Molecularly Engineered Lithium–Chromium Alkoxide for Selective Synthesis of LiCrO<sub>2</sub> and Li<sub>2</sub>CrO<sub>4</sub> Nanomaterials

oleh: Olusola Ojelere, David Graf, Sanjay Mathur

Format: Article
Diterbitkan: MDPI AG 2019-02-01

Deskripsi

Achieving control over the phase-selective synthesis of mixed metal oxide materials remains a challenge to the synthetic chemist due to diffusion-driven growth, which necessitates the search for new compounds with pre-existent chemical bonds between the phase-forming elements. We report here a simple solvothermal process to fabricate LiCrO<sub>2</sub> and Li<sub>2</sub>CrO<sub>4</sub> nanoparticles from bimetallic single-source precursors, demonstrating the distinctive influence of molecular design and calcination conditions on the resulting nanomaterials. The chemical identity of [Li<sub>2</sub>Cr(O<i><sup>t</sup></i>Bu)<sub>4</sub>Cl(THF)<sub>2</sub>] (<b>1</b>) and [LiCr(O<i><sup>t</sup></i>Bu)<sub>2</sub>(PyCH=COCF<sub>3</sub>)<sub>2</sub>(THF)<sub>2</sub>] (<b>2</b>) was unambiguously established in the solid state by single-crystal X-ray diffraction, revealing the formation of a coordination polymeric chain in compound <b>1</b>, whereas electron paramagnetic resonance spectroscopy (EPR) studies revealed a monomeric structure in solution. TEM analysis of synthesized LiCrO<sub>2</sub> nanoparticles showed nearly uniform particles size of approximately 20 nm. The sensitivity of the LiCrO<sub>2</sub> phase towards oxidation was investigated by X-ray diffraction, revealing the formation of the stable Li<sub>2</sub>CrO<sub>4</sub> after calcination in air.