Synthesis and Mechanism of Formation of Metal Nanosponges and their Catalytic and Hydrogen Sorption Properties

摘要

Metal nanosponges of silver, gold, palladium, platinum, and copper have been prepared via simple reduction of their salts using ammonia borane or substituted amine boranes. This synthetic method involves metal salt reduction using amine borane which forms nanoparticles in the absence of capping agent in high dielectric solvent; these colloidal particles attach together to form three dimensional porous metal nanosponges. Hydrogen storage properties of these metal nanosponges were investigated by measuring pressure-composition isotherms. Furthermore, the catalytic activities of these metal nanosponges were tested for 4-nitrophenol reduction which showed better catalytic activity as compared to their bulk state. Among all the metal nanosponges, palladium showed highest catalytic activity which was found to be recyclable over several cycles and the porous structure remained intact after catalysis. Herein, improvement in the catalytic activity and hydrogen storage characteristics of porous metals with respect to their bulk analogues further signifies the importance of nanoporous structures.