Solar steam generation is emerging as promising solar-energy conversion technology for potential applications in desalination, sterilization and chemical purification. Despite the recent use of photon management and thermal insulation, achieving optimum solar steam efficiency requires simultaneous minimization of radiation, convection and conduction losses without compromising light absorption. Inspired by the natural transpiration process in plants, here we report a 3D artificial transpiration device with all three components of heat loss and angular dependence of light absorption minimized, which enables over 85% solar steam efficiency under one sun without external optical or thermal management. It is also demonstrated that this artificial transpiration device can provide a complementary path for waste-water treatment with a minimal carbon footprint, recycling valuable heavy metals and producing purified water directly from waste water contaminated with heavy metal ions.

sterilization techniques in the off-grid areas has been exposing human beings to high risk of various epidemic diseases. [3][4][5] Therefore, there have been efforts to develop various solar autoclaves, [6][7][8][9] aiming to provide a reliable off-grid sterilization solution.Recently, interfacial solar steam generation is attracting a lot of attention, with exciting progress in nanoscale designs of materials, light absorption, thermal management, and water supply, [10][11][12][13][14][15][16][17][18][19][20] promising for water purification, solar desalination, ground water extraction, power generation, and various other applications. [21][22][23][24][25][26][27][28][29][30][31][32][33] Most, if not all, of the previous works focus on the high solar to steam energy transfer efficiency, as the absorbers can concentrate the absorbed solar power into the top layers of water for vaporizing with minimized energy loss. In this work, we reveal the kinetic advantage of interfacial solar steam generation, and demonstrate that primarily because of much reduced thermal mass of interfacial heating, interfacial solar steam generation can enable fast responsive, energy efficient, and effective off-grid sterilization. In addition, the entire sterilization setup can be built with low cost and operated with minimum carbon footprint.A typical sterilization process includes heating phase (for steam temperature to increase from room temperature to sterilization temperature), exposure phase (for steam temperature to maintain at sterilization temperature), and cooling phase (for steam temperature to decrease from sterilization temperature to 100 °C to open the sterilizer). [34] As shown in Figure 1a, most, if not all, of the previous steam sterilization devices are based on volumetric heating, with the entire bulk water being heated for steam generation. As a result, during the heating phase, a long period of time (typically 30-60 min for commercialized autoclaves) together with high energy consumption per-unit volume (≈110 J mL −1 for steam of the commercialized autoclave reaching 121 °C) are necessary to offset the sensible heat stored in the bulk water. For exposure phase, the required duration for effective sterilization depends on the sterilization temperature. Steam with a higher temperature can enable effective sterilization within a shorter period, with typical sterilization conditions Steam sterilization is widely used as one of the most reliable sterilization methods for public health. However, traditional steam sterilization mainly relies on electricity, a constrained resource for many developing countries and areas. The lack of available and affordable sterilization techniques in these areas is exposing human beings to a high risk of various epidemic diseases, and calls for the development of off-grid sterilization solutions. For the first time, the kinetic advantages of interfacial solar steam generation is fundamentally revealed and it is demonstrated that interfacial solar steam generation can enable fast-responsive (a...

The effect of isovalent isomorphism to minimize lithium trapping enables a high initial Coulombic efficiency of Si anode.

Epoxy resins with enhanced thermal conductivity are in great demand to improve the thermal management of electrical motors. However, the thermal conductivity of epoxy resin is typically low, comparable to 0.2 W/(m K), and a predictive understanding of the connection between molecular structure and thermal conductivity is not yet established. In this work, we present data for the thermal conductivity of seven thermosets synthesized from one commercially available diepoxide (resorcinol diglycidyl ether) and seven phenylenediamines to systematically examine the dependence of thermal conductivity on the molecular structure of the phenylenediamine hardener. Variations in the molecular structure of phenylenediamines, for example, positions of amine groups and the addition of an electron-withdrawing group, produce up to a factor of 2 change in the thermal conductivity of the cured resins. The highest thermal conductivity of 0.27 W/(m K) is obtained with 5-chloro-m-phenylenediamine; the lowest thermal conductivity of 0.14 W/(m K) is obtained with o-phenylenediamine. Thermal conductivities of these seven epoxy resins are 10−40% lower than the prediction of the minimum thermal conductivity model.

Lithium dendrite growth during repeated charge and discharge cycles of lithium‐metal anodes often leads to short‐circuiting by puncturing the porous separator. Here, a morphological design, the nano‐shield, for separators to resist dendrites is presented. Through both mechanical analysis and experiment, it is revealed that the separator protected by the nano‐shield can effectively inhibit the penetration of lithium dendrites owing to the reduced stress intensity generated and therefore mitigate the short circuit of Li metal batteries. More than 110 h of lithium plating life is achieved in cell tests, which is among the longest cycle life of lithium metal anode and five times longer than that of blank separators. This new aspect of morphological and mechanical design not only provides an alternative pathway for extending lifetime of lithium metal anodes, but also sheds light on the role of separator engineering for various electrochemical energy storage devices.

High thermal conductivity polymers are in great demand as thermal management materials. However, the thermal conductivity of polymers is typically low, ∼0.2 W/(m K), and a predictive understanding of the relationship between the thermal conductivity and the molecular structure of polymers is not yet established. In this work, 14 epoxy resin thermosets are synthesized from one aliphatic epoxide and one aromatic epoxide with seven amine hardeners. These thermosets are used to systematically examine the dependence of the thermal conductivity on the molecular structure of the epoxide and the hardener. In general, aromatic structures have a higher thermal conductivity than aliphatic structures. Moreover, naphthalene-based hardeners provide the highest thermal conductivity, 0.34 W/(m K), 230% higher than the lowest thermal conductivity among the 14 epoxy resin thermosets. The cross-linking density is controlled by mixing different molar ratios of diamine and triamine and does not influence the thermal conductivity, volumetric heat capacity, density, or longitudinal speed of sound. Measured thermal conductivities of 14 epoxy resins lie between 50 and 115% of the prediction of the minimum thermal conductivity model.

Plant transpiration, a process of water movement through a plant and its evaporation from aerial parts especially leaves, consumes a large component of the total continental precipitation (≈48%) and significantly influences global water distribution and climate. To date, various chemical and/or biological explorations have been made to tune the transpiration but with uncertain environmental risks. In recent years, interfacial solar steam/vapor generation is attracting a lot of attention for achieving high energy transfer efficiency. Various optical and thermal designs at the solar absorber–water interface for potential applications in water purification, seawater desalination, and power generation appear. In this work, the concept of interfacial solar vapor generation is extended to tunable plant transpiration by showing for the first time that the transpiration efficiency can also be enhanced or suppressed through engineering the solar absorber–leaf interface. By tuning the solar absorption of membrane in direct touch with green leaf, surface temperature of green leaf will change accordingly because of photothermal effect, thus the transpiration efficiency as well as temperature and relative humidity in the surrounding environment will be tuned. This tunable transpiration by interfacial absorber‐leaf engineering can open an alternative avenue to regulate local atmospheric temperature, humidity, and eventually hydrologic cycle.

Dynamic covalent networks are a class of polymers containing exchangeable bonds. The influence of the thermodynamics and kinetics of dynamic bond exchange on the thermal conductivity and mechanical properties of dynamic networks is important for understanding how they differ from thermoplastics and thermosets. In this work, a series of ethylene dynamic networks are synthesized from benzene diboronic acid and alkane diols with different precise ethylene linker lengths. The thermal conductivity of these ethylene dynamic networks at 40 °C decreases from 0.19 to 0.095 W/(m K) when the ethylene linker length increases from 4 to 12 carbons. The thermal conductivity also has a strong temperature dependence, decreasing by a factor of 3 over the temperature range from −80 °C to 100 °C. The minimum thermal conductivity model predicts these trends of the thermal conductivity with variations in ethylene linker length and temperature.