Superhydrophilic Research Articles

Fabricating physicochemical microstructures with super hydrophilicity on Cf/SiC composites surface via picosecond-laser induced ablation

Cf/SiC composites are advanced high-temperature materials for thermal protection and high-performance braking systems in the aerospace industry. Their surface wettability significantly affects the adhesion properties of the coatings. This study investigated the physical and chemical transformations of Cf/SiC composites during picosecond laser ablation and successfully fabricated micro-structured surfaces with super-hydrophilicity. The findings revealed that three-scale microstructures were formed on Cf/SiC composites after picosecond laser-ablating, which were orderly composed of regular convex plates (20–60 μm), agglomerate ablative products (1–5 μm), and nano particles (100–500 nm). The relative content of O on the laser-ablating surface was mostly>25%, both Si–O and Si–C bonds were found on the Si2p peak of the XPS spectrum. The primary content of the ablative products was crystalline and amorphous SiO2, resulting from the oxidation of the SiC matrix. The initial surface of the Cf/SiC composites was hydrophobic, and its contact angle was 92.7°. Conversely, the laser-ablating surfaces showed significant absorption of water droplets owing to the presence of the hydroxyl group in the amorphous SiO2, and the droplets quickly disappeared from the surface through the micro “tubular channels” caused by carbon fibers sublimating and oxidizing under the high laser temperature. Consequently, the superhydrophilic surfaces of the Cf/SiC composites were obtained via picosecond laser ablation, and the motion of the droplets was closely related to the laser power and scanning distance.

Chitosan and TiO2 functionalized polypropylene nonwoven fabrics with visible light induced photocatalytic antibacterial performances

Chitosan/TiO2 functionalized polypropylene (CS/TiO2/PP) nonwoven fabrics were fabricated through crosslinking of chitosan with glutaraldehyde followed by loading of TiO2 nanoparticles. The functionalized CS/TiO2/PP has super hydrophilicity and excellent visible light induced photocatalytic antibacterial properties owing to the synergistic effects of CS and TiO2. The photocatalytic degradation performance was determined by assessing the degradation of methyl blue under simulated visible light irradiation and its recyclability was also evaluated. In addition, SEM images demonstrated that TiO2 nanoparticles were distributed evenly on the surface of the 2 g/L CS/TiO2/PP. Meanwhile, the polypropylene surface showed a significant increase in hydrophilicity after being treated with chitosan and TiO2. The photocatalytic degradation results revealed that CS/TiO2/PP had higher photocatalytic properties than those of pure PP under visible light, and the degradation rate of methylene blue reached 96.4 % after 90 min of light exposure. Compared to pure PP, the antibacterial properties of CS/TiO2/PP significantly increased, and the bacterial reduction percentages were increased to 98.7 % and 96.3 %, against E. coli and S. aureus, respectively. The functionalized CS/TiO2/PP composites exhibited promising potential in environmentally friendly antibacterial materials.

Pool boiling on a biphilic surface where bubbles can move horizontally on the surface

In pool boiling on a horizontal surface, the flow of vapor is mainly the departure of vapor bubbles from the boiling surface. If the surface is composed of specially laid-out areas with varied wettabilities, vapor can move on the surface and out of the boiling region. In the present work, a silicon surface with such a function is fabricated using laser ablation and silanization grafting methods, and pool boiling on the surface is experimentally studied. On the biphilic surface, the boiling region is super-hydrophilic (SHI), and two opposite sides of the SHI region each is in connection to a wedge-shaped SHO (super-hydrophobic) track. The two sides of the SHO track are bounded by HO (hydrophobic) areas. Tests with air bubbles underwater show that the SHO tracks enable the directional spontaneous movement of the air bubbles on the surface, and the driving force for the natural motion is analyzed. Boiling heat transfer on the surface is compared with a SHI surface without the SHO tracks. The biphilic surface shows noticeable enhancement of heat transfer for low heat fluxes (< ∼150W/cm2) but reduces heat transfer for high heat fluxes in nucleate boiling. In addition, the biphilic surface extends the heat flux and surface temperature ranges of nucleate boiling, showing ∼14% increase of critical heat flux. The effects on boiling heat transfer are related to the observations of vapor transport by the SHO tracks.

Capillary performance of vertically grooved wicks on laser-processed aluminum surfaces with different wettability

Ultra-thin heat pipes have been employed extensively for the thermal management of electronic devices. Their capacity for heat transfer is significantly influenced by the capillary performance of the wicking structure in the pipes. In this study, superhydrophilic (SHPi) and superhydrophobic (SHPo) background surfaces were prepared on aluminum sheets using a nanosecond fiber laser. SHPi grooves with widths ranging from 0.1 to 0.4 mm were then produced on the surfaces with the same laser. The effects of the background wettability on the capillary performance of the grooves were investigated. The fastest ascent of the water in the grooves on the SHPo background surface occurred when the groove widths were between 0.1 and 0.2 mm. As the groove width increased to 0.3–0.4 mm, the water level rose most quickly in the groove on the SHPi surface. Furthermore, water absorption was always larger on the SHPi background surface for grooves of the same width as on the other two surfaces. As a result, a wettable background surface that matches the application requirements should be selected. The SHPo background surface should be used when a rapid water rise in the groove is desired. The SHPi background surface, on the other hand, increases water absorption capacity. Water absorption achieved a maximum of 6.8 mg with a groove width of 0.4 mm, and capillary performance parameters reached 4.62 × 10–7 N, which was 117.9% higher than the pristine background surface. This study presents fresh suggestions for increasing the capillary performance of vertically grooved wicks.

Mapping the low abundant plasma glycoproteome using Ranachrome-5 immobilized magnetic terpolymer as improved HILIC sorbent

HILIC (hydrophilic interaction liquid chromatography) materials enrich glycopeptides. The non-specific interactions because of support material and inadequate hydrophilicity render loss of less abundant glycopeptides in SPE-based enrichments. In this work, magnetic terpolymer (Fe3O4@MAA/DVB/1,2-Epoxy-5-hexene) is functionalized with Ranachrome-5 to generate enhanced hydrophilicity. Amine, carboxylic, and amide groups of ranachrome-5 provide zwitterionic chemistry. Material’s magnetic core contributes to ease of operation while higher surface area 97.0711 m2 g−1 immobilizes better quantities of Ranachrome-5. Homogeneous morphology, nano-size, and super hydrophilicity enhance enrichment. Ranachrome-5 functionalized polymeric core-shell beads enrich 25, 18 and 16 N-linked glycopeptides via SPE strategy from tryptic digests of model glycoproteins i.e., immunoglobulin G (IgG), horseradish peroxidase (HRP) and chicken avidin, respectively. Zwitterionic chemistry of ranachrome-5 helps in achieving higher selectivity (1:250, HRP / Bovine Serum Albumin), and lower detection limit (100 attomole, HRP digest) with complete glycosylation profile of each standard digest. High binding capacity (137.1 mg/g) and reuse of affinity material up to seven cycles reduce the cost and amount of affinity material for complex sample analysis. A recovery of 91.76% and relative standard deviation (RSD) values less than 1 define the application of HILIC beads for complex samples like plasma. 508 N-linked intact low abundant glycopeptides corresponding to 50 glycoproteins are identified from depleted human plasma samples via nano-Liquid Chromatography-Tandem Mass Spectrometry (nLC-MS/MS). Using Single Nucleotide Variances (BioMuta) for low abundant plasma glycoproteins, the potential association of proteins to four cancers, i.e., breast, lung, uterine, and melanoma is evaluated. Via the bottom-up approach, HILIC beads can analyze clinically important low-abundant glycoproteins.

Degradation of sulfamethoxazole by super-hydrophilic MoS2 sponge co-catalytic Fenton: Enhancing Fe2+/Fe3+ cycle and mass transfer

To promote the cycle of Fe2+/Fe3+ in co-catalytic Fenton and enhance mass transfer in an external circulation sequencing batch packed bed reactor (ECSPBR), super-hydrophilicity MoS2 sponge (TMS) modified by tungstosilicic acid (TA) was prepared for efficiently degrading sulfamethoxazole (SMX) antibiotics in aqueous solution. The influence of hydrophilicity of co-catalyst on co-catalytic Fenton and the advantages of ECSPBR were systematically studied through comparative research methods. The results showed that the super hydrophilicity increased the contact between Fe2+ and Fe3+ with TMS, then accelerated Fe2+/Fe3+ cycle. The max Fe2+/Fe3+ ratio of TMS co-catalytic Fenton (TMS/Fe2+/H2O2) was 1.7 times that of hydrophobic MoS2 sponge (CMS) co-catalytic Fenton. SMX degradation efficiency could reach over 90% under suitable conditions. The structure of TMS remained unchanged during the process, and the max dissolved concentration of Mo was lower than 0.06 mg/L. Additionally, the catalytic activity of TMS could be restored by a simple re-impregnation. The external circulation of the reactor was conducive to improving the mass transfer and the utilization rate of Fe2+ and H2O2 during the process. This study offered new insights to prepare a recyclable and hydrophilic co-catalyst and develop an efficient co-catalytic Fenton reactor for organic wastewater treatment.

Experimental study on pool boiling enhancement by unique designing of porous media with a wettability gradient

High heat flux dissipation can be achieved in pool boiling heat transfer through regulating the bubble escape and liquid replenishment paths over the heated surfaces. In this work, a unique design of copper foam with a wettability gradient is presented to generate separate liquid–vapor pathways for pool boiling enhancement. The effect of copper foam with a wettability gradient on bubble dynamics during nucleate boiling period is evaluated using bubble visualization experiment. Results demonstrated that the liquid replenishment and bubble escape flow is determined by copper foam with different wettability gradient. Comparing with the super-hydrophilic (SHPi) copper foam and super-hydrophobic (SHPo) copper foam, the super-hydrophilic top with super-hydrophobic bottom (SHPiT-SHPoB) copper foam structure and super-hydrophobic top with super-hydrophilic bottom (SHPoT-SHPiB) copper foam structure can achieve the critical heat flux (CHF) of 113.3 W/cm2 and 108.3 W/cm2, corresponding to the maximum heat transfer coefficient (HTC) of 5.93 W/cm2·K and 5.28 W/cm2·K, respectively. Two bubble escape forms and liquid replenishment models are established to give detailed explanations on the pool boiling enhancement. It is evident that when bubbles escape from sides, the bubble escape path is shorter, resulting in a faster bubble escape rate and a smaller bubble departure diameter. The experimental results also reveal that liquid replenishment rate of the SHPiT-SHPoB copper foam is also the best amongst all samples, providing a trade-off between the bubble escape and liquid replenishment in diverse conditions.

Synthesis and Photocatalytic Activity of Si-doped TiO2 Nanotube/SnS Hybrids for Environmental Decontamination

Background: Heterostructures with nanoscale sizes have great superiorities in photocatalytic environment decontaminant because of their efficient interface charge transfer and great surface area. Objective: This work reports the facile fabrication of nano-tubular TiO2 and Si-doped TiO2 (NTs) hybridizing SnS nanocrystallites and their high-efficient photocatalytic activity. Methods: The modified hydrothermal processes were used to synthesize the nanotubes. A chemical bath deposition process was used to hybridize SnS nanocrystallines with the nanotubes. Results: The fabricated nanostructures show wide light absorption in the UV-visible region. The SBET, light absorption, hydrophilicity, and photo-induced super hydrophilicity were enhanced by Si-doping and SnS modification. Moreover, high-efficient interface charge transfer was produced after the SnS modification and further enhanced by the Si doping because of band structure modulation. Conclusion: Thus, the Si-doped TiO2 nanotubes/SnS heterostructures showed remarkably enhanced photocatalytic and Fenton-like photocatalytic activity in dye wastewater treatment than the TiO2 NTs. This work suggests potential materials and their facile fabrication process for the photocatalytic application of environmental decontamination.

Improving the hydrophilicity and antifouling performance of PVDF membranes via PEI amination and further poly (methyl vinyl ether-alt-maleic anhydride) modification

Polyvinylidene fluoride (PVDF) is an excellent material for porous membranes due to its outstanding chemical resistance, thermal stability, and film formability. However, the lower surface energy and the hydrophobicity of PVDF, result in poor wettability and organic fouling. In the present work, polyethyleneimine (PEI) was covalently bound on PVDF through the amination reaction in the casting solution. After converting the solution into membranes by phase inversion, the PEI-aminated PVDF membrane was further modified with poly (methyl vinyl ether-alt-maleic anhydride) (PEOSMA). The PEOSMA-modified membranes possess super hydrophilicity and antifouling performance. The protein adsorption capacity of the modified membrane was extremely low, only 5.65 μg/cm2. The pure water recovery rate (FRR) reached 97%, with BSA rejection over 97%. The presented protocol offers an effective in-situ covalent modification method for PDVF membranes with a high potential in large-scale applications.

A potential biogenetic membrane constructed by hydrophilic carbonized rice husk for sustaining electricity generation from hydrovoltaic conversion

In recent years, the research on hydrovoltaic conversion has made rapid progress, showing potential prospect in the field of power generation. However, it still faces many issues, such as expensive, uncontrollable engineering, undetermined mechanism and difficulty in commercialization. To provide a low-cost, undemanding and practical strategy, the carbonized rice husk was first used to construct a biogenetic membrane device in this work, giving a sustaining hydrovoltaic voltage at ∼160 mV. Relevant studies that associated with mechanism and key factors for hydrovoltaic process were also implemented founded on different test conditions. It is proved that the fluids flow driven by evaporation and capillary effect is an essential prerequisite for hydrovoltaic conversion. The mechanism for generating electricity should be attributed to the streaming potential theory, which can provide an electric potential difference by selective transmission of ions owing to the Debye shielding effect. Based on this as-proposed theory, the controlling projects like improving pressure difference (ΔP) of fluid, ambient temperature and humidity, which generally enhance the hydrodynamic driving force and effective flowing area, logically demonstrate positive answers on hydrovoltaic performance. Moreover, in view of the super hydrophilicity of carbonized rice husk, this biogenetic membrane has demonstrated strong sensitivity on human breath monitoring with rapid response for every breath, which provides a potential way for the practical application of hydrovoltaic effect.

Wetting and evaporative performance analysis of wet channels in indirect evaporative cooler with hydrophilic nano-coating

The wetting condition is an important factor that affects the cooling performance of an indirect evaporative cooler (IEC). Applying hydrophilic coatings to the wet channels is an effective way to enlarge the wetting area and enhance evaporative cooling. However, long-term hydrophilic durability tests for the coated surface are rarely discussed in existing studies. Moreover, the evaluation of performance improvement of a hydrophilic-coated IEC is usually based on testing the prototype as a whole, without giving attention to the internal wetting behavior inside the core. Therefore, a TiO2/SiO2 nano-coated polypropylene (PP) IEC is manufactured for studying the wetting and evaporative performance by considering the hydrophilic durability and internal wetting behavior with a specially-designed visualized experiment, aiming at promoting its application and guiding the design. Firstly, the microstructure, thermal conductivity, drop-surface characteristics and hydrophilic durability of the coated samples were studied. Secondly, the internal water distribution was studied under the influence of spray time (5 s ∼ 180 s), water flow rate (2 L/min ∼ 6 L/min), air velocity (2 m/s ∼ 3.5 m/s) and nozzle height (50 mm ∼ 250 mm) by combining fluorescence tracer and digital image processing methods. Lastly, the evaporative performance of the nano-coated IEC was tested under two spray strategies. Results show the hydrophilicity of polished nano-coated PP is durable in a dark and water-scouring environment with a steady contact angle of 30.9°. The coated core shows super hydrophilicity by forming a thin water film and being fully wetted within 60 s. Compared to the continuous spray, the intermittent spray can provide a larger evaporative mass transfer coefficient by 23.5% and a higher coefficient of performance by 114%.

Preparation of salt-tolerant chitosan hydrogels and their anti-biofouling behavior study

The hydration of wettable materials can help to improve their anti-biofouling effect, but their hydration stability under high salinity conditions is a challenge considering the future applications in natural marine environments. Inspired by the self-cleaning properties of crustaceans, chitosan (CS)/Poly (vinyl alcohol) (PVA) hydrogels have been prepared, and their anti-biofouling and salt tolerant mechanism were deeply investigated using surface analysis and molecular dynamics simulation. Interestingly, it is found that CS/PVA hydrogels can be controllably triggered at a low pH, and they can self-adjust to enhance anti-biofouling performance following the changes of environmental conditions. The hydration of CS/PVA hydrogels is enhanced in seawater because of a low salt sensitivity factor (f) of these hydrogels with a value of less than 0. Super hydrophilicity of CS/PVA hydrogels makes water drop achieve super spreading within 66.5 ms. Compared to PVA hydrogels, almost no crude oil, protein and algae can adhere to the surface of the prepared CS/PVA (0.2:1) hydrogel. The field tests in the south sea of China also demonstrate that CS/PVA (0.2:1) hydrogel has an excellent anti-biofouling ability after 6 months of testing. The anti-biofouling mechanism is also discussed according to the experimental results and molecular dynamics simulation.

Response of Human Gingival Fibroblasts and Porphyromonas gingivalis to UVC-Activated Titanium Surfaces

Ultraviolet (UV) photofunctionalization has been demonstrated to synergistically improve the osteoblast response and reduce biofilm formation on titanium (Ti) surfaces. However, it remains obscure how photofunctionalization affects soft tissue integration and microbial adhesion on the transmucosal part of a dental implant. This study aimed to investigate the effect of UVC (100-280 nm) pretreatment on the response of human gingival fibroblasts (HGFs) and Porphyromonas gingivalis (P. g.) to Ti-based implant surfaces. The smooth and anodized nano-engineered Ti-based surfaces were triggered by UVC irradiation, respectively. The results showed that both smooth and nano-surfaces acquired super hydrophilicity without structural alteration after UVC photofunctionalization. UVC-activated smooth surfaces enhanced the adhesion and proliferation of HGFs compared to the untreated smooth ones. Regarding the anodized nano-engineered surfaces, UVC pretreatment weakened the fibroblast attachment but had no adverse effects on proliferation and the related gene expression. Additionally, both Ti-based surfaces could effectively inhibit P. g. adhesion after UVC irradiation. Therefore, the UVC photofunctionalization could be more potentially favorable to synergistically improve the fibroblast response and inhibit P. g. adhesion on the smooth Ti-based surfaces.

Preparation Janus membrane via polytetrafluoroethylene membrane modification for enhanced performance of vacuum membrane distillation desalination

In this study, we developed novel Janus membranes with multilevel hierarchical structures to prevent membrane pore wetting and enhance the performance for desalination simultaneously. Here, a Janus membrane with multilevel roughness was tailored via a polydopamine (PDA) coating followed by deposition of Fe3O4 nanoparticles and PDA sealing. These novel Janus membranes demonstrated outstanding antiwetting properties and salt rejection performances in comparison to pristine polytetrafluoroethylene (PTFE) membrane. Particularly, the specific flux of Janus membranes was maintained in a relatively stable state (0.6–0.7) after membrane cleaning with pure water, meanwhile, the permeate conductivity was maintained in the range of 0–30 µS/cm with the desalination rate of 99.9% during the vacuum membrane distillation (VMD) tests by using 6.98 wt.% feed solutions, indicating that these Janus membranes (i.e., P/Fe/P-PTFE membrane) can improve the performance for VMD desalination without membrane wetting throughout the test duration. Furthermore, we ascribed these Janus membranes’ superior performances to the coupled effects of super hydrophilicity brought about by PDA layer and self-healing mechanism provided by Fe3O4 nanoparticles. This work highlights the great potential of novel Janus membranes with multilevel hierarchical structures for water reclamation from challenging high-salinity wastewater through VMD.

Double cross-linked transparent superhydrophilic coating capable of anti-fogging even after abrasion and boiling.

The commercial application of surfaces with superhydrophilic (SHPL) properties is well known as an efficient strategy to address problems such as anti-fogging, anti-frosting, and anti-biological contamination. However, current SHPL coatings are limited by their poor water and abrasion resistances. Thus, herein, to solve these problems active glass was employed as a substrate, and a stable and transparent SHPL solution was prepared via the spraying process. Aqueous polyacrylic resin (PAA), SiO2 nanoparticles (NPs), tetraethyl orthosilicate (TEOS), and sodium allyl sulfonate (SDS) were utilized as the four main components of the PAA-TEOS-SiO2 coating. The durability properties including anti-abrasion, resistance to water, and contact component loss were investigated via the Taber abrasion test, boiling water immersion test, and anti-fogging test, respectively. Furthermore, the structure, composition, and wettability of the coating before and after the friction and water immersion tests were compared via water contact angle (WCA) measurements. Furthermore, the effect of the type of resin on the properties of the coating was investigated. The surface morphology of the blended water-based polyacrylic acid (PAA) resin was uniform and flat and its adhesion to the substrate was the highest (4.21 MPa). Considering the durability and optical properties of the coating, the optimal blend was 3 wt% PAA resin, which exhibited a transmittance of 90%. When the content of TEOS, which enhanced the crosslinking in the coating, was increased to 2 wt%, the results showed that the SHPL coating maintained good anti-friction, boiling resistance, and anti-fogging properties under the conditions of 300 cycle Taber friction with 250 g load and soaking in hot water at 100 °C for 1 h. In particular, the excellent durability of strong acid and alkali resistance, heat resistance, and long-term aging resistance will facilitate the commercial viability and expand the application of SHPL coating in various research fields.

Dissolvable templates to prepare Pt-based porous metallic glass for the oxygen reduction reaction.

Oxygen reduction reaction (ORR) plays a crucial role in electrochemical energy conversion and storage devices such as metal-air batteries and water electrolyzers. Herein, a hierarchical nanoporous platinum-based metallic glass (NPMG) was developed by a facile fabrication method by dissolving in a liquid. The surface topography of the sample can be easily modulated by controlling the particle size of sodium chloride. As a result, the NPMG was proved to be efficient and robust as the ORR catalysts with super hydrophilicity and self-renewal capacity. The half-wave potential of the platinum-based porous material was 835 mV at 0.1 M KOH, even higher than that of the commercial Pt/C catalyst (823 mV) and the previously reported platinum material. In particular, platinum-based porous materials have extremely long stability (more than 500 h) through the self-renewal surface, which perfectly meets the requirements of catalyst stability in batteries. Our study has a better inspiration for developing and applying novel catalysts to prepare metal-air batteries.

Design and construction of a Laplace and wettability gradient field for efficient water collection.

A hydrophilic-hydrophobic hybrid surface with a vein-like pattern was prepared on a copper substrate using 3D printing technology and laser scanning technology. Under the action of the Laplace pressure gradient and wettability gradient, the superhydrophilic (SHL) vein-like pattern on the superhydrophobic (SHB) surface aided the directional transport of water droplets. The presented scheme combined with the wettability and surface pattern could achieve a water-collection efficiency of 4258.59 mg cm-2 h-1.

Synthesis, Characterization and Statistical Optimization of Hydrophobic/Oleophilic Polystyrene Coated ZnO-Cotton Composite as Vegetable Oil Adsorbent

Cotton being easily available, low cost and highly porous natural material is excellent candidate as adsorbent base. However, its super hydrophilicity hinders its applications as oleophilic adsorbent. In the present study, pristine cotton was impregnated with ZnO and stearic acid to provide it with rough surface and hydrophobic properties followed by dip coating of polystyrene for further enhancement of its oil adsorption capacity. The surface morphology of polystyrene coated ZnO impregnated non-woven cotton (PS@ZnO-NWCotton) and polystyrene coated ZnO impregnated woven cotton (PS@ZnO-WCotton) showed increased surface area, roughness and pores as compared to pristine cotton. FTIR spectra confirmed conjugation of polystyrene and ZnO with cotton. Different thermal degradation behavior of pristine cotton and PS@ZnO-NWCotton further confirmed the presence of ZnO and polystyrene onto cotton. PS@ZnO-WCotton exhibited lotus-effect high hydrophobicity with a water contact angle of 145and#177;2o and super oleophilicity with an oil contact angle of 0o. Oil adsorption capacities of synthesized composites were found to have an inverse relationship with viscosity of adsorbate oil which could be due to easy mobility of lighter oils. Oil adsorption capacity of PS@ZnO-NWCotton for coconut oil was maximized by optimizing temperature, duration and oil/water ratio using central composite design (CCD). Good agreement was found between predicted values obtained by the model and the experimental values (R2 = 0.8904) for adsorption of coconut oil by PS@ZnO-NWCotton. Under the optimum conditions, the PS@ZnO-NWCotton adsorbed more than 12 times of its weight with acceptable reusability till third cycle

Recent advances in photocatalytic self-cleaning performances of TiO2-based building materials.

TiO2-based photocatalytic building materials can keep the building surface clean, and have decontamination, antibacterial effects and so on, which greatly reduces the maintenance cost and the risk of cleaning work, and these materials have great application potential in pollution and carbon reduction in the future. However, due to the wide band gap of TiO2, the low utilization of solar energy and the instability of super hydrophilicity have always been the difficulties in the field of photocatalysis. Based on the relevant research of TiO2-based photocatalytic materials in recent years, this review summarizes the modification strategies that can effectively improve the photocatalytic activity of TiO2-based photocatalytic materials. At the same time, the influence of complex environmental factors and substrate properties on the self-cleaning behavior of TiO2-based building materials was analyzed. This paper aims to provide effective guidance for the future application of TiO2-based photocatalysts in the construction field, improve people's understanding of photocatalytic building materials (PBM) and photocatalytic self-cleaning characteristics, and provide more possibilities for the extensive application of photocatalysis technology in the construction field, as well as to promote the realization of global carbon neutrality and other strategic goals of pollution and carbon reduction.

Magnetic field assisted synthesis of JANUS Fe3C@ Enteromorpha doped graphene aerogels for simultaneous recovery of fresh water and salt in high salinity wastewater

Solar-driven evaporation technology has captured great attention in the fields of desalination and separation due to its eco-friendliness and minor energy costs. It is difficult to maintain durable stability and high efficiency for the evaporation process due to salt contamination. Herein, Fe3C@ Enteromorpha doped graphene aerogel (GEF) was synthesized by a one-step hydrothermal reduction method for the simultaneous recovery of fresh water and salt in high salinity wastewater. Enteromorpha was doped between graphene lamellae to construct the structural basis for the rapid water evaporation and salt resistance of aerogel. Fe3C was concentrated on the surface of aerogel with the assist of magnetic field, which not only improves the hydrophilicity of GEF by increasing the roughness and increasing hydrophilic groups, but also concentrates the heat on the evaporation surface. The rich microporous structure with super hydrophilicity endows the GEF with exceptional evaporation performance. Water evaporation rate and photothermal conversion efficiency can reach 3.76 kg·m−2·h−1 and 127 %, respectively, under 1 sun irradiation. The multi-layer structure of GEF enables the salt precipitation on the side, assisting the evaporation and crystallization. GEF has a stable evaporation rate of 3.2 kg·m−2·h−1 for 20 % NaCl solution during 10 h continuous evaporation for 5 days. The GEF aerogel shows excellent photothermal properties and salt resistance, and practical ability to recover clean water and salt resources from the actual treatment of high-salt wastewater.