Research Projects

The technique of laser ablation in liquid (LAL) has seen rapid and exciting progress in recent years, thanks to its capability to produce nanoparticles of numerous materials such as metals, semiconductors, and ceramics [Adv. Funct. Mater., 34(40), (2024), Article 2405457; C. Byram, et al., J. Opt. (Topical Review), 25, 043001, 2023]. The pulsed LAL technique is a green method (no precursors involved) for producing either pure or alloyed, ligand-free nanoparticles in different sizes and shapes. Further, nanocomposites of various materials can be achieved using reactive LAL. TMDC nanomaterials can be produced/fabricated easily using the ultrafast ablation technique [Adv. Mater., 2023, 35, 2301129; Nanoscale, 2024, 16, 15640; PNAS, 2022, 119(39), e2208830119]. This proposal examines the potential of these nanomaterials (prepared using ultrafast LAL) in SERS-based vapor sensing of hazardous materials, photonics, and memory devices. TMDCs exhibit a robust excitonic response, leading to interesting optical phenomena permitted by the strong light-matter interactions. TMDCs also possess excellent optical properties such as (i) high RI in the visible, IR spectral regions (n = 4 to 6) (ii) carrier dynamics in the ultrafast domain (iii) large oscillator strength/unit area (iv) huge exciton binding energy (100 meV), (v) long lifetimes (ns) and (vi) third-order optical nonlinearities that are comparable to plasmonic nanoparticles [M.E. Maldonado, et al., ACS Photonics 2020, 7(12), 3440–3447]. MXenes exhibit tunable electrical characteristics, exceptional conductivity, and possess a multitude of surface functional groups, making them highly appealing for applications in gas sensing [Sensors & Actuators: B. Chemical 441 (2025) 137939]. Various fabrication techniques of such materials include (a) mechanical exfoliation (b) chemical vapor deposition technique (CVD) (c) liquid phase exfoliation (d) wet chemical synthesis (e) laser ablation techniques. Nevertheless, the shift from basic research to real-world applications involving these 2D materials has faced numerous challenges. Some of the major issues with these materials are (i) mono-layer controllability (ii) defect engineering (iii) doping/alloying (iv) long-term stability issues [https://doi.org/10.1021/acsmaterialsau.5c00015]. Another significant barrier is the complexity involved in nanostructuring these materials, requiring the creation of nanostructures that possess the appropriate size, shape, and characteristics, which is crucial for their incorporation into cutting-edge technologies/devices. We believe that femtosecond (fs) LAL will solve these issues. Ultrafast LAL is a unique technique that can address most of these issues [see a very recent review article by Tselikov et al. https://doi.org/10.1021/acsnano.5c00546 wherein they demonstrated the outstanding versatility of the fs laser fabrication method to produce such nanomaterials]. Objectives 1. Prepare efficient 2D nanomaterials (TMDCs of MoS2, MoSe2, WS2, WSe2 and MXenes/nanocomposites such as Ag-Ti3C2) using ultrashort pulse LAL and Gaussian/Bessel/Vortex beam profiles. [VRS group] 2. Functionalize these nanomaterials with plasmonic metals (Ag, Au, Ag-Au) for superior SERS performance/utilization of these 2D nanomaterials with existing plasmonic nanostructures for improved SERS performance. (See schematic below right) [VRS group] 3. Exploring the memory-related (RRAM) applications of these 2D nanocomposites (either in bi-layer, few-layer form, or quantum dots doped in polymers) [SVSN group] 4. Investigate the photonic/optoelectronic applications of the prepared 2D TMDC nanostructures (temperature-dependent PL, NLO studies using the Z-scan technique). [SSKR and VRS groups] 5. Explore the ultrafast dynamics in these nanocomposites using femtosecond transient absorption spectroscopy. [SSKR group]