One-step fabrication of nanostructured Ni film with lotus effect from deep eutectic solvent

We report a procedure to fabricate nanostructured Ni films via programmed electrochemical deposition from a choline-chloride-based ionic liquid at a high temperature of 90 °C. Three electrodeposition modes using constant voltage, pulse voltage, and reverse pulse voltage produce a variety of nanostructured Ni films with micro/nanobinary surface architectures, such as nanosheets, aligned nanostrips, and hierarchical flowers. The nanostructured Ni films possess face-centered cubic crystal structure. Amazingly, it is found that the electrodeposited Ni films deliver the superhydrophobic surfaces without any further modifications by low surface-energy materials, which might be attributed to the vigorous micro/nanobinary architectures and the surface chemical composition. The electrochemical measurements reveal that the superhydrophobic Ni film exhibit an obvious passivation phenomenon, which could provide enhanced corrosion resistance for the substrate in the aqueous solutions.     

Electrochemical fabrication of metallic nanostructured electrodes for electroanalytical applications

The use of electrodeposited metal-based nanostructures for electroanalytical applications has recently received widespread attention. There are several approaches to creating nanostructured materials through electrochemical routes that include facile electrodeposition at either untreated or modified electrodes, or through the use of physical or chemical templating methods. This allows the shape, size and composition of the nanomaterial to be readily tuned for the application of interest. The use of such materials is particularly suited to electroanalytical applications. In this mini-review an overview of recently developed nanostructured materials developed through electrochemical routes is presented as well as their electroanalytical applications in areas of biological and environmental importance.     

碱性介质中多孔纳米结构镍/钯-镍电极上甲醇电氧化反应(英文)

A nanostructured Ni/Pd-Ni catalyst with high activity for methanol oxidation in alkaline solution was prepared by electrodeposition followed by galvanic replacement, that is, electrodeposition of Ni-Zn on a Ni coating with subsequent replacement of the Zn by Pd at the open circuit potential in a Pd-containing alkaline solution. The surface morphology and composition of the coatings were examined by energy dispersive X-ray spectroscopy and scanning electron microscopy. The Ni/Pd-Ni coatings were porous and were composed of discrete Pd nanoparticles of about 58 nm. The electrocatalytic activity of the Ni/Pd-Ni electrodes for the oxidation of methanol was examined by cyclic voltammetry and electrochemical impedance spectroscopy. The onset potentials for methanol oxidation on Ni/Pd-Ni were 0.077 V and 0.884 V, which were lower than those for flat Pd and smooth Ni electrodes, respectively. The anodic peak current densities of these electrodes were 4.33 and 8.34 times higher than those of flat Pd (58.4 mA/cm2 vs 13.47 mA/cm2) and smooth Ni (58.4 mA/cm2 vs 7 mA/cm2). The nanostructured Ni/Pd-Ni electrode is a promising catalyst for methanol oxidation in alkaline media for fuel cell application.     

Electrodeposited lead dioxide coatings

Lead dioxide coatings on inert substrates such as titanium and carbon now offer new opportunities for a material known for 150 years. It is now recognised that electrodeposition allows the preparation of stable coatings with different phase structures and a wide range of surface morphologies. In addition, substantial modification to the physical properties and catalytic activities of the coatings are possible through doping and the fabrication of nanostructured deposits or composites. In addition to applications as a cheap anode material in electrochemical technology, lead dioxide coatings provide unique possibilities for probing the dependence of catalytic activity on layer composition and structure (critical review, 256 references).     

Electrodeposition of Ni and Te‐doped Cobalt Triantimonide in Citrate Solutions

Skutterudite compounds form a new class of potential candidates for thermoelectric applications. Cobalt triantimonide (CoSb₃) shows good thermoelectric properties at medium and high temperatures. Doping this system with substitution elements, for either Co or Sb or both, may result in an increase of the thermoelectric figure of merit (ZT). This work focused on the electrochemical doping and characterization of films and nanowires of Co‐Sb system in citrate solutions using gold‐coated PCTE templates. The electrodeposition was performed on gold surface that was pre‐treated electrochemically to ensure reproducible results. The electrochemical treatment acted as an annealing process for the surface, which resulted in an increase in Au(111) as demonstrated by XRD. Detailed electrochemical studies including deposition‐stripping experiments was performed in order to develop a better understanding of the co‐deposition kinetics and a better control over the composition of doped Co‐Sb system. Scanning electron microscopy (SEM/EDS) helped study the morphology and the composition of the doped and undoped Co‐Sb system. Co‐deposition of Co‐Sb showed that the amount of Co is higher in nanowires than in film or mushroom caps due to the slow Sb deposition rate dictated by slow Sb(III) complex diffusion. Doped nanowires have been also obtained. Both Ni and Te electrochemical doping of the Co‐Sb system affected the composition of the deposit but there was no effect on nanowire morphology.     

Fabrication of hydrophobic fluorinated amorphous carbon thin films by an electrochemical route

A novel electrochemical route for the preparation of hydrophobic fluorinated amorphous carbon (a-C:F) films with nanostructured surfaces on single crystal silicon substrate was reported. The films were investigated in terms of the surface morphology, chemical composition, microstructure and hydrophobic behavior. The results showed that a highly uniform and densely packed bamboo shoot-like nanostructure was obtained without any use of template. The incorporation of fluorine presented mainly in the forms of CF₂ chains and CCF_x (x = 1, 2) in the films. Sessile drop water contact angle measurements showed that the contact angle of a-C:F films deposited by electrochemical route was about 145°, which can be attributed to the lower surface energy of CF_x groups and higher diffusion resistance of the special nanostructured surface to water. Moreover, the related growth mechanism of the resulting films in liquid-phase electrodeposition is discussed as well.     

Spatio-temporal organization in alloy electrodeposition: a morphochemical mathematical model and its experimental validation

This paper proposes a novel mathematical model for the formation of spatio-temporal patterns in electrodeposition. At variance with classical modelling approaches that are based on systems of reaction–diffusion equations just for chemical species, this model accounts for the coupling between surface morphology and surface composition as a means of understanding the formation of morphological patterns found in electroplating. The innovative version of the model described in this work contains an original, flexible and physically straightforward electrochemical source term, able to account for charge transfer and mass transport: adsorbate-induced effects on kinetic parameters are naturally incorporated in the adopted formalism. The relevant non-linear dynamics is investigated from both the analytical and numerical points of view. Mathematical modelling work is accompanied by an extensive, critical review of the literature on spatio-temporal pattern formation in alloy electrodeposition: published morphologies have been used as a benchmark for the validation of our model. Moreover, original experimental data are presented—and simulated with our model—on the formation of broken spiral patterns in Ni–P–W–Bi electrodeposition.     

Synthesis of nanostructured films from template electrodeposition technique

In this report, the use of a simple and versatile technique of templated electrodeposition through colloidal templates to produce nanostructured films of Pt and Au with regular submicron spherical holes arranged in a hexagonal close-packed structure is described. The templates were produced by self assembly of a monodispersed suspension of polystyrene spheres on gold substrates using capillary forces. The self assembly process was modified through the chemical modification of the gold substrate with cysteamine thiol. Films of Pt and Au were prepared by electrochemical deposition through the template. The electrochemical deposition charge and the current time curve were used to control the film height with a precision of approximately 10 nm. The colour of the nanostructured films changed as the film thickness was changed. On the other hand, high surface area of the nanostructured Pt film on top of the gold substrate was calculated using electrochemical cyclic voltammogram. About 55 roughness factor was obtained. SAXS measurements showed strong scattering at low angles indicating the presence of a well-ordered mesostructure.     

The electrochemistry of nanostructured Ni–W alloys

This work reports on the features that Ni–W nanostructured alloys, electrodeposited on carbon steel by different current pulse programs, may present depending on their surface morphology and surface composition. The Ni–W nanostructured coating, with a cauliflower structure, lack of fragility, and high WO₃/W surface composition ratio, is a stable electrode to catalyze hydrogen evolution reaction, exceeding bulk and electrodeposited Ni catalytic activity. Also, the nanostructured alloys must have a low WO₃/W surface composition ratio for Ni and its oxides to provide protection and improve corrosion resistance in sulfate media.     

Quantitative electrochemical SERS of flavin at a structured silver surface

In situ electrochemical surface enhanced Raman spectra (SERS) for an immobilized monolayer of a flavin analogue (isoalloxazine) at nanostructured silver surfaces are reported. Unique in the present study, the flavin is not directly adsorbed at the Ag surface but is attached through a chemical reaction between cysteamine adsorbed on the Ag surface and methylformylisoalloxazine. Even though the flavin is held away from direct contact with the metal, strong surface enhancements are observed. The nanostructured silver surfaces are produced by electrodeposition through colloidal templates to produce thin (<1 microm) films containing close-packed hexagonal arrays of uniform 900 nm sphere segment voids. The sphere segment void (SSV) structured silver surfaces are shown to be ideally suited to in situ electrochemical SERS studies at 633 nm, giving stable, reproducible surface enhancements at a range of electrode potentials, and we show that the SER spectra are sensitive to subfemtomole quantities of immobilized flavin. Studies of the SER spectra as a function of the electrode potential show clear evidence for the formation of the flavin semiquinone at the electrode surface at cathodic potentials.     

Liquid-Phase Synthesis of Iron Oxide Nanostructured Materials and Their Applications

Owing to their high natural abundance, low cost, easy availability, and excellent magnetic properties, considerable interest has been devoted to the synthesis and applications of iron oxide nanostructured materials. Liquid-phase synthesis methods are economical and environmentally friendly with low energy consumption and volatile emissions, and as such have received much attention for the preparation of iron oxide nanostructured materials. Herein, the liquid-phase synthesis methods of iron oxide nanostructured materials including the co-precipitation method, microemulsion method, conventional hydrothermal and solvothermal methods, microwave-assisted heating method, sonolysis method, and other methods are summarized and reviewed. Many iron oxide nanostructured materials, self-assembled nanostructures, and nanocomposites have been successfully prepared, which are of great significance to enhance their structure-dependent properties and applications. The specific roles of liquid-phase chemical reaction parameters in regulating the chemical composition, structure, crystallinity, morphology, particle size, and dispersive behavior of the as-prepared iron oxide nanostructured materials are emphasized. The biomedical, environmental, and electrochemical energy storage applications of iron oxide nanostructured materials are discussed. Finally, challenges and perspectives are proposed for future investigations on the liquid-phase synthesis and applications of iron oxide nanostructured materials.     

Solvent-controlled synthesis and electrochemical lithium storage of one-dimensional TiO2 nanostructures

In this paper, one-dimensional (1-D) nanostructured TiO2 of different morphologies and structures have been selectively synthesized via a convenient, low-temperature solvothermal route and following calcination. Transmission electron microscopy, selected area electron diffraction, X-ray diffraction, and Brunauer-Emmett-Teller methods were used to characterize the morphology, crystalline structure, and specific surface area of these nanostructured TiO2. The formation of different morphologies, including nanowires and nanotubes, was achieved through a deliberate control of the cosolvent. In addition to the solvent-controlled procedures, another important feature of the synthesis in the present study was that either single-crystalline nanowires (TiO2-B) or polycrystalline nanotubes (anatase and TiO2-B) were achieved by heat treatment at 350 degrees C. The electrochemical performances of the nanowires and nanotubes were further explored in terms of their potential application as anode materials for lithium-ion batteries. The lithium-insertion reactions involved in the two materials were elucidated by means of a galvanostatic method, cyclic voltammetry, and electrochemical impedance spectroscopy. The results suggest that both the crystalline structure and the unique 1-D morphology might be responsible for their favorable electrochemical properties. This work will be valuable for the understanding of the formation of nanostructured TiO2 by the wet-chemistry process and further applications.     

碳纤维上电沉积Pd-Ag合金纳米粒子链及其氢传感性能

在碳纤维上采用三脉冲电沉积的方法制备出钯银合金纳米粒子链.把表面覆盖有Pd-Ag合金纳米粒子链的碳纤维组装成氢气传感器.采用扫描电子显微镜(SEM)和X射线能谱(EDX)表征了合金纳米粒子链的形貌和成分,应用CHI660B电化学工作站测试其氢传感性能.结果表明,在钯、银离子摩尔比为15∶1的电解液中,在-1.0--1.5 V下,成核5-40 ms;在-0.25--0.35 V,生长200-300 s的条件下,即可获得银的质量分数为16.0%-25.0%的钯银合金纳米粒子链阵列.在室温下,传感器对在0.30%-5.00%(φ,体积分数,下同)范围内的氢气有响应,最快响应时间约为300 s,灵敏度最高可达31.0%;氢在0.30%-1.20%的范围内响应电流与氢气浓度成线性关系,超过4.00%时响应电流不再随浓度的增加而变化;在低于3.50%的浓度下氢传感器的重现性良好.     

Directed electrodeposition of polymer films using spatially controllable electric field gradients

We report a method for the directed electrodeposition of polymer films in various patterns using spatially controllable electric field gradients. One- and two- dimensional surface electric field gradients were produced by applying different potential values at spatially distinct locations on an electrode surface. Variations in the resulting local electrochemical potentials were used to spatially manipulate the rate of electrodeposition of several polymers. By controlling the electric field gradient in the presence of sequentially varying deposition solutions, complex polymer patterns could be produced. One-dimensional structures consisting of alternating bands of polyaniline and either poly(phenylene) oxide or poly(aminophenylene) oxide were produced, as well as more complex two-dimensional structures. Film characterization was achieved through optical imaging, UV-vis spectroscopy, and ellipsometry. Results indicate that this directed deposition technique is a simple strategy to create complex, millimeter-sized surface patterns of electrodeposited materials.     

Electrochemical Preparation of a Nanostructured Poly(amino napthalene sulfonic acid) Electrode Using CTAB as a Soft Template and Its Electrocatalytic Application for the Reduction of Iodate

A nanostructured poly(5‐amino‐2‐naphthalene sulfonic acid) (nanostructured PANS) electrode has been prepared using cetyltrimethyl ammonium bromide (CTAB) as a soft template by potentiodynamic method. The effect of CTAB at various concentrations was analyzed during electrochemical synthesis of the PANS electrode. As the concentration was near to cmc of CTAB, well growth and nanostructured PANS electrode was obtained. The formation mechanism and the reason for the increase of the peak current of the nanostructured PANS electrode are discussed. The surface morphology of PANS electrode was investigated using scanning electron microscopy (SEM) and a nanoribbon like structured PANS polymer was obtained near cmc of CTAB. The electrochemical properties of nanostructured PANS electrode were studied. The catalytic utility of nanostructured PANS electrode was investigated and it exhibited electrocatalytic activity for the reduction of iodate with a low potential. The amperometric detection of iodate was tested at nanostructured PANS electrode. Linear range and detection limit were found to be 0.1 to 0.4 µM and 0.1 µM, respectively. The present work involves a simple, and one‐step approach to fabricate a nanostructured PANS film with unique electrochemical properties, which can have great potential in various applications such as sensors, and energy source systems.     

Electrochemical method for the preparation nanocomposites based on carbon nanotubes and chromium oxides for oxygen electrodes

An electrochemical method for the preparation of nanostructured composites based on multiwalled carbon nanotubes and chromium oxide is proposed. The method involves electrodeposition of chromium oxides from a solution of hexavalent chromium oxide in sulfuric acid on carbon nanotubes. By varying the electrolysis conditions one can obtain deposited—catalyst particles of different size and vary the amount of catalyst. Oxygen electrodes have been made from the materials obtained for fuel cells with alkaline electrolyte, which showed good electrocatalytic properties.     

Prospects of electrochemically synthesized hematite photoanodes for photoelectrochemical water splitting: A review

Hematite (α-Fe₂O₃) is found to be one of the most promising photoanode materials used for the application in photoelectrochemical (PEC) water splitting due to its narrow band gap energy of 2.1 eV, which is capable to harness approximately 40% of the incident solar light. This paper reviews the state-of-the-art progress of the electrochemically synthesized pristine hematite photoanodes for PEC water splitting. The fundamental principles and mechanisms of anodic electrodeposition, metal anodization, cathodic electrodeposition and potential cycling/pulsed electrodeposition are elucidated in detail. Besides, the influence of electrodeposition and annealing treatment conditions are systematically reviewed; for examples, electrolyte precursor composition, temperature and pH, electrode substrate, applied potential, deposition time as well as annealing temperature, duration and atmosphere. Furthermore, the surface and interfacial modifications of hematite-based nanostructured photoanodes, including elemental doping, surface treatment and heterojunctions are elaborated and appraised. This review paper is concluded with a summary and some future prospects on the challenges and research direction in this cutting-edge research hotspot. It is anticipated that the present review can act as a guiding blueprint and providing design principles to the scientists and engineers on the advancement of hematite photoanodes in PEC water splitting to resolve the current energy- and environmental-related concerns.     

Surface enhanced raman scattering of aromatic thiols adsorbed on nanostructured gold surfaces

In this paper we describe the use of a simple and versatile technique of templated electrodeposition through polystyrene sphere templates to produce nanostructured films of gold with regular submicron spherical holes arranged in a hexagonal close-packed structure. The templates were produced by self assembly of a monodispersed suspension of polystyrene spheres on gold substrates using capillary forces. The self assembly process was modified through the chemical modification of the gold substrate with cysteamine thiol. Films of gold were prepared by electrochemical deposition through the template. The electrochemical deposition charge and the current time curve were used to control the film height with a precision of approximately 10 nm. The colour of the nanostructured films changed as the film thickness was changed. Surface enhanced Raman Scattering spectra were recorded and used to identify very low concentrations of aromatic thiol molecules, 4-Nitrobenzenethiol (4-NBT) and 4-Aminobenzenethiol (4-ABT), adsorbed on the surface of the nanostructured gold substrates.      

多孔纳米结构Fe/Pt-Fe电极对碱性介质中甲醇电氧化的催化活性（英文）

An electrochemical approach to fabricate a nanostructured Fe/Pt-Fe catalyst through electrodeposition followed by galvanic replacement is presented. An Fe/Pt-Fe nanostructured electrode was prepared by deposition of Fe-Zn onto a Fe electrode surface, followed by replacement of the Zn by Pt at open-circuit potential in a Pt-containing alkaline solution. Scanning electron microscopy and energy-dispersive X-ray techniques reveal that the Fe/Pt-Fe electrode is porous and contains Pt. The electrocatalytic activity of the Fe/Pt-Fe electrode for oxidation of methanol was examined by cyclic voltammetry and chronoamperometry. The electrooxidation current on the Fe/Pt-Fe catalyst is much higher than that on flat Pt and smooth Fe catalysts. The onset potential and peak potential on the Fe/Pt-Fe catalyst are more negative than those on flat Pt and smooth Fe electrodes for methanol electrooxidation. All results show that this nanostructured Fe/Pt-Fe electrode is very attractive for integrated fuel cell applications in alkaline media.