As global temperature rises rapidly, the impact of refrigeration consumption on the growth of global electricity demand is becoming increasingly significant. Radiative sky cooling is an emerging passive cooling technology, which, through spectral manipulation, radiates energy as heat into outer space through the "atmospheric window", thereby lowering building temperatures without energy input. In recent years, with the development of radiative cooling materials (such as photonic crystals), radiative cooling has demonstrated potential applications not only at night but also under sunlight. This paper was aimed to review the principles and structural designs of radiative sky cooling technology from the perspective of material development and analyzes the challenges faced by integrated building-radiative cooling systems. Finally, by summarizing the applications of radiative cooling materials in cool roofs and building cooling systems, it is aimed to provide new insights into the preparation of sky radiative cooling materials.

Rational design of electrocatalysts is important for a sustainable oxygen evolution reaction (OER). It is still a huge challenge to engineer active sites in multi-sizes and multi-components simultaneously. Here, a series of CoP nanoparticles (NPs) confined in an SiO₂ matrix (SiO₂/Co_xP) is designed and synthesized as OER electrocatalysts. The phosphorization of the hydrolyzed Co-phyllosilicate promotes the formation of ultrasmall and small Co₂P and CoP. These are firmly confined in the SiO₂ matrix. The coupling of multi-size and multi-component CoP catalysts can regulate reaction kinetics and electron transfer ability, enrich the active sites, and eventually promote the intrinsic OER activity. The SiO₂ matrix provides abundant porous structure and oxygen vacancies, and these facilitate the exposure of active sites and improve conductivity. Because of the synergy and interplay of multi-sized/component Co_xP NPs and the porous SiO₂ matrix, the unique SiO₂/CoP heterostructure exhibits low overpotential (293 ​mV@10 ​mA ​cm^-2), and robust stability (decay 12 ​mV after 5000 CV cycles, 97.4% of initial current after 100 ​h chronoamperometric) for the OER process, exceeding many advanced metal phosphide electrocatalysts. This work provides a novel tactic to design low-cost, simple, and highly efficient OER electrocatalysts.