Facile Synthesis of Vertically Aligned One-Dimensional (1D) La(OH)₃and La₂O₃Nanorods by Pulse Current Deposition

Abstract

Cathodic electrodeposition of La(OH)3 from lanthanum nitrate bath was performed for the first time. The deposition experiments were conducted at the pulse current mode with a typical on-time and off-time (ton = 5 s and toff = 10 s) and an average current density of 1 mA cm−2 (Ia = 1 mA cm−2) for 50 min. The prepared deposit was then heat treated at 600°C for 3h in dry air atmosphere. The products were characterized by XRD, CHN, FT-IR and SEM techniques. The results revealed that the large scale and vertically aligned one-dimensional (1D) La(OH)3 nanorods have been prepared at the applied conditions. It is also seen that heat-treatment of the prepared hydroxide nanorods resulted the La2O3 nanorods without any change in their morphology. By recording the potential–time curve during the electrodeposition process, it was fund that water reduction reaction has the major role in the electrogeneration of base at the cathode surface. Based on the H2 bubbling on the cathode surface, the mechanism of the formation and the growth of La(OH)3 nanorods was proposed and discussed. Results of this work showed that large-scale, uniform and vertically aligned nanorods of La(OH)3 and La2O3 are achievable by pulse electrodeposition followed by heat-treatment.

Electroprecipitation of Nanometer-Thick Films of Ln(OH)3 [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

“…Previous studies have demonstrated that the simultaneous reduction of O 2 , H 2 O, and NO 3 – results in the formation of La­(OH) 3 nanostructures. − However, there are no reports detailing the formation of La­(OH) 3 films resulting from the oxygen reduction reaction (ORR).…”

“…Lanthanide hydroxides [Ln­(OH) 3 ] are used for defluoridation, in batteries, , for photoluminescence, , as supercapacitors, − as absorbents, , for photoelectrochemical water splitting, as emulsifying agents, and as a precursor to lanthanide oxides . Electroprecipitation has proven to be a powerful tool to fabricate Ln­(OH) 3 nanostructures such as (La, Nd) nanowires, (La) nanotubes, nanospindles, nanorods, − nanocapsules, and (La, Gd) nanoparticles . Precipitation on the electrode surface occurs in acidic or neutral solutions when the local pH near the electrode surface becomes basic during base-generating reactions, for example, NO 3 – + H 2 O + 2e – → NO 2 – + 2OH – . , Beyenal and co-workers demonstrated the correlation between La­(OH) 3 precipitation with an increase in local pH, based on electrochemical quartz crystal microbalance (eQCM) and local pH measurements. , The formation of nanometer-thick Ln­(OH) 3 films was confirmed with scanning electron microscopy (SEM), atomic emission spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS) analyses.…”

Preparation of LaTiO2N Using Hydrothermally Synthesized La2Ti2O7 as a Precursor and Urea as a Nitriding Agent

“…In addition, it also contains peaks attributed to La(OH) 3 . [49][50][51][52] Therefore, these nanorods co-existing with the main product can be assumed to be La(OH) 3 . Similar to previous reports, [46][47][48] rectangular nanosheets with an edge size on the submicrometer scale were observed.…”

One-step electrochemical preparation and characterization of nanostructured hydrohausmannite as electrode material for supercapacitors

“…H 2 bubbles can also affect the surface morphology of the deposit and also act as a dynamic template for the formation and the growth of deposit. 28 In the chemical step, Mn 2+ cations can react with the OH À ions produced on electrochemical step in two different ways, which can result in the formation of MnOOH (eqn (2)) and Mn 3 O 4 (eqn (3)) deposits, as schematically shown in Fig. 4b.…”