Silver nanosheets with a nanogap smaller than 10 nm and high reproducibility were constructed through simple and environmentally friendly electrodeposition method on copper plate. The sizes of the nanogaps can be varied from around 7 to 150 nm by adjusting the deposition time and current density. The nanosheets with different nanogaps exhibited varied surface-enhanced Raman scattering (SERS) properties due to electromagnetic mechanism (EM). The optimized high density silver nanosheets with a nanogap smaller than 10 nm showed effective SERS ability with an enhanced factor as high as 2.0 × 105. Furthermore, the formation mechanism of the nanosheets during the electrodeposition process has been investigated by discussing the influence of boric acid and current density. This method has proved to be applicable on different metal substrates, which exhibits the potential to be widely used in different fields.

In this work, we report the synthesis of a Si/Cu nanocone-array (NCA) electrode via a facile ambient electrodeposition method with subsequent magnetron sputtering deposition. The close connection between the Cu NCA and the silicon layer facilitates the charge transfer in the system and supports a binder-free technique of preparing lithium ion battery (LIB) anodes. The void spaces between Si cylinders allow not only greater alleviation of the strain caused by the Si expansion during lithiation but also a significantly enhanced rate performance due to the increasing electrode/electrolyte contact area, and shortening path lengths for electronic and Li+ transport. Such engineered electrodes exhibit a long cycle life up to 2000 cycles and can be very promising for high-performance anode applications.

Micro-/nanoscale noble metal (Ag, Au, and Pt) particle-decorated 3D porous nickel electrodes for hydrogen evolution reaction (HER) in alkaline electrolyte are fabricated via galvanostatic electrodeposition technique. The developed electrodes are characterized by field emission scanning electron microscopy and electrochemical measurements including Tafel polarization curves, cyclic voltammetry, and electrochemical impedance spectroscopy. It is clearly shown that the enlarged real surface area caused by 3D highly porous dendritic structure has greatly reinforced the electrocatalytic activity toward HER. Comparative analysis of electrodeposited Ag, Au, and Pt particle-decorated porous nickel electrodes for HER indicates that both intrinsic property and size of the noble metal particles can lead to distinct catalytic activities. Both nanoscale Au and Pt particles have further reinforcement effect toward HER, whereas microscale Ag particles exhibit the reverse effect. As an effective 3D hydrogen evolution cathode, the nanoscale Pt-particle-decorated 3D porous nickel electrode demonstrates the highest catalytic activity with an extremely low overpotential of −0.045 V for hydrogen production, a considerable exchange current density of 9.47 mA cm–2 at 25 °C, and high durability in long-term electrolysis, all of which are attributed to the intrinsic catalytic property and the extremely small size of Pt particles.Keywords: 3D porous nickel electrode; electrocatalyst; electrochemical impedance spectroscopy; electrodeposited noble metal particles; hydrogen evolution reaction;

A three-dimensional porous nickel supported Sn–O–C composite thin film anode is fabricated by the galvanostatical electrodeposition of an active material, Sn, onto a patterned three-dimensional porous nickel current collector from an organic electrolyte. The unique structure enables the homogeneous coating of Sn–O–C composite thin film, 100 nm in thickness, on highly porous dendritic Ni particles. Along with the existence of inter-particle spacings, this could efficiently accommodate great volume changes caused by the lithiation and delithiation of active material, Sn. The morphology, crystalline structure and chemical composition of Sn–O–C composite are characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy with an energy dispersive X-ray analyzer (TEM-EDX), respectively. The results demonstrate that the Sn–O–C composite is composed of agglomerated Sn nanocrystals, which are inhomogeneously distributed in the decomposition products of organic electrolyte. Moreover, the electrochemical behavior of the Sn–O–C composite anode is investigated by cyclic voltammetry (CV), galvanostatic charge/discharge tests and electrochemical impedance spectroscopy (EIS). This anode delivers a discharge capacity of 573.4 mA h (g of Sn)−1, (0.0883 mA h cm−2) after 100 cycles at 0.2 C-rate. The augmentation in total SEI and interfacial charge transfer impedance adequately explained the gradual capacity fading as cycle number increases.

Inspired by the self-cleaning of cicada wings, well-aligned Au-coated Ni nanocone arrays (Au@Ni NAs) have been fabricated by a simple and cheap electrodeposition method. After surface modification of n-hexadecanethiol, self-cleaning can be realized on this long-lived superhydrophobic surface with extremely low adhesive force. Switchable adhesion is obtained on its complementary porous surface. The porous Au structure is fabricated by a geometric replica of the nanocone arrays. After the same surface modification, it shows superhydrophobicity with high adhesion. The different adhesive behaviors on the two lock-and-key Au structures are ascribed to their different contact modes with a water droplet. Combining the superhydrophobic properties of the two complementary structures, they can be used to transport precious microdroplets without any loss. The bioinspired periodic Au@Ni NAs can also be potentially employed as surface-enhanced Raman scattering (SERS) substrates due to its electromagnetic enhancement effect, especially at the tips of the nanocones. Thus, superhydrophobic, SERS, long-lived, self-cleaning, microtransportation functions are realized on the basis of the two surfaces.

In this work, three-dimensional hierarchical nickel–cobalt alloy coating for hydrogen evolution cathode was fabricated by electrodeposition processes. The coatings’ morphology evolves from sea cucumber-like nanostructure to caterpillar-like one with the increase of cobalt content. A large amount of nanometric “steps,” served as the active sites for hydrogen evolution reaction, were observed. According to Tafel polarization measurements, the exchange current density of the as-synthesized coating with hierarchical nanostructure was 21.9 times compared with that of flat nickel coating. In addition, the hierarchical coating also displayed good electrochemical stability from the galvanostatic test.

Caterpillar-like hierarchical structured Cu/Ni–Co coatings were fabricated by a simple two-step method of combined electroless and electrodeposition. Both contact angles and sliding angles were measured to investigate the hydrophobicity after stearic acid modification. The results revealed the contact angle was as high as 165.5°(superhydrophobic), while the sliding angle was only 3.5°, which makes it very promising as self-cleaning material. Wetting transition from slippery hydrophobicity to sticky hydrophobicity happened upon heat treatment. The scanning electron microscopy (SEM) analysis disclosed the morphology change of the hierarchical structure during the heat treatment leading to the wetting state transition. Different models of wetting states were raised and calculated to provide further confirmation of the transition. The contact angle remained larger than 156° when the pH value ranged from 1 to 14 and the heat-treatment temperature was from 100 to 250 °C. Such hierarchical micronanostructure and its special hydrophobicity are expected to have practical application in industry.

Silver films with different morphologies were chemically deposited by controlling the bath composition. It is found that the wettability and surface enhanced Raman scattering (SERS) properties were closely connected with the surface morphology. Due to the perfect 3D morphology and the 3D electromagnetic field enhanced by three types of nanogaps distributed uniformly, the 3D microball/nanosheet (MN) silver film shows better SERS properties than those of 2D nanosheets (NSs) and nanoparticles (NPs). The MN silver film showed high adhesive superhydrophobic properties after an oxidation process without any functionalization. It can hold the liquid droplet and trace the target molecules in a rather small volume. The SERS properties of the oxidized MN substrate were enhanced remarkably compared to those of the freshly prepared substrate because of the concentrating effect of the superhydrophobicity. The as-prepared 3D MN silver substrate has also exhibited good performances in reproducibility and reutilization which makes it a promising substrate for molecule tracing.

Hollow nitrogen-doped carbon spheres (HNCSs) were prepared by a facile method as non-precious catalysts for the oxygen reduction reaction (ORR). The HNCS catalysts exhibited ORR activity comparable with a commercial Pt/C catalyst and superior stability in alkaline electrolyte medium.

Lotus leaf-like and petal-like substrates were fabricated by chemical deposition, which have quite different superhydrophobic properties. Excellent, non-sticky, self-cleaning and durable properties were obtained based on the lotus leaf-like substrate.

A series of Ni–Co alloy nanocones arrays were fabricated by means of electrodeposition method without using any template. The alloy nanocones crystallized in the face-centered cubic lattice structure and grew preferentially along <110> directions. The aspect ratio of the alloy cones was found to increase with increasing cobalt content. The chemical potential difference of the solid–liquid interface and the synergistic effect of twinning were proposed to explain this phenomenon. By adjusting the electrodeposition conditions, the morphology and size of the alloy nanocrystal can be modulated. The crystal modifier plays an important role in controlling the step distance and the morphology of the spiral growth layer. These Ni–Co alloy nanocones arrays are expected to have significant potential applications in the fields of catalysis and magnetic storage.

•A new kind of chip with a special TSV structure was used in this paper.•ANSYS® was used to simulate the overall electric field distribution.•Simulation and electroplating shows bottom-up filling of conventional TSV.•Deposition of special TSV is mainly controlled by the electric field distribution.The filling mechanism of a special through silicon vias (TSV) structure is investigated by electrochemical test and simulation technique compared with the conventional TSV structure in this paper. The effects of additives in methanesulfonic solution are briefly studied by cyclic voltammetry to obtain the suitable copper plating condition for conventional TSV. The electric field distribution in the special TSV during the electrodeposition has been simulated by the software ANSYS. Different from the conventional TSV, the electric field gathered at the bottom of the via in the initial stage of special TSV, which benefit the bottom up filling in the via. And after the deposited copper spread to the whole surface of the chip, the electric field distribution becomes similar to the conventional TSV. With the help of the additives, the void free copper electrodeposition in special TSV was finally achieved.

Non-sticky and highly adhesive superhydrophobic microball-nanosheet hierarchically structured silver films were obtained after surface modification and storage respectively.

•A Fe3O4/Cu-cone arrayed anode was synthesized by a two-step chemical and electrochemical deposition.•The tri-ethanol-amine changes from 0.1 M to 0.2 M resulted in Fe3O4 nanoparticles and nanoflakes.•The synergistic effect between Cu-cone array structure and Fe3O4 crystallinity led to enhanced cyclability.•The Fe3O4 nanoparticle-90 s anode retained the best discharge capacity of 442.96 mAh g− 1 after 100 cyclesA novel 3D nanostructured Fe3O4/Cu-cone arrays (Cu-CAs) anode is prepared by template-free chemical deposition of Cu-CAs on a flat Cu current collector followed by galvanostatic electrodeposition of polycrystalline Fe3O4 nanoparticles (NPs) and Fe3O4 nanoflakes (NFs) from electrolyte containing 0.1 M tri-ethanol-amine (TEA) and 0.2 M TEA, respectively. The developed anodes are characterized by X-ray diffraction, field emission scanning electron microscope, transmission electron microscopy and X-ray photoelectron spectroscopy. Galvanostatic charge/discharge tests are carried out to evaluate the cycling performance of all the anodes at a constant current density of 680 mA g− 1 and cyclic voltammetry measurements are performed to characterize the charge/discharge potentials. The Fe3O4 NPs/Cu-CAs anode fabricated by 90 s electrodeposition exhibits the best performance with a reversible discharge capacity of 442.96 mAh g− 1 after 100 cycles at 1 C-rate due to the optimal synergistic effect of crystallinity and reinforcement effect of Cu-CAs substrate. While the better performance of Fe3O4 NFs/Cu-CAs anode fabricated by 120 s electrodeposition is attributable to the enhanced surface porosity and reinforcement effect of Cu-CAs. However, the comparison between anodes electrodeposited with 0.1 M and 0.2 M TEA indicates that the reinforcement effect of Cu-CAs plays the dominant role in determining the cycling performance of developed Fe3O4/Cu-CAs anodes.Download high-res image (390KB)Download full-size image

In this work, resistance switching behaviours in solution processed chromium (Cr)-doped strontium titanate (SrTiO3) films have been investigated. Undoped SrTiO3 film shows I-V characteristics of typical nonlinear resistor and no resistance hysteresis loops are observed. On the contrary, Cr-doped SrTiO3 films show stable and reversible hysteresis loops, which can be controlled by applying different voltage bias. Based on a series of characterization results, including X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS), we infer that Ti4+ is substituted by Cr3+, giving rise to increased concentration of oxygen vacancies. Therefore, the observed resistance switching phenomenon is attributed to voltage driven oxygen vacancy migration. Furthermore, gradually decreased overall resistance is also realized under repeated sweeping cycles.Download high-res image (111KB)Download full-size image

In this work, we report the synthesis of a Si/Cu nanocone-array (NCA) electrode via a facile ambient electrodeposition method with subsequent magnetron sputtering deposition. The close connection between the Cu NCA and the silicon layer facilitates the charge transfer in the system and supports a binder-free technique of preparing lithium ion battery (LIB) anodes. The void spaces between Si cylinders allow not only greater alleviation of the strain caused by the Si expansion during lithiation but also a significantly enhanced rate performance due to the increasing electrode/electrolyte contact area, and shortening path lengths for electronic and Li+ transport. Such engineered electrodes exhibit a long cycle life up to 2000 cycles and can be very promising for high-performance anode applications.

Non-sticky and highly adhesive superhydrophobic microball-nanosheet hierarchically structured silver films were obtained after surface modification and storage respectively.

Lotus leaf-like and petal-like substrates were fabricated by chemical deposition, which have quite different superhydrophobic properties. Excellent, non-sticky, self-cleaning and durable properties were obtained based on the lotus leaf-like substrate.

Hollow nitrogen-doped carbon spheres (HNCSs) were prepared by a facile method as non-precious catalysts for the oxygen reduction reaction (ORR). The HNCS catalysts exhibited ORR activity comparable with a commercial Pt/C catalyst and superior stability in alkaline electrolyte medium.