•Alumina sol-gel film is prepared on NdFeB magnets by electro-deposition and hydrothermal methods.•The alumina sol (AS) film improves the corrosion resistance and thermal stability of NdFeB.•The kinetics features of alumina sol particles under electric field are investigated.•The phase transition from alumina particle to boehmite layers on AS film are studied.•The AS film is useful for the preparation of no magnetic loss protection film on NdFeB magnets.Alumina film is effective for improving the corrosion resistance and protecting the magnetic properties of NdFeB magnets, but the complicated preparation method limits its application. In this study, we prepare alumina sol (AS) film on NdFeB magnets with an electric chemistry method from modified alumina sol. And a hydrothermal treatment (HTT) improves the combination and protection ability of AS film on NdFeB. Microstructural investigation suggests that the uniform AS film can be prepared on NdFeB under optimized electric conditions and the hydrothermal treatment helps to repair defects on the AS film. With the formation of electro-deposited AS film, the corrosion current density value reduces more than an order of magnitude and the intergranular corrosion of NdFeB is obviously suppressed in corrosive environments. The thermal stability of NdFeB magnets is also improved by the AS film. The morphology, composition and phase transition of the AS film are systematically investigated. In addition, the underlying formation mechanisms for electro-deposited AS film have been analyzed by zeta potential measurement and cathode polarization measurement at the sol–metal interface. These results have important implications for the preparation of protection film to prevent magnetic loss on sintered NdFeB magnets.

•2D Fe-S is embedded into 3D carbon by 3C method.•This structure of CE provides more active sites.•A breaking FF of 0.64 is obtained.•3C is universal to fabricate metal sulfide/carbon materials.Iron sulfide has been proved to be a promising material for counter electrode (CE) of QDSCs in our previous work. However, the fill factor is still much below expectation, owing to the poor catalytic activity. Herein, iron sulfide nanosheets are embedded into porous carbon. This structure exhibits good interfacial contact between iron sulfide and carbon. As a result, it improves the stability of the CE, promotes the interfacial electron transfer rate between iron sulfide and carbon, and increases active sites leading to superior catalytic activity. Consequently, the QDSC based on this optimal structure obtains a power conversion efficiency of 5.61% with higher FF (0.64) compared with those with Pt or other conventional sulfide based CEs. Besides, we developed a novel facile, reproducible and printable preparation process: compositing and chemical conversion (3C).Download high-res image (175KB)Download full-size image

The effect of 2-mercaptobenzothiazole (2-MBT) on laser-assisted electroless copper plating, using formaldehyde as a reducing agent as well as ethylenediaminetetraacetic acid (EDTA) and ethylenediaminetetrapropionic acid (EDTP) as complexing agents, has been investigated. The surface morphology, roughness, and crystallinity of copper coating depend on the 2-MBT concentration. The plating rate enhances significantly with the increase of 2-MBT contents. Accelerating mechanism of electroless copper plating has been studied by means of Tafel plots and linear sweep voltammetry. It is found that the appropriate amount of 2-MBT can improve the quality of copper coatings and accelerate the electroless copper plating process due to the promotion of the controlling step, as 2-MBT additions can form new electrostatic forces resulting in the decrease of absorption of [CH2(OH)O−]ad or Had and then make the controlling step occur more easily.

•FeS/NF CE is fabricated by electrochemical deposition.•FeS/NF exhibits excellent electrocatalytic activity in polysulfide electrolyte.•The QDSC based on FeS/NF CE achieves a high fill factor of 0.58.•The electrode can transform between FeS/NF and Fe2O3/NF spontaneously.•The FeS/NF CE shows excellent stability in photoelectric performance.A stable and efficient FeS/nickel foam (NF) counter electrode for quantum dots-sensitized solar cells (QDSCs) is first fabricated by electrochemistry deposition and characterized with scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), current voltage and impedance spectroscopy. The QDSC based on FeS/NF CE achieves a power conversion efficiency (PCE) of 4.39% attributing to the high fill factor (FF) of 0.58, and the PCE is much higher than that of based on FeS/FTO CE (2.76%) and other reported FeS CEs (1.76% and 3.34%). The phenomenon that the electrode can transform between FeS/NF (in the polysulfide electrolyte) and Fe2O3/NF (in the air) spontaneously is first reported. And the excellent stability in photoelectric performance of the CE is also demonstrated in the present work. Therefore, the FeS/NF is very promising as a stable and efficient CE for QDSCs.

•Flower-like Zn4(OH)6SO4·4H2O nanosheets was prepared by electrodeposition.•ZnO porous nanosheets were obtained by sintering Zn4(OH)6SO4·4H2O precursor.•Effect of electrodeposition parameters on the precursor were systematically studied.•QDSCs based on ZnO porous nanosheets exhibited a promising performance.Flower-like ZnO nanosheets with porous structure are obtained by an indirect electrodeposition method. That is, flower-like Zn4(OH)6SO4·4H2O as precursor is first electro deposited in the Zn(NO3)2 electrolyte containing K2S2O8 followed by a simple thermal treatment. The effects of some important electrodeposition parameters, such as K2S2O8 concentration, electrodeposition potential and duration, on the morphology of flower-like Zn4(OH)6SO4·4H2O nanosheets are systematically studied. The Zn4(OH)6SO4·4H2O nanosheets could be converted to ZnO porous nanosheets by a simple heat treatment process. The ZnO porous nanosheets still present the flower-like structure and are composed of the ZnO nanocrystals about tens of nanometers in size. For the primary application, the quantum dot-sensitized solar cells based on ZnO porous nanosheets show a promising performance, obviously higher than those based on Zn4(OH)6SO4·4H2O nanosheets.

We developed an in situ method to prepare silica particle-containing zinc coatings on NdFeB. Silica sols with silica nanoparticles of 30–150 nm in diameter were prepared through the hydrolysis and condensation of tetraethyl orthosilicate with an acid catalyst. Zinc coatings were prepared on NdFeB magnets using plating baths that contained the silica sols. The effect of the volume content of silica sols on the zinc coatings was studied via scanning electron microscopy (SEM), X-ray diffraction (XRD) and electrochemical analysis. The SEM results showed that the silica nanoparticles were embedded in the zinc particles. Compared with the zinc coatings that were electroplated in the other plating baths, the surface morphology of the zinc coating formed when the silica sol content in the plating bath was in a proper range exhibited better uniformity. The decrease in the corrosion current density value and the increase in the impedance value that were measured via electrochemical testing demonstrated that the embedded silica nanoparticles, which served as corrosion inhibitors, improved the corrosion resistance capability of the zinc coatings on the NdFeB magnets.

Fluorine-containing polymers play an important role in coatings. In this paper, a novel route was developed to prepare fluorine-containing copolymers with long perfluoroalkyl side chains. Hydrophobic films were formed from the copolymers and correlative stoichiometric curing agent. In order to prepare the anticipated fluorine-containing copolymers, a new kind of fluorinated monomer was designed and synthesized. The chemical structure of the monomer and the corresponding copolymers were confirmed by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (1H NMR and 19F NMR). Glass-transition temperature (Tg) of the copolymers was determined with differential scanning calorimetry (DSC). Molecular weight and its distribution of the copolymers were investigated by gel permeation chromatography (GPC). The surface properties of the copolymer films were characterized by static water contact angle, X-ray photoelectron spectrometry (XPS) and atomic force microscopy (AFM). Results showed that the fluorinated monomer and the fluorine-containing copolymers were prepared as expected. Both branching degree and molecular weight of the copolymers increased as fluorine content thereof increased, resulting in an increasing Tg and a broader molecular weight distribution and larger polydispersity. XPS proved an enrichment of the fluorinated segments on the film surfaces. AFM results showed that surface roughness of the copolymer films increased with the use level of the monomer. As a result, the hydrophobicity of the copolymer films was enhanced with the increasing amount of the fluorinated monomer.

We demonstrate a method for fabricating a Cu1.8S/CuS nanoplate counter electrode (CE) via the alternating current (AC) etching of brass. The photoelectrochemical performance and electrocatalytic properties of Cu1.8S/CuS CE with a η value of 3.22% are much higher than those of Pt and conventional Cu2S CEs. Furthermore, it offers a simple and low cost method for producing CuS counter electrodes in the future.

Ultra-thin porous ZnO nanosheets with high regularity were obtained by electrodeposition followed by annealing. The nanosheets were first electrodeposited by controlling the concentration of potassium acetate (KAc) in nitrate electrolyte. The effects of KAc concentration on the electrochemical behavior, the composition and morphology of samples were further discussed. It was indicated that the as-deposited nanosheets were a mixture of ZnO and zinc acetate hydroxide hydrate (ZAHH). After annealing at 450 °C for 30 min, ZnO/ZAHH nanosheets with smooth surfaces were converted to pure ZnO nanosheets with porous structure, which were oblong in shape, ultra-thin (about 20 nm in thickness) and constructed with well-distributed single-layer ZnO nanoparticles with the size of 30–60 nm. As preliminary application in quantum dots-sensitized solar cells (QDSCs), porous ZnO nanosheets were co-sensitized with CdS and CdSe QDs and the QDSCs based on porous ZnO nanosheets deposited for 15 min achieved a high efficiency of 2.67%.

Exploiting new and efficient wide-band gap semiconductors is an important way to improve the performance of photoelectrochemical cells (dye-sensitized solar cells (DSSCs) and quantum dots-sensitized solar cells (QDSCs)). In this paper, Zn5(OH)8Cl2·H2O semiconductor that is a common corrosion product for zinc-contained materials in the electrolytes containing Cl− ions is for the first time explored as wide-band gap semiconductor in the photoelectrode of photoelectrochemical cells. The QDSCs based on CdS QDs-sensitized Zn5(OH)8Cl2·H2O nanosheets achieve the promising power conversion efficiencies of 0.62% and 1.11% for Pt and Cu2S counter electrodes, respectively. Furthermore, combining Zn5(OH)8Cl2·H2O and ZnO to form ZnO/Zn5(OH)8Cl2·H2O composite photoelectrode greatly increases the conversion efficiencies of QDSCs to 1.39% and 1.92% for Pt and Cu2S counter electrodes, respectively, which are higher than those based on conventional ZnO (1.11% and 1.53% for Pt and Cu2S counter electrodes, respectively) or TiO2 porous films (1.07% for Pt counter electrode). Therefore, Zn5(OH)8Cl2·H2O has shown much promise as an efficient wide-band gap semiconductor in the photoelectrode of photoelectrochemical cells.

•The effects of fluorine and silicon components were studied in acrylic copolymers.•The two components had little influence on the latex particle size and morphology.•The fluorine component contributed better hydrophobicity.•The silicon component contributed better heat resistant property.•The two components resulted in a more rough and hydrophobic surface.A series of silicon-containing acrylic copolymers, fluorine-containing acrylic copolymers with two kinds of fluorinated acrylic monomers, as well as fluorosilicone acrylic copolymers were synthesized via seeded emulsion polymerization. Effects of fluorine and silicon components on properties of the copolymers were studied. Chemical structure of the copolymers was characterized by Fourier transform infrared spectrum (FT-IR) and 19F NMR. Glass transition temperature (Tg) of the copolymers was tested via differential scanning calorimetry (DSC). Molecular weight distribution of the copolymers was investigated by gel permeation chromatography (GPC). Morphology and particle size distribution of the copolymer latexes were investigated by transmission electron microscope (TEM) and particle size distribution analysis, respectively. Thermostability of the copolymers was explored by thermo gravimetric analysis (TGA). Hydrophobicity of the copolymer films was studied by the water contact angle data measured via sessile-drop method. Surface feature was investigated by atomic force microscope (AFM). The results showed that fluorine and/or silicon components which were incorporated chemically within the copolymers had little influence on the particle size and morphology of the latexes. The silicon component contributed better heat resistance, while the fluorine component contributed better hydrophobicity to the copolymers. The synergic effect of the two components resulted in a rough surface. The existence of both fluorine and silicon components, as well as the surface roughness, gave rise to a more hydrophobic film.A series of acrylic copolymers were synthesized via a seeding polymerization route. The effects of fluorine and silicon components were studied. Both the two components were helpful to the hydrophobicity of the copolymers. The synergic effect of the two components resulted in a roughness surface. The existence of fluorine and silicon components, as well as the surface roughness, gave rise a more hydrophobic film.

In this paper, ITO porous films were prepared by the doctor-blade technique to support metal sulfide (CuS, CoS, NiS, and PbS) counter electrodes (CEs) in quantum-dot-sensitized solar cells (QDSCs). The successive ionic layer adsorption and reaction (SILAR) method was used to deposit metal sulfides on the ITO porous films. Since the ITO porous films have high mechanical properties and could offer a large surface area for the large deposition of metal sulfides, the ITO porous film-supported metal sulfide CEs exhibited much higher catalytic activity for polysulfide electrolyte than ITO glass-supported metal sulfide CEs. As a result, the photoeletrochemical performance of QDSCs was greatly improved. In addition, ITO porous film-supported CuS CEs at 12 SILAR cycles exhibited the highest catalytic activity and performance among different CEs, and ITO porous film-supported CoS CEs achieved the second highest catalytic activity and performance, still far higher than the Pt CE, while both ITO porous film-supported NiS and PbS CEs showed similar catalytic activity and performance, significantly lower than that of Pt CE. It is also suggested that many more CE materials can be easily explored and investigated by employing ITO porous films as substrates.

•Preparing conditions had great effects on the electrodeposited nanostructures.•Nanosheets, nanospikes and nanowires could be controllably electrodeposited.•ZnO porous nanosheets were obtained by sintering as-electrodeposited nanosheets.In this paper, effects of preparing conditions on the nanostructures electrodeposited from the Zn(NO3)2 electrolyte containing KCl were systematically studied. The electrodeposition conditions, such as concentrations of KCl and Zn(NO3)2, electrodeposition potential and temperature, had significant influence on the morphology and composition of electrodeposited nanostructures. A typical nanosheet structure composed of ZnO, Zn5(OH)8Cl2·H2O and Zn was obtained from the electrolyte containing 0.1 M Zn(NO3)2 and higher concentration of KCl (≥ 0.1 M). In the electrolyte containing 0.1 M KCl, lower concentration of Zn(NO3)2 (≤ 0.02 M) could induce the electrodeposition of ZnO nanospike structures, while the thick and closely packed nanosheets composed of ZnO and Zn5(NO3)2·(OH)8·2H2O were obtained at a higher concentration (0.5 M). Varying the potential from 0.1 to 1.0 V could not obviously change the morphology and composition of nanosheets from the electrolyte containing 0.1 M Zn(NO3)2 and 0.1 M KCl, but single and multi-layer nanosheets could be obtained at higher (− 0.1 V) and lower (≤− 0.4 V) potentials, respectively. Nanosheets were electrodeposited at the temperature higher than 45 °C, and both the thickness and width of nanosheets increased as temperature increased. At a low temperature of 30 °C, bundles of elongated and entangled nanowires surrounded by a large amount of tiny nanocrystals were deposited, which were mainly composed of ZnO and Zn. After heat treatment at 450 °C for 30 min, the as-electrodeposited nanosheets were converted to ZnO porous nanosheets due to the decomposition of Zn5(OH)8Cl2·H2O and oxidation of Zn.

Anodization is widely recognized as one of the most important surface treatments for magnesium alloys. However, since high voltage oxidation films are limited in some applications due to porosity and brittleness, it is worthwhile to explore the non-sparking oxidizing process. In this work, AZ91D was electrochemically anodized at different AC voltages in an electrolyte containing 120 g/L NaOH and 80 g/L Na2SiO3·9H2O. The effects of voltage on the surface morphology, composition and reaction process, especially the non-sparking discharge anodic film formation process, were investigated. The results showed that four different processes would appear according to the applied voltage variation from 6 V to 40 V, and that the non-sparking film formation process occurred in the range of 6–10 V. The film formed on the AZ91D surface under 10 V AC was mainly composed of Mg2SiO4 with a lamellar structure. The horizontal and vertical expansion of the lamellar structure resulted in the formation of a multi-layered structure with a stable, linear growth rate for 30 min. The non-sparking film formation process can be considered to be the result of a balance of electrochemical dissolution and chemical deposition reaction.Highlights► Four different processes appear on magnesium alloys with applied voltage increase. ► Non-sparking film formation process occurred in the range of 6–10 V AC. ► The film was composed of Mg2SiO4 with a stable growth rate in 30 min. ► Film growth was a balance of electrochemical dissolution and chemical deposition.

1ZnOHF was for the first time applied in the photoelectrodes of quantum dots-sensitized solar cells (QDSCs). The QDSCs based on ZnOHF nanostructures achieved more promising performance than those based on ZnO nanorod arrays. Therefore, ZnOHF has shown much prospects in photoelectrochemical cells (QDSCs and DSSCs).

In this paper, petal-like porous ZnO nanosheets were prepared by indirect electrodeposition with Zn4SO4(OH)6·4H2O (ZSH4) as precursor. Petal-like ZSH4 nanosheets were firstly electrodeposited by adding K2SO4 into the electrolyte of Zn(NO3)2 solution and the growth process of ZSH4 nanosheets was also studied. After heat treatment, it is of great interest that the overall morphology of ZSH4 nanosheets was well maintained but ZSH4 nanosheets were completely converted to the porous ZnO nanosheets composed of the ZnO nanoparticles with about 50–100 nm in size. As preliminary application, the photocatalytic ability of porous ZnO nanosheets was investigated. Since porous ZnO nanosheets possess large surface area, it is expected to be widely applied in sensors, photocatalysis and photoelectrochemical cells.

In this paper, flower-like porous ZnO nanosheets were synthesized by indirect electrodeposition method using zinc hydroxide nitrate hydrate (Zn5(OH)8(NO3)22H2O) as precursor. The flower-like Zn5(OH)8(NO3)22H2O nanosheets were first electrodeposited by controlling the concentration of Zn(NO3)2 in electrolyte and the electrochemical behavior and growth process of Zn5(OH)8(NO3)22H2O were also discussed in comparison with those of ZnO. Flower-like porous ZnO nanosheets were obtained by heat treatment due to the decomposition of Zn5(OH)8(NO3)22H2O. The nanosheets were highly porous and were composed of the ZnO nanoparticles with the grain size about tens of nanometers. The characterization measurements indicated that the flower-like porous ZnO nanosheets were an n-type semiconductor with a band gap of 3.16 eV and a carrier concentration of 2.05 × 1020 cm−3. Besides, the flower-like porous ZnO nanosheets displayed a broad green emission at around 475 nm. Once applied in quantum dots-sensitized solar cells (QDSCs), the flower-like porous ZnO nanosheets exhibited a good performance as the photoanode of QDSCs.

Porous ZnO nanosheets show much prospect in many applications. In this letter, highly porous ZnO nanosheets with new and interesting morphology were synthesized by electrodeposition followed by annealing process. The electrodeposition of the nanosheets was conducted by introducing 1 M KBr into 0.1 M Zn(NO3)2 electrolyte. The obtained porous nanosheet is polycrystalline structure composed of ZnO nanoparticles with the grain size about tens of nanometers. The porous ZnO nanosheets were measured to be an n-type semiconductor with a band gap of 3.2 eV. It is expected that the porous ZnO nanosheets could exhibit a good performance in photocatalysis, sensors and photoelectrochemical cells.Highlights► Highly porous ZnO nanosheet was obtained by electrodeposition followed by annealing. ► The electrodeposition was conducted in the Zn(NO3)2 electrolyte containing KBr. ► Porous nanosheet was composed of ZnO nanoparticles with tens of nanometers in size.

1ZnOHF was for the first time applied in the photoelectrodes of quantum dots-sensitized solar cells (QDSCs). The QDSCs based on ZnOHF nanostructures achieved more promising performance than those based on ZnO nanorod arrays. Therefore, ZnOHF has shown much prospects in photoelectrochemical cells (QDSCs and DSSCs).