Surface-terminated MXenes to act as dynamic solid-liquid interfaces: Enhancing colloidal stability and interfacial chemistry for biomedical applications.
Jul 2026· Advances in Colloid and Interface Science· Vol 356, pp.
103991
· 1 citation· 205 references
Medicine
Abstract
MXenes are a rapidly expanding family of two-dimensional transition-metal carbides, nitrides, and carbonitrides whose physicochemical behavior in aqueous and biological environments is dominated by their surface terminations (e.g., -O, -OH, and -F), rendering them intrinsically active solid-liquid interfaces. These terminations regulate interfacial charge distribution, hydration structure, adsorption equilibria, and colloidal stability, positioning MXenes as dynamic interfacial systems rather than passive nanomaterials. Rational control of surface termination chemistry therefore represents a central strategy for governing MXene interactions with electrolytes, proteins, and biological media. This review provides a comprehensive and critical analysis of recent advances in MXene surface-termination engineering from the perspective of interfacial and colloidal science, with emphasis on etching routes, post-synthetic modification, dimensional tailoring (2D, 3D, and emerging 4D architectures), and characterization approaches relevant to interfacial behavior. We examine how termination chemistry controls key interfacial properties, including zeta potential, dispersion stability in physiological electrolytes, hydration-mediated wetting, and protein corona formation, and how these interfacial factors collectively shape biological responses such as cytotoxicity, inflammatory signaling, antibacterial activity, and reactive oxygen species generation. Particular attention is devoted to termination-driven charge regulation and coordination chemistry at solid-liquid interfaces, which govern adsorption-desorption dynamics, molecular loading, and stimulus-responsive release, as well as the modulation of optical and magnetic responses. By critically comparing reported systems and explicitly addressing unresolved challenges related to termination heterogeneity, interfacial aging, and scalability, this review clarifies structure-interface-function relationships that underpin MXene performance in complex environments. Finally, we identify emerging strategies and open questions for designing surface-terminated MXenes with predictable and controllable interfacial behavior, highlighting their broader relevance as model systems for dynamic solid-liquid interfaces with bio-functional implications.
MXenes combine metallic conductivity, solution processability, and chemically addressable surfaces, but the reactive interfaces that enable functionalization also accelerate oxidation, restacking, and property drift. This Mini Review develops a chemistry-first framework in which surface terminations, defects, adsorbates, and interlayer species are treated collectively as a coupled state variable rather than as independent descriptors. We link etching and delamination chemistry to termination populations and discuss the effects of water and oxygen on spatially heterogeneous degradation. We then examine how molecular ligands, polymers, inorganic phases, and mesoscale assembly modulate interfacial reactions and transport pathways. We organize recent studies according to a causal sequence: chemical intervention, nanoscale structural consequence, transport response, functional output, and failure mode. This sequence helps explain why nominally similar Ti3C2Tx materials can exhibit divergent electrochemical, catalytic, sensing, mechanical, and electromagnetic behavior. We argue that further progress depends less on identifying isolated applications than on controlling and reporting the evolving interfacial state across synthesis, storage, processing, and operation. We propose testable design rules for termination-aware synthesis, kinetic stabilization, interface-selective assembly, and operando validation. This framework positions MXenes as programmable reactive nanoarchitectures and identifies reproducibility, scalable fluorine-lean chemistry, and state-resolved characterization as priorities for nanoscience.
Haotian Wu, Yinxu Xie, Shengjun Ji et al.· Frontiers in Chemistry· 0 citations
MXenes have emerged as a rapidly expanding family of two-dimensional transition-metal carbides, nitrides, and carbonitrides, characterized by exceptional compositional diversity, tunable surface chemistry, metallic conductivity, hydrophilicity, mechanical flexibility, and rich redox activity. These characteristics make MXenes highly attractive for next-generation technologies, including energy storage and conversion, catalysis, electromagnetic interference shielding, sensors, water purification, biomedical systems, and smart functional devices. However, the performance of MXene-based materials is strongly governed by their synthesis routes, defect structures, interlayer spacing, surface terminations, oxidation stability, and interfacial interactions with polymers, metals, oxides, and other two-dimensional materials. Therefore, a structure–property-oriented understanding is essential for moving MXene research from empirical material development toward rational functional design. Unlike application-centered summaries, this review develops a cross-application engineering framework that connects MXene synthesis and processing with multiscale structure, functional properties, performance trade-offs, and translational requirements. First, major synthesis and processing strategies are discussed, including selective etching, delamination, intercalation, surface modification, and scalable fabrication. Next, the relationships between MXene composition, morphology, surface chemistry, electrical conductivity, electrochemical behavior, mechanical properties, and environmental stability are analyzed. Recent advances in functionalization, heterostructure construction, and composite engineering are then highlighted to illustrate how MXene properties can be tailored for emerging applications. Finally, key challenges related to oxidation, restacking, long-term stability, environmental safety, reproducibility, and industrial translation are critically evaluated. This review aims to establish a design framework for engineering MXene nanomaterials toward high-performance, stable, and scalable emerging technologies.
Electrochemical energy storage systems demand electrode materials that simultaneously combine high electrical conductivity, large ion-accessible surface area, chemical stability, and mechanical integrity, requirements that are rarely satisfied by single-component materials. Rationally engineered heterostructures have therefore emerged as an effective strategy to integrate complementary functionalities. Among them, MXenes, a class of two-dimensional (2D) transition-metal carbides and nitrides, provide metallic conductivity, hydrophilic surfaces, and abundant functional terminations, while covalent organic frameworks (COFs) offer ordered porosity, tunable chemistry, and intrinsic redox activity. The integration of these materials into MXene/COF heterostructures has demonstrated significant performance improvements; however, achieving true synergy critically depends on the nature of the interface. Here, we establish a linker-centric framework, highlighting that the MXene/COF interface acts as an active regulator of charge-transfer kinetics, ion transport, and structural stability rather than a passive boundary. We systematically classify interfacial interactions into covalent linkers (imine, azine, β-ketoenamine, amide, and hydrazone) and non-covalent interactions (hydrogen bonding, electrostatic coupling, and π-π stacking), and evaluate how their bonding characteristics govern the trade-offs among electronic coupling, ion accessibility, and durability. Finally, synthesis strategies, characterization approaches, representative applications, and future directions are discussed to guide the rational design of next-generation MXene/COF energy storage systems.
Cheru Fekadu Molla, B. B. Gicha, Indra Memdi Khoris et al.· Small· 0 citations
Two-dimensional transition-metal carbides and nitrides (MXenes) are increasingly adopted in advanced electronic devices, where their metallic conductivity, optical tunability, and chemically addressable surfaces support next-generation multifunctional optoelectronics. Their practical performance, however, depends not only on their intrinsic properties but also on the heterogeneous interfaces where charges, photons, and ions interact. Unlike earlier reviews organized around synthesis routes or separate device categories, this review takes interfacial chemistry as a single organizing principle and follows it from surface terminations through to integrated systems. The structural and surface-chemical characteristics of MXenes are described first, showing how dynamic terminations and interfacial dipoles regulate work functions and energy-level alignment. We then discuss molecular functionalization, defect passivation, and heterojunction formation as strategies for reducing Schottky barriers and improving charge-transfer kinetics. Optoelectronic platforms built on these engineered interfaces, including high-efficiency photovoltaics, broadband photodetectors, and stretchable wearable systems, are subsequently detailed, together with emerging architectures that merge self-powered sensing with neuromorphic visual functions, a scope seldom treated alongside conventional devices in previous surveys. By connecting surface chemistry with device integration, this review outlines a materials-to-systems pathway toward more reliable and scalable MXene-based optoelectronic technologies.
Se-Eun Byeon, S. Jung, Junseo Lee et al.· Micromachines· 0 citations
MXenes, a burgeoning family of two-dimensional transition metal carbides, nitrides, and carbonitrides, have garnered significant attention due to their metallic conductivity, hydrophilicity, and surface-rich chemistry, offering immense potential across electrochemical energy storage, catalysis, and advanced sensing. Achieving precise control over their surface chemistry is pivotal for tailoring physicochemical properties and unlocking application-specific functionalities. This review comprehensively summarizes recent progress in MXene chemistry modulation via advanced synthesis protocols and post-synthetic modifications, with an emphasis on surface terminations and interlayer engineering. We discuss the influence of etching conditions, delamination strategies, and intercalation chemistries on the structural and electronic characteristics of MXenes. Moreover, mechanistic insights into ion intercalation and surface functional group evolution are critically analyzed to guide rational design strategies. Key challenges-including batch-to-batch variability, limited scalability, and insufficient mechanistic understanding of surface transformations-are also addressed. This review provides a forward-looking perspective on engineering MXenes with tunable interfaces for next-generation applications in energy, catalysis, and flexible electronic skin systems.
Zhifang Liu, Yipeng Cui, Yilin Sun et al.· Small· 0 citations
The emergence of MXenes, 2D layered transition metal carbides, nitrides, and carbonitrides, has unlocked different possibilities in supercapacitor (SC) electrode design. The metallic electronic conductivity, hydrophilic surfaces, adjustable surface chemistry, and open interlayer spacing enable efficient charge storage via pseudocapacitance and rapid ion intercalation, distinguishing them from traditional carbon-based and metal-oxide materials. The different synthesis methods, which included selective etching with hydrofluoric acid (HF), alkali, electrochemical, molten salts, and non-etching techniques, as well as chemical vapor deposition (CVD), lithiation-expansion, ammonization, and mechanical delamination, improved researchers' ability to control MXene morphology, functional groups, and interlayer spacing, which resulted in changes to ion mobility and charge storage behavior. Structural engineering techniques, through their application of surface functionalization, interlayer modification, graphene, CNT, TMD, transition metal oxide, and conductive polymer integration, provided solutions to three main challenges, which included oxidation, restacking, and slow ion accessibility. The MXene-based electrodes reached outstanding electrochemical performance because they achieved specific capacitances (Csp) above 1500 F/g, energy densities close to 80 Wh/kg, power densities greater than 10 kW/kg, and capacitance retention over 90% after 10,000 cycles. Mechanistic insights show that electric double-layer capacitor (EDLC) and pseudocapacitive ion intercalation and surface redox reactions function together to control charge storage and self-discharge characteristics. This review integrates synthesis methods, charge storage mechanisms, and performance correlations, which emphasize new applications in SCs and wearable electronics. MXenes demonstrate their potential as a platform for advanced energy storage systems (ESSs) through their future development capabilities, which enable multifunctional device integration, structural stabilization, and scalable fabrication.
Ramanakeerti P, Asfaq Ali, Karthick Raja et al.· ACS Applied Materials and In...· 0 citations
