Bottom-up mechanochemical synthesis of metal nanoparticles

Abstract

Metal nanoparticles (NPs) have numerous properties, making them suitablematerials for application in catalysis, energy conversion, sensing and biomedicine. Theconstant need for a more sustainable chemistry and materials preparation has motivatedthe research for alternative eco-friendly routes of synthesis. In such context, solid-statemechanochemical means, such as ball milling, have been of great interest. Thepreparation of metal nanoparticles using milling have been extensively explored fromtop-down approach. This is, from the comminution and severe plastic deformation of thebulk material. However, top-down approaches are incapable of controlling thenanoparticles structure, particularly the morphology. On the other hand, the synthesis ofmetal nanoparticles from the bottom-up approach, i.e., by the chemical reduction of themetal precursor, enables the construction of the nanostructure by controlling the rate ofthe chemical reaction, nucleation and growth of the nanoparticle. The bottom-up mechanochemical synthesis of metal nanoparticles is relatively recent and manychallenges remain in controlling the size and morphology of the nanoparticles.There isa lack of studies intending to control the nanoparticle design via mechanochemistry. In this project, a diversity of metal nanoparticles will be prepared using bottom-upmechanochemical approach. Ag, Pd as well as Cu NPs will be synthesized in ball millingdevices. The reaction conditions, including the metal precursor, the reducing and thecapping agent will be studied. The effect of the milling device planetary and vibratorymill , i.e., the type of mechanical energy input, on the size and morphology of thenanoparticles will also be investigated. The material will be characterized usingTransmission electron microscopy (TEM), Powder X-ray Diffraction (PXRD) and X-rayphotoelectron Spectroscopy (XPS). The use of synchrotron-based techniques is alsoenvisaged for in situ characterizations. This project will enable to understand the effectsof the reaction conditions on the nanoparticles structure. Additionally, we expect tounravel the mechanisms of nanoparticles formation using advanced characterizationtechniques. The relevant materials will be tested in catalytic reactions. This project willbe paving the way for the controlled mechanochemical design of advanced activematerials for technological ends.