Integrated radiative and evaporative cooling beyond daytime passive cooling power limit

Radiative cooling technologies can passively gain lower temperature than that of ambient surroundings without consuming electricity, which has emerged as potential alternatives to traditional cooling methods. However, the limitations in daytime radiation intensity with a net cooling power of less than 150 W·m−2 have hindered progress toward commercial practicality. Here, we report an integrated radiative and evaporative chiller (IREC) based on polyacrylamide hydrogels combined with an upper layer of breathable poly(vinylidene fluoride-co-trifluoroethylene) fibers, which achieves a record high practical average daytime cooling power of 710 W·m−2. The breathable fiber layer has an average emissivity of over 76% in the atmospheric window, while reflecting 90% of visible light. This IREC possesses effective daytime radiative cooling while simultaneously ensuring evaporative cooling capability, enhancing daytime passive cooling effectively. As a result, IREC presents the practicability for both personal cooling managements and industrial auxiliary cooling applications. An IREC-based patch can assist in cooling human body by 13 °C low for a long term and biocompatible use, and IREC can maintain the temperature of industrial storage facilities such as oil tanks at room temperature even under strong sunlight irradiation. This work delivers the highest performance daytime passive cooling by simultaneous infrared radiation and water evaporation, and provides a new perspective for developing highly efficient, scalable, and affordable passive cooling strategy

A Microstructured Graphene/Poly(N-isopropylacrylamide) Membrane for Intelligent Solar Water Evaporation

Intelligent solar water evaporation (iSWE) was achieved with a thermally responsive and microstructured graphene/poly(N-isopropylacrylamide) (mG/PNIPAm) membrane. As the solar intensity varies, the water evaporation is tuned through reversible transformations of microstructures reminiscent of the stomatal opening and closing of leaves. Consequently, this mG/PNIPAm membrane displays a high water evaporation rate change (Delta WER) of 1.66 kg m(-2) h(-1) under weak sunlight (intensity < 1 sun) and a low WER of 0.24 kg m(-2) h(-1) under intense sunlight (1sun < intensity < 2 sun). Because of the double-layer structure with predictable shape and dynamics, the leaf-like membrane can further autonomously modulate the water evaporation by self-curling under intense solar irradiation in accordance with simulation results. This mG/PNIPAm membrane provides a smart material platform with self-adaptability in response to changing environments

Moisture adsorption-desorption full cycle power generation

Environment-adaptive power generation can play an important role in next-generation energy conversion. Herein, we propose a moisture adsorption-desorption power generator (MADG) based on porous ionizable assembly, which spontaneously adsorbs moisture at high RH and desorbs moisture at low RH, thus leading to cyclic electric output. A MADG unit can generate a high voltage of similar to 0.5 V and a current of 100 mu A at 100% relative humidity (RH), delivers an electric output (similar to 0.5 V and -50 mu A) at 15 +/- 5% RH, and offers a maximum output power density approaching to 120 mW m(-2). Such MADG devices could conduct enough power to illuminate a road lamp in outdoor application and directly drive electrochemical process. This work affords a closed-loop pathway for versatile moisture-based energy conversion

A reconfigurable and magnetically responsive assembly for dynamic solar steam generation

Interfacial solar vapor generation is a promising technique to efficiently get fresh water from seawater or effluent. However, for the traditional static evaporation models, further performance improvement has encountered bottlenecks due to the lack of dynamic management and self-regulation on the evolving water movement and phase change in the evaporation process. Here, a reconfigurable and magnetically responsive evaporator with conic arrays is developed through the controllable and reversible assembly of graphene wrapped Fe3O4 nanoparticles. Different from the traditional structure-rigid evaporation architecture, the deformable and dynamic assemblies could reconfigure themselves both at macroscopic and microscopic scales in response to the variable magnetic field. Thus, the internal water transportation and external vapor diffusion are greatly promoted simultaneously, leading to a 23% higher evaporation rate than that of static counterparts. Further, well-designed hierarchical assembly and dynamic evaporation system can boost the evaporation rate to a record high level of 5.9 kg m(-2) h(-1). This proof-of-concept work demonstrates a new direction for development of high performance water evaporation system with the ability of dynamic reconfiguration and reassembly. Despite a promising water harvesting approach solar steam generation low efficiency remains a challenging obstacle. Here, authors present a macro- and microscopically reconfigurable and magnetically responsive assembly towards a dynamic evaporation system with improved performance and salt resistance.</p