Electroless Ni Plating Research Articles

Comparative study of Ni nanoparticles synthetized using electroless Ni plating waste and an analytical Ni reagent. Characterization and possible application in magnetic fluids

Wastewater from the electroless industry represents a potential danger to the environment and health, mainly due to its heavy metal content. In this study, nickel nanoparticles were synthesized through chemical reduction precipitation by using an electroless nickel plating waste and hydrazine sulfate as reducing agent. The aim of the present work is twofold. First we want to extract the metal from the aqueous medium, minimizing its content to levels allowed by environmental regulations. Second, we aim to valorize the residue by recovering the precipitated nickel to be applied as a solid phase in a magnetic fluid (MF). It is found that the present synthesis method using N2H4 as reducing agent, allowed us to minimize the Ni concentration in the aqueous waste in 97.49 %. The properties of the recovered Ni precipitate is compared with the Ni nanoparticles (NPs) obtained from a solution prepared with analytical grade nickel sulfate. The synthesized materials from both the waste (Ni-R) and analytical reagent (Ni-A) were characterized by comparing their chemical, physical, and morphological properties. In both cases, the Ni-R and Ni-A precipitates, spherical Ni NPs of 8–10 nm crystallite sizes are obtained, agglomerated in a bimodal size distribution centered at 174.6 and 383.4 nm, and a monomodal size distribution centered at 63.6 nm, respectively. Both Ni precipitated samples are ferromagnetic, but the Ni-R sample has a higher magnetic saturation of 40 emu/g compared to 8 emu/g of the Ni-A sample. The difference in the rheological behavior of both precipitates could be attributed to the presence of surface oxidation having a relatively less contribution in the case of the Ni-R particles due to the higher average size of the particles. The Fe content, probably coming from the nickel-plated parts in spent baths, is slightly higher in the Ni-R sample. Thus, the present work shows that it is possible to valorize an industrial Ni-based residue, by obtaining Ni precipitates that in magnetic fluids give even better results than those expected under more rigorous experimental conditions, i.e., in cases where the quality of the chemical precursors is usually a determining factor.

Electroless Deposition of Ni Nanoparticles on Boron Particles: Physicochemical and Oxidation Properties

Elemental boron also has a high volumetric heat of combustion (136 kJ/cm3), the third highest gravimetric heat of combustion (58.5 MJ/kg) and its oxidation is a highly exothermic process. All these features make boron an attractive constituent of propellants, explosives, and high energy density solid fuels for air-breathing propulsion as an energetic material. Given these uses, researchers have worked on the ignition and combustion processes of boron. However, boron has several serious issues that limit its practical use, including large ignition delay, inefficient combustion, and a complex burning process in solid propellants due to the formation of a defensive boron oxide (B2O3) layer on the boron surface. Previous studies have found that the ignition and combustion performance of boron can be improved by coating it with metal particles, metal oxides, or organic materials, as well as by removing the boron oxide layer.In the literature, there are limited studies on metal particle coating of a boron surface using the electroless Ni plating method. The electroless coating has several impressive advantages over conventional electrolytic coating. The prime advantage is that electroless plating does not require any electricity to operate and is a low-cost process. Among other advantages, it provides a uniform coating and can be used with all kinds of substrates with complex shapes. Conductive and non-conductive materials/powders can be coated with constant thickness with good adhesion.The present work investigated Ni nanoparticle coating on irregularly shaped/non-spherical boron particles using the electroless Ni-plating method at room temperature to prevent the oxidation of boron particles. This is preferable since it is very difficult to coat large quantities at relatively high temperatures. The four different simple paths were chosen during the electroless Ni plating to coat Ni on boron particles: no rinsing and no drying (Path A), only drying (Path B), both rinsing and drying (Path C) and only rinsing (Path D). Previous studies have explored the effect of bath concentration, pH, and temperature on the Ni coating. However, the influence of the four different paths mentioned above on Ni coating with boron particles or any other materials has rarely been investigated. Surface morphology confirmed the Ni nanoparticles coating on the surface of boron particles. The size of the Ni nanoparticles varied between 10 and 120 nm concerning the chosen paths used for preparation using TEM. XRD characterization results of the Ni coated boron particles showed the formation of crystalline Ni nanoparticles. EDAX and XPS results showed the presence of the primary B and Ni elements in samples synthesized in the present study. Thermogravimetric analysis conducted in air atmosphere found the boron particles coated with Ni nanoparticles had enhanced oxidation resistance compared to bare boron particles. Also, the Ni coated boron particles showed a shift in exothermic peak to a lower temperature and higher heat evolution than the bare boron particles.Acknowledgements:This work was supported by the National Research Foundation (NRF) of Korea grant funded by the Korea government (MSIT) No. 2019R1A2C1010862, 2022R1A2C2013508

Determination of selective laser melting process parameters of tungsten carbide powders coated with nickel via electroless plating for improved interface properties

Tungsten carbide powders are commonly used at various industrial applications due to their high hardness. However, these powders may exhibit low binding and processing challenges without a binder. Therefore, various binding methods such as electroless Ni coating are used to hold WC powders together, increase their processability and improve the mechanical properties of the final product. Electroless Ni plating plays an important role in the use of WC powders, especially in processes such as selective laser melting. The structural, tribological, and mechanical properties of parts manufactured by SLM method are significantly influenced by the parameters employed in the process. Hence, optimizing process variables is essential to unlock the full potential of this advanced manufacturing technique. The main objective of this study was to identify the optimum process parameters for the SLM method of WC-Ni composite powders, which were prepared by coating WC powder materials with electroless Ni. Experimental investigations focused on analyzing the laser power, scanning speed, and hatch spacing parameters. The effects of these parameters on the mechanical and tribological properties of WC-Ni composite material were investigated using microhardness tester, tribometer device, optical microscope, 3D optical profilometer and scanning electron microscope. Eventually, it was determined that the manufacturing parameters employed in the SLM method had a significant impact on relative density, microstructure, surface roughness, hardness, and tribological properties. Samples exhibited a relative density of nearly 99%, and the highest observed hardness value was 1962 HV. This article supports a specialized SLM manufacturing process developed specifically to enhance durability and performance across a broad spectrum of industrial applications through interface improvement and the optimization of manufacturing parameters.

Efficient simultaneous removal of nickel, phosphorus and COD from electroless nickel plating wastewater by three dimensional electrodialytic system

The simultaneous removal of nickel (Ni), phosphorus (P) and chemical oxygen demand (COD) from electroless Ni plating (ENP) wastewater by a three-dimensional electrodialysis (3D ED) system with graphite as the third electrode was investigated in this study. Compared to conventional two-dimensional electrodialysis (2D ED) system a significantly higher removal efficiency of complexed Ni, P and COD was achieved. The optimal process conditions were determined as dilution factor of 20, voltage of 20 V, treatment time of 10 h and particle electrode addition of 3 %, with removal rates of 95.8 %, 97.7 %, and 91.8 % for Ni2+, total phosphorus (TP) and COD, respectively. The decomplexed Ni2+ was recovered in the form of Ni(OH)2. Additionally, the mechanisms of enhanced ENP wastewater treatment was discussed and analyzed through SEM-EDS and XPS on solid and liquid products prior to and after treatment. This study provides crucial theoretical and practical support for the application of electrochemical technology in the treatment of ENP wastewater. It also offers new insights for achieving resource-efficient wastewater treatment and environmentally friendly electroplating industries.

Effect of Secondary Phase on Electroless Ni Plating Behaviour of Super Duplex Stainless Steel SAF2507 for Advanced Li-Ion Battery Case.

The development of Li-ion battery cases requires superior electrical conductivity, strength, and corrosion resistance for both cathode and anode to enhance safety and performance. Among the various battery case materials, super duplex stainless steel (SDSS), which is composed of austenite and ferrite as two-phase stainless steel, exhibits outstanding strength and corrosion resistance. However, stainless steel, which is an iron-based material, tends to have lower electrical conductivity. Nevertheless, nickel-plating SDSS can achieve excellent electrical conductivity, making it suitable for Li-ion battery cases. Therefore, this study analysed the plating behaviour of SDSS plates after nickel plating to leverage their exceptional strength and corrosion resistance. Electroless Ni plating was performed to analyse the plating behaviour, and the plating behaviour was studied with reference to different plating durations. Heat treatment was conducted at 1000 °C for one hour, followed by cooling at 50 °C/s. Post-heat treatment, the analysis of phases was executed using FE-SEM, EDS, and EPMA. Electroless Ni plating was performed at 60-300 s. The plating duration after the heat treatment was up to 300 s, and the behaviour of the materials was observed using FE-SEM. The phase analysis concerning different plating durations was conducted using XRD. Post-heat treatment, the precipitated secondary phases in SAF2507 were identified as Sigma, Chi, and CrN, approximating a 13% distribution. During the electroless Ni plating, the secondary phase exhibited a plating rate equivalent to that of ferrite, entirely plating at around 180 s. Further increments in plating time displayed growth of the plating layer from the austenite direction towards the ferrite, accompanied by a reduced influence from the substrate. Despite the differences in composition, both the secondary phase and austenite demonstrated comparable plating rates, showing that electroless Ni plating on SDSS was primarily influenced by the substrate, a finding which was primarily confirmed through phase analysis.

Study of Electroless Nickel Plating on Super Duplex Stainless Steel for Lithium-Ion Battery Cases: Electrochemical Behaviour and Effects of Plating Time

With increasing demand for Li-ion batteries, studies are focusing on enhancing battery performance and safety. However, studies on battery cases remain scarce. Herein, we propose the use of super duplex stainless steel SAF2507, which is a two-phase (austenite + ferrite) steel, for battery casings. Unlike conventional AISI304, SAF2507 maintains its corrosion resistance and strength at high temperatures and precipitates a secondary phase at approximately 975 °C. However, the effects of Ni plating on this secondary phase are not well documented. Therefore, the electroless Ni plating of SAF2507 after secondary-phase precipitation was studied. Briefly, heat treatment at 1000 °C was used to induce precipitation, and the electroless Ni plating behaviour over varying plating periods was analysed using open-circuit potential, potentiodynamic polarisation, and electrochemical impedance spectroscopy measurements. The plating state and corrosion behaviour were examined using scanning electron microscopy. Heat-treated SAF2507 steel with a secondary phase exhibited excellent electroless Ni plating behaviour, which enhances the safety and durability of Li-ion batteries. Furthermore, uniform plating and electrochemical behaviour were achieved after 180 s, suggesting that SAF2507 is superior to AISI304. These findings contribute to the development of safer and more efficient batteries and address the growing demand for Li-ion battery case materials.

Low-cost and eco-friendly fluidized bed hydrogen reduction assisted electroless plating to synthesize Ni-coated graphite

Electroless plating is the main method for preparing metal-coated composite powders, such as Ni-coated graphite powders with wide applications in electromagnetic shielding materials, sealing coating, and electrocatalysis. However, the issues of uniform and dense coating during synthesis are hindering its practical implementation. Incorporating noble metals, such as Pd, to activate powders is a typical technique to prepare an electroless Ni coating. However, noble metal utilization is hindered by issues such as high costs and substantial wastewater. Herein, a novel low-cost and eco-friendly activation method based on fluidized bed hydrogen reduction is designed to prepare densely coated Ni@irregular graphite particles (Ni@IGP) using a low Ni content. This method can be used to construct a uniform and dense Ni coating for composite powders without acid alkali treatment and use of precious metals during the overall manufacturing process. Results demonstrated that the Ni@IGP particle obtained through this approach have good electrical conductivity and ferromagnetic properties. In addition, the uniformity and integrity of the Ni plating were adjusted, and the dense coating of graphite at a low Ni content of 35 wt% was effectively achieved. This new activation method sheds light on the field of electroless Ni plating on powders.

Effect of Microstructure on Electroless Ni Plating Behavior on Super Duplex Stainless Steel SAF2507 in Li-Ion Batteries

The demand for Li-ion batteries has significantly increased in recent years, driven by the growing need for electric vehicles and electronic devices like smartphones. Among various materials, super duplex stainless steel (SDSS) is considered a suitable material for Li-ion batteries due to its excellent strength and corrosion resistance. However, SDSS is sensitive to heat-treatment conditions, necessitating research on heat treatment and Ni plating for battery case usage. While extensive research has been conducted on SDSS and its heat-treatment conditions, there is a research gap concerning the Ni plating of SDSS. This study addresses this gap by performing Ni plating on heat-treated SDSS. Ni plating can be executed via two methods: electroless and electro-Ni plating. To achieve a uniform plating layer, Ni plating was conducted after heat treatment at temperatures ranging from 1000 °C to 1300 °C, followed by an analysis of the behavior of electroless Ni plating. The heat-treated SDSS displayed three primary characteristics: secondary phase precipitation, solution annealing, and ferritization (ferrite fractions of 61% and 73%). The presence of secondary phases led to a slower Ni plating rate due to its lower reactivity with Ni. Post-solution annealing, the texture of SDSS exhibited the thickest Ni plating layer at the same plating time. As the volume fraction of ferrite increased from 50% to 73% on electrochemical impedance spectroscopy, the resistance of the Ni plating layer decreased from 45 kOhms to 13 kOhms. The lowest resistance was observed when the ferrite fraction reached 73%, attributed to the lower reactivity of ferrite compared to austenite. Both secondary phases and ferrite contributed to reducing the thickness of the electroless Ni plating layer. Therefore, optimizing the volume fraction of SDSS using solution annealing proves beneficial for optimizing Ni plating and enhancing corrosion resistance.

Examination of the metallization behaviour of an ABS surface

ABSTRACT The main scope of this work is the metallization of high density Acryonitrile Butadiene Styrene (ABS) surfaces for aerospace applications. Originality and main focused area of the study is to grasp the mechanism of physical properties of the surface and the effect of wet chemical processes on the surface of the ABS substrate. After surface sensitization and metallization with nano-sized ions, the polyurethane surface is metallized and nickel (Ni) coated with electroless and elecrolytic Ni plating processes. The ultimate goal of these advances is the production of composite lay-up tools for the production of primary and secondary composite aircraft parts from nanoscale to macro level. Composite lay-up tool requirements of the aerospace industry include a minimum thickness of 5 mm, acceptability of airtightness testing and reduced surface roughness. Results show that increasing current density adversely affects the surface morphology and metallization processes enhance the surface conductivity of the foam.

Microstructure evolution and mechanical properties of 3YSZ/Ni composites with uniform phase distribution prepared by core-shell structure microspheres

Yttrium-stabilized zirconia(3YSZ) microspheres with different size ranges were prepared by sol-gel method, followed by electroless Ni plating on their surfaces. The as-prepared core-shell structure 3YSZ/Ni microspheres were then spark plasma sintered (SPS) into 3YSZ/Ni composites, in which a uniform distribution of ceramic and metal phases was achieved. The underlying correlations among microsphere size, Ni concentration, microstructure, and resultant mechanical properties were experimentally analyzed. Results show that: continuous and smaller microsphere sizes can obtain relatively high-density samples with good mechanical properties, which can be proved by the Minimum Solid Area (MSA) model. 3YSZ sample prepared with the optimized microsphere size range of 0–50 μm exhibits the highest relative density and fracture toughness of 98.8% and 5.51 ± 0.33 MPa·m1/2, respectively. Furthermore, the core-shell structure 3YSZ/Ni microspheres with varying Ni contents exhibited a uniform composite of flakes and particles Ni metal after sintering, among which 3YSZ/10 wt%Ni composites have achieved better mechanical properties, with density, hardness and fracture toughness of 96.9%, 8.61 ± 0.35 GPa, 7.92 ± 0.71 MPa·m1/2, respectively. Firstly, the uniformly dispersed Ni metal flakes or particles provide multiple toughening effects, including crack bridging, pull-out, interfacial debonding, crack deflection, etc. Secondly, due to residual stress, cracks tend to deflect near Ni metal, extending the crack path. Thirdly, the 3YSZ matrix's transition from an intergranular to a transgranular fracture also increases fracture energy consumption. Compared to the pure 3YSZ sample with a wide microsphere size range of 0–100 μm, the fracture toughness of 3YSZ/10 wt%Ni composites with a microsphere size of 0–50 μm is increased by 73.9%.

Development and analysis of a nano-triangular wave-shaped polarizer

As society becomes smarter, advanced optical sensing and imaging technologies utilizing visible and near-infrared regions have become increasingly prevalent. Wire-grid polarizers, which are available for broadband electromagnetic waves, are effective in improving the signal-to-noise ratio of such optical systems and enabling more advanced object detection and analysis. However, to be implemented in everyday products, low-cost manufacturing methods must be developed while maintaining high-performance optical functions. To meet these requirements, we conducted an analysis of the geometry of wire-grid polarizers, and designed and developed a wire-grid polarizer with a nano-triangular wave-shaped structure that can be fabricated using general-purpose manufacturing equipment. Once the mould is prepared, this polarizer can be fabricated via nanoimprinting and metal deposition with a normal angle or electroless plating processes. The polarizer fabricated through electroless Ni plating achieves a transmittance of 40%, which is approximately 1.4 times higher than that achieved in a previous study using electroless Ni plating on a rectangular structure with the same period. In addition, the polarizer fabricated through normal angle Al deposition operates over a wide range of wavelengths from visible light to near-infrared, and achieves a polarization extinction ratio of 24 dB at a wavelength of 550 nm and a high transmittance of 81%. High-performance polarizers can be obtained through normal-angle deposition using general-purpose equipment in contrast to the oblique-angle deposition method employed in the manufacture of conventional rectangular structure-based wire-grid polarizers, thereby contributing to cost reduction and improved manufacturability.

Directly preparing well-dispersed ultra-hydrophilic NiFeP nanoparticle/Mxene complexes from spent electroless Ni plating solution as efficient hydrogen evolution catalysts

A novel approach is proposed to prepare well-dispersed ultra-hydrophilic NiFeP nanoparticle/Mxene complex by recovering Ni, P, and organic acid from spent electroless Ni-plating solution. The mechanism of NiP-based nanoparticle formation and size regulation during the hydrothermal process is analyzed. Ni2+ chelated with sodium citrate in the electroless Ni plating effluent anchors on the Ti3C2 surface with -OH functional groups by chemical reaction and charge adsorption owing to Mxene surface negativity. The as-prepared ultrafine NiFeP nanodots are connected with alkali-induced Ti3C2 Mxene nanosheets, which possess ultra-hydrophilic performance and rapid H2 bubble desorption behavior. The introduction of alkali-induced Ti3C2 MXene as a substrate controls particle agglomeration in the hydrothermal crystallization process and achieves perfect dispersed distribution of NiFeP nanoparticles to further increase the specific surface area of catalyst. Consequently, the NiFeP/Ti3C2 nanohybrid catalyst exhibits outstanding hydrogen evolution reaction (HER) electrocatalyst performance as a result, with an overpotential of 122 mV at 10 mA cm−2, quick reaction kinetics of 68 mV dec−1, and strong long-term stability over 24 h in 1 M KOH. This research develops a strategy for directly preparing high-value catalyst materialization from spent electroless Ni-plating solution.

Flexible spiral-like multilayer composite with Fe3O4@rGO/waterborne polyurethane-Ni@polyimide for enhancing electromagnetic shielding

A well-designed multilayer composite with a unique spiral structure consisting of polyimide (PI) fabric and waterborne polyurethane (WPU) created by hot compression molding method for lightweight and flexible electromagnetic interference (EMI) shielding materials. Electroless Ni plating was employed to prepare the Ni@PI fabric and Fe3O4@rGO was evenly distributed throughout the WPU to provide conductivity and magnetism. Based on the reduced graphene oxide/WPU (rGO/WPU) composites, the addition of Fe3O4 nanoparticles improves the EMI shielding effectiveness (SE) of Fe3O4@rGO/WPU composites, especially the absorption efficiency. The continuous conductive network included in the Fe3O4@rGO/WPU-Ni@PI composite firmly locks electromagnetic wave as they enter the interior and provides more interfaces to increase multiple reflection losses, thus showing higher SE than traditional multilayer composites. The maximum SE value (36.8 dB) of the spiral structure composite with only 6.2 wt% Ni and 8.53 wt% Fe3O4@rGO loading is higher than that of conventional multilayer composites (27.0 dB), breaking through the bottleneck of high filler loading and low SE of conductive polymeric composites. Furthermore, after 1000 bending cycles, the composite with spiral structure retains significant EMI SE. The composite offers a wide range of applications, including electromagnetic protection for flexible electronic devices and the next generation of communication equipment.

Enhanced Capacity and Cyclability of Si@NiSi2 Nanocomposite Anodes Fabricated by Facile Electroless Ni Plating

Although silicon (Si) has been proposed as the most promising anode material in lithium-ion batteries due to their high capacity (∼4000 mA h g–1), the poor cyclability resulting from the strain-induced pulverization caused by the severe volume change during charge/discharge hinders the industrial applications. Here, Si nanoparticles were conformally coated with either Ni, NiO, or NiSi2 to suppress the tremendous volume change of Si, hence leading to prolonging the cycle life of the Si anode to a different degree. Both Si@Ni and Si@NiO nanocomposites were synthesized by one-step self-reducing (SR) electroless nickel plating without/with heat treatment, respectively, whereas Si@NiSi2 nanocomposites were obtained by a two-step (SR + electroless nickel deposition, EN) process, followed by heat treatment. Among all these three nanocomposite anodes, Si@NiSi2 prepared by 5 min of SR, 30 min of EN, and 400 °C annealing in sequence achieved the highest capacity of ∼1390 mA h g–1 and the best capacity retention of ∼86.6% with a Coulombic efficiency of 99% over 70 cycles. For comparison, the capacity retention of the Si@Ni and Si@NiO electrode over 70 cycles is estimated to be ∼67 and 75%, respectively. These results suggest that NiSi2 could be a promising protective coating layer to effectively buffer the volume change of Si and promote the battery life.

A neotype carbon-based Ni foam achieved by commercial strategy towards smooth and light Li metal anodes

Commercial Ni foam (NF) as substrate is widely used in lithium metal anode for uniform Li deposition and dendrite-free condition by reduced local current density. However, it's high mass density of 8.902 g cm−3 and bulky skeleton tend to the heavy weight, which remarkedly decreases the energy density of lithium metal batteries. Herein, three-dimensions carbon foam completely coated by Ni metal (Ni@CMF) is fabricated as an alternative to NF through commercial electroless Ni plating. The noneffective inner Ni metal, occupying most of mass and volume of NF, is masterly replaced by light carbon foam, which is carbonized from cost-effective melamine foam (MF), resulting in sharply reduced areal density from ∼24.8 mg cm−2 to ∼2.2 mg cm−2 and improved electrochemical performance compared with commercial NF. As a result, the superior Coulombic efficiency stability of 240 cycles for Ni@CMF substrate is achieved companying reduced Li nucleation overpotential of ∼11 mV compared with that of NF (∼53 mV). Moreover, the pouch Li metal full cell enlightens the light-emitting diode (LED) lights in both flat and deformation states. The neotype Ni foam, proposed in this work, with huge commercial value can be produced in large scale in lighter weight, lower cost and enhanced property.

Microstructure and mechanical properties of Cu–Fe-ZTA cermets prepared by vacuum hot pressing sintering

Cermets with Cu and Fe as matrix and zirconia toughened alumina (ZTA) as reinforcement phase were prepared by vacuum hot pressing sintering. Electroless Ni plating was carried out on ZTA particles to improve the interfacial bonding ability between ZTA and metal matrix. Cu-xFe-ZTA cermets (x = 20, 50, 80) were prepared by using different proportions of Cu powders and Fe powders as the binder in order to investigate the influence of binder types on the grinding performance of cermets. The phase composition, microstructure, mechanical properties and grinding properties of Cu–Fe-ZTA cermets were systematically studied. It revealed that the difference of cermet grinding performance lay in the bonding force between metal matrix and abrasive. The coating ability of abrasive is stronger with the increase of Cu content in the matrix. Because the matrix is soft and easy to grind, the cermet grinding wheel material has strong self-sharpening, and Cu–20Fe-ZTA grinding effect is the best. The friction coefficient of Cu–20Fe-ZTA cermets was 0.405, the grinding surface roughness was 7.972 μm, and the residual stress σx and σy were 180.5 and 89.6 MPa, respectively. As the Fe content decreased, the grinding mechanism changed from ploughing and cutting to friction.

Preparation and electrochemical properties of porous SiO/Ni anode materials for lithium-silicon batteries

To alleviate the volume expansion and improve the electrical conductivity of silicon monoxide (SiO) anode materials for lithium-silicon batteries, porous SiO (P-SiO) was prepared by silver-assisted chemical etching, and then porous SiO/Ni (P-SiO/Ni) composites were prepared by electroless Ni plating. The effect of SiO particle size on the microstructure of P-SiO and its electrochemical properties and the effect of Ni+ concentration in the plating solution on the microstructure of P-SiO/Ni and its electrochemical properties were systematically investigated, and the process mechanism of the preparation porous SiO by silver assisted chemical etching was firstly clarified. The results show that both the refinement and porosity of the SiO raw material are beneficial to alleviate the volume expansion of the P-SiO electrodes during the lithiation and delithiation process, and thus improve their the electrochemical performance. The electroless plating of nickel on the surface of P-SiO is also beneficial to further alleviate the volume expansion and increase the electrical conductivity of P-SiO electrode, thus further improving its specific capacity and cycling stability, the P-SiO/Ni anode with 3.03 wt% Ni content prepared at the Ni2+ concentration of 13 g/L has the best electrochemical performance, which the first discharge specific capacity reaches 1725.67 mAh/g, the first coulomb efficiency reaches 69.53%, and the reversible specific capacity after 200 cycles reaches 811.34 mAh/g at 1 A g−1 with a capacity retention rate of 62.39%.

Fabrication of Efficient Gold−Nickel-Supported Titania Nanotube Electrocatalysts for Sodium Borohydride−Hydrogen Peroxide Fuel Cells

Here we report the optimization of the fabrication conditions for AuNi bimetallic catalysts supported on self-ordered titania nanotube arrays (AuNi-TiO2ntb). A series of efficient AuNi-TiO2ntb catalysts with small amounts of Au in the range of 1.74 to 15.7 μgAu·cm−2 have been fabricated by anodization, electroless Ni plating, and galvanic displacement techniques. The electrocatalytic activity of the catalysts has been evaluated for BH4− ion oxidation in an alkaline medium using cyclic voltammetry and chronoamperometry. The performance of a NaBH4-H2O2 fuel cell with Ni-TiO2ntb and AuNi-TiO2ntb anode catalysts has been investigated at different temperatures. It was found that the electrocatalytic activity of AuNi-TiO2ntbs catalysts was improved remarkably when the Ni layer of 100 and 400 nm was used for the deposition of Au crystallites. The Ni-TiO2ntb catalyst generates the maximum power density values of ca. 85–121 mW·cm−2 at a temperature of 25–55 °C, whereas the AuNi-TiO2ntb catalysts that have the Au loading of 3.07 and 15.7 μgAu·cm−2 achieve the power density values of ca. 104–147 and 119–170 mW·cm−2, respectively, at a temperature of 25–55 °C.

Preparation of nickel@polyvinyl alcohol (PVA) conductive membranes to couple a novel electrocoagulation-membrane separation system for efficient oil-water separation

Efficient separation of oil-in-water emulsion remains a decisive step for success of oily wastewater treatment. To achieve this goal, a novel strategy regarding combining membrane separation with in situ electrocoagulation based on sacrificial anodes and cathodic hydrogen evolution via conductive metalized fabric membrane was proposed. As a key component of this novel coupling system, nickel functionalized fabric membrane with high hydrophilicity and electrical conductivity (electrical resistance of ∼2 Ω cm−1) was successfully prepared via a low-cost and facile route, including steps of PVA (polyvinyl alcohol)/Ni coating and autocatalytic electroless Ni plating. The optimized conductive membranes exhibited high permeate flux (19.3 × 105 L m−2 h−1·bar−1), separation efficiencies (99.5%), and separation stability to separate oil/water mixtures during the gravity-driven filtration process. To achieve the ideal performance to separate oil-in-water emulsion, a coupled electrocoagulation-membrane separation system was constructed with Ni@PVA membrane and Al mesh as the cathode and anode, respectively. It was shown that the coupled electrocoagulation-membrane separation system could achieve 99.4% rejection with high flux of 12.0 × 103 L m−2 h−1·bar−1 for oil/water emulsion separation, under the current density of 8 mA cm−2 and 20 min electrolysis time. This study revealed that the proposed electrocoagulation-membrane separation system based on Ni@PVA membrane is a promising technique in oil/water separation.

Enhanced corrosion resistance of porous microarc oxidation coating sealed with electroless nickel plating under pressure impregnation

The corrosion protection ability of the microarc oxidation (MAO) coating cannot be maximized due to its inherent defective structure, and further hole sealing treatment has been a prevailing strategy for enhancing the corrosion resistance. Herein, the electroless Ni plating under pressure impregnation was demonstrated to be significantly effective to remedy the defects of the porous MAO coating, the voids and cracks in the MAO coating were filled with Ni well, resulting in the blockage of the invasive route of the corrosive Cl− ions, and the ionization of the metal matrix was unable to occur, the MAO coating with ultrahigh electrical resistivity hardly transferred the electron from the Ni layer to substrate, hence, the corrosion property of the MAO coating was obviously enhanced.