No abstract

Heat dissipation is a severe barrier for ever-smaller and more functionalized electronics, necessitating the continuous development of accessible, costeffective, and highly efficient cooling solutions. Metals, such as silver and copper, with high thermal conductivity, can efficiently remove heat. However, ultralow infrared thermal emittance (<0.03) severely restricts their radiative heat dissipation capability. Here, a solution-processed chemical oxidation reaction is demonstrated for transfiguring "infrared-white" metals (high infrared thermal reflectance) to "infrared-black" metametals (high infrared thermal emittance). Enabled by strong molecular vibrations of metal-oxygen chemical bonds, this strategy via assembling nanostructured metal oxide thin films on metal surface yields infrared spectrum manipulation, high and omnidirectional thermal emittance (0.94 from 0 to 60°) with excellent thermomechanical stability. The thin film of metal oxides with relatively high thermal conductivity does not hinder heat dissipation. "Infrared-black" metaaluminum shows a temperature drop of 21.3 °C corresponding to a cooling efficiency of 17.2% enhancement than the pristine aluminum alloy under a heating power of 2418 W m −2 . This surface photon-engineered strategy is compatible with other metals, such as copper and steel, and it broadens its implementation for accelerating heat dissipation.

Water shortage is a critical global issue that threatens human health, environmental sustainability, and the preservation of Earth’s climate. Desalination from seawater and sewage is a promising avenue for alleviating this stress. In this work, we use the hornet nest envelope material to fabricate a biomass-based photothermal absorber as part of a desalination isolation system. This system realizes an evaporation rate of 3.98 kg m –2 h –1 under one-sun illumination, with prolonged evaporation rates all above 4 kg m –2 h –1 . This system demonstrates a strong performance of 3.86 kg m –2 h –1 in 3.5 wt % saltwater, illustrating its effectiveness in evaporation seawater. Thus, with its excellent evaporation rate, great salt rejection ability, and easy fabrication approach, the hornet nest envelope constitutes a promising natural material for solar water treatment applications.