Anupma Thakur

The protein corona (PC) that forms on the surface of nanomaterials upon contact with biological fluids provides a molecular snapshot of the host’s physiological and pathological state. Here, we investigate two-dimensional (2D) titanium carbide (Ti3C2Tx) MXene nanosheets as nanobiointerfaces for capturing Alzheimer’s disease (AD)–associated plasma protein signatures. Ti3C2Tx MXene flakes were incubated with plasma from clinically diagnosed AD patients and age-matched healthy controls (HC), leading to the formation of Ti3C2Tx MXene–PC complexes. Physicochemical characterization using dynamic light scattering, zeta potential analysis, and transmission electron microscopy revealed disease-dependent changes in hydrodynamic size, surface charge, and PC profile. Proteomic analysis of the isolated PC layers quantified 1,611 proteins without prior fractionation, demonstrating broad plasma proteome coverage. Principal component analysis (PCA) revealed disease-associated separation between AD and HC-derived Ti3C2Tx MXene PC proteomes along specific principal components despite interindividual heterogeneity. Differential abundance analysis identified selective enrichment of heterogeneous nuclear ribonucleoproteins (hnRNPs), annexins, and inflammatory mediators in AD-derived PC, implicating dysregulated RNA metabolism, membrane stress responses, and immune activation, hallmark processes in AD pathology. Our findings demonstrate that Ti3C2Tx MXene–PC interfaces reshape the detectable plasma proteome and enable disease-associated molecular phenotyping, establishing a versatile nanointerface-driven framework for AD-related proteomic fingerprinting and molecular profiling. These results provide a foundation for future studies exploring MXene-based biointerfaces for plasma biomarker discovery and translational diagnostic applications.

In-situ electrochemical spectroscopic ellipsometry (EC-SE) can enable real-time monitoring of optical properties and thickness changes of surfaces and thin films. This method can provide a broad range of information on the evolution of the microenvironment of an electrode during electrochemical reactions. However, to avoid modeling artifacts, accurate data analysis is critical. Here, we outline key steps in data analysis that can help prevent overfitting and misinterpretation of results. For example, determining the refractive index of the electrolyte at the air/electrolyte interface, along with measurements of the electrode’s dielectric data in dry conditions, can yield more accurate results than simultaneous fitting of all parameters for the electrolyte and electrode. We also present detailed modeling strategies tailored to fitting in-situ cyclic voltammetry (CV) data on various types of thin films, by providing two distinct examples: the thickness change of catalyst polymer films due to swelling by the electrolyte, and the simultaneous change in thickness and optical properties of Ti3C2Tx MXene films due to both reversible (electrochromic effect) and irreversible (degradation) processes. These details can help guide the informed selection of models in similar conditions by providing practical guidelines. The step-by-step approach to modeling can be more broadly adopted to enhance the accuracy and reproducibility of EC-SE experiments for interfacial studies relevant to energy conversion and storage, as well as other electrochemical reactions.

In this study, we present an approach to the selective detection of mercury (Hg ²⁺ ) using organic fluorophores, guided by biomimetic design principles. Conventional approaches predominantly employ sulfur‐containing functionalities, which, although effective, often suffer from cross‐reactivity with competing metal ions such as As ³⁺ , Pb ²⁺ , and Cu ²⁺ . Here, oxygen‐ and nitrogen‐based functional groups are incorporated with naphthalene diimide (NDI) derivatives, inspired by biological coordination environments, to enhance selectivity. NDI derivatives, including NDI‐A, NDI‐A*, and NDI‐Cys*, are synthesized with strategically positioned hydroxyl and carboxylate moieties to modulate metal‐ligand interactions. Among the prepared compounds, the NDI‐A* derivative exhibits improved selectivity toward Hg ²⁺ over fifteen potential interfering ions and demonstrates suitability for real‐sample analysis. The sensing performance is further evaluated by fluorescence spectroscopy and density functional theory (DFT) calculations. DFT studies provide mechanistic insights, which reveal favourable binding energies and a ligand‐to‐metal charge‐transfer (LMCT) pathway governing fluorescence quenching. The NDI‐A* derivative‐based sensor achieves a limit of detection of ^∼ 42 ppb and a limit of quantification of ∼141 ppb, with a linear detection range spanning 42–1330 ppb for selective Hg ²⁺ detection.

The oxygen evolution reaction (OER) remains a key bottleneck in electrochemical energy systems owing to its sluggish kinetics and high overpotential. Here, we present a piezoelectric-enhanced electrocatalysis strategy integrating titanium carbide (Ti3C2Tx) MXene with copper-nickel-iron (CuNiFe) (oxy)hydroxides. In a conventional H-cell, the Ti3C2Tx overlayer reduces the OER overpotential by over 12% at both 10 and 100 mA cm-², while improving short-term stability (degradation rate 0.0024 V h-1 versus 0.0051 V h-1 for pristine CuNiFe over 10 h at 100 mA cm-2). In a flow-cell configuration, Ti3C2Tx@CuNiFe achieves a lower overpotential of 232 mV at optimized flow (60 mL min-1, 10 mA cm-2) and maintains stable operation beyond 90 h with minimal loss (0.601 mV h-1). Flow-rate-dependent measurements with reversible sonication confirm that the enhancement stems from the piezoelectric response of Ti3C2Tx rather than structural degradation: mechanical stimulation generates local electric fields that facilitate charge transfer and accelerate OER kinetics. Critically, a reduced graphene oxide control (rGO@CuNiFe) with comparable 2D conductivity but no piezoelectric activity shows no enhancement in either configuration, confirming that the acceleration originates from MXene-specific electronic coupling rather than a generic conductive coating. These findings provide direct evidence of piezoelectric modulation in MXene-based electrocatalysts.

Ordered double transition-metal (DTM) MXenes are a subfamily of two-dimensional (2D) carbides, nitrides, and carbonitrides, predicted to outperform single-metal MXenes in hydrogen evolution reaction (HER) catalysis due to the synergistic effect of two metals and their nonmetal (X) sublattice tailoring (X = C, N), resulting in tunable electronic structures. However, all synthesized DTM MXenes to date contain only carbon in the X sublattice. Here, we report the synthesis of a series of out-of-plane ordered DTM carbonitride MXenes (o-MXenes), Mo₂Ti(CN)₂T_x and Mo₂Ti₂(CN)₃T_x, to systematically investigate the role of carbon to nitrogen ratio. To determine the optimal nitrogen content, we first evaluated the HER activity of the Mo₂TiC_2-yN_yT_x MXenes with density functional theory calculations and identified that 0.3 to 0.6 mol of nitrogen give enhanced performance compared to the carbide. We next synthesized and characterized 11 carbonitride MXenes with varying their C:N ratios and found nitrogen incorporation enhances HER activity compared to their carbide counterparts. Among them, Mo₂TiC_2-yN_yT_x MXene with 0.6 mol of nitrogen (y = 0.6) achieved the best performance, with an overpotential of ∼155 mV at 10 mA/cm² under acidic conditions, compared with ∼236 mV for Mo₂TiC₂T_x. Our experimental and computational findings indicate that carbonitrides with ∼25–30 atom % nitrogen outperform all other o-MXene counterparts, with the improved performance arising from nitrogen-induced modulation of the electronic structure. This study identifies nonmetal sublattice control as a critical frontier in optimizing MXenes for sustainable energy applications.

This work establishes a comprehensive thermodynamic framework for vapor transport in hierarchical titanium carbide (Ti₃C₂T_x) MXene-poly(vinylidene fluoride) (PVDF) coated polytetrafluoroethylene (PTFE) composite membranes through integrated physics-based analysis and experimental validation. The composite architecture leverages PTFE’s exceptional hydrophobicity of 135° with PVDF’s processability, creating triple interfaces governed by Gibbs excess surface thermodynamics. Controlled spinodal decomposition during nonsolvent-induced phase separation yielded β-phase-rich PVDF matrices with uniformly dispersed Ti₃C₂T_x MXene nanosheets forming angstrom-precision transport channels. Vapor flux governed by Maxwell–Stefan multicomponent diffusion theory, coupled with molecular kinetic models for two-dimensional material interlayers, resulted in experimental vapor fluxes of 42 ± 3.1 kg·m^–2·h^–1 representing 80% enhancement over pristine PVDF membranes. The Ti₃C₂T_x MXene-based nanochannels created thermodynamic selectivity barriers enabling >99.6% salt rejection over 36 h operation. The composite membranes exhibited substantially reduced NaCl crystallization/deposition compared to pristine PVDF, attributed to modified surface energetics and hierarchical pore architectures that disrupt salt nucleation. Thermal analysis revealed a compounding energy benefit: higher membrane porosity reduced the effective thermal conductivity and conductive heat loss while the enhanced vapor flux increased the evaporative heat flux, raising thermal efficiency from 49% for pristine PVDF to 68% for the optimized MXene-PVDF composite and demonstrating that flux enhancement and energy efficiency can be improved simultaneously rather than traded off against each other.

Two-dimensional (2D) materials have emerged as potential candidates for various technological applications due to their intriguing properties and tunable functionalities. In recent years, considerable focus has been devoted to investigating the potential of 2D materials as electrodes in supercapacitors, owing to their high surface area, excellent electrical conductivity, and exceptional mechanical strength. This chapter provides a comprehensive overview of the recent developments and challenges in utilizing 2D materials, including graphene, transition metal dichalcogenides (TMDs), MXenes, and beyond, for supercapacitor electrodes. Each material's unique structural and electronic properties, synthesis methods, and performance as supercapacitor electrodes are discussed. The influence of electrolyte composition on the capacitive behavior and cycling stability of 2D-material electrodes is also highlighted. Furthermore, this chapter highlights the strategies employed to enhance the electrochemical performance of 2D material-based electrodes, such as defect engineering, heterostructuring, and hybridization with other materials. This chapter discusses the outlook for future research directions and emerging opportunities in this rapidly evolving field, including integrating 2D materials into flexible and wearable energy-storage devices and their application in next-generation sustainable energy systems.

MXene–clay heterostructure with Ni(OH) ₂ in the interlayer captures CO ₂ , with residual 30% of CO ₂ after desorption. Heterostructure enlarges available pressure window compared to pure MXene.