Crystal morphology control of synthetic Giniite by alkaline cations and pH variations

Abstract

The synthetic analogue of the mineral giniite is a promising material for capture of phosphopeptides from complex tryptic digests, photocatalysis and cathode for lithium battery applications. In all these applications, the crystal morphology of giniite shows to be extremely important, however, the reported synthesis and crystal morphologies are scattered among a variety of approaches. Here we report a hydrothermal synthesis that allows achieving five different morphologies of giniite only by changing the pH by addition of three different alkaline cations (Na+, Li+ and K+) in form of hydroxides. At pH 2, micrometric sphere-like assemblies of nanoparticles were obtained. At pH 4, fractal dendritic crystals as well as intergrown flower-like and asterisk-like crystals were synthesized. At pH 6, the synthesis resulted in dagger-like crystals of dissolved dendritic structures.