Photothermal Evaporation Research Articles

In-situ lignin regeneration facilitated corn straw-based photothermal evaporator with high cost-effectiveness

Solar evaporators are one of the most efficient and sustainable water purification strategies, but it requires the use of expensive photothermal materials. Herein, the surface of waste corn straw was modified with condensed lignin by means of in-situ lignin regeneration. The resulting material was composited with hydrophilic chitosan and then applied as a sustainable and cost-effective photothermal material to construct a solar evaporator. The non-radiative transport was conferred by π-π stacking between conjugated aromatic rings of lignin, allowing the composites to demonstrate promising photothermal conversion ability. The composites presented a max evaporation rate of ∼1.44 kg m−2 h−1 under 1 sun, plus they consistently produced clean water in aqueous organic dye solutions (100 ppm RhB dye and 100 ppm MB dye) and seawater. Due to the ultra-low cost of raw materials and uncomplicated manufacturing procedure, these composites displayed a cost-effectiveness of ∼475 g h−1 $−1. Thus, this work provides a green and sustainable method for converting agricultural waste into functional photothermal evaporators, which is meaningful for both materials and environmental science.

Photothermal evaporation of the ferromagnetic nanofluid droplets under a magnetic field

The ferromagnetic nanofluid droplets evaporating on the photothermally heated substrate exhibits different behaviors when compared with the water droplets. This paper establishes a droplet evaporation model, where the simulation results of the mixed mode evaporation have a good agreement with the operated experiments. The residual mass and evaporation rate of the water droplets and ferromagnetic nanofluid droplets at different temperatures and light intensities are investigated, indicating that the magnetic particles have a promoting effect on the droplet evaporation. Afterwards, a periodic magnetic field has been installed, and variations in the temperature and velocity fields during droplet evaporation are explored. The magnetic field further promotes the droplet evaporation, which can be attributed to the deformation of the droplets induced by the periodicity of the magnetic field. The current study investigates the influence of the magnetic particles and a magnetic field on the evaporation of the heated droplets, providing a theoretical guidance for the application of electric heaters, cooling fluids and heat pipes.

Integration of photothermal water evaporation with photocatalytic microplastics upcycling via nanofluidic thermal management

Photothermal heating and photocatalytic treatment are two solar-driven water processing approaches by harnessing NIR and UV-vis light, respectively, which can fully utilize solar energy if integrated. However, it remains a challenge to achieve high performance in both approaches when integrated in a material due to uncontrollable heat diffusion. Here, we report a demonstration of heat confinement on photothermal sites and fluid cooling on photocatalysis sites at the nanoscale, within a well-designed heat and fluid confinement nanofiber reactor. Photothermal and photocatalytic nanostructures were alternatively aligned in electrospun nanofibers for on-demand nanofluidic thermal management as well as easy folding into 3D structures with enhanced light utilization and mass transfer. Such a design showed simultaneously high photothermal evaporation rate (2.59 kg m-2 h-1, exceeding the limit rate) and efficient photocatalytic upcycling of microplastics pollutant into valued products. Enabled by controlled photothermal heating, the valued main product (i.e., methyl acetate) can be evaporated out with 100% selectivity by in situ separation.

Water-flow-induced high-efficiency solar vapor generation and electricity collection

The interface photothermal evaporator still face challenges such as unstable operation, low evaporation efficiency, and insufficient energy utilization, particularly in high-concentration saltwater environments. This study proposes integrating a flow-induced power generation device within a photothermal-driven interface water evaporation system to address these issues. By leveraging the negative charge of carbon nanoparticles, a dual-electrode microchannel structure was optimized to establish an in-plane potential difference along the water transport path. The performance of the synchronized evaporation-flow-induced power generation system, with the carbon nanoparticle fabric as the core component, was thoroughly investigated, including its photothermal interface evaporation and power generation capabilities. Additionally, the controllability of the moisture content and water supply rate of the evaporation interface was achieved by adjusting the contact angle between the carbon nanoparticle fabric and bulk water, as well as the width of the water supply non-woven fabric. The synchronized evaporation-power generation system achieved an interface water evaporation rate of 1.44 kg m−2 h−1 and an output power density of 0.3 mW m−2 under 1 sun illumination (at a solar flux of q = 1 kW m−2). This study successfully obtained additional electrical energy output while prioritizing the evaporation rate, providing new insights for maximizing the energy efficiency of interfacial photothermal evaporation systems.

Three-dimensional freeze-casting solar evaporator for highly efficient water evaporation and high salinity desalination

The escalating global freshwater crisis demands sustainable water management strategies, such as solar-driven interfacial steam generation (SISG). Three-dimensional (3D) photothermal evaporators emerge as a promising solution due to significantly higher evaporation rates compared to two-dimensional (2D) counterparts. This study described the design and fabrication of M-shaped 3D evaporators using the freeze-casting technique with graphite nanopowder (GNP) and polyvinylidene fluoride (PVDF). Under 1.0 kW m−2 solar irradiation and 4 m s-1 convective flow, a high evaporation rate of up to 10.5 kg m−2 h−1 in pure water was achieved. The M-shaped 3D evaporators demonstrated excellent performance in solar desalination and wastewater treatment, maintaining stability even in a 20 wt% sodium chloride (NaCl) solution at 1.0 kW m−2 solar irradiation and 2 m s−1 convective flow, with a rate of approximately 3.8 kg m−2 h−1. These findings highlight the significant potential for leveraging the synergistic interplay between solar energy and convective flow, which can be harnessed through the fabrication of customized 3D evaporators via freeze-casting. This innovative approach offers a scalable and cost-effective solution, contributing to both efficient water evaporation and environmentally sustainable high salinity desalination for future water treatment.

Synergistic Densification in Hybrid Organic‐Inorganic MXenes for Optimized Photothermal Conversion

AbstractOptimizin the efficient light‐trapping in the photothermal conversion by enhancing localized surface plasmon resonance (LSPR) is crucial in improving light‐heat‐conversion efficiency of Ti3C2Tx MXene. However, its susceptibility to oxidation makes it prone to oxides formation, diminishing its metallic properties and significantly reducing the LSPR effect. This work synthesizes a kind of air‐stable hybrid Ti3C2Tx MXenes by a synergistic densification strategy that incorporates sulfhydryl‐bonding between organic and inorganic parts by reacting Ti3C2Tx MXene with thiocarboxylic acids. The resultant shortening of electron transport pathways, enhanced charge density, and the generation of additional electronic states around the Fermi level collectively contribute to an augmented LSPR effect. Additionally, the hybrid Ti3C2Tx MXenes also demonstrate high‐temperature resistance and reduced water interactions. These combined effects substantially elevate photothermal conversion efficiency through thiocarboxylic acids modification, reaching a photothermal evaporation rate of 1.77 kg m−2 h−1 with 94.56% efficiency in hybrid Ti3C2Tx MXenes. The approach paves the way for the design and development of a three‐in‐one strategy for photothermal conversion.

Carbonized balsa wood-based photothermal evaporator for treating inorganic chemical wastewater.

Solar desalination provides a sustainable and eco-friendly solution for purifying wastewater, addressing environmental challenges associated with wastewater treatment. This study focuses on the purification of inorganic contaminants from laboratory chemical wastewater (ICWW) using a spherical solar still (SSS). To enhance the evaporation rate and overcome the impact of heavy metals on absorption efficiency, a carbonized balsa wood (CBW) solar evaporator was employed. Balsa wood pieces, carbonized at 250 °C for 15 min, were arranged in a SSS configuration. The CBW-integrated SSS demonstrated a remarkable freshwater productivity of 2.33 L/m2 for ICWW, surpassing the conventional SSS, which produced only 1.5 L/m2. The presence of heavy metal ions (Na+, Ca+, K+, and Mg2+) in ICWW significantly affected the evaporation rate, and the CBW solar evaporator exhibited an impressive removal efficiency of approximately 99%. Water quality parameters, including pH and chemical oxygen demand (COD), were investigated before and after treatment. The CBW-integrated SSS achieved an outstanding COD removal efficiency of about 99.77%, reducing the COD level from 229.51 to 0.521 mg/L. These results underscore the efficacy of the proposed solar desalination system in purifying ICWW, offering a promising approach to address environmental concerns associated with wastewater treatment.

Hotspots and trends in solar-driven interfacial evaporation technology based on bibliometric management and analysis

The solar-driven interface evaporation technology (SDIE) is an innovative and environmentally friendly desalination method, highly favored by researchers due to its low energy consumption, high efficiency, absence of secondary pollution, and alignment with sustainable development principles. By utilizing widely distributed solar energy as the driving force and employing simple and portable photothermal evaporation structures as the core component, SDIE achieves efficient energy conversion and demonstrates excellent seawater desalination capabilities. Consequently, it has gained significant attention from researchers in both seawater desalination systems and water treatment applications. This paper presents a knowledge framework on seawater SDIE through scientometric analysis of academic documents from 2014 to 2023. The technology is visually analyzed using collaborative networks, reference co-citation networks, and keyword co-discovery techniques. The results demonstrate an exponential increase in the number of documents published over time, highlighting the growing significance of SDIE techniques in interdisciplinary research. Furthermore, this manuscript clarifies the main focus areas in current research including desalination performance evaluation, development of high efficient photothermal materials, system design optimization as well as mechanism analysis. Additionally, existing challenges and future research directions are proposed to provide guidance for SDIE further research.

Manganese Oxide Hydrogel for Efficient Removal of Volatile Organic Compound in the Photothermal Water Purification

In recent years, the photothermal evaporation technology that effectively solves the problem of fresh water shortage has attracted great interest, but the problem is that volatile organic compounds (VOCs) always enter the condensate with vapor during the evaporation process, so the combination of photothermal evaporation and photocatalysis is considered. Herein, narrow‐bandgap β‐MnO2 is selected as the material for photothermal evaporation and catalysis, and a β‐MnO2 porous hydrogel (β‐MnO2‐PH) interfacial evaporator with high evaporation efficiency and catalytic degradation of organic pollutants is designed using porous and hydrophilic hydrogels as carriers. The optimized evaporation rate can reach 3.5 kg m−2 h−1 and achieve high light absorption of 93.4% in the full spectral range. This is better than the performance of most MnO2‐based solar evaporator reported so far. In addition, β‐MnO2‐PH has the function of photocatalytic purification and effectively degrades VOCs such as phenol. By combining photothermal action of evaporator with photocatalytic performance, it provides unlimited potential application in solar desalination and industrial wastewater treatment.

A coal-based multifunctional membrane for solar-driven seawater desalination and power generation

Water evaporation systems driven by solar energy delivers great potential for seawater desalination and sustainable energy generation, which is of great significance to relieve the worldwide shortage of fresh-water and energy. However, the achievement of well-designed materials and configuration for water evaporation systems remains a great challenge, hindering the realization of high evaporation rates and stable energy output. Herein, conductive coal-based nanocarbon material was creatively fabricated to assemble a novel multifunctional membrane based evaporation system for simultaneous solar thermal desalination of seawater and power generation. The coal-based multifunctional membrane (CBMM) possesses a permanently asymmetric wetting structure, which can ensure high photothermal evaporation efficiency and stable energy output. The constructed device unit demonstrate a long and stable operation in seawater under one sun irradiance for 100 h, achieving a high evaporation rate of 1.81 kg m−2 h−1 and a large voltage output of 410 mV. Especially, multiple units of the devices can be easily connected in series or parallel to power small electronic devices. This work provides a cost-effective and large scale method for the fabrication of coal-based nanomaterials and the creative application in high-perforamnce water evaporation systems for seawater desalination and sustainable energy generation.

Micronleaf-shape graphene interfaces on wood transverse sections as advanced photothermal evaporators for water purification

Similar to transpiration, the formulation of interfacial solar evaporation has been designed to perform water treatment. The concept involves wood-based support (tree) with a graphene-based layer acting as leaves. To enhance light absorption and solar-thermal conversion capacity, a novel holly-leaf graphene (HLG) layer with an individual hollowed-out structure was engineered. The formation mechanism of this HLG was shown to be linked to the strong capillarity forces in the polyporous wood. By creating biomimetic leaves made of graphene, the light-to-heat conversion performance can be improved, while exhibiting substantially lower thermal conductivity (0.074 W/(m K)) than natural wood. Under solar irradiation, HLG/wood exhibits an outstanding evaporation rate of 1.96 kg/(m2 h), with an impressive efficiency of 94.2 %. A theoretical model of HLG/wood based on the thermal management capability was built to further confirm its structural superiority in facilitating photothermal conversion. Consequently, a bilayer evaporator based on HLG/wood has the potential to revolutionize water purification processes, including desalination of seawater, removal of heavy metal ions, and treatment of organic dye-contaminated wastewater.

2D/2D ultrathin polypyrrole heterojunct aerogel with synergistic photocatalytic-photothermal evaporation performance for efficient water purification

Green photocatalysis has played a crucial role in resolving energy shortage and wastewater treatment. However, poor photogenerated electron-hole separation efficiency is still a great challenge. Notably, the thermal energy generated by photothermal materials through photothermal conversion provides a greater concentration of energy for the separation and utilization of the photoexcited electron-hole. Herein, we prepare 2D/2D reduced graphene oxide/polypyrrole (c-GPP) aerogel with both photocatalytic degradation and photothermal evaporation performance via interface-confined synthesis. The broad spectral response of rGO and PPy endows the aerogel excellent light-harvesting capabilities and facilitates the generation of photogenerated carriers. The π-π interaction between rGO and PPy give rise to built-in electric fields and electron delocalization effects, resulting in excellent photogenerated electron-hole separation efficiency. The aerogel shows excellent degradation of dyes and antibiotics under natural sunlight irradiation (up to 97 % degradation of dyes). In addition, the c-GPP exhibits a satisfactory photothermal evaporation rate of 1.59 kg m−2 h−1 and photothermal evaporation efficiency of 92.52 %. This work provides an effective route for solar-driven photocatalysis-photothermal synergy for efficient and sustainable water purification.

Scalable absorber with tuneable water supply fabricated via centrifugal spinning for highly efficient and stable solar-driven interfacial desalination

Although realising tuneable water supply in photothermal evaporation is an effective way to boost solar-driven interfacial evaporation for water desalination, simultaneously achieving continuous water transport and appropriate water content in evaporators remains a significant challenge. To address this challenge, centrifugal spinning technology is proposed herein to fabricate a scalable, flexible and stable photothermal evaporator from a hydrophilic (polyacrylonitrile, (PAN)) and hydrophobic polymer medium (polyurethane, (PU)). Efficient water management can be realised by tuning the parameters of polymer materials to permit vapour escape and achieve salt resistance. In addition, the arched design of the evaporator allows for omnidirectional evaporation, which enhances the photothermal conversion efficiency. The scalable centrifugal spinning nonwoven membrane-based arched evaporator prepared at the optimal hydrophilic–hydrophobic polymer ratio (21 wt% PAN and 2 wt% PU) after polypyrrole modification (PPy/21PAN/2PU CSMAE) offers a highly efficient evaporation rate of 1.82 kg m−2 h−1 with photothermal efficiency of 97.33 % under 1-sun illumination and excellent salt resistance against high-salinity brine (10 wt%). Thus, the unique properties of centrifugal spinning technology enable the large-scale preparation application of multicomponent polymeric materials for realising tuneable water supply in solar-driven interfacial evaporation and desalination.

Facial preparation of porous SACB hydrogel beads for efficient solar interface evaporation

This work presented a highly efficient, porous and floatable sodium alginate/carbon black (SACB) gel beads by instantaneous gelation method for photothermal interfacial evaporation. We thoroughly examined how NaHCO3 and CB affect the performance of photothermal evaporation. As a consequence, the ideal porous SACB gel beads displayed an exceptional evaporation rate of 1.39 kg m−2 h−1 and a superior photothermal conversion efficiency of 97.76 % under 1 sun illumination. Additionally, the resulted SACB gel beads maintained good recyclability even after 10 repeated evaporation cycles, and the fresh water collected after evaporation complies with WHO and US Environmental Protection Agency (EPA). The SACB gel beads developed in this work have a remarkable capacity for photothermal conversion and would be a strong contender for solar-powered seawater desalination.

A stable and efficient hydrogel/sponge solar evaporator with splendid water supply

Solar-driven interfacial evaporation is an effective and realizable way of water purification. However, a short supply of water limits the evaporation performance of evaporator greatly. Here, an integrated photothermal evaporator owning double-layer structure of hydrogel and sponge with strong water transport ability is successfully prepared by cross-linking and dopamine modification. Abundant pores and hydrophilic functional groups in hydrogel and modified sponge benefit to enhance water transport of the whole evaporator and further relieve salt accumulation. Carbon black having the advantages of low cost and full spectrum absorption is dispersed into hydrogel networks to improve the capacity of photothermal conversion. Under the illumination of 1 kW m−2, the evaporator exhibits an excellent evaporation rate of 1.71 kg m-2h−1, corresponding to an evaporation efficiency of 93.8 %. Furthermore, the evaporator shows excellent stability during 8 cycles of solar evaporation. And the evaporator demonstrates superior salt tolerance in 3.5 wt% NaCl solution during the continuous evaporation of 8 h and has an outstanding efficiency of 99.8 % in 4-NP wastewater purification. The outdoor experiment proves that the evaporator of 1 m2 can produce 7.28 L of fresh water per day, which meet the drinking water demand of two adults. The hydrogel/sponge integrated photothermal evaporator has great application potential in seawater desalination and wastewater purification.

Efficient solar-driven freshwater generation through an inner hierarchical porous metal-carbon layer bridging synergistic photothermal evaporation and adsorption photodegradation.

Solar-driven interfacial evaporation has emerged as a promising avenue for clean water production, leveraging solar energy to extract water vapor from salty and polluted water sources. However, a critical challenge remains, during the photothermal evaporation process, organic pollutants and small water-soluble molecules can transfer into distilled steam, degrading the purity of the collected water. Herein, we develop a multifunctional clean water generation system that integrates photothermal conversion, adsorptive filtration and subsequent photocatalytic purification within a unified platform. This system features an inner hierarchical porous metal-carbon layer derived from ZIF-67 carbonization, seamlessly bridging a wood carbon scaffold and BiOBr nanosheets (BiOBr@ZCW) to smoothly facilitate synergistic actions between photothermal evaporation and adsorption-photodegradation processes. This BiOBr@ZCW configuration not only minimizes thermal dissipation, facilitating a high evaporation rate of 1.67 kg m-2 h-1 and an efficiency of 85% under standard solar irradiation but also enhances the photocatalytic degradation of the rhodamine B organic pollutant with a remarkable 98.43% degradation rate within just 20 minutes. This integrated system offers a robust solution to the challenges of water purification by ensuring both high efficiency in solar steam generation and effective pollutant degradation.

Solar-driven water evaporation using a collaborative photothermal conversion material system based on carbonized waste polyphenylene sulfide and copper sulfide.

Recently, water resources have become scarce due to the growing global population and human impact on the environment, coupled with the effects of climate change. For solving the problem of global freshwater shortage and increasing the value of discarded polyphenylene sulfide (PPS) filter bags, in this study, balsa wood was used as the base of a photothermal solar evaporator, chitosan solution was used as the binder, and the main photothermal conversion materials used were polyphenylene sulfide (CP) carbide and copper sulfide. In order to create synergistic photothermal conversion materials, freeze-drying and in situ precipitation were used to deposit the photothermal conversion materials on top of the balsa wood. The prepared CP/CuS-wood evaporator has excellent water evaporation performance and light conversion capability, with a water evaporation rate of 2.68 kg m-2 h-1 and a photothermal conversion efficiency of 93.2% under simulated one solar intensity irradiation. In addition, the evaporator can effectively remove organic dyes such as methylene blue and methyl orange. The evaporator's durability and seawater desalination capability have also been confirmed through seawater desalination experiments and outdoor tests. Studies have shown that solar interface photothermal evaporators are a viable solution for desalination and wastewater treatment. This eco-friendly, economically viable and stable photothermal evaporator mentioned in this paper has pioneering features and will be a new paradigm for desalination and wastewater treatment.

MXene nanosheet-reinforced chitosan as a stable photothermal evaporator for efficient solar evaporation

We have developed a solar evaporator with high efficiency, superior stability, simple process and adaptability to complex water environments.

Coupling photothermal evaporation into photocatalysis for enhanced hydrogen production from water

Coupling photothermal evaporation into photocatalysis for enhanced hydrogen production from water

Monolith floatable dual-function solar photothermal evaporator: efficient clean water regeneration synergizing with pollutant degradation.

Meeting the growing demands of attaining clean water regeneration from wastewater and simultaneous pollutant degradation has been highly sought after. In this study, nanometric CuFe2O4 and plasmonic Cu were in situ confined into graphitic porous carbon nanofibers (CNF) through electrospinning and controlled graphitization, which were integrated onto a melamine sponge (S-FeCu/CNF) as a monolithic evaporator via a calcium ion-triggered network crosslinking method using sodium alginate (SA). This monolithic evaporator serves a dual purpose: harnessing solar-driven photothermal energy for water regeneration and facilitating synchronous contaminant mineralization through advanced oxidation processes (AOPs). The metal-modified FeCu/CNF graphitic porous carbon exhibited an enhanced light absorption property (≥95%) and was further securely anchored on the sponge by a calcium ion-triggered SA crosslinking technique, thereby efficiently restraining salt deposition. The FeCu/CNF evaporator demonstrated a solar-vapor conversion efficiency of 105.85% with an evaporation rate of 1.61 kg m-2 h-1 under one sun irradiation. The evaporation rate of the monolithic S-FeCu/CNF evaporator is close to 1.76 kg m-2 h-1, and an evaporation rate of 1.54 kg m-2 h-1 can be achieved even in 20% NaCl solution, with resistance to salt deposition and cycling stability. Synchronously, the monolithic D-S-FeCu/CNF evaporator also acts as a heterogeneous catalyst to activate peroxymonosulfate (PMS) and trigger rapid pollutant degradation, which also shows excellent catalytic cycling stability, producing clean water that satisfies the World Health Organization (WHO) standards. This work provides a potentially valuable solution for addressing desalination and wastewater treatment.