The application of cellulosic-based materials on interfacial solar steam generation for highly efficient wastewater purification: A review

The world's population is growing,leading to an increasing demand for freshwater resources for drinking,sanitation,agriculture,and industry.Interfacial solar steam generation(ISSG)can solve many problems,such as mitigating the power crisis,minimizing water pollution,and improving the purification and desalination of seawater,rivers/lakes,and wastewater.Cellulosic materials are a viable and ecologically sound technique for capturing solar energy that is adaptable to a range of applications.This review paper aims to provide an overview of current advancements in the field of cellulose-based materials ISSG devices,specifically focusing on their applications in water purification and desalination.This paper examines the cellulose-based materials ISSG system and evaluates the effectiveness of various cellulosic materials,such as cellulose nanofibers derived from different sources,carbonized wood materials,and two-dimensional(2D)and 3D cellulosic-based materials from various sources,as well as advanced cellulosic materials,including bacterial cellulose and cellulose membranes obtained from agricultural and industrial cellulose wastes.The focus is on exploring the potential applications of these materials in ISSG devices for water desalination,purification,and treatment.The function,advantages,and disadvantages of cellulosic materials in the performance of ISSG devices were also deliberated throughout our discussion.In addition,the potential and suggested methods for enhancing the utilization of cellulose-based materials in the field of ISSG systems for water desalination,purification,and treatment were also emphasized.

Amphipathic Janus Nanofibers Aerogel for Efficient Solar Steam Generation

Solar steam generation is a promising water purification technology due to its low-cost and environmentally friendly applications in water purification and desalination.However,hydrophilic or hydrophobic materials alone are insufficient in achieving necessary characteristics for constructing highquality solar steam generators with good comprehensive properties.Herein,novel hydrophile/hydrophobe amphipathic Janus nanofibers aerogel is designed and used as a host material for preparing solar steam generators.The product consists of an internal cubic aerogel and an external layer of photothermal materials.The internal aerogel is composed of electrospun amphipathic Janus nanofibers.Owing to the unique composition and structure,the prepared solar steam generator integrates the features of high water evaporation rate(2.944 kg m^(-2)h^(-1)under 1 kW m^(-2)irradiation),selffloating,salt-resisting,and fast performance recovery after flipping.Moreover,the product also exhibits excellent properties on desalination and removal of organic pollutants.Compared with traditional hydrophilic aerogel host material,the amphipathic Janus nanofibers aerogel brings much higher water evaporation rate and salt resistance.

Enhanced entropy generation and heat transfer characteristics of magnetic nano-encapsulated phase change materials in latent heat thermal energy storage systems

The objective of the current study is to investigate the importance of entropy generation and thermal radiation on the patterns of velocity,isentropic lines,and temperature contours within a thermal energy storage device filled with magnetic nanoencapsulated phase change materials(NEPCMs).The versatile finite element method(FEM)is implemented to numerically solve the governing equations.The effects of various parameters,including the viscosity parameter,ranging from 1 to 3,the thermal conductivity parameter,ranging from 1 to 3,the Rayleigh parameter,ranging from 102 to 3×10^(2),the radiation number,ranging from 0.1 to 0.5,the fusion temperature,ranging from 1.0 to 1.2,the volume fraction of NEPCMs,ranging from 2%to 6%,the Stefan number,ranging from 1 to 5,the magnetic number,ranging from 0.1 to 0.5,and the irreversibility parameter,ranging from 0.1 to 0.5,are examined in detail on the temperature contours,isentropic lines,heat capacity ratio,and velocity fields.Furthermore,the heat transfer rates at both the cold and hot walls are analyzed,and the findings are presented graphically.The results indicate that the time taken by the NEPCMs to transition from solid to liquid is prolonged inside the chamber region as the fusion temperatureθf increases.Additionally,the contours of the heat capacity ratio Cr decrease with the increase in the Stefan number Ste.

A novel oxidation-resistible Mg@Ni foam material for safe,efficient,and controllable hydrogen generation

As a promising in-situ hydrogen generation material,magnesium(Mg)has been seeking a promotion in its hydrogen generation property.Increasing the specific surface area,for example,replacing the Mg bulk using Mg powder,can greatly increase the hydrogen generation property,but it brings a high explosion risk,a difficulty in controlling the hydrogen generation,and an oxidation problem.In this work,we prepare a novel Mg@Ni foam material with Mg deposits on Ni foam by a physical vapor deposition method.The Ni foam not only increases the hydrolysis reaction areas of Mg by improving its specific surface area,but also kinetically accelerates the hydrolysis reaction rate of Mg by forming a uniform Mg-Ni galvanic cell.As a result,the Mg@Ni foam material realizes a near-theoretical hydrogen generation amount of Mg and a hydrogen generation rate significantly higher than those realized by the bulk Mg-based materials.The Mg@Ni foam material with the excellent hydrogen generation property is also free from explosion risk,easy to be controlled,and resistible to oxidation.A hydrogen fuel cell powered by the hydrogen generated by the Mg@Ni foam material can yield a steady voltage and run a small car for a long distance.

Lignocellulosic biomass as sustainable feedstock and materials for power generation and energy storage

Lignocellulosic biomass has attracted great interest in recent years for energy production due to its renewability and carbon-neutral nature.There are various ways to convert lignocellulose to gaseous,liquid and solid fuels via thermochemical,chemical or biological approaches.Typical biomass derived fuels include syngas,bio-gas,bio-oil,bioethanol and biochar,all of which could be used as fuels for furnace,engine,turbine or fuel cells.Direct biomass fuel cells mediated by various electron carriers provide a new direction of lignocellulose conversion.Various metal and non-metal based carriers have been screened for mediating the electron transfer from biomass to oxygen thus generating electricity.The power density of direct biomass fuel cells can be over 100 mW cm^(-2),which shows promise for practical applications.Lignocellulose and its isolated components,primarily cellulose and lignin,have also been paid considerable attention as sustainable carbonaceous materials for preparation of electrodes for supercapacitors,lithium-ion batteries and lithium-sulfur batteries.In this paper,we have provided a state-of-the-art review on the research progress of lignocellulosic biomass as feedstock and materials for power generation and energy storage focusing on the chemistry aspects of the processes.It was recommended that process integration should be performed to reduce the cost for thermochemical and biological conversion of lignocellulose to biofuels,while efforts should be made to increase efficiency and improve the properties for biomass fuelled fuel cells and biomass derived electrodes for energy storage.

Utlra-fast hydrolysis performance of MgH_(2) catalyzed by Ti-Zr-Fe-Mn-Cr-V high-entropy alloys

Hydrogen energy is one of the ideal energy alternatives and the upstream of the hydrogen industry chain is hydrogen production,which can be achieved via the reaction of inorganic materials with water,known as hydrolysis.Among inorganic materials,the high hydrogen capacity for hydrolysis of MgH_(2)(15.2 wt%)makes it a promising material for hydrogen production via hydrolysis.However,the dense Mg(OH)_(2) passivation layer will block the reaction between MgH_(2) and the solution,resulting in low hydrogen yield and sluggish hydrolysis kinetics.In this work,the hydrogenyield and hydrogen generation rate of MgH_(2) are considerably enhanced by adding Ti-Zr-Fe-Mn-Cr-V high-entropy alloys(HEAs) for the first time.In particular.the MgH_(2)-3 wt% TiZrFe_(1.5)MnCrV_(0.5)(labelled as MgH_(2)-3 wt% Fe_(1.5)) composite releases 1526.70 mL/g H_(2) within 5 min at 40℃,and the final hydrolysis conversion rate reaches 95.62% within 10 min.The mean hydrogen generation rate of the MgH_(2)-3 wt% Fe_(1.5) composite is 289.16 mL/g/min,which is 2.38 times faster than that of pure MgH_(2).Meanwhile,the activation energy of the MgH_(2)-3 wt% Fe_(1.5) composite is calculated to be 12.53 kJ/mol. The density functional theory(DFT) calculation reveals that the addition of HEAs weakens the Mg-H bonds and accelerates the electron transfer between MgH_(2) and HEAs,Combined with the cocktail effect of HEAs as well as the formation of more interfaces and micro protocells,the hydrolysis performance of MgH_(2) is considerably improved.This work provides an appealing prospect for real-time hydrogen supply and offers a new effective strategy for improving the hydrolysis performance of MgH_(2).

Cascade utilization of full spectrum solar energy for achieving simultaneous hydrogen production and all-day thermoelectric conversion

Solar-driven photocatalytic water/seawater splitting holds great potential for green hydrogen production.However,the practical application is hindered by the relatively low conversion efficiency resulting from the inadequate utilization of solar spectrum with significant waste in the form of heat.Moreover,current equipment struggles to maintain all-day operation subjected to the lack of light during nighttime.Herein,a novel hybrid system integrating photothermal catalytic(PTC)reactor,thermoelectric generator(TEG),and phase change materials(PCM)was proposed and designed(named as PTC-TEG-PCM)to address these challenges and enable simultaneous overall seawater splitting and 24-hour power generation.The PTC system effectively maintains in an optimal temperature range to maximize photothermal-assisted photocatalytic hydrogen production.The TEG component recycles the low-grade waste heat for power generation,complementing the shortcoming of photocatalytic conversion and achieving cascade utilization of full-spectrum solar energy.Furthermore,exceptional thermal storage capability of PCM allow for the conversion of released heat into electricity during nighttime,contributing significantly to the overall power output and enabling PTC-TEG-PCM to operate for more than 12 h under the actual condition.Compared to traditional PTC system,the overall energy conversion efficiency of the PTC-TEG-PCM system can be increased by∼500%,while maintaining the solar-to-hydrogen efficiency.The advancement of this novel system demonstrated that recycling waste heat from the PTC system and utilizing heat absorption/release capability of PCM for thermoelectric application are effective strategies to improve solar energy conversion.With flexible parameter designing,PTC-TEG-PCM can be applied in various scenarios,offering high efficiency,stability,and sustainability.

Hydrogen generation from NaBH_(4) for portable proton exchange membrane fuel cell

Sodium borohydride(NaBH_(4)) is considered as the most potential hydrogen storage material for portable proton exchange membrane fuel cells(PEMFC)because of its high theoretical hydrogen capacity.However,the slow and poor kinetic stability of hydrogen generation from NaBH_(4) hydrolysis limits its application.There are two main factors influencing the kinetics stability of hydrogen generation from NaBH_(4).One factor is that the alkaline byproducts(NaBO_(2)) of the hydrolysis reaction can increase the pH of the solution,thus inhibiting the reaction process.It mainly happens in the NaBH_(4) solution hydrolysis system.Another factor is that the monotonous increase in reaction temperature leads to uncontrollable and unpredictable hydrolysis rates in the solid NaBH_(4) hydrolysis system.This is due to the excess heat generated from this exothermic reaction in the initial reaction of NaBH_(4) hydrolysis.In this perspective,we summarize the latest research progress in hydrogen generation from NaBH_(4) and emphasize the design principles of catalysts for hydrogen generation from NaBH_(4) solution and solid state NaBH_(4).The importance of carbon as catalyst support material for NaBH_(4) hydrolysis is also highlighted.

Computational Analysis of the Effect of Nano Particle Material Motion on Mixed Convection Flow in the Presence of Heat Generation and Absorption

The present study is concerned with the physical behavior of the combined effect of nano particle material motion and heat generation/absorption due to the effect of different parameters involved in prescribed flow model.The formulation of the flow model is based on basic universal equations of conservation of momentum,energy and mass.The prescribed flow model is converted to non-dimensional form by using suitable scaling.The obtained transformed equations are solved numerically by using finite difference scheme.For the analysis of above said behavior the computed numerical data for fluid velocity,temperature profile,and mass concentration for several constraints that is mixed convection parameterλt,modified mixed convection parameterλc,Prandtl number Pr,heat generation/absorption parameterδ,Schmidt number Sc,thermophoresis parameter Nt,and thermophoretic coefficient k are sketched in graphical form.Numerical results for skin friction,heat transfer rate and the mass transfer rate are tabulated for various emerging physical parameters.It is reported that in enhancement in heat,generation boosts up the fluid temperature at some positions of the surface of the sphere.As heat absorption parameter is decreased temperature field increases at position X=π/4 on the other hand,no alteration at other considered circumferential positions is noticed.

Study and performance test of 10 kW molten carbonate fuel cell power generation system

The use of high-temperature fuel cells as a power technology can improve the efficiency of electricity generation and achieve near-zero emissions of carbon dioxide.This work explores the performance of a 10 kW high-temperature molten carbonate fuel cell.The key materials of a single cell were characterized and analyzed using X-ray diffraction and scanning electron microscopy.The results show that the pore size of the key electrode material is 6.5 lm and the matrix material is a-LiAlO_(2).Experimentally,the open circuit voltage of the single cell was found to be 1.23 V.The current density was greater than 100 mA/cm^(2)at an operating voltage of 0.7 V.The 10 kW fuel cell stack comprised 80 single fuel cells with a total area of 2000 cm^(2)and achieved an open circuit voltage of greater than 85 V.The fuel cell stack power and current density could reach 11.7 kW and 104.5 mA/cm2 at an operating voltage of 56 V.The influence and long-term stable operation of the stack were also analyzed and discussed.The successful operation of a 10 kW high-temperature fuel cell promotes the large-scale use of fuel cells and provides a research basis for future investigations of fuel cell capacity enhancement and distributed generation in China.

A novel nanoporous Mg-Li material for efficient hydrogen generation

Hydrogen generation material is a new kind of energy material that can supply hydrogen by reacting with water and is drawing more and more attention with the development of hydrogen economy. In this study, a novel nanoporous magnesium-lithium material prepared by a physical vapor deposition method exhibits an excellent hydrogen generation property. It generates hydrogen efficiently and quickly with saltwater, reaching a hydrogen generation amount of 962 mL g^(-1) and hydrogen generation rates of 60 mL g^(-1)min^(-1), 109 mL g^(-1)min^(-1),256 mL g^(-1)min^(-1) and 367 mL g^(-1)min^(-1) at 0 ℃, 25 ℃, 35 ℃ and 50 ℃, respectively. The nanoporous magnesium-lithium material is composed of a solid solution phase with a magnesium-lithium atomic ratio of 17:3. By synchrotron radiation analysis, the sizes of the nanopores are in the range of 100 nm ~ 600 nm with an average size of 280 nm, and the porosity is calculated to be ~42.4%. The improved hydrogen generation property is attributed to the nanoporous structure with a high specific surface area, and the addition of lithium element which acts as active sites in hydrogen generation process.

Preparation and Characterization of PZT Piezoelectric Thick Film Generation Materials Enhanced by PZT Nanoparticles

The use of piezoelectric materials to capitalize on the ambient vibrations surrounding a system is one method that has seen a dramatic rise in use for power harvesting.Lead zirconate titanate,one of the most popular piezoelectric materials,has larger piezoelectric response than piezoelectric materials,such as ZnO and AlN.Ferroelectric films are suitable for vibration energy harvesting.Dense and crack-free(100)oriented PZT piezoelectric thick film is prepared on Pt/Cr/SiO2/Si substrate by sol-gel using PZT nanoparticles as reinforcing phase.The thick film possesses single-phase perovskite structure and perfectly(100)oriented.The influences of crystalline and amorphous PZT nanoparticles on the(100)oriented degree and the influences of the molar concentration ratio of amorphous PZT nanoparticles and PZT sol on surface morphology of PZT piezoelectric thick film are investigated.Experimental results show that,amorphous PZT nanoparticles are more helpful than the crystalline nanoparticles for the PZT thick film preferred orientation growth along the(100)direction.The 3μm-thick PZT thick film enhanced by amorphous PZT nanoparticles annealed at 700℃for 5min has the strongest(100)orientation degree,being 82.3%,and the surface is dense,smooth and crack-free.

Imaging the crystal orientation of 2D transition metal dichalcogenides using polarization-resolved second-harmonic generation

We use laser-scanning nonlinear imaging microscopy in atomically thin transition metal dichalcogenides(TMDs)to reveal information on the crystalline orientation distribution,within the 2D lattice.In particular,we perform polarization-resolved second-harmonic generation(PSHG)imaging in a stationary,raster-scanned chemical vapor deposition(CVD)-grown WS2 flake,in order to obtain with high precision a spatially resolved map of the orientation of its main crystallographic axis(armchair orientation).By fitting the experimental PSHG images of sub-micron resolution into a generalized nonlinear model,we are able to determine the armchair orientation for every pixel of the image of the 2D material,with further improved resolution.This pixel-wise mapping of the armchair orientation of 2D WS2 allows us to distinguish between different domains,reveal fine structure,and estimate the crystal orientation variability,which can be used as a unique crystal quality marker over large areas.The necessity and superiority of a polarization-resolved analysis over intensity-only measurements is experimentally demonstrated,while the advantages of PSHG over other techniques are analysed and discussed.

Existence results for unilateral contact problem with friction of thermo-electro-elasticity

This work studies a mathematical model describing the static process of contact between a piezoelectric body and a thermally-electrically conductive foundation. The behavior of the material is modeled with a thermo-electro-elastic constitutive law. The contact is described by Signorini＇s conditions and Tresca＇s friction law including the electrical and thermal conductivity conditions. A variational formulation of the model in the form of a coupled system for displacements, electric potential, and temperature is de- rived. Existence and uniqueness of the solution are proved using the results of variational inequalities and a fixed point theorem.

Modulation of the second-harmonic generation in MoS_(2) by graphene covering

Nonlinear optical frequency mixing,which describes new frequencies generation by exciting nonlinear materials with intense light field,has drawn vast interests in the field of photonic devices,material characterization,and optical imaging.Investigating and manipulating the nonlinear optical response of target materials lead us to reveal hidden physics and develop applications in optical devices.Here,we report the realization of facile manipulation of nonlinear optical responses in the example system of MoS_(2) monolayer by van der Waals interfacial engineering.We found that,the interfacing of monolayer graphene will weaken the exciton oscillator strength in MoS_(2) monolayer and correspondingly suppress the second harmonic generation(SHG)intensity to 30%under band-gap resonance excitation.While with off-resonance excitation,the SHG intensity would enhance up to 130%,which is conjectured to be induced by the interlayer excitation between MoS_(2) and graphene.Our investigation provides an effective method for controlling nonlinear optical properties of two-dimensional materials and therefore facilitates their future applications in optoelectronic and photonic devices.

Analysis of silicon-based integrated photovoltaic–electrochemical hydrogen generation system under varying temperature and illumination

Last decade witnessed tremendous research and development in the area of photo-electrolytic hydrogen generation using chemically stable nanostructured photo-cathode/anode materials. Due to intimately coupled charge separation and photo-catalytic processes, it is very difficult to optimize individual components of such system leading to a very low demonstrated solar-to-fuel efficiency (SFE) of less than 1%. Recently there has been growing interest in an integrated photovoltaic–electrochemical (PV–EC) system based on GaAs solar cells with the demonstrated SFE of 24.5% under concentrated illumination condition. But a high cost of GaAs based solar cells and recent price drop of poly-crystalline silicon (pc-Si) solar cells motivated researchers to explore silicon based integrated PV–EC system. In this paper a theoretical framework is introduced to model silicon-based integrated PV–EC device. The theoretical framework is used to analyze the coupling and kinetic losses of a silicon solar cell based integrated PV–EC water splitting system under varying temperature and illumination. The kinetic loss occurs in the range of 19.1%–27.9% and coupling loss takes place in the range of 5.45%–6.74% with respect to varying illumination in the range of 20–100 mW/cm2. Similarly, the effect of varying temperature has severe impact on the performance of the system, wherein the coupling loss occurs in the range of 0.84%–21.51% for the temperature variation from 25 to 50 °C. © 2016 Science Press

Automatic Migration of a Software Task to Hardware Component in MPSoC Systems

The authors will focus on the study of the design of Multiprocessor Systems on Chip （MPSoC）, specifically in the context of improving the performance of applications located on the MPSoC architecture. The objective of this research is to study the problems of transition from a pure software implementation for an embodiment admitting one or more hardware components and to develop a methodology for automatic generation of migration of a software task into a hardware component in MPSoC. The transformation of a software task into a hardware task led to many changes, hardware part （connection, the requirement of an interrupt controller...）, software part （at least one task, I/O （I/O）, synchronization...） and an architectural point of view, the remarkable aspects of data storage. The experiment is done on the MJPEG decoder to illustrate the effectiveness of the authors＇ tool for automatic generation of migration.

Application of Power Electronics Converters in Renewable Energy

Against the backdrop of global energy shortages and increasingly severe environmental pollution,renewable energy is gradually becoming a significant direction for future energy development.Power electronics converters,as the core technology for energy conversion and control,play a crucial role in enhancing the efficiency and stability of renewable energy systems.This paper explores the basic principles and functions of power electronics converters and their specific applications in photovoltaic power generation,wind power generation,and energy storage systems.Additionally,it analyzes the current innovations in high-efficiency energy conversion,multilevel conversion technology,and the application of new materials and devices.By studying these technologies,the aim is to promote the widespread application of power electronics converters in renewable energy systems and provide theoretical and technical support for achieving sustainable energy development.

Researches on Classification Features of Rural and Urban Domestic Waste in Tianjin City Under Secondary Classification Mode

In order to investigate the influence of secondary classification mode on waste generation features, this study classified domestic waste generated by 310 rural and urban households at urban areas and Shuigaozhuang Village of Xiqing District into 3 groups： compostable materials, recyclable materials and toxics on the basis of the constructed secondary classification mode of domestic waste. The study focused on waste generation strength and classification features, compared the waste generation features between rural and urban residents, and analyzed the re- lation between waste generation strength and economic and cultural factors. The re- sults indicated that the average generation speed of urban domestic waste was 423.08 g/（d.capita）, and that of rural domestic waste was 629.89 g/（d.capita）, there was significant difference between rural and urban compost generation strength （P= 0.00002）, while the generation strength of recyclable materials and toxics between rural and urban areas had no significant difference （P=0.471 and P=0.099, respec- tively）. Secondary classification mode is an effective source classification mode for domestic wastes and has positive effects on waste reduction and treatment.

Efficient nanocatalysis of Ni/Sc_(2)O_(3)@FLG for magnesium hydrolysis of hydrogen generation

Magnesium is one of the most promising candidates of light metal materials for hydrogen production by hydrolysis due to its efficient and economical properties.Various modification methods have been investigated to improve the hydrolytic properties of Mg.However,the direction of the design of efficient catalysts is unclear and needs to be guided by a richer catalytic mechanism of hydrolysis.In this work,a simple approach was used to synthesize Few Layer Graphene(FLG)-loaded ultra-fine highly dispersed Ni/Sc_(2)O_(3)nanocatalyst,which achieves impressive catalytic hydrolysis results.Here,the addition of 4 wt%Ni/Sc_(2)O_(3)@FLG catalyst allows Mg to produce 833 mL g^(-1)of H_(2) in 20 s at 30℃.There is an initial hydrogen release rate as high as 5942 mL g^(-1)min^(-1),a final hydrogen yield of 859 mL g^(-1)(99.13%),and almost complete conversion of Mg to Mg(OH)_(2).Furthermore,surprisingly,even with only 0.2 wt%catalysts added,Mg still has an initial hydrogen generation rate of 3627 mL g^(-1)min^(-1),which is over 20 times faster than that of Mg.It also produces 690 mL g^(-1)of H_(2) in 30 s at 30℃.Hydrolysis kinetic curves and microscopic morphology tests show that FLG could shape and hold Mg into thin sheets,giving them an ultra-high hydrolysis rate and conversion rate.The formation of micro-galvanic cells between Ni and Mg accelerates the electrochemical corrosion of Mg and greatly enhances electron transfer during hydrolysis.This work provides a new strategy for the preparation of efficient nanocatalysts,which is expected to make“Mg-efficient catalyst”the most ideal light metal-based material for hydrogen production by hydrolysis.