Direct Solution Synthesis of Transition Metal Borides

Abstract

Recent years have seen an increase in the study of metal borides due to their multifaceted applications, ranging from abrasive materials to superconductors. This variety in function emerges from the distinctive bonding properties of boron, which gives rise to diverse structures and stoichiometries in metal borides. An area of significant exploration is the use of metal borides in the electrocatalysis of water, specifically in hydrogen evolution and oxygen evolution reactions, as well as hydrogen storage. Notably, successful hydrogen storage has only been achieved with MgB2 (i.e., interconversion with Mg(BH4)2) among all the metal borides studied so far. Synthesizing metal borides, however, presents a challenge. In response to this, I have investigated the direct solution synthesis using chemical reduction using a Schlenk techniques at 280 °C and using high pressure high temperature reactors at 180 °C. The materials studied included nickel boride, zirconium boride, cobalt boride, and a nickel-zirconium bimetallic boride. Although only the synthesis of nickel and zirconium borides were found to successfully produce well-defined crystalline nanoparticles, these outcomes provide promising indicators for future efforts in creating crystalline transition metal boride nanoparticles.