In the present work TiO 2 nanotubes (TNT) have been synthesized by alkaline hydrothermal transformation. Then they have been doped with Gd element. Characterizations of doped and undoped TNT have been done with TEM and SEM. The chemical composition was analyzed by EDX, Raman and FTIR spectroscopy. The crystal structure was characterized by XRD. Carbon paste electrode has been fabricated and mixed with Gd doped and undoped TNT to form a nanocomposite working electrode. Comparison of bare carbon paste electrode and Gd doped and undoped TNT carbon paste electrode for 1.0 ×10 −3 M K 4 [Fe(CN) 6 ] voltammetric analysis; it was observed that Gd doped TNT modified electrode has advantage of high sensitivity. Gd doped TNT modified electrode has been used as working electrode for itopride assay in a pharmaceutical formulation. Cyclic voltammetry analysis showed high correlation coefficient of 0.9973 for itopride (0.04-0.2 mg/mL) with a limit of detection (LOD) and limit of quantitation values (LOQ) of 2.9 and 23.0 µg.mL −1 respectively.
Self-organized anodic double layer TiO 2 nanotube arrays (TNTAs) were sensitized by an electrochemical anodization process on a Ti sheet with a two-step anodization method. The prepared sample, followed by hydrothermal treatment with Nd(NO 3 ) 3 and/or Gd(NO 3 ) 3 and/or PtCl 4 solution at 180 C for 2 h, produced Nd-Pt-TNTAs, Gd-Pt-TNTAs, Nd-Gd-Pt-TNTAs and Pt-TNTAs. The morphological and structural properties were studied by SEM, XRD and Raman spectra techniques. The hydrogen evolution reaction (HER) performance on Lanthanides-Pt-TNTAs was investigated using the Tafel linear polarization technique. The calculated values of the activation energy are in good agreement with the trend in catalytic activity. The excellent performance of doped TNTAs with low activation energy (E a ) is due to the formation of an excitation energy level below the conduction band of TiO 2 from the binding of electrons with oxygen vacancies decreasing the excitation energy resulting in robust electrocatalytic activity. The very low value of E a for Nd-Gd-Pt-TNTAs (2.02 kJ/mol) compared to other electrochemical catalysts used for hydrogen evolution reactions containing titanium nanotubes was achieved for the first time. This makes the Lanthanides -Pt-TNTAs prepared in the present work optimal catalysts for electrodes and promising for applications in fuel cells or as water splitting materials.
HIGHLIGHTSSynthesis of self-organized anodic double layer TiO 2 nanotube arrays (TNTAs) on a Ti sheet with a two-step anodization method. Nd, Gd, Pt were deposited on anodic TNTAs arrays by hydrothermal method. The HER mechanisms on Lanthanides-Pt-TNTAs in acidic media has been discussed. The order of catalytic activity based on the values of activation energy was Nd-Gd-Pt-TNTAs > Gd-Pt-TNTAs > Nd-Pt-TNTAs > Pt-TNTAs > undoped TNTAs.
Titanium dioxide (TiO 2 ) doped with neodymium (Nd) and/or Gadolinium (Gd) rare-earth elements were fabricated into nanotubes via the hydrothermal method in a KOH solution and in-situ doping. Titanium dioxide nanotubes (TNTs) and in-situ Nd-doped and/or Gd-doped TNTs were characterized with transmission and scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, Raman spectroscopy, and Fourier-transform infrared spectroscopy. Morphologies indicated a network of aggregated nanotubes. The phase and composition analyses revealed that the lanthanide TNTs had anatase phases with Nd and/or Gd nanoparticles in the TNT lattice. The nanoparticles were uniformly deposited on the surface because of hydroxyl groups on the TNT surfaces, resulting in a very high loading density. The outer diameter and the length of the TNTs increased with doping. The mechanisms for the formation of multiwall TNTs are discussed.
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