Hydroxide‐Derived Nanostructures: Scalable Synthesis, Characterization, Properties, and Potential Applications

Abstract

Metal oxide nanostructures have received an increasing attention owing to their unique chemical and physical properties along with their widespread applications in various fields. In this article, we provide an overview of our recent discovery – christened Hydroxides‐Derived Nanostructures, or HDNs – in which we react hydroxide aqueous solutions (mostly tetramethylammonium hydroxide, TMAH) at temperatures < 100 °C and under atmospheric pressure with various metal‐containing precursors to scalably prepare novel metal oxide nanostructures. In one case, we converted a dozen commercial and earth abundant Ti‐containing powders such as binary carbides, nitrides, borides, among others, into new, one‐dimensional TiO2–based lepidocrocite (1DL) nanofilaments (NFs). Application‐wise, 1DLs show outstanding performance in a number of energy, environmental, and biomedical fields such as photo‐ and electrocatalysis, water splitting, lithium‐sulfur and lithium‐ion batteries, water purification, dye degradation, cancer therapy, and polymer composites. In addition to 1DL, the HDNs family encompasses other metal oxides nanostructures including magnetic Fe3O4 nanoparticles and MnO2 birnessite‐based crystalline two‐dimensional (2D) flakes. The latter showed promise as a bifunctional electrocatalyst for water oxidation and oxygen reduction, as well as cathodes in aqueous asymmetric supercapacitor and in an aqueous ammonium ion battery. Our developed recipe provides a new vista in the molecular self‐assembly synthesis of metal oxide nanomaterials that can advance the field with a library of novel nanostructures with substantial implications in a multitude of fields.This article is protected by copyright. All rights reserved

Investigation of Ultramicroporous Structure of One-Dimensional Lepidocrocite Titanates Using Carbon Dioxide and Nitrogen Gases

“…The SEM micrograph shown in Figure A, clearly shows the 1D nature of our material. Based on these results, we conclude that our material is a 1DL titanate. , Figure B shows a high-resolution TEM image of our sample. The sample possesses a wire-like structure consistent with the SEM image, and black circle regions can be observed.…”

“…Recently, we discovered a simple, single pot, scalable method to make a truly one-dimensional, 1D, TiO 2 . Because the structure is that of lepidocrocite, we refer to this new form of TiO 2 as 1DL. − Using a combination of X-ray diffraction, XRD, and high resolution transmission electron microscope (HRTEM) images, we concluded that the 1DL are nanofilaments (NF) 5 × 7 Å 2 in minimum cross-section and tens of nanometers in length. , Figure A shows a schematic of a single 1DL comprised of 2 × 2 edge shared TiO 6 octahedra.…”