High Solar Conversion Efficiency Research Articles

Unidirectional freezing robust PPy@GO-SA aerogel for stable and efficient solar desalination

Solar interfacial evaporation technology is an effective and sustainable method for seawater desalination. It is crucial to achieve high photothermal conversion efficiency, rapid evaporation rate, and long-term stability. In this study, a vertically aligned porous aerogel evaporator is prepared using sodium alginate as the substrate material and graphene oxide (GO) and polypyrrole (PPy) as the photothermal materials through a directional freezing technology. The polypyrrole@graphene oxide-sodium alginate evaporator exhibits a high solar photothermal conversion efficiency as high as 98.6 % and an evaporation rate of up to 4.66 kg·m−2·h−1 under 1 sun. During the 144-hour desalination, the evaporator transports brine for evaporation in the daytime and removes salt residue from the evaporator surface at night. It has demonstrated a self-cleaning behavior and restored its desalination stability. Thus, this aerogel evaporator with a high evaporation rate and stable salt resistance shows great potential for practical applications in solar thermal conversion and seawater desalination.

Efficient interfacial solar evaporation using a novel carbonized foam as photo-thermal converter

Recent research shows that one of the effective and green methods to reduce freshwater scarcity is interfacial solar evaporation. This method does not require energy consumption. One of the important challenges that should be taken into consideration in interfacial solar evaporator systems is the fabrication of solar absorbers with easy, environmentally friendly, cost-effective, efficient and scalable methods. Herein, a carbonized melamine foam (CMF) fabricated via a one-step, fast, low-cost and easy method for solar desalination. The CMF is fabricated by an electrical heat gun within a few minutes and is characterized by various techniques. The prepared CMF as a black foam shows excellent properties for solar desalination such as superhydrophilicity, high light absorption, high water transportation rate, good photo-thermal conversion, high rate of water evaporation and salt resistance. The prepared CMF shows repeatable performance in solar evaporation at consecutive evaporation cycles with solar evaporation rate of 3 kg m−2h−1 and high solar thermal conversion efficiency of 90 % under 1000 W m−2 illumination.

Comparative Numerical Energy and Performance Analysis of Solar Photovoltaic and Solar Thermal Power Generation

This study analyses fixed and tracking solar photovoltaics and, solar thermal power. Performance in different locations was analysed for each configuration and technology using simulations based on a Typical Meteorological Year data. The study analysed a 25MWp solar photovoltaic and solar thermal power plants in each of the eleven selected locations in Zimbabwe. The performance of the solar photovoltaic and solar thermal power plants under different meteorological variables were assessed for all the selected locations. It was shown that different configurations together with different technologies have different conversion efficiencies. A high solar thermal conversion efficiency was found to be 18.718% in Gweru while it was 15.502% for solar photovoltaics in Mutare. The study also showed that highest insolation and clearness index values were found in Gweru. The average energy generated by the fixed photovoltaic collectors, tracking photovoltaic collectors and the Concentrating Solar Power plant were respectively 47.38GWh, 68.18GWh and 192.86GWh. There was a maximum percentage difference in the LCoE generated of 32.03% between the fixed PV collectors and the Concentrating Solar Power plant and a difference of 4.74% was realised between the tracking photovoltaics and Concentration Solar Power.

Single-layer GaInS3: Water-splitting photocatalyst with high solar conversion efficiency and long carrier lifetime from first-principles investigation

Two-dimensional (2D) materials with a high solar to hydrogen (STH) conversion are in high demand due to the escalating energy crisis and environmental degradation. The STH efficiency is strongly correlated with the charge carrier separation, which can be improved by the inside electric dipole. Herein, the water-splitting capabilities of single-layer (SL) GaInS3 are explored by employing first-principles calculations. Theoretical outcomes reveal that SL GaInS3 exhibits a large intrinsic electric dipole and has a thermally stable structure at 300 K. SL GaInS3 displays a direct bandgap of 1.83 eV, as well as suitable band edges and abundant visible absorption (105 cm−1) for solar-driven water-splitting. The electronic structure and carrier mobility calculations demonstrate the high separation efficiency of charge carriers, which is strongly affirmed by the quite long carrier lifetime of 8.26 ns. The overpotential analysis of charge carriers suggests that the oxygen generation of SL GaInS3 can be accomplished without a cocatalyst, while hydrogen generation can be completed with the aid of cocatalysts. The STH efficiency of SL GaInS3 reaches up to 16.8%, apparently surpassing the commercial standard (10%). In brief, the high STH and long carrier lifetime promise the possible application of SL GaInS3 for solar water splitting. What's more, this work provides straight evidence that 2D photocatalysts with inside dipoles exhibit a long carrier lifetime.

(Invited) Development of Perovskite Photovoltaic Devices Using Electrodeposition

Photovoltaic energy is considered today as the most useful natural energy source. To date, different types of solar technologies are industrially available, and the attempts in research and development to improve their potential are continuing. While a number of different materials with different efficiencies can achieve photovoltaic solar energy conversion, so far, no particular material or combination is cheap enough to compete with large-scale fossil fuel-generated electricity. Nowadays, Si-based cells are the most marketed, and they produce high solar conversion efficiencies. However, expensive high temperature and high vacuum processes are adopted in order to elaborate pure Si. Another active material, called perovskite, newly emerged in the solar community. It has attracted major attention worldwide because of its outstanding photovoltaic performance, easy fabrication process, adaptable band-gap, high extinction coefficient, and high carrier mobility. As perovskite is capable of generating a power conversion efficiency approaching that of the leading silicon and that the solar devices fabrication cost is lower, perovskite solar cells tend to be considered as the future of the photovoltaic technology.However, the most used method to deposit perovskite active layer is spin coating, which presents many constraints such as limited surface coverage, non-homogeneity, undefined perovskite crystallinity, and poor stability. Perovskite obtained by spin-coating requires working in inert environment (glove box) and adding some toxic additives to maintain the stability of the perovskite. This increases its cost and enables the deposition only on small surfaces. There is thus a need to look up for alternative deposition methods, more ecofriendly, at lower costs, applicable for large-scale production of perovskite solar cells.Electrodeposition recently started to be explored as an efficient alternative for perovskite fabrication. There have been several attempts over the past years to optimize the electrodeposited perovskite layer and adjust its crystallization on dissimilar layers. All sub-techniques started by electrodepositing an initial layer (PbO, PbO2 or PbI2) followed by one or several conversions of the as-deposited layer. In the presented work, we were able to develop different types of perovskites using electrodeposition, understand the impact of the different deposition parameters on their structure, and improve their stability comparing to the spin-coated ones. Along with the simple MAPbI3 perovskite, the electrodeposition of mixed MAPbI3-xClx and MA1-yFAyPbI3-xBrx perovskites will be presented. The present study is one of its kind, since these mixed perovskite were never developed using electrodeposition before. It was observed that using electrodeposition afford enhanced stability compared to spin-coating process, and the different fabricated perovskites were also proved to experience a positive maturation phenomenon during their first 500 hours of life.The electrodeposition process is easy to manipulate, and the electrodeposited films could grow on surfaces as large as desired, inside an electrolyte, allowing its application in ambient atmosphere, with no need of a glove box. It is also eco-friendly in terms of solvent engineering, since no toxic solvents are needed to stabilize or enhance the morphology of the obtained films. The main solvents used are deionized water, ethanol and isopropanol.

The influence of intrinsic electric field regulation on photocatalytic activity in Janus group-III chalcogenide heterostructure

The intrinsic electric field is crucial to the charge transfer and separation of photogenerated carriers in Janus photocatalysts. However, the issue of how to effectively regulate the intrinsic electric field to improve photocatalytic activity remains unclear. We show that the Janus group-III chalcogenide heterostructure (AlS/InAlS) is a promising photocatalyst for highly-efficient overall water splitting using first-principles calculations. By replacing different layers of metal elements in the group-III chalcogenide, intrinsic electric field size of Janus heterostructure can be changed, promoting photogenerated electron-hole pair separation, and thereby improving photocatalytic performance. Its band edges cross the water-splitting reaction's redox potential. The high optical absorption coefficient (4.4 × 105 cm−1), high solar power conversion efficiency (14.31 %) indicate that AlS/InAlS heterostructure can efficiently utilise solar power. In addition, the overpotential of HER in the AlS/InAlS heterostructure can reach the level achieved by photogenerated electrons and holes.

Highly efficient solar water evaporation by wood through one-step in-situ synthesis of carbon dots

Solar evaporation provides an effective solution to solve the scarcity of freshwater resources. Biomass-based solar evaporators have attracted significant interest, because of their environmental safety. However, due to the high latent heat of evaporation for water, most biomass-based solar evaporators exhibit low water vapor generation rates. In this work, we have developed a wood-based solar evaporator (CDs-Wood) by just one step in-situ synthesis of carbon dots (CDs) using the lignin in wood as the carbon source, and the latent heat of evaporation for water in CDs-Wood has significantly decreased from 2257.5 J g−1 to 1003.8 J g−1, which has resulted in a water vapor generation rate as high as 2.86 kg m−2h−1. CDs-Wood exhibits extensive optical absorption capacity (95.3 %), high solar steam conversion efficiency (80 %), significant adaptability to low-temperature conditions, and excellent salt resistance. This work provides an efficient and potentially scalable solution for designing all-biomass-based solar steam evaporators.

Flexible photothermal-triggered MOF-composite nanofibers textures for freshwater harvesting with high efficiency and stability

Vast freshwater reserves in the atmosphere have been investigated as a sustainable source of water for the alleviation of the water crisis with suitable sorbent-based atmospheric water harvesting (AWH) materials. In this work, we design a flexible photothermal-triggered MOF-composite nanofiber texture (PMNT), which is fabricated by combining nanofibers to be optimally integrated with UiO-66-NH2, carbon black and lithium chloride. PMNT achieves not only efficient water molecule uptake but also high solar thermal conversion efficiency. The PMNT effectively harvests atmospheric water to ∼ 1.44 g g−1 under 60 % RH in 80 min and quickly releases water over 30 min under 1 sun. In particular, PMNT outdoors collects water of ∼ 1.16 g g−1, even if the light intensity is ∼ 1.16 kW m−2 and the temperature is ∼ 34 °C, the RH is only 23 %. PMNT outdoors can achieve a total water yield of ∼ 4.61 g g−1 through 5 uptake-release cycles per day, along with stability and low energy consumption for AWH. It has been demonstrated that the as-harvesting water via PMNT meets the WHO standard. This study provides insight into the design of novel materials for AWH performance, which can be extended to practical applications, e.g., water engineering in arid regions, water harvesting devices and systems in industry.

Novel anti-freeze and self-adhesive gellan gum/P3HT/LiCl based gel electrolyte for quasi solid dye sensitized solar cells

Gellan gum/poly(3-hexylthiophene)/lithium chloride gels with different ratios of LiCl containing I-/I3- liquid electrolyte were synthesized in one-pot reaction and used as gel electrolytes in the dye sensitized solar cells (DSSCs). Due to hygroscopic nature of LiCl, presence of 6 M LiCl was prevented shrinkage of gels by blocking water loss. In addition, by increasing LiCl amount in prepared gels, surface energy values increased that can cause good adhesive property. Furthermore, LiCl contained prepared gels were flexible at about − 20°C after being kept at − 60°C for 24 h. Anti-freezing and self-adhesive gel electrolytes can extend the usage of DSSCs at different conditions and cell architecture. Finally, with the usage of gel electrolytes, open circuit potentials of prepared DSSCs were increased above 1 V and high solar conversion efficiency was obtained at a 4.64% by using 6 M LiCl. The developed gel electrolyte can be a good alternative for solving the leakage and evaporation problems of liquid electrolytes used in DSSCs.

Janus film evaporator with improved light-trapping and gradient interfacial hydrophilicity toward sustainable solar-driven desalination and purification

Solar-driven desalination and purification offers a promising approach to water treatment, while the clean water yields under natural sunlight can be further increased by developing well-designed evaporators. Herein, a TiN/GO//GO Janus film was fabricated to realize the synergetic effect of effective photothermal conversion and water transportation. The top TiN/GO hybrid layer possesses high solar absorption and thermal conversion efficiency, while the bottom GO layer promotes expeditious water transport. Moreover, the film maintains gradient interfacial hydrophilicity due to the reservation of oxygen-functional groups, which facilitate the formation of thin liquid film at water-film interface and increase heat utilization efficiency. Therefore, the Janus film is demonstrated to possess high evaporation rate of 1.70 kg m−2 h−1 for various non-conventional water resources under 1 solar illumination, which is comparable or better than most of the film evaporators. The excellent durability is demonstrated in a wide acid–base range (pH 2–11) and salinity range (0–250‰) over 30 cycles. The outdoor device with Janus film exhibits daily water yield of 7.44 kg m−2, indicating a potential application in efficient solar-driven desalination and non-conventional water treatment.

Synergistic effect of electrochemically fabricated polyaniline nanofibers and silver for efficient solar steam generation

Solar steam generation (SSG) has been recognized as a promising and green technology to resolve the scarcity of drinking water in the near future. On the other hand, there are still several challenges associated with SSG system to its practical utilization. Design of suitable photothermal materials with high solar absorption and conversion efficiency is one of the challenges associated with the SSG technology. Herein, we demonstrated a strategy for the fabrication of bilayer structure of porous polyaniline (PANI) nanofibers and conducting silver (Ag) on a carbon cloth (PANI/Ag@CC) substrate using a facile electrochemical deposition approach. As prepared binder-free PANI/Ag@CC showed an excellent steam generation rate of 2.21 kg/m2h with superior evaporation efficiency of 98.0 % under 1 sun illumination when used for the SSG application. Furthermore, the bilayered PANI/Ag@CC exhibited excellent durability, effective seawater desalination and wastewater purification. The superior SSG performance is associated with the synergistic effect of surface plasmon resonance of Ag and porous PANI nanofibers. Therefore, practically simple fabrication, outstanding evaporation rate and water purification properties convince that the PANI/Ag@CC structure can be a promising candidate for SSG applications.

Performance Evaluation of Novel Concentrating Photovoltaic Thermal Solar Collector under Quasi-Dynamic Conditions

Concentrating Photovoltaic Thermal (CPVT) collectors are suitable for integration in limited roof space due to their higher solar conversion efficiency. Solar sunlight can be used more effectively by CPVT collectors in comparison to individual solar thermal collectors or PV modules. In this study, the experimental investigation of a novel CPVT collector called a PC (power collector) has been carried out in real outdoor conditions, and the test set-up has been designed based on ISO 9806:2013. A quasi-dynamic testing method has been used because of the advantages that this method can offer for collectors with a unique construction, such as the proposed collector, over the steady-state testing method. With a quasi-dynamic testing method, it is possible to characterize the collector within a wide range of incidence angles and a complex incidence angle modifier profile. The proposed novel collector has a gross area of 2.57 m2. A maximum power output per collector unit area of 1140 W is found at 0 °C reduced temperature (1000 W/m2 irradiance level), while at a higher reduced temperature (70 °C), it drops down to 510 W for the same irradiance level. The data have been fitted through a multiple linear regression method, and the obtained efficiency curve coefficients are 0.39, 0.192, 1.294, 0.023, 0.2, 0, −5929 and 0 for Kθd, b0, c1, c2, c3, c4, c5 and c6, respectively. The experimental characterization carried out on the collector proved that the output powers calculated by using the obtained parameters of the quasi-dynamic testing method are in good agreement with experimental points.

Polydopamine modified ZIF-L/sodium alginate composites as the highly efficient photothermal membrane for solar steam generation

Interfacial solar steam generation (ISSG) technology is considered to be one of the most promising approaches to alleviating the global shortage of clean water due to its high solar thermal conversion efficiency. However, achieving stable evaporation in high salinity solutions and preventing the occurrence of salt deposition phenomena remains a challenge. Here, an efficient and stable photothermal membrane-based evaporator has been developed, which consists of polydopamine (PDA) modified leaf-like zeolitic imidazolate framework (ZIF-L) implanted in sodium alginate (SA) membrane supported on a melamine sponge (S-ZIF-L/PDA sponge), providing more advantages for boosting the photothermal conversion performance and preventing salt deposition. This S-ZIF-L/PDA sponge displays an excellent light absorption (>95 %), and remarkable evaporation rate of 1.66 kg·m−2·h−1 with a solar-thermal efficiency of 91.06 % under 1.0 sun (1 kW·m−2) illumination. Benefiting from the super hydrophilic feature of the melamine sponge and the rejection properties of the SA membrane structure, the obtained sponge effectively prevents salt and contaminants from depositing on the surface. Particularly, the S-ZIF-L/PDA sponge achieves an evaporation efficiency of 86.17 % in 20 wt% NaCl solution, along with excellent resistance to salt deposition and marvelous stability in cycling tests. The salt ion concentration of the obtained fresh water is much lower than the World Health Organization (WHO) drinking water standard, and the organic removal rate exceeds 99 %. This work provides a competitive solution for high-salinity desalination and wastewater treatment.

Modulating Surface Electron Density of Heterointerface with Bio-Inspired Light-Trapping Nano-Structure to Boost Kinetics of Overall Water Splitting.

Herein, inspired by natural sunflower heads' properties increasing the temperature of dish-shaped flowers by tracking the sun, a novel hybrid heterostructure (MoS2 /Ni3 S2 @CA, CA means carbon nanowire arrays) with the sunflower-like structure to boost the kinetics of water splitting is proposed. Density functional theory (DFT) reveals that it can modulate the active electronic states of NiMo atoms around the Fermi-level through the charge transfer between the metallic atoms of Ni3 S2 and MoMo bonds of MoS2 to boost overall water splitting. Most importantly, the finite difference time domain (FDTD) could find that its unique bio-inspired micro-nano light-trapping structure has high solar photothermal conversion efficiency. With the assistance of the photothermal field, the kinetics of water-splitting is improved, affording low overpotentials of 96 and 229mV at 10mAcm-2 for HER and OER, respectively. Moreover, the Sun-MoS2 /Ni3 S2 @CA enables the overall alkaline water splitting at a low cell voltage of 1.48 and 1.64V to achieve 10 and 100mAcm-2 with outstanding catalytic durability. This study may open up a new route for rationally constructing bionic sunflower micro-nano light-trapping structure to maximize their photothermal conversion and electrochemical performances, and accelerate the development of nonprecious electrocatalysts for overall water splitting.

Janus mesoporous wood-based membrane for simultaneous oil/water separation, aromatic dyes removal, and seawater desalination

Directional transport of liquid is crucial for many applications including seawater desalination , oil/water separation, fog collection, membrane distillation and so forth. Particularly, Janus wood membranes, with asymmetric special wetting property on two sides, and mechanically robust bio-based substrate with ample pores and open nano-/micro-channels, present enticing opportunities to address this challenge. In this study, we report a Janus mesoporous wood-based membrane demonstrating the capabilities for simultaneous oil/water separation, aromatic dyes removal, and seawater desalination. Thanks to the inner driving force arising from the asymmetric special wettability, unique wood microchannels for the transpiration of trees, and the synergistic effect of PPy and Ag/AgCl NPs anchored to wood matrix, Janus mesoporous wood-based membrane would promote the desired transport without any external energy input for high-efficiency seawater desalination and switchable oil/water separation. Meanwhile, the aromatic dyes and other organic compounds in industrial wastewater or polluted seawater would get more opportunities to contact with the anchored Ag/AgCl NPs during flowing through the wood microchannels. Above advantages endow the Janus mesoporous wood-based membrane with excellent pollutant degradation efficiency (MB: 86.4 %, RhB: 91.9 %), high solar conversion efficiency (95.33 %), outstanding separation efficiency towards oil-in-water emulsion (∼99.51 %), remarkable oil adsorption capacity (∼8 times of its own weight), and great antibacterial efficiencies (E. coli: 99.87 %, S. aureus: 99.78 %, B. subtilis: 99.96 %). Results also show that this Janus mesoporous wood-based membrane has the satisfactory resistance to acid and base, robust mechanical structure, good recycling stability, high salinity tolerance and remarkable self-desalting capability. This study represents a new avenue for fabrication and design of Janus wood-based photothermal materials, and certainly will contribute to alleviating the global water and energy shortage issue. Asymmetric special wettability, unique wood microchannels, and the synergistic effect of PPy and Ag/AgCl NPs anchored to wood matrix endow the as-presented Janus mesoporous wood-based membrane with excellent aromatic dyes degradation efficiency (MB-86.4 %, RhB-91.9 %), high solar conversion efficiency (95.33 %), outstanding separation efficiency towards O/W emulsion (∼99.51 %), remarkable oil adsorption capacity (∼8 times of its own weight), great antibacterial efficiencies (E. coli-99.87 %, S. aureus-99.78 %, B. subtilis-99.96 %), and remarkable salinity tolerance. It certainly will contribute to alleviating the global water and energy shortage issue. • Mechanically robust wood membrane with asymmetric special wettability, ample pores and open microchannels was fabricated. • Janus wood membrane can simultaneously complete oil/water separation, aromatic dyes removal, and seawater desalination. • PPy/Ag/AgCl NPs endow the wood with excellent MB/RhB degradation efficiency, and high solar conversion efficiency (95.33 %). • It has oil/water separation efficiency (99.51 %), oil adsorption capacity (∼8 times), and antibacterial efficiency (99.96 %). • Such Janus mesoporous wood-based membrane will contribute to alleviating the global water and energy shortage issue.

Сравнительное изучение наноматериалов в условиях их работы в составе цветосенсибилизированных и перовскитных солнечных батарей

The prospects for creating the photoelectrochemical solar energy converters or solar cells based on the color-sensitized wide-gap semiconductors and perovskites were studied. Possible design, materials and technologies required in creation of such converters were considered. Based on the study of numerous literature data, it was demonstrated that the use of sensitized mesoporous titanium dioxide as a photoanode was quite expedient. The mesoporous titanium oxide film has a developed surface and, accordingly, a large area for the sensitizer adsorption. Mediator systems were studied, which were one of the key components of a photoelectrochemical cell; their characteristics significantly affect efficiency and stability of devices in general, as well as the electrocatalysts required in regeneration of the oxidized mediator component. Color-sensitized solar cells based on the mesoporous semiconductors are of the increasing interest because of their relatively low cost, simple manufacturing technology and high solar light conversion efficiency. Perovskites were studied; they include a group of materials with similar crystal structure able to compete with traditional silicon solar cells due to their flexibility, low cost of films and relative simplicity in the manufacturing process. Photoelectrochemical converters based on color-sensitized wide-gap semiconductors and perovskites are interesting from a practical point of view as an alternative to the traditional silicon technology

Semitransparent polymer solar cell/triboelectric nanogenerator hybrid systems: Synergistic solar and raindrop energy conversion for window-integrated applications

Development of photovoltaic (PV)-derived hybrid power systems can overcome the weather-dependent electricity production and increase the amount of dispatchable renewable energy generation. Herein, monolithic hybrid devices are developed via rational integration of high-performance semitransparent polymer solar cells (ST-PSCs) and liquid−solid triboelectric nanogenerators (TENGs). High-performance PSCs with efficiencies of 17.4% for rigid and 15.7% for flexible devices are achieved. Further electrode modifications and integration of transparent TENGs synergistically balance the above-bandgap photon harvesting and transparency in a broad wavelength range (380 − 1000 nm), yet significantly reduce the transmittance in the near-infrared wavelength range (1000 − 2500 nm) of hybrid devices. The hybrid devices simultaneously provide high visible light transparency, good color fidelity, efficient heat resistance and possibility to integrate on rigid and flexible substrates. The hybrid devices attain a high solar conversion efficiency of 10.1% under 1 sun, indicating efficient light-to-electricity conversion (a maximum electrical power output: 101 W m−2) on sunny days. The hybrid devices can also generate a maximum electrical power output of 2.62 W m−2 through waterdrop energy conversion, implying complementary green electricity production on rainy days. The controlled ambient temperature and specific transmittance windows provided by the hybrid devices sustain plant growth and highlight their great potential in agricultural applications. Gratifyingly, this work demonstrates the first example of ST-PSC/TENG hybrid systems for scaling up renewable power generation in different weather conditions, considering architectural and agricultural applications.

Parameters Optimization of Intermediate Band Solar Cells: Cases of PbTe/CdTe, PbSe/ZnTe and InN/GaN Quantum Dots

Photovoltaic cells, based on quantum dots implementation in the intrinsic region, are one of the most widely studied concepts nowadays to obtain a high solar conversion efficiency. The challenge in this third generation of solar cells is to find a good combination of materials that allows obtaining higher efficiency with low cost. In this study, we consider a juxtaposition of two kinds of quantum dots (dot/barrier) inside the I region of the PIN junction: the first combination of semiconductors includes the two configurations, PbTe/CdTe and PbSe/ZnTe, and the second combination is InN/GaN. Thus the intermediate band can be tailored by controlling the size of the dots and the inter-dot distances. The principal interest of this investigation is to determine the optimized parameters (the dot size and the inter-dot distance), leading to obtain a better solar cell efficiency. Intermediate bands, their positions, and their widths, are determined using 3D confined particles (electron and hole). Their energy levels are determined by solving the Schrödinger equation and solving the well-known dispersion relation in the Kronig–Penney model.

Three-Dimensional Artificial Transpiration Structure Based on 1T/2H-MoS2/Activated Carbon Fiber Cloth for Solar Steam Generation.

The rise of solar steam generation is an effective strategy to mitigate clean water shortages. However, achieving further improvements in conversion efficiency and stability remains a challenge. Here, 1T/2H-MoS2 nanosheets were uniformly assembled on activated carbon fiber cloth (A-CFC) through a facial hydrothermal method, and a three-dimensional (3D)-artificial transpiration device (ATD) was prepared using the plant transpiration process. The combination of activated carbon fiber cloth and 1T/2H phase MoS2 exhibits high light absorption (∼97.5%), excellent mechanical stability, large evaporation area, and easy escape of vapor. Additionally, the 3D hollow cone of the MoS2/carbon fiber cloth can effectively reduce radiative and convective energy loss and then achieve the enhancement of energy collection from the environment. An outstanding evaporation rate of 1.61 kg·m-2·h-1 with an optimum conversion efficiency of 97% under one sun is reached. Based on the facile fabrication, excellent stability, and high solar conversion efficiency, this nature-inspired design of 3D 1T/2H-MoS2/A-CFC is expected to facilitate large-scale applications for seawater purification and desalination.

Selective absorber and emitter boost water evaporation and condensation toward water collection

Solar evaporation has attracted much attention for water collection. However, previous studies on the traditional interface evaporation pay little attention to the selective spectral properties of solar absorbers, leading to mid-infrared radiative heat loss. Besides, during the vapor condensation, the scatter and absorption of the droplets reduce the incident solar intensity on the evaporation interface below. In this work, a freshwater collection strategy combining solar selective absorber and daytime passive radiative cooling techniques is proposed. The solar selective absorber achieves a high solar thermal conversion efficiency (ηevap = 0.894 at 1 sun) to enhance solar evaporation. The passive daytime radiative cooling coating achieves a high solar reflectance R¯solar = 0.927 and thermal emittance ε¯LWIR = 0.929 in the atmospheric transmission window to cool the condensation surface and enhance vapor condensation. In addition, the contact angle is optimized to be 79° by manipulating the hydrophilicity of the condensation surface to ensure the droplet nucleation and shedding. Indoor experiments show that the water collection rate reaches 0.43 kg m−2 h−1. This work provides a promising water collection strategy through solar heating and radiative cooling.