Nano/Micro Metal–Organic Framework‐Derived Ceramics for Sustainable Energy Saving/Capturing

Abstract To combat the global energy crisis, passive radiative cooling materials provide more sustainable solutions to save energy for cooling buildings and capture renewable energy for powering them. However, the design of passive radiative cooling materials is subject to a trade‐off between solar reflectance and practicality. To overcome this dilemma, a low‐temperature co‐firing ceramic is reported that integrates hierarchically structured alumina particles—derived from nano/micro metal–organic frameworks—within a glass matrix. These alumina particles enhance light backscattering by utilizing optimized geometric parameters and high porosity to achieve near‐perfect solar reflectance (>0.98), while the glass matrix ensures high long‐wave infrared emittance (0.93). This synergy enables a maximum sub‐ambient temperature reduction of 7.4 °C during the daytime and a midday short‐circuit current boost of 10.46 mA. Global simulations project a net CO 2 emission reduction of 1.43 billion metric tons through reducing cooling demands and enhancing photovoltaic output. Combined with robust mechanical strength (43 MPa), UV resistance (>2000 h), superhydrophobicity (150° water contact angle, maintaining an exceptional solar reflectance of 0.97), flame resistance (>1000 °C tolerance), and near‐100% recyclability, this low‐cost and scalable ceramic provides an effective strategy to accelerate the global transition toward climate‐neutral infrastructure.