RESUMEN
Passive radiative cooling using nanophotonic structures is limited by its high cost and poor compatibility with existing end uses, whereas polymeric photonic alternatives lack weather resistance and effective solar reflection. We developed a cellular ceramic that can achieve highly efficient light scattering and a near-perfect solar reflectivity of 99.6%. These qualities, coupled with high thermal emissivity, allow the ceramic to provide continuous subambient cooling in an outdoor setting with a cooling power of >130 watts per square meter at noon, demonstrating energy-saving potential on a worldwide scale. The color, weather resistance, mechanical robustness, and ability to depress the Leidenfrost effect are key features ensuring the durable and versatile nature of the cooling ceramic, thereby facilitating its commercialization in various applications, particularly building construction.
RESUMEN
Transparent wood (TW) has emerged as a sustainable alternative to conventional glass as an energy-efficient window glazing material owing to its exceptional optical transparency and superior mechanical and thermal performances. However, it is challenging to develop the TW-based color-switching smart windows with both high optical performance and mechanical strengths. In this work, an optically switchable and mechanically robust perovskite-coated thermochromic transparent wood (PTTW) is developed for use as smart windows to achieve an effective solar modulation and thermal management. PTTW exhibits a substantial solar modulation ability Δτsol of 21.6% and a high clear-state luminous transmittance τlum of 78.0%, which enable an efficient thermal regulation while ensuring high visual clarity. PTTW also offers enhanced mechanical properties (i.e., tensile strength σtens = 71.4 MPa and flexural strength σflex = 93.1 MPa) and improved thermal properties [i.e., thermal conductivity K = 0.247 W/(m·K) and heat capacity C = 1.69 J/(g·°C)] compared to glass-based smart windows, as well as excellent performance stability (i.e., 200 heating-cooling cycles), manifesting its applicability in real building scenarios. In addition, PTTW also demonstrates a remarkable thermal-regulating performance (i.e., 5.44 °C indoor air temperature regulation) and an energy-saving potential (i.e., 12.9% heating, ventilation, and air conditioning energy savings) in Hong Kong. Overall, this study contributes to the progression toward energy-efficient and sustainable buildings.
RESUMEN
Uncontrolled sunlight entering through windows contributes to substantial heating and cooling demands in buildings, which leads to high energy consumption from the buildings. Recently, perovskite smart windows have emerged as innovative energy-saving technologies, offering the potential to adaptively control indoor solar heat gain through their impressive sunlight modulation capabilities. Moreover, harnessing the high-efficiency photovoltaic properties of perovskite materials, these windows have the potential to generate power, thereby realizing more advanced windows with combined light modulation and energy harvesting capabilities. This review summarizes the recent advancements in various chromic perovskite materials for achieving light modulation, focusing on both perovskite structures and underlying switching mechanisms. The discussion also encompasses device engineering strategies for smart windows, including the improvement of their optical and transition performance, durability, combination with electricity generation, and the evaluation of their energy-saving performance in building applications. Furthermore, the challenges and opportunities associated with perovskite smart windows are explicated, aimed at stimulating more academic research and advancing their pragmatic implementation for building energy efficiency and sustainability.
RESUMEN
Benefitting from the coalescence-induced droplet jumping on superhydrophobic surfaces, the condensing droplets on heat exchangers can be removed efficiently, significantly improving the condensation heat-transfer performance of various thermal applications. However, the enhancement of droplet jumping height and self-removal to further improve the condensation heat-transfer performance of the thermal applications remains a challenge due to considerable interfacial adhesion caused by the inevitable partial-Wenzel state condensing droplets on superhydrophobic surfaces. In this study, a biphilic nanostructure is developed to effectively improve the droplet jumping height by decreasing the interfacial adhesion with the formation of Cassie-like droplets. Under atmospheric conditions, â¼28% improvement of droplet jumping height is achieved on a biphilic surface compared to that of a superhydrophobic surface. Additionally, the droplet contact electrification on biphilic surfaces discovered in this work allows the droplets to jump â¼137% higher compared with that under atmospheric conditions. Furthermore, the droplet jumping and electrification mechanisms on the biphilic surface are revealed by building a theoretical model that can predict the experimental results well. Apart from being a milestone for the droplet jumping physics development on biphilic nanostructures, this work also provides new insights into the micro-droplet discipline.
