Phase Change Material Enhanced Radiative Cooler for Temperature-Adaptive Thermal Regulation.

Passive radiative cooling (PRC), as an electricity-free and environmentally friendly cooling strategy, is highly desirable in improving the global energy landscape. Despite numerous efforts, most designs for PRC are so devoted to improving the cooling performance in the daytime that they neglect the triggered overcooling at night. Herein, we approached an effective design for temperature-adaptive thermal management through integrating PRC and temperature control of room-temperature phase change material. Compared with conventional radiative coolers, the developed phase change material-enhanced radiative cooler (PCMRC) can adjust its performance according to the temperature of day and night. The PCMRC achieved an average subambient temperature drop of ∼6.3 °C under direct sunlight and an average temperature rise of ∼2.1 °C above ambient temperature at night, as well as a reduced temperature difference between day and night. The temperature-adaptive PCMRC shows great promise for passive radiative cooling regulation, which can further extend the applications of passive radiative cooling.

Poly(lactic acid)/artificially cultured diatom frustules nanofibrous membranes with fast and controllable degradation rates for air filtration.

The worldwide pandemic, coronavirus COVID-19, has been posing a serious threat to the global economy and security in last 2 years. The monthly consumption and subsequent discarding of 129 billion masks (equivalent to 645,000 tons) pose a serious detrimental impact on environmental sustainability. In this study, we report a novel type of nanofibrous membranes (NFMs) with supreme filtration performance and controllable degradation rates, which are mainly composed of polylactic acid (PLA) and artificially cultured diatom frustules (DFs). In this way, the filtration efficiency of particular matter (PM) and the pressure drop were significantly improved in the prepared PLA/DFs NFMs as compared with the neat PLA NFM. In specific, with incorporation of 5% DFs into fibers, PM0.3 removal with a filtration efficiency of over 99% and a pressure drop of 109 Pa were achieved with a membrane thickness of only 0.1 mm. Moreover, the yield strength and crystallinity degree of the PLA/DFs5 NFMs were sharply increased from 1.88 Mpa and 26.37% to 2.72 Mpa and 30.02%. Besides those unique characters, the PLA/DFs5 presented excellent degradability, accompanied by the degradation of 38% in 0.01 M sodium hydroxide solution after 7 days and approximately 100% in natural condition after 42 days, respectively. Meanwhile, the environmentally friendly raw materials of the composite polylactic acid and artificially cultured diatom frustules could be extracted from corn-derived biomass and artificially cultivated diatoms, ensuring the conformance to carbon neutrality and promising applications in personal protection. Supplementary information: The online version contains supplementary material available at 10.1007/s42114-022-00474-7.

Fast Self-Healing Superhydrophobic Thermal Energy Storage Coatings Fabricated by Bio-Based Beeswax and Artificially Cultivated Diatom Frustules.

Diatom frustules (DFs) with delicate hierarchical pores and a large specific surface area are extracted from artificially cultured diatoms, showing their utilization potential as shape-stabilized phase change materials (ss-PCMs). Herein, we successfully prepared a fully biomass-based ss-PCM, superhydrophobic thermal energy storage (STES) coating by employing beeswax (BW) as phase change materials (PCMs) and DFs as supporting materials via a facile spraying method. DFs can adsorb as much as 65 wt % BW without leakage, accompanied with a high heat storage capacity of 112.57 J/g. The thermal stability test demonstrates that the DF/BW coating can undergo 500 heating-freezing cycles with the reduction of the phase change enthalpy being less than 5%. Simultaneously, the DF also endows BW with a higher thermal degradation temperature (from ∼200 to ∼250 °C). In addition, the DF/BW coating shows superhydrophobicity due to the incorporation of the low surface energy of BW and the micro/nanostructures of DFs. This superhydrophobic surface can quickly and repeatedly recover its excellent water repellency through a simple heat treatment (80 °C, 20 min) after being damaged by a water impact or strong acid and alkali corrosion. This self-healing ability can effectively overcome the poor durability of traditional superhydrophobic materials. Our research can expand the application of DFs in the field of ss-PCMs and guide the preparation of durable superhydrophobic surfaces with rapid self-healing performance.