Probing the dynamics of Cu nanoparticle growth inside metal-organic frameworks upon electron beam irradiation

•In situ TEM allows observing the growth of NPs from constituent parts of MOFs.•The dynamic of the growth of NPs can be modeled by JMAK.•Tuning the e-beam parameters allows one to manipulate the NP diameter and rate of growth. Metal-organic frameworks (MOFs) represent a unique platform for fabrication of nanoparticles (NPs) of diverse composition and crystallinity. The growth of NPs from constituent parts of MOFs is usually initiated by external stimuli such as temperature, light and electron irradiation. Herein, the kinetics and NP growth mechanisms remain unexplored. Here, we utilized electron irradiation to initiate the nucleation and growth of crystalline Cu NPs of tunable size from several nanometers to hundreds of nanometers inside MOF as a precursor. Simultaneously, the process of the NPs growth, captured in real time using transmission electron microscope, demonstrates the evolution of their size, shape and spatial distribution. We also analyze the NP growth by the classical kinetic theory taking into account a phase transformation. Our results contribute to crystal engineering and developing of functional MOF-based nanocomposites.