Reducing human reliance on energy-inefficient cooling methods such as air conditioning would have a large impact on the global energy landscape. By a process of complete delignification and densification of wood, we developed a structural material with a mechanical strength of 404.3 megapascals, more than eight times that of natural wood. The cellulose nanofibers in our engineered material backscatter solar radiation and emit strongly in mid-infrared wavelengths, resulting in continuous subambient cooling during both day and night. We model the potential impact of our cooling wood and find energy savings between 20 and 60%, which is most pronounced in hot and dry climates.
HIGHLIGHTS Covalent organic frameworks (COFs) are first used in tumor photodynamic therapy BODIPY-decorated COFs are synthesized via bonding defects functionalization BODIPY-decorated COFs have excellent anti-tumor efficacy in vitro and in vivo COFs show great promise as nanoplatforms for biomedical applications
The ability to produce
a diverse spectrum of hollow nanostructures
is central to the advances in many current and emerging areas of technology.
Herein, we report a general method to craft hollow nanostructures
with highly tunable physical and chemical parameters. The key strategy
is to regenerate the nanoscale sacrificial templates in a galvanic
replacement reaction through site-selective overgrowth. As examples,
we demonstrate the syntheses of nanocages and nanotubes made of silver,
gold, palladium, and/or platinum with well-controlled wall thicknesses
and elemental distributions. Using the nanocages of silver and gold
as models, we demonstrate they possess intriguing plasmonic properties
and offer superior performance in biosensing applications. This study
provides a powerful platform to customize hollow nanostructures with
desired properties and therefore is expected to enable a variety of
fundamental studies and technologically important applications.
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