Perchloric Acid Solutions Research Articles

Measuring the Capacitance at Few- and Many-Layered Graphene Electrodes in Aqueous Acidic Solutions

The differential capacitance of 1–2 layered and 6–7 layered graphene (LG) was measured in aqueous 0.01, 0.1, 1.0, and 3 M perchloric and sulfuric acid solutions. The total measured capacitance was evaluated for approx. ±500 mV either side of the potential of zero charge to observe the contribution from the quantum capacitance and shielding effects on the measured capacitance. The experimental results were compared to the recent theoretical evaluations of similar electrode–electrolyte interfaces for supercapacitor applications. At 6–7 LG electrodes, the measured differential capacitance was dependent on the solution and electrical double layer structures, and although the 1–2 layered electrode showed far fewer differences upon changing solution conditions, it was not strictly independent. The concept of shielding effects within the graphene electrode and a dielectric capacitance as proposed by theory would account for these observations.

Pt-Pd Bimetal Popcorn Nanocrystals: Enhancing the Catalytic Performance by Combination Effect of Stable Multipetals Nanostructure and Highly Accessible Active Sites.

Exploration of highly efficient electrocatalysts is significantly urgent for the extensive adoption of the fuel cells. Because of their high activity and super stability, Pt-Pd bimetal nanocrystals have been widely recognized as one class of promising electrocatalysts for oxygen reduction. This article presents the synthesis of popcorn-shaped Pt-Pd bimetal nanoparticles with a wide composition range through a facile hydrothermal strategy. The hollow-centered nanoparticles are surrounded by several petals and concave surfaces. By exploring the oxygen reduction reaction on the carbon supported Pt-Pd popcorns in perchloric acid solution, it is found that compared with the commercial Pt/C catalyst the present catalysts display superior catalytic performances in aspects of catalytic activity and stability. More importantly, the Pt-Pd popcorns display minor performance degradations through prolonged potential cycling. The enhanced performances can be mainly attributed to the unique popcorn structure of the Pt-Pd components, which allows the appearance and long existence of the high active sites with more accessibility. The present work highlights the key roles of accessible high active sites in the oxygen reduction reaction, which will ultimately guide the design of highly durable Pt-Pd catalysts.

Morphological changes of porphine films on graphite by perchloric and phosphoric electrolytes: An electrochemical-AFM study

Organic molecules have been proposed as promising candidates for electrode protection in acidic electrolytes. The use of tetraphenyl-porphines (H2TPP) as graphite surface-protecting agents in sulphuric acid (H2SO4) is one of the newest. With the aim of unveiling the mechanism of such a protective effect, in this paper we test the stability of a H2TPP thin film immersed in perchloric and phosphoric acid solutions that differently interact with porphyrins.The protective role of H2TPP is tested in the electrochemical potential range where the pristine graphite undergoes an oxidation process that erodes the surface and eventually exfoliate the stratified crystal. The electrochemical analysis is performed in a three-electrode cell, while the surface morphology is monitored ex-situ and in-situ by atomic force microscopy. Electrospray mass analysis is also employed to investigate the presence of H2TPP fragments in the solution. We find that the organic film is not stable in perchloric solution, while it is stable and avoids graphite surface corrosion in phosphoric acid solution. These results provide a rationale for the role played by free-base porphines in graphite protection.

Size-controllable synthesis of dendritic Pd nanocrystals as improved electrocatalysts for formic acid fuel cells’ application

Control over size and shape of Pd nanocrystals is critical for highly active and stable catalysts in direct formic acid fuel cells’ application. In this work, dendritic Pd nanocrystals have been successfully synthesized using a facile, environmentally friendly approach in an aqueous solution below 100 °C. The size of as-synthesized dendritic Pd nanocrystals has a narrow distribution, about 57.5 ± 7.5 nm. The dendritic Pd nanocrystals exhibit much superior electrocatalytic properties for formic acid oxidation compared with commercial Pd black in acidic medium. The specific activity and mass activity toward formic acid oxidation on dendritic Pd nanocrystals are 5.14 mA/cm2 and 3.3 A/mg in perchloric acid solution, 2.0 mA/cm2 and 1.08 A/mg in sulfuric acid solution, respectively. And for commercial Pd black, the specific activity and mass activity are 2.08 mA/cm2 and 0.36 A/mg in perchloric acid solution, 0.68 mA/cm2 and 0.12 A/mg in sulfuric acid solution. Furthermore, chronoamperometric measurements show that the dendritic Pd nanocrystals have excellent stability over commercial Pd black.

Detection of ten biogenic amines in Chinese commercial soybean paste by HPLC

ABSTRACTThis paper aimed to develop a high-performance liquid chromatography (HPLC) method that can simultaneously detect ten biogenic amines (BAs) in commercially available soybean paste and to determine the contents of BAs in these products. Heptylamine (Hep) was used as the internal standard reagent and benzoyl chloride as the sample derivatization reagent; Inertsil ODS-3 chromatographic column was set as the stationary phase while the acetonitrile and 5 mmol/L ammonium acetate solution as the mobile phases; the samples were treated with gradient elution and detected at 254 nm (UV). Perchloric acid solution (0.4 mol/L) was employed as the sample extraction solvent to determine the contents of ten BAs in soybean paste products. All BAs were separated within 20 min. The methodological validation suggested good linearity, whereas the linear correlation coefficient of all standards was greater than 0.99 with the linear range of 0.1–80 μg/g, detection limits of 0.01–0.03 μg/g, and quantitation limits of 0.03–0.10 μg/g. For 17 commercially available soybean paste products involved in our study, different samples were distinguished from each other not only by the dramatic differences in the contents of BAs but also by the variance in BA types. Of these BAs, tyramine (Tyr) and agmatine (Agm) were found to be the highest contents in soybean paste products; the contents of histamine (His), 2-phenylethylamine (Phe), serotonin (Ser), spermidine (Spd), and putrescine (Put) were lower, followed by cadaverine (Cad), tryptamine (Try), and spermine (Spm). This method proved to be highly sensitive and effective in determining the contents of BAs in soybean paste products; there was a dramatic difference in the contents of ten BAs among different soybean paste products.

Simultaneous and selective electrochemical determination of hydroquinone, catechol and resorcinol at poly(1,5-diaminonaphthalene)/glassy carbon-modified electrode in different media.

The electrochemical behavior of phenolic isomers hydroquinone (HQ), catechol (CC) and resorcinol (RC) was examined in poly(1,5-diaminonaphthalene)/glassy carbon-modified electrode (P1,5-DAN/GC M.E.) by cyclic voltammetry (CV), square wave voltammetry (SWV) and chronoamperometry (CA) techniques in perchloric acid (HClO4) and phosphate buffer solution (PBS, pH 7.0). P1,5-DAN/GC M.E. was investigated for simultaneous determination of HQ, CC and RC in single, binary and ternary systems. Oxidation peak potentials were negatively shifted with increasing oxidation peak current for HQ, CC and RC at P1,5-DAN/GC M.E. compared with bare GC electrode. The obtained results illustrate that the former electrode exhibits better performance towards the three isomers in PBS rather than in HClO4 solution. The catalytic currents for different concentrations of HQ, CC and RC showed good relationship in the range of 0.1–100 μM for all analytes and low detection limits (LOD) of 0.034, 0.059 and 0.14 μM for them, respectively, in a ternary system in PBS at pH 7.0. This method has been practically applied for the detection of these isomers in tap water with acceptable results.

Electrochemical Roughening of Thin-Film Platinum for Neural Probe Arrays and Biosensing Applications

We report a method for electrochemical roughening of thin-film platinum (Pt) electrodes that increases active surface area, decreases electrode impedance, increases charge injection capacity, increases sensitivity of biosensors and improves adhesion of electrochemically deposited films. First, a well-established technique for electrochemical roughening of thick Pt electrodes (wires and foils) by oxidation-reduction pulses was modified for use on thin-film Pt. Optimal roughening of thin-film Pt electrodes with this established protocol in a sulfuric acid solution was found to occur at about four times lower frequency than that typically used for thick Pt. This modification in established procedure created a 21x surface area increase but showed nanoscale cracks from inter-grain Pt dissolution that compromised film integrity. A crack free surface with Pt nanocrystal re-deposition (20–30 nm in size) and higher enhancement in surface area (44x) was obtained when the electrolyte was switched to a non-adsorbing perchloric acid solution. These electrochemically roughened electrodes have charge injection limits comparable to titanium nitride and just below carbon nanotube-based materials. Roughened microelectrodes showed a 2.8x increase in sensitivity to hydrogen peroxide detection, indicative of improved enzymatic biosensor performance. Platinum iridium and iridium oxide coatings on these roughened surfaces showed an improvement in adhesion.

RP-LC Method for the Determination of Seven Antiviral Drugs and Bioanalytical Application for Simultaneous Determination of Lamivudine and Penciclovir in Human Plasma

An RP-LC method was developed and validated for separation and determination of seven antiviral drugs in their drug substances and drug products, using a BDS Hypersil C8 column at ambient temperature. The mobile phase was composed of 0.01 M KH2PO4 (pH 4):acetonitrile in gradient mode and the quantification was achieved at 245 nm for acyclovir, ganciclovir, penciclovir and valacyclovir hydrochloride, and at 220 nm for lamivudine, oseltamivir phosphate and ribavirin. Run time was 8 min, except for the oseltamivir-containing mixture where the run time was extended to 20 min. The validation of the method was assessed according to ICH guidelines. Linearity, accuracy and precision were satisfactory over the concentration ranges 3–100 µg mL−1 for acyclovir, ganciclovir and penciclovir; 5–100, 4–100, 7–120 and 5–120 µg mL−1 for valaciclovir HCl, lamivudine, oseltamivir phosphate and ribavirin, respectively. The developed method is suitable for the quality control and routine analysis of the cited drugs separately or in combinations. Moreover, the proposed method can be used for counterfeit drug detection. Also, simultaneous determination of lamivudine and penciclovir in spiked human plasma has been developed, using valaciclovir hydrochloride as an internal standard. Protein precipitation using perchloric acid solution was used for the extraction of the drugs from plasma. With modified chromatographic conditions, quantification was achieved at 254 nm. Validation of the method was performed according to European Medicines Agency guidelines with linearity over the range 0.056–4.0 and 0.14–10.0 μg mL−1 for lamivudine and penciclovir, respectively.

Specific features of decomposition of hydroxamic acids in two-phase nitric acid systems with alcohols and TBP, as applied to 99Mo stripping

Hydrolysis is the prevalent mechanism of decomposition of benzo- and caprinohydroxamic acids (HAs) in nitric and perchloric acid solutions and in the equilibrium organic phase based on heptanol, decanol, and 30% TBP in С13 paraffin diluent. In the nitric acid system with alcohols, HAs undergo autocatalytic oxidation at temperatures raised over 50°С. In the case of BHA, the process occurs in both phases taken separately and on their mixing. In the case of caprinohydroxamic acid poorly soluble in HNO3 solutions, the autocatalytic process occurs only at 70–80°С on mixing the phases; it tends to fade as the phase ratio n = О/A is increased from 1 to 10. This trend determines the conditions for Mo stripping in this system. In the practice of the 99Mo production, the stripping efficiency can be increased by repeated contact with the addition of non-salt complexing agents (H2O2, H2C2O4, CH3CONHOH) into the system.

Squaric acid adsorption and oxidation at gold and platinum electrodes

The adsorption and oxidation of squaric acid (3,4-dihydroxycyclobut-3-ene-1,2-dione, H2C4O4, SQA) at platinum and gold electrodes were studied spectroelectrochemically in perchloric acid solutions. Voltammetric experiments demonstrate that reversible adsorption takes place at gold electrodes in the double-layer region. As a difference with platinum electrodes, no dissociative adsorption processes leading to the blocking of the electrode surface are detected. ATR-SEIRAS experiments show potential-dependent adsorbate bands at potentials below 1.20V vs RHE that, according to DFT calculations, can be assigned to adsorbed squarate. For platinum electrodes, the potential-dependent adsorption of squarate anions is coupled with the oxidative stripping of adsorbed carbon monoxide, which is formed upon dissociative SQA adsorption. Bonding of squarate species to the platinum and gold surfaces involves two oxygen atoms in a bidentate configuration, with the molecular plane perpendicular to the metal surface. The ATR-SEIRA spectra obtained for gold electrodes in the SQA oxidation region show bands for adsorbed bicarbonate anions formed from dissolved carbon dioxide molecules. In the case of platinum, distinct bands are observed for adsorbed oxidation products which probably are formed upon opening of the SQA ring.

Electroreduction of nitrate anions on cubic and polyoriented platinum nanoparticles modified by copper adatoms

In this work, electroreduction of nitrate anions on bare and copper-modified platinum nanoparticles (Pt NPs) supported on glassy carbon is studied using cyclic voltammetry. Two types of Pt NPs are chosen for this purpose: unshaped (polyoriented) NPs and cubic NPs displaying the preferential (100) orientation of faces. The modification of cubic and polyoriented Pt NPs by copper adatoms with submonolayer coverages is performed in a controlled way in solutions containing small concentrations of Cu2+ ions, 10−5M. Nitrate reduction is studied first in copper-free solutions and then in the presence of 10−5M Cu2+. The transmission electron microscopy and voltammetric measurements of the cubic NPs indicate the presence of a significant amount of Pt(100) terraces on the surface of these NPs. In perchloric acid solutions containing 0.02M NaNO3 and 10−5M Cu2+, accumulation of copper adatoms on the NPs results in a fast increase in the currents of nitrate electroreduction. These reduction currents on the cubic NPs are up to three times higher than on the polyoriented NPs at Cu coverages of 0.20–0.35. The comparison of the data on Pt NPs with the data for single crystal electrodes with (100) terraces of different width (Pt(610), Pt(210)) shows that the behavior of NPs can be simulated on the basis of the data for single crystal faces with wide (cubic NPs) and narrow (unshaped NPs) (100) terraces. Thus, cubic NPs manifest rather a high electrocatalytic activity in the studied reaction of nitrate anion electroreduction, which is typical for single crystal surfaces with relatively wide Pt(100) terraces. At the same time, in comparison with macro single crystalline electrodes, these NPs are characterized by sufficiently higher stability, larger specific surface area, and flexibility in application.

Extraction of REE(III), U(VI), and Th(IV) from HNO3 and HClO4 solutions with (α-pyridyl)tetraphenylmethylenediphosphine N,P,P'-trioxide

Extraction of microamounts of U(VI), Th(IV), and REE(III) from HNO3 and HClO4 solutions with solutions of (α-pyridyl)tetraphenylmethylenediphosphine N,P,P'-trioxide in dichloroethane was studied. The stoichiometry of the extractable complexes was determined, and the influence of the extraction structure and aqueous phase composition on the efficiency and selectivity of the extraction of U(VI), Th(IV), and REE(III) into the organic phase was studied. Introduction of the pyridine N-oxide fragment into the methylene bridge of the tetraphenylmethylenediphosphine dioxide molecule to obtain (α-pyridyl)tetraphenylmethylenediphosphine N,P,P'-trioxide leads to a decrease in its ability to extract U(VI), Th(IV), and REE(III) from nitric acid solutions, whereas the U/REE separation factors increase. The REE(III) extraction efficiency considerably increases in going from nitric acid to perchloric acid solutions.

Enhanced Ru Utilization with High Stability of (RuxCoy)Se2/C Electrocatalyst toward Oxygen Reduction Reaction

The ruthenium (Ru) precursor was introduced into carbon supported cobalt selenide (CoSe2/C) nanoparticles, which were prepared via a simple microwave route, to obtain the ternary carbon supported ruthenium cobalt selenide (RuCoSe/C) nanoparticles by chemical reduction of Ru on the CoSe2/C surface. Upon the subsequent heat treatment of RuCoSe/C at 400 ℃, a small amount of Ru introduced substituted some Co sites in the CoSe2 through the phase transformation of orthorhombic to cubic CoSe2, which led to the formation of a new cubic phase of (RuxCo1-x)Se2/C. The half-wave and onset potentials were 0.68 V and 0.88V (vs. RHE), respectively, in 0.1 mol·L-1 perchloric acid (HClO4) solutions. The mass activity was as high as 0.09 mA·μg-1 Ru at 0.75 V, which is comparable to that of the commercial Pt/C (0.10 mA·μg-1 Pt). Only 15 mV loss in the half-wave potential was observed after 1000 cycles in 0.1 mol·L-1 HClO4, suggesting the efficient Ru utilization and excellent electrocatalytic stability.

High-Performance Pyrochlore-Type Yttrium Ruthenate Electrocatalyst for Oxygen Evolution Reaction in Acidic Media.

Development of acid-stable electrocatalysts with low overpotential for oxygen evolution reaction (OER) is a major challenge to produce hydrogen directly from water. We report in this paper a pyrochlore yttrium ruthenate (Y2Ru2O7-δ) electrocatalyst that has significantly enhanced performance toward OER in acid media over the best-known catalysts, with an onset overpotential of 190 mV and high stability in 0.1 M perchloric acid solution. X-ray absorption near-edge structure (XANES) indicates Y2Ru2O7-δ electrocatalyst had a low valence state that favors the high OER activity. Density functional theory (DFT) calculation shows this pyrochlore has lower band center energy for the overlap between Ru 4d and O 2p orbitals and is therefore more stable Ru-O bond than RuO2, highlighting the effect of yttrium on the enhancement in stability. The Y2Ru2O7-δ pyrochlore is also free of expensive iridium metal and thus is a cost-effective candidate for practical applications.

Electrooxidation of Pt(111) in acid solution

The electrochemical oxidation of Pt has regained new interest in recent years, motivated by its importance for Pt electro-catalyst stability. New experimental data obtained by in situ methods, detailed electrochemical studies, and complementary results from ab initio theory and gas-phase studies have led to significant advances in the understanding of this process on the atomic scale. Here, an overview of recent work on the electrooxidation of Pt(111) single crystals in acidic electrolytes, primarily perchloric acid solution, will be given. The complex potential- and time-dependent changes in the adsorbate layer on the electrode surface, the place exchange of oxygen species with Pt surface atoms, the formation of an ultrathin Pt oxide layer, and the structural changes of the electrode surface structure upon oxidation/reduction cycles will be described.

Extraction of REE(III), U(VI), and Th(IV) from perchloric and nitric acid solutions with N,N,N′,N′-tetrabutyl-2-(di-p-anisylphosphinoyl)butanediamide

Extraction of microamounts of REE(III), U(VI), and Th(IV) from HClO4 solutions with solutions of N,N,N′,N′-tetrabutyl-2-(di-p-anisylphosphinoyl)butanediamide (I) in organic diluents was studied. The stoichiometry of the extractable complexes was determined, and the effect of the organic diluent and aqueous phase composition on the efficiency and selectivity of the extraction of U(VI), Th(IV), and REE(III) into the organic phase was considered. In going from nitric to perchloric acid solutions, the efficiency of the extraction of REE(III), U(VI), and Th(IV) with solutions of I considerably increases, but the extraction of U(VI) and REE(III) becomes less selective. The “perchlorate effect” is the most pronounced in extraction with solutions of I in o-xylene.

Hydroxyurea electrooxidation at gold electrodes. In situ infrared spectroelectrochemical and DFT characterization of adsorbed intermediates

The oxidation of hydroxyurea (H2NCONHOH, HU) at Au(100), Au(111) and Au(111)–25nm thin film electrodes is studied spectroelectrochemically in perchloric acid solutions. HU, which in agreement with DFT results interacts weakly with the gold surfaces, oxidizes irreversibly at gold electrodes irrespective of the surface orientation. The in situ infrared external reflection spectra prove the formation of dissolved carbon dioxide and adsorbed cyanate as products of the HU electrooxidation reaction. A band at ca. 2230cm−1 can be related both to dissolved isocyanic acid coming from the protonation of adsorbed cyanate or to nitrous oxide coming from the oxidation of hydroxylamine, which is formed (together with adsorbed cyanate) upon the chemical decomposition of hydroxyurea. ATR-SEIRAS experiments allow the observation of other adsorbate bands that can be tentatively ascribed to reaction intermediates that conserve the NCN skeleton and are bonded to the metal by the nitrogen atoms at near on-top positions. Bonding to the surface can be either unidentate or bidentate, involving covalent-type bonds or dative bonding through the lone pairs of the N atoms. Some of the signals of the experimental spectra, in particular those appearing around 1800cm−1, can be assigned to the CO stretch of adsorbed intermediates having a nitrosyl group formed by oxidation of the NOH moiety (namely, adsorbed nitrosoformamide or its deprotonated form). The bands observed around 1650cm−1 can correspond either to the NO stretching mode of the former species or to the CO stretching modes of adspecies conserving the NOH group.

Reaction of Np(VI) with nitrilotriacetic acid in perchloric acid solutions

Stoichiometry of the reaction of Np(VI) with N(CH2COOH)3 (NTA) in a 0.05 M HClO4 solution was studied by spectrophotometry. With excess Np(VI), 1 mol of NTA reduces 2 mol of Np(VI) to Np(V). In 0.05–0.98 M HClO4 solutions (the ionic strength I = 1.0 was maintained by adding LiClO4) containing 5–30 mmol of NTA, at 25–45°С Np(VI) at a concentration of 0.3–2 mM is consumed in accordance with a firstorder rate law until less than 1/3 of Np(VI) remains in the solution. After that, the reaction decelerates. The reaction is first-order with respect to NTA and has an order of–2 with respect to Н+ ions. The activated complex is formed with the loss of two Н+ ions. The activation energy of the reaction is 100 ± 2 kJ mol–1.

Performance of Pt-Ni Alloy Nanoparticles Supported on Carbon Nanotubes in Proton Exchange Membrane Fuel Cell

Proton exchange membrane fuel cells (PEMFCs) have attracted a lot of attention for alternative and green energy sources owning to their low-carbon emissions and high efficiencies. Pt-based electrocatalysts used in PEMFC electrodes are the main contributor to the high cost. More research focusing on the use of Pt group alloys is still required to achieve enhanced catalytic activity while decreasing the Pt loading. In this study, Pt-Ni binary catalysts by pulse electrodeposition and electroless-deposition process were developed for the enhancement of oxygen reduction reaction. The Pt-Ni catalysts were deposited on carbon nanotubes (CNTs) directly grown on carbon cloths. CNTs used for catalyst nanostructured supports can decrease the needs of Pt and improve the performance of fuel cells. The nickel nanoparticles were deposited on CNTs by pulse electro-planting to form large-area flake structures. Then the platinum nanoparticles were reduced on them in a potassium hydroxide solution containing platinum precursor and ethylene glycol at 75 oC for the deposition time of 3, 4, 5 hours. The sample with the commercial Pt/C and Pt/CNTs were also prepared for comparison. Structure and elementary composition of catalysts were measured by SEM, XRD and ICP-MS. Ni/CNTs sample showed a uniform distribution of Ni nanoparticles on the surface of CNTs, which was provided for the deposition of Pt nanoparticles with average particle size of about 5 nm. Electrochemical characteristics of PtNi/CNTs and Pt/CNTs samples were investigated via cyclic voltammetry (CV) analysis and rotating disk electrode (RDE) test in 0.1 M perchloric acid solution. In terms of both limiting current density and onset potential, the PtNi/CNTs samples were better than those of Pt/CNTs samples. All PtNi/CNTs samples with different Pt deposition time showed very similar LSV curves using RDE tests. In single cell test, the PtNi/CNTs, as the cathode catalyst, has a higher maximum power density (763 mW/cm2) than the commercial Pt/C. Among the PtNi/CNTs samples, the better performance of PtNi/CNTs sample with 4-hours Pt deposition time can be attributed to the more convenient Pt availability for the oxygen reduction reaction (ORR). It can be also found that the open circuit voltage of this sample could reach up to 1V due to a significant decrease of the polarization loss. The main outcome of this study was that Pt–Ni binary alloy catalysts had better oxygen reduction reaction for cathode of PEMFC.

Titania nanotube powders obtained by rapid breakdown anodization in perchloric acid electrolytes

Titania nanotube (TNT) powders are prepared by rapid break down anodization (RBA) in a 0.1M perchloric acid (HClO4) solution (Process 1), and ethylene glycol (EG) mixture with HClO4 and water (Process 2). A study of the as-prepared and calcined TNT powders obtained by both processes is implemented to evaluate and compare the morphology, crystal structure, specific surface area, and the composition of the nanotubes. Longer TNTs are formed in Process 1, while comparatively larger pore diameter and wall thickness are obtained for the nanotubes prepared by Process 2. The TNTs obtained by Process 1 are converted to nanorods at 350°C, while nanotubes obtained by Process 2 preserve tubular morphology till 350°C. In addition, the TNTs prepared by an aqueous electrolyte have a crystalline structure, whereas the TNTs obtained by Process 2 are amorphous. Samples calcined till 450°C have XRD peaks from the anatase phase, while the rutile phase appears at 550°C for the TNTs prepared by both processes. The Raman spectra also show clear anatase peaks for all samples except the as-prepared sample obtained by Process 2, thus supporting the XRD findings. FTIR spectra reveal the presence of O-H groups in the structure for the TNTs obtained by both processes. However, the presence is less prominent for annealed samples. Additionally, TNTs obtained by Process 2 have a carbonaceous impurity present in the structure attributed to the electrolyte used in that process. While a negligible weight loss is typical for TNTs prepared from aqueous electrolytes, a weight loss of 38.6% in the temperature range of 25–600°C is found for TNTs prepared in EG electrolyte (Process 2). A large specific surface area of 179.2m2g−1 is obtained for TNTs prepared by Process 1, whereas Process 2 produces nanotubes with a lower specific surface area. The difference appears to correspond to the dimensions of the nanotubes obtained by the two processes.