Natural high-porous diatomaceous-earth based self-floating aerogel for efficient solar steam power generation

The application of solar steam generation in seawater desalination is an effective way to solve the shortage of fresh water resources.At present,many kinds of photothermal conversion materials have been developed and used as evaporators in seawater desalination.However,some evaporators need additional thermal insulation or water supply devices to achieve efficient photothermal conversion.In addition,their complex,time consuming and no scalable preparation process,high cost of raw materials and poor salt resistance hinder the practical application of these evaporator.Owing to its distinctive nanoporous structure,diatomite as fossilized single-cells algae diatoms is a promising natural silica-based material for seawater desalination.They are taken from sea and that makes true sense to use them in the sea.Herein,we report the first example of synthesis robust three-dimensional(3D)natural-diatomite composite by assembling polyaniline nanoparticles covered diatomite into the polyvinyl alcohol pre-treated melamine foam frameworks and demonstrate its application as new evaporator for seawater desalination.The porous framework does not only improve the sunlight scattering efficiency,but also offer large network of channels for water transportation.The inherent mechanism behind salt desalination process involves the absorption of water molecules on the surface of the internal silica micro-nano pores,and evaporation under the heat induced by the polyaniline absorbed sunlight.Meanwhile,the metal ions are segregated by many available pores and channels to achieve the self-desalting effect.The developed evaporator possesses the superiority of multi-stage pore structure,strong hydrophilicity,low thermal conductivity,excellent light absorption,fast water transportation and salt-resistant crystallization as well as good durability.The evaporation rate without an additional device is found to be 1.689 kg m^(-2)h^(-1)under 1-Sun irradiation,and the energy conversion efficiency is as high as 95%.This work creates a platform and develops the prospect of employing green and sustainable natural-diatomite composite evaporator for practical applications of seawater desalination.

Self-Supporting Nanoporous Copper Film with High Porosity and Broadband Light Absorption for Efficient Solar Steam Generation

Solar steam generation(SSG)is a potential technology for freshwater production,which is expected to address the global water shortage problem.Some noble metals with good photothermal conversion performance have received wide concerns in SSG,while high cost limits their practical applications for water purification.Herein,a self-supporting nanoporous copper(NP-Cu)film was fabricated by one-step dealloying of a specially designed Al_(98)Cu_(2)precursor with a dilute solid solution structure.In-situ and ex-situ characterizations were performed to reveal the phase and microstructure evolutions during dealloying.The NP-Cu film shows a unique three-dimensional bicontinuous ligament-channel structure with high porosity(94.8%),multi scale-channels and nanoscale ligaments(24.2±4.4nm),leading to its strong broadband absorption over the 200–2500 nm wavelength More importantly,the NP-Cu film exhibits excellent SSG performance with high evaporation rate,superior efficiency and good stability.The strong desalination ability of NP-Cu also manifests its potential applications in seawater desalination.The related mechanism has been rationalized based upon the nanoporous network,localized surface plasmon resonance effect and hydrophilicity.

Poly(ionic liquid)-crosslinked graphene oxide/carbon nanotube membranes as efficient solar steam generators

Graphene oxide(GO)is regarded as a promising candidate to construct solar absorbers for addressing freshwater crisis,but the easy delamination of GO in water poses a critical challenge for practical solar desalination.Herein,we improve the stability of GO membranes by a self-crosslinking poly(ionic liquid)(PIL)in a mild condition,which crosslinks neighbouring GO nanosheets without blemishing the hydrophilic structure of GO.By further adding carbon nanotubes(CNTs),the sandwiched GO/CNT@PIL(GCP)membrane displays a good stability in pH=1 or 13 solution even for 270 days.The molecular dynamics simulation results indicate that the generation of water nanofluidics in nanochannels of GO nanosheets remarkably reduces the water evaporation enthalpy in GCP membrane,compared to bulk water.Consequently,the GCP membrane exhibits a high evaporation rate(1.87 kg m^(-2)h^(-1))and displays stable evaporation rates for 14 h under 1 kW m^(-2)irradiation.The GCP membrane additionally works very well when using different water sources(e.g.,dye-polluted water)or even strong acidic solution(pH=1)or basic solution(pH=13).More importantly,through bundling pluralities of GCP membrane,an efficient solar desalination device is developed to produce drinkable water from seawater.The average daily drinkable water amount in sunny day is 10.1 kg m^(-2),which meets with the daily drinkable water needs of five adults.The high evaporation rate,long-time durability and good scalability make the GCP membrane an outstanding candidate for practical solar seawater desalination.

Janus aramid nanofiber aerogel incorporating plasmonic nanoparticles for high-efficiency interfacial solar steam generation

Interfacial solar steam generation(ISSG)is a novel and potential solution to global freshwater crisis.Here,based on a facile sol-gel fabrication process,we demonstrate a highly scalable Janus aramid nanofiber aerogel(JANA)as a high-efficiency ISSG device.JANA performs near-perfect broadband optical absorption,rapid photothermal conversion and effective water transportation.Owning to these features,efficient desalination of salty water and purification of municipal sewage are successfully demonstrated using JANA.In addition,benefiting from the mechanical property and chemical stability of constituent aramid nanofibers,JANA not only possesses outstanding flexibility and fire-resistance properties,but its solar steaming efficiency is also free from the influences of elastic deformations and fire treatments.We envision JANA provides a promising platform for mass-production of high-efficiency ISSG devices with supplementary capabilities of convenient transportation and long-term storage,which could further promote the realistic applications of ISSG technology.

Self-Floating Efficient Solar Steam Generators Constructed Using Super-Hydrophilic N,O Dual-Doped Carbon Foams from Waste Polyester

Solar evaporation is recognized as a prospective technique to produce freshwater from non-drinkable water using inexhaustible solar energy.However,it remains a challenge to fabricate low-cost solar evaporators with obviously reduced water evaporation enthalpy to achieve high evaporation rates.Herein,N,O dual-doped carbon foam(NCF)is fabricated from the lowtemperature carbonization of poly(ethylene terephthalate)(PET)waste by melamine/molten salts at 340℃.During carbonization,melamine reacts with carboxylic acids of PET degradation products to yield a crosslinking network,and then molten salts catalyze the decarboxylation and dehydration to construct a stable framework.Owing to rich N,O-containing groups,3D interconnected pores,super-hydrophilicity,and ultra-low thermal conductivity(0.0599 W m^(−1) K^(−1)),NCF not only achieves high light absorbance(ca.99%)and solar-to-thermal conversion,but also promotes the formation of water cluster to reduce water evaporation enthalpy by ca.37%.Consequently,NCF exhibits a high evaporation rate(2.4 kg m^(−2) h^(−1)),surpassing the-state-of-the-art solar evaporators,and presents good antiacid/basic abilities,long-term salt-resistance,and self-cleaning ability.Importantly,a large-scale NCF-based outdoor solar desalination device is developed to produce freshwater.The daily freshwater production amount per unit area(6.3 kg)meets the two adults’daily water consumption.The trash-to-treasure strategy will give impetus to the development of low-cost,advanced solar evaporators from waste plastics for addressing the global freshwater shortage.

Eutectic-derived synthesis of hierarchically nanoporous copper for electrochemical actuation and solar steam generation

The utilization of nanoporous copper(np-Cu)as a metallic actuator has gained attention in recent years due to its cost-effectiveness in comparison to other precious metals.Despite this,the enhancement of np-Cu’s actuation performance remains a challenge due to limitations in its strain amplitude and actuation rate.Additionally,np-Cu has been deemed as a promising material for solar absorption due to its localized surface plasmon resonance effect.However,practical applications such as solar steam generators(SSGs)utilizing np-Cu have yet to be documented.In this study,we present the development of hierarchically nanoporous copper(HNC)through the dealloying of a eutectic Al-Cu alloy.The hierarchical structure of the HNC features a combination of ordered flat channels and randomly distributed continuous nanopores,which work in synergy to improve actuation performance.The ordered flat channels,with a sub-micron scale,facilitate rapid mass transport of electrolyte ions,while the nano-sized continuous pores,due to their large specific surface area,enhance the induced strain.Our results indicate that the HNC exhibits improved actuation performance,with a two times increase in both strain amplitude and rate in comparison to other reported np-Cu.Additionally,the HNC,for the first time,showcases excellent solar steam generation capabilities,with an evaporation rate of 1.47 kg·m^(-2)·h^(-1) and a photothermal conversion efficiency of 92%under a light intensity of 1 kW·m^(-2),which rivals that of nanoporous gold and silver film.The enhanced actuation performance and newly discovered solar steam generation properties of the HNC are attributed to its hierarchically porous structure.

A portable and washable solar steam evaporator based on graphene and recycled gold for efficient point-of-use water purification

A solar steam evaporator provides a sustainable and efficient alternative water purification solution to address the global freshwater shortage.Previous efforts have made significant advances in maximizing its water evaporation rate,but no single evaporator has all the properties necessary for practical point-of-use application,including a high efficiency for generation of drinkable water,an excellent portability critical for on-site water purification,good washability for mitigating evaporator fouling,and good reusability.We report a strategy to produce a high-performance photothermal material for point-of-use water purification.By simultaneously incorporating graphene and gold particles grown from recycled electronic waste in a mechanically strong sponge,we achieved highly efficient water purification under realistic conditions.In addition to a high evaporation rate(3.55 kg/m^(2)/h under one-sun irradiation)attributed to a control of atomic structure of graphene and the size-dependent surface plasmon resonance of gold nanoparticles,it is portable which can be folded,vacuum compacted,dried and rehydrated without compromising performance.It also allows repeated washing to remove contaminant fouling so that it can be reused.The evaporator transforms various types of contaminated water into drinkable clean water,and can be mounted at any angle to optimize the incident solar irradiation.Furthermore,the assembled steam evaporator device could gain purified water meeting the World Health Organization drinking water standards with a high evaporation rate of 9.36 kg/m^(2)/h under outdoor sunlight.

Nanoporous black silver film with high porosity for efficient solar steam generation

Given the challenges brought by the shortage of freshwater resources,solar water evaporation has been regarded as one of the most promising technologies for harnessing abundant sunlight to harvest clean water from the sea.Nanostructured metals have attracted extensive attention in solar water evaporation due to their localized surface plasmon resonance effect,but highly porous metallic films with high evaporation efficiency are challenging.Herein,a self-supporting black nanoporous silver(NP-Ag)film was fabricated by dealloying of an extremely dilute Al99Ag1 alloy.The choice of the dilute precursor guarantees the formation of the NP-Ag film with high porosity(96.5%)and low density(0.3703 g·cm^(-3),even smaller than the lightest metal lithium).The three-dimensional ligament-channel network structure and the nanoscale(14.6 nm)of ligaments enable the NP-Ag film to exhibit good hydrophilicity and broadband absorption over 200‒2,500 nm.More importantly,the solar evaporator based on the NP-Ag film shows efficient solar steam generation,including the efficiency of 92.6%,the evaporation rate of 1.42 kg·m^(-2)·h^(-1)and good cycling stability under one sun irradiation.Moreover,the NP-Ag film exhibits acceptable seawater desalination property with the ion rejection for Mg^(2+),Ca^(2+),K^(+)and Na^(+)more than 99.3%.Our findings could provide a new idea and inspiration for the design and fabrication of metal-based photothermal films in real solar evaporation applications.

Recent Advances in Fibrous Materials for Interfacial Solar Steam Generation

The scarcity of fresh water resources has become a serious issue hindering the sustainable development of modern civilization.The interfacial solar steam generation(ISSG)system that produces heat on material surface through photothermal conversion for desalination has been demonstrated as a promising candidate for practical application.Fibrous materials with unique flexibility,durability,processability,practicability,and multifunctionality have attracted considerable attention in the ISSG field.In this review,the basics of fibrous materials,such as their classification,manufacturing methods and flexible fibrous structure,are firstly introduced.Afterward,the outstanding properties of fibrous materials on different dimensions are demonstrated,as well as the versatile morphologies and structures that allow fibrous materials to carry out different roles in ISSG.Moreover,the practicability and multifunctionality of fibrous materials are illustrated in detail by combining specific cases to show their promising potential in practical ISSG application.Finally,existing challenges and future opportunities of fibrous material-based ISSG systems are discussed.

Emulsion‐templated synthesis of 3D evaporators for efficient solar steam generation

Interfacial solar steam generation holds great promise in water desalination thanks to its high energy efficiency by heating only the top layer of water for evaporation.While three‐dimensional(3D)evaporators have been proven to increase the evaporation rate by harnessing the energy from the surroundings,further development is still required in terms of convenient fabrication with potential scalability.Herein,we propose to overcome this challenge by using a high internal phase emulsion(HIPE)to template the synthesis of 3D hierarchically porous evaporators.The HIPE‐templated synthesis combined with a molding process can efficiently fabricate the desired 3D shape without wasting any materials and generate a hierarchically porous internal structure for continuous water supply.Engineering the overall shape and internal pores produces a 3D evaporator that can suppress conduction heat loss and efficiently collect thermal energy from its surroundings,boosting the evaporation rate to 2.82 kg/(m2 h)under 1‐sun illumination,which is significantly higher than conventional 2D evaporators.HIPE‐templating synthesis is an easy but effective way to produce various porous polymers,promising for a wide range of applications where easy production,excellent shape control,and potential scalability are critical.

Plant-leaf-inspired MXene-silk composite for intelligent solar steam generation combined with mechanical actuation

Solar steam generators based on photothermal materials are important in producing fresh water.However,conventional solar steam generators are difficult to self-adapt to the complex external environment as organisms.Herein,inspired by the plant leaf,we propose a photothermal composite based on MXene and silk to add more functionality.On one hand,the composite achieves an evaporation rate of 1.51 kg·m^(−2)·h^(−1)and a conversion efficiency of 86.9%under a solar intensity of 1 kW·m^(−2),mimicking the water transpiration of plant leaf.On the other hand,the MXene-silk-based actuator shows a maximum bending curvature of 0.91 cm^(−1)under a solar intensity of 5 kW·m^(−2).Furthermore,an intelligent solar system is constructed utilizing the synergy of solar steam generator and actuator,which advances the research from the material level to the system level.Mimicking the behavior of plant leaf,the system can automatically open during the day to generate steam and fresh water.And at night or in bad weather,it will automatically close to prevent external pollution such as dust,achieving intelligent anti-fouling.This research will have good application prospects in less developed areas.Meanwhile,it also provides a certain reference value for exploring multi-functional photothermal devices in the future.

Performance of a bi-layer solar steam generation system working at a high-temperature of top surface

Many efforts have been focused on enhancing the vapor generation in bi-layer solar steam generation systems for obtaining as much pure water as possible.However,the methods to enhance the vapor temperature is seldom studied although the high-temperature vapor has a wide use in medical sterilization and electricity generation.In this work,to probe the high-temperature vapor system,an improved macroscopic heat and mass transfer model was proposed.Then,using the finite element method to solve the model,the influences of some main factors on the evaporation efficiency and vapor temperature were discussed,including effects of the vapor transport conditions and the heat dissipation conditions.The results show that the high-temperature vapor could not be obtained by enhancing the heat-insulating property of the bi-layer systems but by applying the optimal porosity and proper absorbers.This paper is expected to provide some information for designing a bi-layered system to produce high-temperature vapor.

Simultaneous Solar-driven Steam and Electricity Generation by Cost-effective,Easy Scale-up MnO 2-based Flexible Membranes

Harvesting solar energy in an effective manner for steam and electricity generation is a promising technique to simultaneously cope with the energy and water crises.However,the construction of efficient and easy scale-up photothermal materials for steam and electricity cogeneration remains challenging.Herein,we report a facile and cost-effective strategy to prepare MnO_(2)-decorated cotton cloth(MCx).The wide adsorption spectrum and excellent photothermal conversion ability of the in situ-formed MnO_(2)nanoparticles make the MCx to be advanced photothermal materials.Consequently,the hybrid device integrated with MCx as the photothermal layer and the thermoelectric(TE)module for electricity power conversion exhibits an extremely high evaporation rate of 2.24 kg m^(−2)h^(−1)under 1 kW m^(−2)irradiation,which is ranked among the most powerful solar evaporators.More importantly,during solar evaporation,the hybrid device produces an open-circuit voltage of 0.3 V and a power output of 1.6 W m^(−2)under 3 Sun irradiation,and outperforms most of the previously reported solar-driven electricity generation devices.Therefore,the integrated device with synergistic solar-thermal utilization opens up a green way toward simultaneous solar vapor and electric power generation in remote and resource-constrained areas.

Synergism of solar-driven interfacial evaporation and photo-Fenton Cr(Ⅵ) reduction by sustainable Bi-MOF-based evaporator from waste polyester

The integration of interfacial solar steam generation and photocatalytic degradation technology has pro-vided a promising platform to simultaneously produce freshwater and degrade pollutants.However,con-structing low-cost,multi-functional evaporators for treating Cr(Ⅵ)-polluted water remains challenging,and the synergistic mechanism on Cr(Ⅵ)reduction is fuzzy.Herein,we propose the combined strategy of ball milling and solution mixing for the sustainable production of Bi-MOF microrod from waste poly(ethylene terephthalate),and construct Bi-MOF-based solar evaporators for simultaneous photo-Fenton Cr(Ⅵ)reduction and freshwater production.Firstly,the evaporator comprised of Bi-MOF microrod and graphene nanosheet possesses high light absorption,efficient photothermal conversion,and good hydro-philic property.Attributing to the advantages,the hybrid evaporator exhibits the evaporation rate of 2.16 kg m^(-2) h^(-1) and evaporation efficiency of 87.5%under 1 kW m^(-2) of irradiation.When integrating with photo-Fenton reaction,the Cr(Ⅵ)reduction efficiency is 91.3%,along with the reaction kinetics of 0.0548 min^(-1),surpassing many advanced catalysts.In the outdoor freshwater production and Cr(Ⅵ)reduction,the daily accumulative water yield is 5.17 kg m^(-2) h^(-1),and the Cr(Ⅵ)reduction efficiency is 99.9%.Furthermore,we prove that the localization effect derived from the interfacial solar-driven evap-oration enhances H_(2)O_(2) activation for the photo-Fenton reduction of Cr(Ⅵ).Based on the result of density functional theory,Bi-MOF microrod provides rich active centers for H_(2)O_(2) activation to produce active sites such as e-or-O_(2).This study not only proposes a new strategy to construct multi-functional solar evaporators for freshwater production and catalytic reduction of pollutants,but also advances the chem-ical upcycling of waste polyesters.

Vertically aligned reduced graphene oxide/Ti_(3)C_(2)T_(x)MXene hybrid hydrogel for highly efficient solar steam generation

Effective utilization of abundant solar energy for desalination of seawater and purification of wastewater is one of sustainable techniques for production of clean water,helping relieve global water resource shortage.Herein,we fabricate a vertically aligned reduced graphene oxide/Ti_(3)C_(2)T_(x)MXene(A-RGO/MX)hybrid hydrogel with aligned channels as an independent solar steam generation device for highly efficient solar steam generation.The vertically aligned channels,generated by a liquid nitrogen-assisted directional-freezing process,not only rapidly transport water upward to the evaporation surface for efficient solar steam generation,but also facilitate multiple reflections of solar light inside the channels for efficient solar light absorption.The deliberate slight reduction endows the RGO with plenty of polar groups,decreasing the water vaporization enthalpy effectively and hence accelerating water evaporation efficiently.The MXene sheets,infiltrated inside the A-RGO hydrogel on the basis of Marangoni effect,enhance light absorption capacity and photothermal conversion performance.As a result,the A-RGO/MX hybrid hydrogel achieves a water evaporation rate of 2.09 kg·m^(−2)·h^(−1)with a high conversion efficiency of 93.5%under 1-sun irradiation.Additionally,this photothermal conversion hydrogel rapidly desalinates seawater and purifies wastewater to generate clean water with outstanding ion rejection rates of above 99%for most ions.

Hierarchical structures hydrogel evaporator and superhydrophilic water collect device for efficient solar steam evaporation

Efficient light absorption and trapping are of vital importance for the solar water evaporation by hydrogel-based photothermal conversion materials.Conventional strategies are focused on the development of the composition and structure of the hydrogers internal network.In our point of view,the importance of the surface structure of hydrogel has usually been underestimated or ignored.Here inspired by the excellent absorbance and water transportation ability of biological surface structure,the hierarchical structured hydrogel evaporators(HSEs)increased the light absorption,trapping,water transportation and water-air interface,which is the beneficial photothermal conversion and water evaporation.The HSEs showed a rapid evaporation rate of 1.77 kg·m^(-2)·h^(-1)at about 92%energy efficiency under one sun(1 kW·m^(-2)).Furthermore,the superhydrophilic window device was used in this work to collect the condensed water,which avoids the light-blocking caused by the water mist formed by the small droplets and the problem of the droplets stick on the device dropping back to the bulk water.Integrated with the excellent photothermal conversion hydrogel and superhydrophilic window equipment,this work provides efficient evaporation and desalination of hydrogel-based solar evaporators in practical large-scale applications.

Enhancing solar steam generation using a highly thermally conductive evaporator support

Interfacial solar steam generation is an efficient water evaporation technology which has promising applications in desalination,sterilization,water purification and treatment.A common component of evaporator design is a thermal-insulation support placed between the photothermal evaporation surface and bulk water.This configuration,common in 2-dimensional(2 D)evaporation systems,minimizes heat loss from evaporation surface to bulk water,thus localizing the heat on the evaporation surface for efficient evaporation.This design is subsequently directly adopted for 3-dimensional(3 D)evaporators without any consideration if it is appropriate.However,unlike 2 D solar evaporators,the 3 D evaporators can also harvest additional energy(other than solar light)from the air and bulk water to enhance evaporation rate.In this scenario,the use of thermal insulator support is not proper since it will hinder energy extraction from water.Here,the traditional 3 D evaporator configuration was completely redesigned by using a highly thermally conductive material,instead of a thermal insulator,to connect evaporation surfaces and the bulk water.Much higher evaporation rates were achieved by this strategy,owing to the rapid heat transfer from the bulk water to the evaporation surfaces.Indoor and outdoor tests both confirmed that evaporation performance could be significantly improved by substituting a thermal insulator with thermally conductive support.These findings will redirect the future design of 3 D photothermal evaporators.

Applications of bio-derived/bio-inspired materials in the field of interfacial solar steam generation

Interfacial solar steam generation(ISSG)system has attracted extensive attention as a sustainable desalination technology because of its cost efficiency and zero fossil-energy consumption.Aiming at optimizing the desalination properties,materials and system design have been the current research focus.Recently,many novel bio-derived/bio-inspired design strategies were proposed owing to their highly efficient structures inherited from nature,which were fine-tuned over eons of evolution,as well as their low cost and ease of treatment.In this review,we are going to systematically report recent progress of various bio-derived/bio-inspired strategies in terms of optical design,wetting,thermal management,and overall system design,presenting an overview of the current challenges of bio-inspired materials in ISSG system and other application fields.This article is intended to provide a comprehensive review of recent developments about bio-derived/bio-inspired materials in ISSG system and conclude with suggestions regarding further research directions for performance enhancement through design of bio-derived/bio-inspired materials.

A photothermal reservoir for highly efficient solar steam generation without bulk water

A solid photothermal reservoir is designed to implement solar-steam generation in the absence of bulk water.The photothermal reservoir is composed of a water absorbing core encapsulated by a photothermal reduced graphene oxide based aerogel sheet which absorbs light and converts it into heat thus evaporating the stored water.The photothermal reservoir is able to store 6.5 times its own weight in water,which is sufficient for one day solar evaporation,thus no external water supplement is required.During solar-steam generation,since no bulk water is involved,the photothermal reservoir minimizes heat conduction loss,and maximizes both of the exposed evaporation surface area and net energy gain from the environment,leading to an energy efficiency beyond the theoretical limit.An extremely high water evaporation rate of 4.0 kg m-2 h-1(normalized to projection area)is achieved in laboratory studies over a cylinder photothermal reservoir with a diameter of 5.2 cm and a height of 15 cm under 1.0 sun irradiation.Practical evaluation of the photothermal reservoir outdoors as part of a desalination device demonstrates a similar evaporation rate where the salinity of the clean water produced is lower than 24 ppb.Thus the photothermal reservoir shows great potential for real world applications in portable solarthermal desalination.

Volcanic relationship between wettability of the interface and water migration rate in solar steam generation systems

Capturing solar energy as heat for water treatment has become a substantial approach to obtain freshwater.To obtain higher performance,the understanding of the mechanism of how water molecules interact with the interface is particularly fundamental,because the migration process of water molecules on the evaporation interface will directly affect the performance of the device.Herein we regulate the number of hydroxyl groups on the surface of reduced graphene oxide quantitatively,to study the effect of different wettability of interfaces on the performance of solar water generators.The water evaporation performance displays a volcanic shape as increasing wettability.Calculated by the computational chemistry method,deviation from proper wetting humidity is not conducive to the migration of water molecules from the surface.The double-edged sword effect of wettability on performances is clarified,and the surface energy density is the key to break through the limit by the finite element method.