Photothermal Layer Research Articles

Symbiotic defect-reinforced bimetallic MOF-derived fiber components for solar-assisted atmospheric water collection

Conversion of atmospheric water to sustainable and clean freshwater resources through MOF-based adsorbent has great potential for the renewable environmental industry. However, its daily water production is hampered by susceptibility to agglomeration, slow water evaporation efficiency, and limited water-harvesting capacity. Herein, a solar-assisted bimetallic MOF (BMOF)-derived fiber component that surmounts these limitations and exhibits both optimized water-collect capacity and short adsorption-desorption period is proposed. The proposed strategy involves utilizing bottom-up interface-induced assembly between carboxylated multi-walled carbon nanotube and hygroscopic BMOF on a multi-ply glass fiber support. The designed BMOF (MIL-100(Fe,Al)-3) skeleton constructed using bimetallic-node defect engineering exhibits a high specific surface area (1,535.28 m2/g) and pore volume (0.76 cm3/g), thereby surpassing the parent MOFs and other reported MOFs in capturing moisture. Benefiting from the hierarchical structure of fiber rods and the solar-driven self-heating interface of photothermal layer, the customized BMOF crystals realize efficient loading and optimized water adsorption-desorption kinetics. As a result, the resultant fiber components achieve six adsorption-desorption cycles per day and an impressive water collection of 1.45 g/g/day under medium-high humidity outdoor conditions. Therefore, this work will provide new ideas for optimizing the daily yield of atmospheric water harvesting techniques.

Biomimetic solar evaporator for continuous clean water production with synergistic organic dye wastewater remediation

Solar-driven water evaporation is recognized as an environment-friendly technology for sustainable clean water generation, serving the needs of both desalination and wastewater purification. However, its practical application is constrained by challenges such as single functionality and significant salt accumulation. Inspired by the transpiration of vascular plant, this work introduces a scalable and cost-effective biomimetic evaporator (PyCOF/Tri-Layers), consisting of a biomimetic hierarchical fibrous membrane (Tri-Layers) and a composite photothermal layer (PyCOF). Furthermore, the PyCOF composite, featuring an aloe-like flower structure, enhances the light trapping (95.1 %) through multiple scattering, realizing simultaneous desalination and azo dye degradation. Based on the PyCOF/Tri-Layers evaporator, we demonstrate a suspended multi-section hanging evaporation structure sustaining a consistent evaporation rate of approximately 1.41 kg m−2 h−1 over 15 days without salt accumulation, achieving above 99.3 % removal of dye pollutants within 120 min under one sun irradiation. Moreover, in outdoor experiments, the improved evaporator realizes a daily clean water yield rate of 8.73 kg m−2 d−1, and the collected water is suitable for supporting crop cultivation within an integrated solar desalination-cultivation system. This work not only provides a one-stone-two-birds approach for generating clean water from polluted seawater, but also presents promising possibilities for offshore self-sustainable agriculture production.

TIO2-MOS2 PAPER BASED MEMBRANE FOR SOLAR EVAPORATION

Clean water scarcity is a critical issue faced by the world. It was caused by insufficient potable water supply and a high cost of water purification systems. As a result, a photothermal evaporator system with the property to absorb light/solar energy and then convert it to heat energy has been rapidly developed. In this work, a solar-driven water evaporation was designed for desalination. The solar evaporator comprises a photothermal molybdenum disulfide-titanium dioxide (MoS2-TiO2) composite layer supported onto a cheap filter paper attached. The filter paper was attached to polystyrene foam for support and cotton thread in the centre of the filter paper for water transportation. MoS2-TiO2 composite was synthesized and coated onto the filter paper using a simple vacuum-assisted method. Before the solar-driven water evaporation testing, the MoS2-TiO2 composite was first characterized using XRD and Raman spectroscopy. The characterization results indicate that MoS2 introduction into the TiO2 structure improved the photosensitivity due to the reduction of the bandgap energy from 3.1 eV for TiO2 to 1.6 eV. The performance of the developed solar evaporator was tested using 35,000 ppm NaCl solution under sunlight for 24 h intermittently. The TiO2-MoS2 solar evaporator was observed to have the highest photothermal ability, with 0.807 kg‧m-2‧h-1 evaporation performance and 55.9 % photothermal efficiency compared to other solar evaporators. This indicated that introducing the photothermal MoS2-TiO2 layer could enhance the solar evaporator performances, making it promising for the desalination application, particularly in impoverished areas with water scarcity.

Dual-Interface Solar Evaporator with Highly-Efficient Thermal Regulation via Suspended Multilayer Design.

Facing the increasing global shortage of freshwater resources, this study presents a suspended multilayer evaporator (SMLE), designed to tackle the principal issues plaguing current solar-driven interfacial evaporation technologies, specifically, substantial thermal losses and limited water production. This approach, through the implementation of a multilayer structural design, enables superior thermal regulation throughout the evaporation process. This evaporator consists of a radiation damping layer, a photothermal conversion layer, and a bottom layer that leverages radiation, wherein the bottom layer exhibits a notable infrared emissivity. The distinctive feature of the design effectively reduces radiative heat loss and facilitates dual-interface evaporation by heating the water surface through mid-infrared radiation. The refined design leads to a notable evaporation rate of 2.83kg m-2 h-1. Numerical simulations and practical performance evaluations validate the effectiveness of the multilayer evaporator in actual use scenarios. This energy-recycling and dual-interface evaporation multilayered approach propels the design of high-efficiency solar-driven interfacial evaporators forward, presenting new insights into developing effective water-energy transformation systems.

Direct deposition of Ti/MgF2 photoabsorber on PTFE membrane with enhanced robustness via plasma pretreatment for photothermal membrane distillation

Deposition of metal-dielectric hybrid composite on the polymer based membrane is important for the electrochemical, photochemical and photothermal reactions on the membrane surface. The hydrophilic reactants such as catalysts and photothermal materials are not easy to be deposited directly on the hydrophobic membrane surface, so in most cases, binder material has been adapted to stably combine them. In this study, commercial PTFE membrane and Ti/MgF2 photothermal layers were combined without any binder. Ar plasma pretreatment was applied to a membrane surface before depositing optimized Ti/MgF2 stacks to fabricate a mechanically robust photothermal membrane. The successful fabrication of Ar plasma pretreated Ti/MgF2 photothermal membrane was demonstrated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), atomic force microscope (AFM) characterization. Through Ar plasma pretreatment, an increase in Ti/MgF2 photothermal membrane heating temperature of 40.5 % was achieved under 1 sun condition compared with unpretreated membrane. This membrane showed improved performance and reduced energy loss in solar desalination. Utilizing these membranes in a membrane distillation system, water flux increased by up to 26.9 %, performance ratio (PR) increased by 18.9 % and thermal efficiency improved by 21.9 %. After 24-h stress test, the Ar plasma pretreated Ti/MgF2 photothermal membranes demonstrated durability and maintained thermal efficiency.

Superhydrophilic and heterostructured NiCu/polyaniline nanocomposites as highly efficient electrocatalyst and photothermal conversion layer integrated thermoelectric device for overall water splitting

The large-scale production of green hydrogen from water electrolysis has recently gained extensive attention. However, the high overpotential leads to the excessive costs of electricity consumption. Herein, a novel research scheme was proposed to design photothermal electrocatalyst with photothermal effect and highly efficient hydrogen evolution reaction (HER) performance, which can be integrated with thermoelectric (TE) device to effectively lower the cell voltage in the overall water splitting. Experimental and DFT calculations results demonstrated that NiCu/PANI/NF catalyst displayed superior HER performance (28 mV@10 mA cm−2, 89 mV@50 mA cm−2), exceptional durability (110 h@10, 50 mA cm−2), as well as good infrared photoresponsivity (93.4 ℃@200 mW cm−2 @10 min). It can be mainly attributed to the synergy of polyaniline and the introduction of Cu, which can effectively modulate the d-band center of Ni active site, and attenuate H adsorption energy, then promote H2 generation. Additionally, superhydrophilicity of NiCu/PANI/NF can facilitate mass transfer and accelerate H2 evolution. Notably, in a self-designed electrolyzer-TE integrated device, the cell voltage was significantly lowered for the overall water splitting (0.29 V @50 mA cm−2). This work presented an efficient photothermal electrocatalyst and provided novel insights for investigations into water electrolysis with cost-effective hydrogen production in the future.

Multi-layer photothermal film inspired by polar bear fur for anti-icing and photothermal de-icing in cold environments

As climatic conditions worsen and time passes, icing becomes an unavoidable issue. Drawing inspiration from the thermal regulatory properties inherent in polar bear fur, we introduce a biomimetic three-layer film. This film comprises a hydrophobic shield, a photothermal conversion layer, and an insulating layer through electrospinning. The multilayered micro/nanostructure within this film amplifies its light absorption capabilities, achieving an average absorption rate of 96.27 % across wavelengths ranging from 200 to 2500 nm. Thanks to the insulation layer's thoughtful design, the film boasts high photothermal conversion efficiency. When exposed to solar radiation for 360 s at an ambient temperature of 20 °C, its surface temperature swiftly climbs to 98.3 ± 1.1 °C. The film's anti-icing capabilities are evidenced by the fact that a droplet of water takes 2964.7 s to freeze on its surface, which is approximately 118 times that of aluminum. Additionally, it demonstrates excellent photothermal de-icing performance, swiftly eliminating thick layers of ice or frost under sunlight. Moreover, this film maintains its anti-icing and hydrophobic qualities even after multiple icing and de-icing cycles, as well as durability testing. It also possesses self-cleaning properties. Given its outstanding performance, this film has tremendous potential for long-term outdoor anti-icing applications.

Highly efficient 3D-screen printed interfacial solar water desalination system

Interfacial solar steam generation (ISSG) using floating devices is one of the most efficient and simple methods of purifying saline water. In this work, multi-layered solar steam generation systems are fabricated using 3D-screen printing. The printed devices with a uniform layer-by-layer structure contain light-harvesting, thermal insulation, thermal conduction, and water-transfer layers. The graphite (Gr) photothermal layer as an absorber layer is screen printed on the felt substrate with three different 3D patterns, which is isolated by transparent hydrophobic silica aerogel (SA) as a light scattering agent to provide efficient photon capturing and heat localization. Furthermore, to transfer the generated heat to the water proficiently, a copper (Cu) layer is coated on the downside of the absorber layer. The devices with the best performances are introduced by evaluating the effect of the fabricated layers thickness and different configurations. The multi-layered device containing a photothermal layer with SP1-3rd pattern and different thicknesses of SA 32 μm (under Cu), Cu 16 μm, Gr 32 μm, and SA 32 μm (on top of the Gr) shows a steam generation efficiency of 97 %, and water evaporation flux of 1.43 kg.m−2.h−1, which are 86 % higher than the performance of the reference system.

Controlling pore size and photothermal layer to improve solar-porous evaporation performance

Controlling pore size and photothermal layer to improve solar-porous evaporation performance

Novel mushroom-like cotton-based evaporator for simultaneous freshwater production and salt harvesting via edge-preferential crystallization

Solar-driven interfacial evaporation (SDIE) has emerged as a promising technology to alleviate the global freshwater scarcity. However, the simultaneous collection of water and salt as resources while maintaining stable evaporation rate without salt contamination at the evaporation interface remains a huge challenge. Herein, we report a novel mushroom-like cotton-based evaporator, inspired by the vertical stem and inclined caps of mushrooms, for simultaneous freshwater production and salt harvesting. By depositing polyaniline (PANI) and carbon nanotubes (CNTs) onto the cotton fabric (CF), an evaporation rate of 1.88 kg m−2h−1 and a high solar evaporation efficiency of 99.4 % can be achieved in 3.5 wt% NaCl solution under one solar irradiation. Furthermore, a significant water collection efficiency of 70.2 % and a high salt harvesting rate of 42.1 g m−2h−1 can be derived. Even exposed to high-concentration (15 wt%) brine, our design still effectively prevents salt contamination. The distinctive edge-preferential crystallization not only avoids the salt contamination but also promotes the salt harvesting, due to the capillary force, the criss-cross water channels from the nature of cotton cloth, as well as the gravity-assisted water transport of the “mushroom cap” during evaporation. In addition, the low thermal conductivity (0.163 W m−1 K−1) of the photothermal layer with the integration of PANI and CNTs, as well as the vertical water upward transport via the “mushroom stem” effectively reduce the heat loss. This research holds great potential for seawater desalination applications with the comprehensive utilization of seawater resources.

Photothermal Synergic Cross-Linking Hole Transport Layer for Highly Efficient RGB QLEDs.

Developing an insoluble cross-linkable hole transport layer (HTL) plays an important role for solution-processed quantum dots light-emitting diodes (QLEDs) to fabricate a multilayer device with separated quantum dots layers and HTLs. In this work, a facile photothermal synergic cross-linking strategy is simultaneous annealing and UV irradiation to form the high-quality cross-linked film as the HTL without any photoinitiator, which efficiently reduces the cross-linking temperature to the low temperature of 130 °C and enhances the hole mobility of the 3-vinyl-9-{4-[4-(3-vinylcarbazol-9-yl)phenyl]phenyl}carbazole (CBP-V) thin films. The obtained high-quality cross-linked CBP-V films exhibited smooth morphology, excellent solvent resistance, and high mobility. Moreover, the high-performance red, green, and blue (RGB) QLEDs are successfully fabricated by using the photothermal synergic cross-linked HTLs, which achieved the maximum external quantum efficiency of 25.69, 24.42, and 16.51%, respectively. This work presents a strategy of using the photothermal synergic cross-linked HTLs for fabrication of high-performance QLEDs and advancing their related device applications.

Enhancing the photothermal efficiency of MoS2 through ultraviolet-ozone exposure for improved solar evaporation

MoS2 has been explored as a photothermal layer for solar-driven water evaporators to produce clean water. However, there have been no reports studying the effects of ultraviolet-ozone (UVO) exposure on the photothermal properties of MoS2. This study investigates the impact of UVO exposure (10, 20, and 30 minutes) on bulk 2H-MoS2 synthesized via a hydrothermal method at 200°C for 16 hours. The freshly prepared MoS2 contained high concentrations of molybdenum oxide phases, which significantly diminished after 10 minutes of UVO exposure, indicating improved purity of MoS2. The increased purity of UVO-exposed MoS2 led to a rise in layer temperature to 47.37°C, surpassing the 43.40°C temperature of MoS2 without UVO exposure. Extending the UVO exposure to 30 minutes further increased the number of surface edge sites, thereby enhancing the wettability of MoS2 due to the increased binding sites for polar water molecules. Consequently, MoS2 exposed to UVO for 30 minutes demonstrated the highest evaporation rate of 1.83 kg m−2 h−1, achieving a photothermal efficiency of 94%, a high salt rejection rate of 99.98%, and a high heavy metal ion rejection rate of 91.84%. Therefore, the application of UVO-exposed MoS2 serves as an effective photothermal layer for sustainable and eco-friendly clean water production technologies.

Noncontact Microfluidics of Highly Viscous Liquids for Accurate Self-Splitting and Pipetting.

Accurate dosing for various liquids, especially for highly viscous liquids, is fundamental in wide-ranging from molecular crosslinking to material processing. Despite droppers or pipettes being widely used as pipetting devices, they are powerless for quantificationally splitting and dosing highly viscous liquids (>100mPa s) like polymer liquids due to the intertwined macromolecular chains and strong cohesion energy. Here, a highly transparent photopyroelectric slippery (PS) platform is provided to achieve noncontact self-splitting for liquids with viscosity as high as 15000mPa s, just with the assistance of sunlight and a cooling source to provide a local temperature difference (ΔT). Moreover, to guarantee the accuracy for pipetting liquids (>80%), the ultrathin MXene film (within a thickness of 20nm) is self-assembled as the photo-thermal layers, overcoming the trade-off between transparency and photothermal property. Compared with traditional pipetting strategies (≈1.3% accuracy for pipetting polymer liquids), this accurate microfluidic chip shows great potential in adhesive systems (bonding strength, twice than using the droppers or pipettes).

A PAM hydrogel surface-coated hydroponic bamboo evaporator with efficient thermal utilization for solar evaporation

Solar-driven interfacial water purification emerges as a sustainable technology for seawater desalination and wastewater treatment to address the challenge of water scarcity. Currently, the energy losses via radiation and convection to surrounding environment minimize its energy efficiency. Therefore, it is necessary to develop strategies to minimize the heat losses for efficient water purification. Here, a novel evaporator was developed through the in situ gelation of PAM hydrogel on the surface carbonized hydroponic bamboo (PSC) to promote energy efficiency. The inherent porous and layered network structures of bamboo, in synergy with the functional hydration capacity of PAM hydrogel, facilitated adequate water transportation, while reducing evaporation enthalpy. The PAM hydrogel firmly covered on the photothermal layer surface effectively minimized the radiation and convection heat losses, while further harvesting those thermal energy that would otherwise dissipate into the surrounding environment. The reduced thermal conductivity of PSC served as a thermal insulator as well, obstructing heat transfer to bulk water and thus diminishing conduction losses. Consequently, the rational designed PSC could efficiently convert solar energy to purified water, leading to the evaporation of 2.09 kg m−2 h−1, the energy efficiency of 87.6 % under one sun irradiation, and yielding 9.6 kg m−2 fresh water over 11 h outdoor operation. Moreover, the PSC also performs excellent salt rejection, and long-term stability at outdoor experiment. These results demonstrated high and stable solar evaporation performance could be achieved if turning heat losses into a way of extra energy extraction to further enhance the evaporation performance. This strategy appears to be a promising strategy for effective thermal energy management and practical application.

Elastic, Janus 3D evaporator with arch-shaped design for low-footprint and high-performance solar-driven zero-liquid discharge

Solar-driven zero-liquid discharge (ZLD) is a promising wastewater management strategy for freshwater recovery and solid waste harvesting. However, practical application of the solar-driven ZLD is severely constrained due to its low evaporation efficiency, large footprint, and rapid salt accumulation. Here, we present a Janus arch-shaped solar-driven evaporator (▪) comprising a hydrophobic top photothermal layer for effective light absorption, solar-thermal conversion, and vapor evaporation, which exhibits an evaporation rate of 2.82 kg∙m−2∙h−1 in pure water. The design also includes shapable delignified longitudinal wood (D-L-wood) serving as the hydrophilic bottom water transport layer, which enables dual-directional saltwater transportation and salt crystallization. D-L-wood, with numerous aligned channels, exhibits a low thermal conductivity of 0.04 W·m−1·K−1 along perpendicular direction and can effectively localize heat on the photothermal layer of the evaporator. D-L-wood has excellent hydrophilicity, and the salty water can be transferred quickly along both ends of the wood, providing sufficient salty water for rapid evaporation. The anisotropy of the wood makes the heat transfer quickly along the channel, improving the thermal management ability of the evaporator. Moreover, during vapor evaporation on the hydrophilic-hydrophobic interface, salt is crystallized at the hydrophilic layer, resulting in an enhanced anti-salt performance, a 1.5 folds evaporation rate compared with non-Janus evaporator after 15 h test. Under the conditions of a salt concentration of 3.5 %, a high salt harvest performance of 62.4 g∙m−2∙h−1 can be obtained under AM 1.5 solar irradiation. The arch-shaped design fully utilizes the upper space and effectively reduces evaporator footprint, resulting in an evaporation area to footprint ratio of 1.57:1. The designed evaporator can also be utilized for ZLD treatment of other heavy metal polluted water including Cu2+, CrO42−, Co2+, and so on. Therefore, the Janus-arch-shaped, solar-driven evaporator enables a potentially low-footprint, low-cost, scalable, and practical ZLD strategy for sustainable wastewater treatment.

Biomimetic polyaryl ether-based aerogels for efficient interfacial solar water vapor generation

There is an urgent need to design efficient photothermal layer, continuous water migration pathways, and stable insulation layer to simultaneously achieve ideal water and heat management in solar-powered interfacial evaporation systems. Here, we assemble into a biomimetic aerogel with down-feather-like shape by first introducing rigid polyaryl ether material of sulphonated poly (phthalazinone ether sulfone ketone) (SPPESK) for highly efficient and multifunctional solar interfacial evaporation drawing inspiration from the cavity structure and insulation strategy of the eagle wings. The biomimetic aerogel has an evaporation rate of 2.34 kg m−2h−1 at one solar irradiance, an energy efficiency of 91.7 %, and an output voltage of 316.7 mV when coated. The insights provided by this work into biomimetic structure displayed by chitosan/SPPESK/Mxene aerogels promise to translate photothermal conversion performance benefits measured in laboratories into real-world applications for continuous desalination and wastewater purification. We anticipate that our work is a starting point to utilize the full potential of photothermal properties of polyaryl ether-based materials.

Highly efficient solar-thermal-electric conversion based on asymmetric binary-architecture design in solid-solid composite phase change materials

The application of phase change materials (PCMs) in solar-thermal conversion is largely limited by the inherently inferior thermal conductivity (TC) and poor solar-thermal energy transition capacity of PCMs. Herein, 1,1,1-tri(hydroxymethyl)ethane@melamine foam/cellulose nanofiber/graphene nanoplate (TME@MCGx) shape-stable composite PCMs (ss-CPCMs) are prepared by encapsulating TME into MCGx aerogels. Profited by the effective heat-conducting MCG25 networks, the resulting TME@MCG25 ss-CPCM achieves high TC of 0.73 Wm-1k−1 for internal heat conduction. Meanwhile, the combination of surface photothermal etching and hydrophobic polydimethylsiloxane (PDMS) coating endows the obtained T-TME@MCG25 highly efficient solar-thermal conversation efficiency of 93.1 %, arising from the exposed 3D MCG25 skeletons for absorbing sunlight and the thin PDMS layer for preventing the absorbed solar-thermal energy from radiating and dissipating. Consequently, the solar-thermal-electric (STE) conversion system equipped with T-TME@MCG25 generates the prominent output voltage of 213.0 mV and current of 37.6 mA. Furthermore, the acquired T-TME@MCG25 exhibits remarkable hydrophobicity and self-cleaning performances, due to the micro-nano structures of MCGx skeleton surfaces and the low surface energy of PDMS coating. The design strategy of asymmetric binary-architecture containing 3D photothermal absorption layer and water repellency layer provides a valuable insight into STE energy conversion associated with hydrophobic ss-CPCMs, which can alleviate the looming energy crisis.

Hydrophobic Solid Photothermal Slippery Surfaces with Rapid Self-repairing, Dual Anti-icing/Deicing, and Excellent Stability Based on Paraffin and Etching.

Ice and snow disasters have greatly affected both the global economy and human life, and the search for efficient and stable anti-icing/deicing coatings has become the main goal of much research. Currently, the development and application of anti-icing/deicing coatings are severely limited due to their complex preparation, structural fragility, and low stability. This work presents a method for preparing hydrophobic solid photothermal slippery surfaces (SPSS) that exhibit rapid self-repairing, dual anti-icing/deicing properties, and remarkable stability. A photothermal layer of copper oxide (CuO) was prepared by using chemical deposition and etching techniques. The layer was then impregnated with stearic acid and solid paraffin wax to create a hydrophobic solid photothermal slippery surface. This solves the issue of low stability on superhydrophobic surfaces caused by fragile and irretrievable micro/nanostructures. In addition, the underlying photothermal superhydrophobic surface provides good anti-icing/deicing properties even if the paraffin on the surface evaporates or is lost during operation. The findings indicate that when subjected to simulated light irradiation, the coating's surface temperature increases to 80 °C within 12 min. The self-repair process is completed rapidly in 170 s, and at -15 °C, it takes only 201 s for the ice on the surface to melt completely. The surface underneath the paraffin exhibited good superhydrophobic properties, with a contact angle (CA) of 154.1° and a sliding angle (SA) of 6.8° after the loss of paraffin. Simultaneously, the surface's mechanical stability and durability, along with its self-cleaning and antifouling properties, enhance its service life. These characteristics provide promising opportunities for practical applications that require long-term anti-icing/deicing surfaces.

Preparation of Epoxy Resin/Carbon Black Superhydrophobic Photothermal Materials with Shape Memory Capacity for Anti/De‐Icing

The accumulation of ice can cause damage to various equipment, resulting in numerous economic losses. One promising solution for anti/de‐icing is the use of superhydrophobic materials powered by solar energy. In this study, a multilayer superhydrophobic photothermal materials with anti/de‐icing ability is prepared. First, an epoxy resin (EP) substrate with microstructure is prepared by the template method. Then carbon black (CB) nanoparticles are sprayed on the substrate as the photothermal layer. Finally, fluorine‐modified resin is dip‐coated as the hydrophobic modified layer. The light absorption of this material is 1.6 in the wavelength range of 400–2000 nm. The surface temperature rose to 114.2 °C within 270 s under 1 sun illumination. Additionally, the materials can respond to light stimulation and exhibit shape memory, with a shape recovery rate close to 100%. The air cushions in the micro‐nanostructures delayed the droplet freezing time by nearly two times. The good photothermal properties endowed the materials with photothermal de‐icing performance, which improved the de‐icing efficiency by almost 2.2 times. Furthermore, the materials demonstrate outstanding durability that can resist to mechanical wear, acid‐base corrosion, and UV aging, thermal stability, and self‐cleaning properties, making it highly suitable for outdoor equipment applications.

Photothermal controlled-release microcapsule pesticide delivery systems constructed with sodium lignosulfonate and transition metal ions: construction, efficacy and on-demand pesticide delivery.

Widespread application of controlled-release pesticide delivery systems is a feasible and effective method to improve the utilization efficiency of pesticides. However, owing to the high cost and complicated preparation technologies of controlled-release pesticide delivery systems, their applications in agricultural production have been seriously hindered. This study aimed to construct inexpensive photothermally controlled-release pesticide delivery systems using chitosan (CS) and sodium lignosulfonate (LS) as the wall materials, and a coordination assembly strategy of LS with transition metal ions to encapsulate a model pesticide, avermectin (AVM). The resulting complex or nanoparticle photothermal layers in these systems effectively achieved photothermal conversions, and replaced the use of common photothermal agents. In the prepared pesticide-delivery systems, two systems had remarkable photothermal conversion performance and photothermal stabilities with a photothermal conversion efficiency (η) of 24.03% and 28.82%, respectively, under 808 nm, 2 W near-infrared irradiation. The slow-release and ultraviolet-shielding performance of these two systems were markedly enhanced compared with other formulations. The insecticidal activities of these two systems against Plutella xylostella under irradiation with light-emitting diode (LED)-simulated sunlight were also enhanced by 5.20- and 5.06-fold, respectively, compared with that without irradiation of LED-simulated sunlight. Because of their convenient preparations, inexpensive and renewable raw materials, and excellent photothermally controlled-release performance, these on-demand pesticide delivery systems might have significant potential in improving the utilization efficiency of pesticides in modern agriculture. © 2024 Society of Chemical Industry.