Adsorption Properties Research Articles

Stepwise grafting polyethyleneimine onto silica surface for Cu(II) removal

Polyethyleneimine (PEI) is a novel polymer that contains multiple amine groups that are suitable for chelation with many heavy metal ions (HMI). Anchoring PEI onto the surface of a solid substrate has been widely adopted to develop adsorbent materials with the hope of combining the HMI chelating ability of PEI with the heterogeneity of the substrate. Herein, the preparation of PEI grafted SiO2 (PEI/SiO2) has been demonstrated by a stepwise method in which SiO2 nanoparticles were functionalized with 3-glycidoxypropyltrimethoxysilane (KH560) followed by refluxing with PEI. The method could provide PEI/SiO2 material with 23.4% of PEI by weight. Studying the adsorption properties of PEI/SiO2 with Cu(II) revealed that the adsorption of Cu(II) ions on PEI/SiO2 followed Langmuir and Dubinin-Radushkevich models and included both chemisorption and physisorption. The adsorption capacity was about 25.3-27.3 mg/g. The stepwise method demonstrated in this study may be adopted to fabricated PEI based materials for HMI removal.

New Insights on Iron-Trimesate MOFs for Inorganic As(III) and As(V) Adsorption from Aqueous Media.

Arsenic contamination of water endangers the health of millions of people worldwide, affecting certain countries and regions with especial severity. Interest in the use of Fe-based metal organic frameworks (MOFs) to remove inorganic arsenic species has increased due to their stability and adsorptive properties. In this study, the performance of a synthesized Nano-{Fe-BTC} MOF, containing iron oxide octahedral chains connected by trimesic acid linkers, in adsorbing As(III) and As(V) species was investigated and compared with commercial Basolite®F300 MOF. Despite their similarities in composition, they exhibit distinct structural characteristics in their porosity, pore size, and surface areas, which affected the adsorption processes. The kinetic data of the adsorption of As(III) and As(V) by both Fe-MOFs fitted the pseudo second-order model well, with the kinetic constant being higher for Basolite®F300 given its higher porosity. Intraparticle diffusion was, in both cases, the rate controlling step with the contribution of film diffusion in the adsorption processes, which achieved equilibrium after 1 h. The maximum adsorption capacity for As(V), 41.66 mg g-1, was obtained with Basolite®F300 at the 6.5-10 pH range, whereas Nano-{Fe-BTC} showed a different behaviour as maximum adsorption (14.99 mg g-1) was obtained at pH 2. However, both adsorbents exhibited the same performance for As(III) adsorption, which is not adsorbed at pH < 9. The Langmuir adsorption isotherm model fitted well for As(III) and As(V) adsorption by Nano-{Fe-BTC} and As(III) by Basolite®F300, whereas the Freundlich model fitted best for As(V) given its superior structural properties.

Influence of process parameters in ion exchange on the properties of the obtained 5A zeolite powder

Zeolite 5A is highly regarded in adsorption processes among zeolites, making it valuable for various commercial applications. It is typically synthesized from 4A zeolite by replacing Na+ ions in the crystal lattice with Ca2+ or Mg2+ ions through an ion exchange process. This substitution increases the pore volume, enlarges pore openings, and enhances the zeolite's adsorption capacity. From an industrial and commercial production standpoint, defining the optimal process parameters for producing 5A zeolite is crucial. This study investigates the effects of ion exchange temperature, ion exchange duration, and the concentration of active components in the system on the characteristics of the resulting 5A zeolite powder. The ion exchange process was carried out using a MgCl₂•6H₂O solution to produce the Mg2+ form of 5A zeolite, known as Na,Mg-A zeolite. The powders obtained after ion exchange were analyzed for their chemical composition and water adsorption capacity. Furthermore, the samples were characterized using granulometry and particle size distribution analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR). The results revealed significant correlations between process parameters, ion exchange efficiency, crystallinity, and adsorption properties. These findings provide insights into the optimal conditions required for the effective production of 5A zeolite.

Methanation of carbon dioxide over zirconium-tin oxide-based catalyst

An advanced catalyst, Ni/ZrSn[Formula: see text]Ce[Formula: see text]O4/[Formula: see text]-Al2O3, was synthesized for the methanation of CO2 under moderate conditions of atmospheric pressure and low H2 concentration (4 vol%). The use of scrutinyite-type ZrSn[Formula: see text]Ce[Formula: see text]O4 improved the catalytic activity, likely because of abundant oxygen vacancies for CO2 adsorption and good redox properties for cleavage of the C-O bond of adsorbed CO2. The CH4 yield of 18 wt.% Ni/20 wt.% ZrSn[Formula: see text]Ce[Formula: see text]O4/[Formula: see text]-Al2O3 reached 61.0% with high CO2 conversion (58.4%) at [Formula: see text]C using 1 vol% CO2-4vol% H2-95 vol% Ar at atmospheric pressure.

Nickel removal from synthetic wastewater by novel zeolite-doped magnesium- iron- and zinc-oxide nanocomposites by hydrothermal-calcination technique

This study aims to modify raw zeolite with metal oxide nanocomposites to remove nickel (Ni) ions from synthetic wastewater. Novel zeolite-doped magnesium oxide (MgO), iron oxide (Fe3O4), and zinc oxide (ZnO) nanocomposites were synthesized by hydrothermal-calcination methods. The novel zeolite-doped metal oxide nanocomposites were used as adsorbents to remove Ni (II) ions from synthetic wastewater. Several advanced techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM) were applied to study the structural, morphological, chemical, and magnetic properties of the prepared materials. Doped zeolite with ZnO, MgO, and Fe3O4 significantly enhances the removal of Ni (II) ions from synthetic wastewater. The zeolite-doped MgO + Fe3O4 + ZnO sample achieved a Ni (II) ions removal efficiency of 99.6%, compared to 58.9% for raw zeolites. The removal efficiencies of Ni (II) ions (Ci = 30 mg/L) from highest to lowest were 99.56%, 99.53%, 91.4%, 67.8%, and 58.93% by zeolite-doped MgO + Fe3O4 + ZnO, zeolite-doped MgO, zeolite-doped ZnO, zeolite-doped Fe3O4, and raw zeolite sample, respectively. The highest adsorption capacity was 17.13 mg/g of zeolite-doped MgO + Fe3O4 + ZnO samples. The experimental adsorption data collected were fitted using five isotherm models, and four kinetic models. The Langmuir adsorption isotherm model and the pseudo-second-order kinetic model provided the best fit for the experimental adsorption data. This suggests that the adsorption process is complex, possibly involving electron interactions between the active sites of doped zeolite and Ni (II) species. The obtained data indicates that zeolite-doped with MgO, Fe3O4, and ZnO notably enhances the adsorptive properties of Ni (II) from synthetic wastewater. The obtained thermodynamic values confirmed that the adsorption process is spontaneous and endothermic, with increased randomness at the solid-solution interface during the adsorption process.

Biomimetic intelligent nanoplatform with cascade amplification effect for tumor synergy therapy

Tumor heterogeneity, immune-suppressive microenvironment and the precise killing of tumor cells by drugs are important factors affecting tumor treatment. In this study, we developed environment-responsive drug delivery system (FM@IQ/PST&ZIF-8/DOX) based on ZIF-8 for tumor photothermal/immunotherapy/chemotherapy synergistic therapy. The prepared FM@IQ/PST&ZIF-8/DOX nanoplatfrom not only has highly drug loading capacity for chemotherapeutic drug-doxorubicin, but also erythrocyte membrance modified on their surface can endow their immunity-escaping property and prolong their blood circulation time. More important, the neurotransmitter serotonin was encapsulated on the surface of ZIF-8/DOX by oxidative polymerization, which can effectively avoid the premature leakage of DOX in the blood circulation. And the formed polyserotonin shell has superior photothermal conversion performance, as well as the adsorption property of polyserotonin shell was utilized to load imiqumod. When FM@IQ/PST&ZIF-8/DOX entered the tumor tissue, the surface modified folate molecules can specifically bind to the folate receptors on the surface of tumor cells to improve FM@IQ/PST&ZIF-8/DOX uptake by tumor cells. In vitro and in vivo results showed that FM@IQ/PST&ZIF-8/DOX nanoplatform could generate a large amount of heat under near-infrared light irradiation, and then induce the apoptosis of tumor cells, release tumor associated antigens, and effectively solve the problem of tumor heterogeneity. In addition, the loaded imiquimod could effectively improve the immunosuppressive microenvironment, enhance the body’s anti-tumor immune response, to inhibit tumor metastasis and recurrence. Therefore, the novel FM@IQ/PST&ZIF-8/DOX nanoplatform designed in this research can not only achieve controllable and precise drug release, but also it is expected to become a promising new strategy for tumor treatment and provide corresponding inspiration for the later research and development of environment-responsive drugs.

Cationized Cellulose Materials: Enhancing Surface Adsorption Properties Towards Synthetic and Natural Dyes.

Cellulose is a homopolymer composed of β-glucose units linked by 1,4-beta linkages in a linear arrangement, providing its structure with intermolecular H-bonding networking and crystallinity. The participation of hydroxy groups in the H-bonding network results in a low-to-average nucleophilicity of cellulose, which is insufficient for executing a nucleophilic reaction. Importantly, as a polyhydroxy biopolymer, cellulose has a high proportion of hydroxy groups in secondary and primary forms, providing it with limited aqueous solubility, highly dependent on its form, size, and other materialistic properties. Therefore, cellulose materials are generally known for their low reactivity and limited aqueous solubility and usually undergo aqueous medium-assisted pretreatment methods. The cationization of cellulose materials is one such example of pretreatment, which introduces a positive charge over its surface, improving its accessibility towards anionic group-containing molecules or application-targeted functionalization. The chemistry of cationization of cellulose has been widely explored, leading to the development of various building blocks for different material-based applications. Specifically, in coloration applications, cationized cellulose materials have been extensively studied, as the dyeing process benefits from the enhanced ionic interactions with anionic groups (such as sulfate, carboxylic groups, or phenolic groups), minimizing/eliminating the need for chemical auxiliaries. This study provides insights into the chemistry of cellulose cationization, which can benefit the material, polymer, textile, and color chemist. This paper deals with the chemistry information of cationization and how it enhances the reactivity of cellulose fibers towards its processing.

Effect of Ethanol Treatment and Calcination Temperature on Water Vapor Adsorption properties of MCM-41.

MCM-41, a mesoporous material with a high surface area and tunable pore size, shows great potential for water vapor adsorption. However, due to its large pore size, the effective adsorption capacity at medium to low relative partial pressures is limited in adsorption chiller applications. In this work, MCM-41 was successfully synthesized at room temperature using cetyltrimethylammonium bromide (CTAB) as a templating agent. Pore size modulation was achieved by treating the MCM-41 gel with ethanol. The results indicated that ethanol likely exerted an inward force on the pore channels, reducing the pore size from 3.418 to 2.583 nm. The water vapor adsorption properties and hydrothermal stability of the ethanol-treated samples were significantly enhanced. Additionally, a dual-atmosphere calcination process at 450 °C was established, showing results comparable to the conventional 550 °C process in terms of template removal. The sample, which combined dual-atmosphere calcination with ethanol treatment, demonstrated a significant increase in the water vapor adsorption capacity, achieving a 1.3-fold improvement compared to the untreated sample. These results provide a feasible reference for the application of MCM-41 in adsorption chillers.

Irradiated Gao Miao Zi Bentonite for Uranium Retention: Performance and Mechanism

Bentonite has been considered as backfill material in the long-term deep geological disposal sites for radioactive waste. The performance of raw and irradiated bentonite based on the retention of radioactive nuclides, such as U(VI), is a critical factor for its application. Herein, the intrinsic features and adsorption behavior of Gao Miao Zi (GMZ) bentonite based on uranyl ions was investigated. In aqueous solutions, bentonite can achieve an adsorption rate of up to 100% for U(VI). The primary mechanism of U(VI) adsorption by GMZ bentonite is ion exchange, supplemented by surface complexation. Strong irradiation can introduce slight structural changes and framework fractures in bentonite, reducing its adsorption capacity for U(VI). This study provides an in-depth analysis of the adverse effects of high doses of radiation (100 kGy) on the microstructure and adsorption properties of bentonite, offering important insights for the safe storage of radioactive waste.

Minimum-Run Resolution IV Design for Optimized Bio Removal of Fe2+ Using Enteromorpha intestinalis Aqueous Extract and Its Extract-Coated Silver Nanoparticles.

Biosorbents have demonstrated considerable potential for the remediation of metals in aqueous environments. An aqueous extract of Enteromorpha intestinalis L. (EiE) and its extract-coated silver nanoparticles have been prepared and employed for the removal of iron. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-visible spectroscopy, transmission electron microscopy (TEM), gas chromatography-mass spectroscopy (GC-MS), and zeta potential were employed to characterize the prepared biosorbents. The adsorption properties of the biosorbents were investigated in batch experiments, with a range of factors taken into account, including pH, contact time, initial ion concentrations, biosorbent dosage, and temperature. A minimum-run resolution IV design (MRR-IV) was developed with the objective of optimizing the removal efficiency. The mechanisms of adsorption were investigated using both the Langmuir and Freundlich isotherms. Kinetic studies were conducted using the pseudo-first-order and pseudo-second-order models. A variety of active constituents, including organic acids, lipids, alcohols, and terpenes, were identified through the use of GC-MS, with the findings supported by FTIR spectra. Transmission electron microscopy (TEM) revealed that the nanoparticle size ranged from 5 to 44 nm, while X-ray diffraction (XRD) demonstrated a high degree of crystallinity. A screening study employing the MRR-IV methodology, facilitated by the Design-Experiment, Ver 13., indicates that three factors exert a considerable influence on the biosorption process. The study demonstrated that the biosorption mechanism is pH-dependent, with an optimal pH of 5. The adsorption performance was found to follow Freundlich isothermal models and pseudo-first-order kinetics.

Enhanced CO2 adsorption properties with bimetallic ZnCe-MOF prepared using a microchannel reactor

Enhanced CO2 adsorption properties with bimetallic ZnCe-MOF prepared using a microchannel reactor

Sulfide and Hydrogen Bond Networks in the Electric Double Layer: Key Factors for Titanium Passivation Film Stability.

Hydrogen sulfide (H2S), carbonyl sulfide (COS), and dimethyl sulfide (DMS) are the primary sulfur compounds found in seawater, which cause pitting corrosion on the oxide passivation film of titanium, known as "the marine metals". In this study, density functional theory (DFT) was used to analyze the adsorption and surface electronic properties of these three small molecules on the anatase TiO2(101) surface. The analysis was conducted through adsorption energy, work function, Mulliken charge population, and density of states (DOS). The hydrogen bond network structure of the electric double layer (EDL) was studied for these small-molecule systems using ab initio molecular dynamics (AIMD). The optimal adsorption configurations for H2S, COS, and DMS on the anatase TiO2(101) surface are 2Ob-vertical, O-down-vertical, and Ob-parallel, with adsorption energies of -1.32, -0.67, and -1.86 eV, respectively. The surface charge transfer was also investigated. Through comparative AIMD simulations of three different aqueous solutions on the TiO2(101) surface, we observed that COS exerts a more pronounced influence on the electrical double layer within 3.00 Å of the TiO2(101) surface. Specifically, the hydrogen atoms of water tend to aggregate toward the Ob atoms, forming hydrogen bonds, which significantly impacts the corrosion resistance of the TiO2 surface.

Calixarene-Based Functional Fabric for Simultaneously Adsorptive Removal of Anionic and Cationic Dyes.

This study investigated the adsorptive properties of functionalized fabric containing dimethylaminomethyl calix[4]arene (DMAM-Calix) to remove anionic methyl orange (MO) and cationic Rhodamine B (RhB) dyes in aqueous media. Adsorption studies were performed using a filtration system packed with DMAM-Calix-functionalized fabric (DCF). The results revealed that the cationic and anionic structures work compatibly in a binary mixture medium. Hydrogen bonding, π-π, cation-π, n-π and electrostatic interactions between dye molecules and DMAM-Calix units of DCF were the main factors affecting the adsorption process. Experiments on real wastewater samples of unknown composition confirmed that the approach could successfully remove MO and RhB dyes from real water samples with high efficiency, especially for RhB. Isotherm and kinetic data for MO were mainly represented by the Langmuir model and pseudo-second-order kinetic model, respectively. The adsorption capacities of DCF were found to be about 4.7 mg g-1 for MO and 1.0 mg g-1 for RhB at pH 6.0, which were evaluated as satisfactory considering the first use of a calixarene-derived coated fabric as an adsorbent, the anionic-cationic dye selectivity of DCF, and the low cost and ease of application of the method.

Preparation of chitin-derived hierarchical porous materials and their application and mechanism in adsorption of mycotoxins.

In this study, the hierarchical porous materials for adsorbing mycotoxins were prepared by one-step carbonization-activation method using potassium permanganate (KMnO4) and chitin as activators and carbon source, respectively. The hierarchical porous materials had different specific surface area and pore distribution owing to different carbonization temperatures. In this paper, the effects of pH, time and temperature of adsorption as well as the concentration of patulin on the adsorption characteristics were systematically investigated. And we analyzed the adsorption properties and mechanism between hierarchical porous materials and patulin. The results showed that the adsorption process conformed to the pseudo-second-order kinetics and Langmuir model. HPC-600 (hierarchical porous chitin prepared in 600°C) had the largest specific surface area (1047.8m2·g-1) and the best adsorption performance with adsorption capacity above 9.2μg/mg. The prepared hierarchical porous materials are expected to be applied to the patulin adsorption.

Retention of Nickel and Cobalt in Boda Claystone Formation

The Boda Claystone Formation (BCF) is considered to serve as a natural barrier to the potential high-level radioactive waste repository in Hungary. In order to evaluate the radionuclide retention capacity of the albitic claystone of the BCF, the adsorption and diffusion properties of the rock for Ni2+ and Co2+ cations (activation products) were investigated separately and in competitive conditions when the two ions were simultaneously added. Batch sorption experiments were performed with powdered and conditioned albitic claystone samples in synthetic pore water to obtain adsorption isotherms. In addition, adsorption tests were performed on petrographic thin sections to check the transferability between dispersed and compact systems. Correlation analysis of microscopic X-ray fluorescence elemental maps recorded on thin sections suggested that nickel is primarily bound to clay minerals (mainly illite and chlorite), which was confirmed by (scanning) transmission electron microscopy measurements. Around illite particles, a newly formed nickel-rich few atomic layer thick phyllosilicate phase was identified. The discrepancy between the experimental and modeled adsorption isotherm at high concentrations could be explained with this nickel-rich new phase. Apart from Cin = 10−3 M and only Ni2+ or Co2+ in the source, the apparent diffusion coefficients of Ni2+ and Co2+ (Cin = 10−3–10−2 M) were found to be similar. Overall, the BCF shows promising capabilities to retain the studied radionuclides.

Constructing Heterojunction Photocatalyst Systems with Spatial Distribution of Au Single Atoms for CO2 Reduction.

In single-atomic photocatalyst systems, the spatial distribution of single atoms on heterojunctions and its impact on photocatalytic processes, particularly on carrier dynamics and the CO2 reduction process involving multielectron reactions, remains underexplored. To address this gap, a WO3/TiO2 nanotube heterojunction with a spatially selective distribution of Au single atoms was developed using an oxygen vacancy anchoring strategy for CO2 photoreduction. By anchoring Au atoms onto the WO3 or TiO2 components, a substantial number of active sites are generated and the electron transfer pathways from the heterojunction toward Au sites are formed, thereby enhancing carrier separation and concentration. As a result, the total yield of CO2 reduction products increases by 6.3 times and 3.9 times, respectively. More importantly, due to significant differences in adsorption properties, energy band structures, and reaction energy barrier, as well as a 2-fold difference in carrier lifetime, the selective distribution of Au single-atom sites results in completely different CO2 photoreduction products: when Au atoms are anchored on WO3 and TiO2 components, the product selectivity is 67.6% CH4 and 82.9% CO, respectively. This study clarifies the vital role of the spatial distribution of single atoms on the selectivity of electron-demanding products.

Adsorption of Methylene Blue on Activated Carbon Surfaces Obtained by Shock Compression of Graphite Using Reactive Molecular Dynamics.

This study explores the formation of functionalized carbon surfaces through shock compression of graphite in the presence of water, modeled using molecular dynamics and the ReaxFF reactive force field. The shock compression method produces activated carbon with surface functionalities, primarily hydroxyl groups, and varying morphological properties. Two approaches, unidirectional and isotropic compression, yield distinct surface structures: the former preserves a relatively flat surface, while the latter generates corrugated features with valleys and ridges. These features significantly impact the adsorption properties of methylene blue (MB), a commonly used dye. Simulations reveal that MB molecules are highly mobile on flat surfaces, aligning with a mobile adsorption model. However, on corrugated surfaces, MB exhibits localized adsorption, with the deepest valleys effectively immobilizing the dye molecules. Additionally, the study highlights the influence of surface hydroxyl groups, which, through interactions with water molecules, prevent MB from occupying these regions. The findings underscore that traditional adsorption models may not fully capture the dynamics of MB adsorption on activated carbons with complex morphologies. These insights are critical for advancing carbon-based adsorbents in water purification applications.

Biocomposite adsorbent (cross-linked chitosan + algae + montmorillonite) for methyl violet 2B dye removal: statistical modelling and optimisation

ABSTRACT Herein, a biocomposite of crosslinked chitosan polyethylene glycol diglycidyl ether (CS-PEDGE), montmorillonite (MMT), and food-grade algae (FGA) was successfully prepared by a hydrothermal technique. The resulting absorbent (CS-PEDGE/FGA/MMT) was assessed for its adsorption property with methyl violet 2B (MV 2B) a toxic cationic dye. The physicochemical properties of CS-EDGE/FGA/MMT were assessed via various analytical techniques, including BET, Elemental analysis, pHpzc, and spectroscopy (FTIR, XRD, SEM-EDX). The influence of three adsorption variables, namely adsorbent dose (A: 0.02–0.1 g/100 mL), solution pH (B: 4–10), and contact time (C: 10–420 min) on the rate of MV 2B dye removal was examined using the Box-Behnken design (RSM-BBD). The findings from the equilibrium isotherm and kinetic analyses suggest that the MV 2B dye adsorption onto the biocomposite surface follow the Freundlich model and pseudo-second-order kinetic models. The biocomposite adsorbent exhibits a maximum dye adsorption capacity (q max ) of 94.2 mg/g. The proposed MV 2B dye adsorption mechanism involves hydrogen bonding, n-π stacking, and electrostatic forces. This research demonstrates the unique structure and outstanding adsorption properties of CS-EDGE/FGA/MMT, which offers a viable solution for removal of detrimental MV 2B dyes from aqueous media.

Enhanced Adsorption Properties of Noble Metal Modified MoS2/WS2 Heterojunctions

AbstractMoS2/WS2 in‐plane heterojunction is constructed using density functional theory (DFT), and its adsorption properties for different gas molecules (CO, CO2, NO2, H2S, SO2, and SO3) are analyzed. Results indicate that the heterojunction exhibits excellent selection toward S‐series gas molecules (H2S, SO2, and SO3), particularly SO3. The adsorption energy is determined to be −3.67 eV. Then, the adsorption properties of the heterojunction are further improved by noble metal (Ag, Au, and Pt) modification. Noble metal atoms alter the surface potential energy of the heterojunction, resulting in stronger adsorption activity. For instance, the binding energies of noble metals in the Ag‐MoS2/WS2, Au‐MoS2/WS2, and Pt‐MoS2/WS2 systems are −1.03, −1.04, and −2.76 eV, respectively. Additionally, there has been a significant alteration in their bandgaps. Notably, the bandgap of Pt‐MoS2/WS2 has decreased to 1.42 eV (24.16%), which is the most pronounced change. Then, the charge density difference and density of states of noble metal‐modified MoS2/WS2 heterojunction adsorbed SO3 are analyzed. The results demonstrate that the adsorption capacity of a noble metal‐modified system for SO3 is enhanced. Finally, raising the temperature can accelerate gas molecule desorption from the system. Combining all calculation results, Ag‐MoS2/WS2 in‐plane heterojunction can be used as a candidate gas‐sensitive material for detecting SO3 at room temperature (300 K). The Pt‐MoS2/WS2 in‐plane heterojunction is demonstrated to possess effective adsorbent properties for trapping SO3 gas molecules at room temperature. This provides a new idea and theoretical basis for gas sensor development.

A review on recent progress in synthesis, properties, and applications of MXenes

Abstract MXenes, a noble class of two-dimensional (2D) material, discovered in 2011 have gained attention in recent years. They have attracted significant attention due to their flexible elemental composition, distinctive 2D-layered architecture, large surface area, and abundant surface terminations. Top-down synthesis techniques such as HF etching, alkaline etching, and electrochemical methods are used for MXene synthesis. Alongside these methods, methods like chemical vapor deposition (CVD), template method and plasma enhanced pulsed layer deposition (PELPD) are also used for the thin-film synthesis of MXenes. The discovery of double transition-metal layered MXene, solid, and high entropy MXene open up the prospect of further novel structures. MXenes are electrically conductive and have promising optoelectronic, mechanical, and thermoelectric properties. MXenes have also shown immense potential in biomedicine and environmental applications. The surface chemistry of MXene make them ideal for biosensors, drug delivery, and photothermal therapy, while their photocatalytic and adsorption properties enable efficient removal of pollutants and contaminants from water. This review examines the various MAX phase synthesis methods, such as solid-state reactions, hot isostatic pressing, and spark plasma sintering, followed by top-down techniques like HF etching, alkaline etching, and electrochemical etching, as well as bottom-up methods like CVD, template approaches, and plasma-enhanced pulsed layer deposition. The review also looks into the optical, chemical, and electronic properties of MXene, as well as their advancements in energy storage, optoelectronics, pollution avoidance, biomedical applications, and more.