Ultrafine Palladium Nanoparticles Stabilized in the Porous Liquid of Covalent Organic Cages for Photocatalytic Hydrogen Evolution

Soluble
covalent organic cages (COCs) were designed to comprise
cryptand inner cavities and multiple metal-chelating sites on windows.
The porous liquid formed by well-dispersed COCs in solution proves
to be an excellent stabilizer for ultrafine palladium nanoparticles
with a critical size of 1–3 nm using NaBH4 or methanol
as a reductant. When transferring palladium nanoparticles stabilized
in the porous liquid of COCs onto carbon nitride (g-C3N4), an efficient heterogeneous photocatalyst could be obtained
to possess high catalytic activity for hydrogen evolution from water
with long-term durability. This provides prospects for the application
of porous liquids in various fields by combining advantages of homogeneous
and heterogeneous attributes together.