Biomolecular-Induced Synthesis of Self-Assembled Hierarchical La(OH)CO₃One-Dimensional Nanostructures and Its Morphology-Held Conversion toward La₂O₃and La(OH)₃

Abstract

Novel hierarchical layer-by-layer self-assembled one-dimensional (1D) La(OH)CO3 nanostructures, with a diameter of around 700 nm and lengths in the range of 6−8 μm, were synthesized by a developed hydrothermal method using La2O3 and glycine as the starting materials. Various experimental conditions, such as the reaction time, temperature, and the molar ratios of the starting reagents, were studied. The obtained 1D La(OH)CO3 nanostructures can be successfully converted to La2O3 and La(OH)3 nanorods via calcination under appropriate conditions. Analytical methods such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and selected area electron microscopy were employed to characterize these products, and the possible growth mechanism of 1D La(OH)CO3 nanostructures was explored. The UV−visible diffuse reflectance absorbance spectra indicate that the 1D nanostructures have enhanced UV-light absorbance properties in contrast to the bulk materials. The electrochemical studies show that 1D La(OH)CO3 nanostructures have a stronger ability to promote electron transfer between ascorbic acid (H2A) and the glass−carbon (GC) electrode than the bulk La(OH)CO3. These layer-by-layer self-assembled hierarchical products have possible application as an efficient support matrix for the immobilization of enzymes and some biomolecules. This one-pot method is likely to be useful in the preparation of many other layered structures.