LAUSR

There has been significant interest in the area of zeolite synthesis, and more broadly in the development of microporous catalysts, to establish methods of reducing crystal size. A promising approach to tailor crystal habit is the use of organic modifiers, which are molecules capable of altering the anisotropic rates of crystal growth to generate crystalline materials with well-defined size and shape. Here, we examine the putative mechanism by which a modifier alters the growth of silicalite-1, a siliceous zeolite that is often used as a model for fundamental studies of crystallization. The modifier selected for this study is the amino acid arginine, which decomposes in situ to ornithine-lactam with the release of acid. A concomitant reduction in solution pH provides a unique opportunity to switch the growth medium from a solution of soluble silicate species (monomers) to one comprising amorphous silica nanoparticle precursors. These distinct growth units operate by disparate modes of action: monomer addi...