Self-floating Ti3C2 MXene-coated polyurethane sponge with excellent photothermal conversion performance for peroxydisulfate activation and clean water production

MXene-based nanocomposites: synthesis, optical properties, and biomedical applications

With the discovery and in-depth research of 2D carbide/nitride MXene, MXene-based nanocomposites have attracted widespread attention due to their unique enhancement and synergistic effects, demonstrating tremendous application potential in the biomedical field. Hence, this review provides a comprehensive discussion of the synthesis methods, optical properties, and biomedical applications of MXene-based nanocomposites. Firstly, it discusses and compares various synthesis methods for MXenes and MXene-based nanocomposites, and categorizes the combination types based on surface engineering strategies and distinct properties. Subsequently, the optical properties of MXene-based nanocomposites are summarized, including localized surface plasmon resonance (LSPR), surface-enhanced Raman scattering (SERS), and photothermal conversion efficiency (PCE). Furthermore, this review provides an in-depth discussion of the applications of MXene-based nanocomposites in biosensors, optical therapeutics, and bioimaging. Finally, we thoroughly explore the challenges and opportunities for the future development of MXene-based nanocomposites, aiming to offer a feasible approach for the development of high-performance materials for biomedical applications.

Carbon Ink Enhanced Calcium Alginate-Based Hydrogel with Response Surface Methodology Optimized for Solar-Driven Salt-Tolerant Desalination

The global shortage of freshwater resources is becoming more and more serious; therefore, it is necessary to obtain freshwater by desalinating seawater resources. Solar-driven interfacial photothermal evaporation, which is an environmentally friendly and energy-efficient technology, has been used to desalinate seawater for water purification and production. Herein, the IPCA hydrogel with abundant pores consisting of carbon ink as a photothermal conversion material and PU sponge loaded with calcium alginate as a water transport medium was successfully prepared and used to obtain portable water. The parameters of the synthesized IPCA are optimized by Response Surface Methodology analysis, and it was found that the IPCA exhibits a high evaporation efficiency of 3.779 kg m-2 h-1 and up to 95.98% of photothermal conversion capacity under one solar intensity. It maintains a high evaporation efficiency and salt resistance after 10 cycles of evaporation in actual seawater. Moreover, IPCA shows a high removal of various organic dye pollutants in wastewater. The results suggest a new approach for the preparation of simple, efficient, and green solar evaporators in practical application.

A Sunlight-Driven Self-Cleaning CuCo-MOF Composite Membrane for Highly Efficient Emulsion Separation and Water Purification

The fouling phenomenon of membranes has hindered the rapid development of separation technology in wastewater treatment. The integration of materials into membranes with both excellent separation performance and self-cleaning properties still pose challenges. Here, a self-assembled composite membrane with solar-driven self-cleaning performance is reported for the treatment of complex oil-water emulsions. The mechanical robustness of the composite membrane is enhanced by the electrostatic attraction between chitosan and metal-organic frameworks (MOF) CuCo-HHTP as well as the crosslinking effect of glutaraldehyde. Molecular dynamics (MD) simulations also revealed the hydrogen bonding interaction between chitosan and CuCo-HHTP. The composite membrane of CuCo-HHTP-5@CS/MPVDF exhibits a high flux ranging from 700.6 to 2350.6 L∙m-2∙h-1∙bar-1 and excellent separation efficiency (>99.0%) for various oil-water emulsions, including crude oil, kerosene, and other light oils. The addition of CuCo-HHTP shows remarkable photothermal effects, thus demonstrating excellent solar-driven self-cleaning capability and antibacterial performance (with an efficiency of ≈100%). Furthermore, CuCo-HHTP-5@CS/MPVDF can activate peroxomonosulfate (PMS) under sunlight, quickly removing oil-fouling and dyes. Density functional theory (DFT) calculations indicate that the bimetallic sites of Cu and Co in CuCo-HHTP effectively promoted the activation of PMS. This study provides distinctive insights into the multifaceted applications of MOFs-derived photothermal anti-fouling composite membranes.

Hydrophilicity and Pore Structure Enhancement in Polyurethane/Silk Protein-Bismuth Halide Oxide Composite Films for Photocatalytic Degradation of Dye

Polyurethane/silk protein-bismuth halide oxide composite films were fabricated using a blending-wet phase transformationin situsynthesis method. The crystal structure, micromorphology, and optical properties were conducted using XRD, SEM, and UV-Vis DRS characterize techniques. The results indicated that loaded silk protein enhanced the hydrophilicity and pore structure of the polyurethane composite films. The active species BiOX were observed to grow as nanosheets with high dispersion on the internal skeleton and silk protein surface of the polyurethane-silk protein film. The photocatalytic efficiency of BiOX/PU-SF composite films was assessed through the degradation of Rhodamine B under visible light irradiation. Among the tested films, the BiOBr/PU-SF composite exhibited the highest removal rate of RhB at 98.9%, surpassing the removal rates of 93.7% for the BiOCl/PU-SF composite and 85.6% for the BiOI/PU-SF composite. Furthermore, an active species capture test indicated that superoxide radical (•O2-) and hole (h+) species played a predominant role in the photodegradation process.

Efficient activation of persulfate by Ti3C2 MXene QDs modified ZnFe2O4 for the rapid degradation of tetracycline

Mxene-based catalysts with specific interfacial characteristics are beneficial for photocatalytic applications. Herein, Ti₃C₂ MXene modified ZnFe₂O₄ nanocomposite materials were prepared for photocatalysis. The morphology and structure of the nanocmposites were characterized by scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), which revealed that Ti₃C₂ MXene as quantum dots (QDs) was uniformly distributed on the ZnFe₂O₄ surface. The Ti₃C₂ QDs modified ZnFe₂O₄ catalyst (ZnFe₂O₄/MXene-15%) under visible light achieved 87% degradation efficiency of tetracycline within 60 min when coupled with persulfate (PS) system. The initial solution pH, PS dosage and co-existing ions were found to be the main factors affecting the heterogeneous oxidation process, while quenching experiments showed that O₂^•- is the main oxidizing species in the removal of tetracycline in ZnFe₂O₄/MXene-PS system. In addition, the cyclic experiments suggested that ZnFe₂O₄/MXene had good stability and thus it may have practical applications in industry.

Application of MXene-based materials in Fenton-like systems for organic wastewater treatment: A review

Recently, Fenton-like systems have been widely explored and applied for the removal of organic matter from wastewater. Two-dimensional (2D) MXene-based materials exhibit excellent adsorption and catalysis capacity for organic pollutants removal, which has been reported widely. However, there is no summary on the application of MXene-based materials in Fenton-like systems for organic matter removal. In this review, four types of MXene-based materials were introduced, including 2D MXene, MXene/Metal complex, MXene/Metal oxide complex, and MXene/3D carbon material complex. In addition, the Fenton-like system usually consists of adsorption and degradation processes. The oxidation process might contain hydrogen peroxide (H₂O₂) or persulfate (PS) oxidants. This review summarizes the performance and mechanisms of organic pollutants adsorption and oxidants activation by MXene-based materials systematically. Finally, the existing problems and future research directions of MXene-based materials are proposed in Fenton-like wastewater treatment systems.

In-situ photothermal activation of peroxydisulfate in a carbon nanotubes membrane-based flow-by reactor toward degradation of contaminants

The energy-induced peroxydisulfate (PDS) activation is a green and effective approach for pollutant degradation, while the huge energy consumption would significantly increase the cost of wastewater treatment. In this study, by taking carbon nanotubes (CNTs) membrane as the light to heat (LTH) conversion materials, we developed a photothermal PDS activation process for degradation of organic contaminants in a flow-by reactor, with hydroxyl radicals (^•OH) and sulfate radicals (SO₄^•-) as the main reactive species. This system has excellent in-situ LTH conversion performance and heat transfer ability. As a result, various pollutants are degraded with an efficiency higher than 90%. More importantly, the LTH device exhibits satisfying stability and could be used for pollutant (i.e., methyl orange (MO)) removal under solar irradiation. In addition, some important factors (i.e., irradiation distance, residence time, solution pH, and PDS dosage) that might significantly influence the removal efficiency of pollutants are optimized. This work provides a novel perspective for the activation of PDS via CNTs as photothermal materials for pollutant degradation with a flow-by reactor.