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)CO 3 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 La 2 O 3 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)CO 3 nanostructures can be successfully converted to La 2 O 3 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)CO 3 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)CO 3 nanostructures have a stronger ability to promote electron transfer between ascorbic acid (H 2 A) and the glass−carbon (GC) electrode than the bulk La(OH)CO 3 . 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.