional Hybrid Halide Heterostructures for X-ray Detection, Multifield Energy Transduction and Photoelectrocatalysis. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Shresth Gupta (19IP011)) 19IP011.pdf - Submitted Version Restricted to Repository staff only Download (33MB)

Abstract

This thesis explores low-dimensional hybrid halides and their heterostructures as a versatile materials platform for integrating electronic, structural, and interfacial functionalities toward applications in sensing, energy transduction, electromagnetic interference (EMI) shielding, and sustainable catalysis. By systematically engineering dimensionality, composition, and interfaces, the work demonstrates how hybrid iodides, particularly bismuth-based systems and their integration with MXenes can be tuned to achieve multifunctional performance. The study begins with low-dimensional hybrid bismuth iodides, where spacer-controlled modulation from one-dimensional to zero-dimensional architectures enables precise tuning of charge transport, defect tolerance, and polarization. The non-centrosymmetric 1D system exhibits strong intrinsic ferroelectricity, enabling efficient charge separation and highly sensitive direct X-ray detection with ultralow detection limits below medical thresholds. These materials also display coupled ferroic responses, including piezoelectricity and pyroelectricity, highlighting their multifunctional nature. Extending this concept, hybrid iodide systems are investigated as multi-field energy transducers capable of responding to electrical, mechanical, thermal, and optical stimuli. Through compositional tuning between Bi- and Sb-based analogues, a balance between polarization, thermal stability, and carrier dynamics is achieved, enabling significant triboelectric, piezoelectric, and pyroelectric outputs along with nonlinear optical responses such as second-harmonic generation for sub-bandgap photodetection. When integrated into multilayer heterostructures, these materials exhibit interfacial polarization gradients and thermally activated transport under coupled stimuli, demonstrating synergistic energy harvesting. The thesis further introduces an interface-engineered multiferroic “Perovxene” system formed by coupling Fe-intercalated Ti₃C₂Tₓ MXene with polar hybrid iodides, where magnetic ordering, conductivity, and ferroelectric polarization coexist. This heterostructure enables enhanced EMI shielding in the X-band, dominated by absorption due to synergistic conductive, dielectric, and magnetic losses, with interfacial magnetoelectric coupling promoting spin-polarized transport and charge redistribution. Finally, hybrid halides are extended to photocatalysis and photoelectrochemistry through radical-mediated processes, where surface-functionalized perovskites enable visible-light-driven generation of reactive species for efficient antibacterial activity. This concept is further applied to selective photoelectrochemical C–N coupling between CO₂ and nitrate using a heterostructured electrode of Cu-intercalated MXene and lead-free perovskite, enabling urea formation under ambient conditions with suppressed side reactions. Overall, it establishes hybrid halide-MXene heterostructures as a scalable framework where dimensionality, ferroic order, and interfacial engineering can be synergistically harnessed for advanced energy, sensing, electromagnetic attenuation, and sustainable chemical synthesis.

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