Micron-sized hexagonal single-crystalline rods of metal nitride clusterfullerene: preparation, characterization, and photoelectrochemical application

Abstract

Micron-sized hexagonal single-crystalline Sc₃N@C₈₀ rods have been successfully prepared for the first time by a liquid–liquid interfacial precipitation (LLIP) method with the first utilization of p-xylene as the solvent dissolving Sc₃N@C₈₀. The effect of the concentration of the Sc₃N@C₈₀ solution on the size and length of the Sc₃N@C₈₀ rods has been studied, indicating that the length of Sc₃N@C₈₀ rods can be readily controlled by varying the concentration of the Sc₃N@C₈₀ solution. The crystal structure of the Sc₃N@C₈₀ rods has been investigated by XRD and the electron diffraction patterns, pointing to a hexagonal system. The growth kinetics of the Sc₃N@C₈₀ rods has been studied by monitoring the morphology evolution of the Sc₃N@C₈₀ crystals, and a plausible mechanism is proposed, featuring an intermediate hexagonal star-shaped prism structure with grooves. Raman spectroscopic characterization confirmed that the Sc₃N@C₈₀ rods are composed of monomeric pristine Sc₃N@C₈₀ molecules and no polymerization has occurred in the crystal lattice, and a significant Raman enhancement in the low-energy region is observed. According to the UV-vis-NIR absorption spectroscopic study of the Sc₃N@C₈₀ rods, where much broader and stronger absorptions in the visible and near-infrared regions than that of the Sc₃N@C₈₀ solution were revealed, we conclude that the electronic structure of the Sc₃N@C₈₀ molecule is largely perturbed upon formation of micron-sized single-crystalline rods because of the strong intermolecular π–π interactions. Finally photoelectrochemical application of the Sc₃N@C₈₀ rods was studied based on a Sc₃N@C₈₀ rods-modified ITO electrode prepared by electrophoretic deposition and revealed a higher photocurrent response than that obtained in the Sc₃N@C₈₀ films drop-coated onto an ITO electrode.