Electroless Plating Approach Research Articles

Recycled industrial waste silicon steel as high-performance electrode for oxygen evolution reaction using electroless plating surface modification

Exploring the large-area, cost-effective, and high-performance electrocatalyticoxygen evolution reaction (OER) electrode for water splitting is of great significance. Inspiring from the ‘waste to resource’ toward the circular economy, herein, the waste silicon steels (SS) were transformed into high-performance CoxFe3-xP/SS OER electrode through a facile electroless plating method. The plating layer of CoxFe3-xP not only endows the CoxFe3-xP/SS with outstanding electrocatalytic OER activity but also improves the corrosion resistance and stability of CoxFe3-xP/SS. The obtained Co2Fe1P/SS electrode exhibits the lowest overpotential of 244 mV at a current density of 10 mA/cm2 in 1 M KOH with a low Tafel slope of 48.7 mV/dec. Even at high current densities and in 6 M KOH and alkaline seawater (seawater + 1 M KOH), the Co2Fe1P/SS electrode also shows relatively low overpotentials, as well as high long-term durability. Specially, a large-area Co2Fe1P/SS OER electrode(40 × 40 cm2)was successfully prepared via the electroless plating approach. Toward the CoxFe3-xP/SS, the bimetallic Co-Fe synergies and phosphating effect promote the exposure of active sites and charge transfer. In addition, generated M(OH)x/MOOH (M = Co or Fe) species during OER activation could synergize with CoxFe3-xP and contribute excellent catalytic activity and stability.

Design Principles of Mediation Layer for Current Collectors Toward High‐Performance Anode‐Free Potassium‐Metal Batteries: A Case Study of Cu6Sn5 on Copper

AbstractAnode‐free potassium (K) metal batteries are promising candidates in high‐energy‐density batteries. Nevertheless, the notorious potassium dendrite growth and poor K plating/stripping efficiency originating from the potassiophobicity of conventional Cu current collectors impede their practical applications. Herein, by means of systematically multi‐scale theoretical simulations, the correlations among K deposition morphology, nucleation sites, and potassiophilicity of mediation layers are well illuminated from thermodynamics and dynamics perspectives. As a proof of concept, a potassiophilic alloy Cu6Sn5 layer is constructed on commercial Cu foils via a facile electroless plating approach. The designed Cu6Sn5@Cu can guide the homogeneous distribution of K+ flux and regulate the electronic field, promoting uniform K+ plating and stripping. Meanwhile, a KF‐rich solid electrolyte interphase (SEI) layer with high mechanical strength is electrochemically induced and formed, facilitating the transport of K+ through SEI and enhancing the stability of SEI. Consequently, Cu6Sn5@Cu delivers great performance with durable stability of up to 600 h (1 mA cm−2 and 1 mAh cm−2) in no‐reservoir half‐cells. Benefiting from the unique mediation layer design, a novel anode‐free K‐metal full‐cell prototype demonstrates ameliorative cyclic stability. This work advances a fundamental understanding and establishes the bridge between the potassium deposition morphology and mediation layer properties for anode‐free potassium‐metal batteries.

Vacuum-assisted continuous flow electroless plating approach for high performance Pd membrane deposition on ceramic hollow fiber lumen

Pd-based membranes have wide applications in H2-related fields given their excellent selectivity in H2 separation. Despite their unique advantages, the fabrication of continuous and dense Pd membrane layer in the lumen side of the hollow fibers remains a great challenge. Herein, a vacuum-assisted continuous flow electroless plating (VCFELP) approach was developed to deposit a 4 μm-thick compact Pd membrane layer on the lumen (i.e., inner surface) of YSZ-Al2O3 composite hollow fiber with outer and inner diameter of 1.5 and 1.0 mm, respectively. The Pd membrane displayed hydrogen flux of ∼0.075 mol m−2 s−1 at 773 K and the nitrogen was undetectable through bubble flow meter and gas chromatograph. Furthermore, the stability and durability of the Pd membrane were significantly improved by the VCFELP approach with the aid of vacuum and continuous flow system. The outstanding membrane stability was verified by the 240-h long-term operation, with up to 24 cycles of H2–N2 gas exchange tests, 40 thermal cycle tests (from high to low temperature) and 20 pressure cycle tests. Furthermore, the Pd membrane showed sufficient stability and excellent reaction performance during the 120-h reaction run in the one-step oxidation of benzene to phenol using hydrogen and oxygen as co-reactants, achieving the benzene conversion and phenol selectivity of 23.5% and 91.6%, respectively.

High-Performance AlGaN/GaN Enhancement-Mode High Electron Mobility Transistor by Two-Step Gate Recess and Electroless-Plating Approaches

In this work, an AlGaN/GaN enhancement-mode high electron mobility transistor (HEMT) with two-step gate recess and electroless plating (EP) approaches is reported. Scanning electron microscopy and atomic force microscopy surface analysis are used to analysis the related properties of the EP-gate structure. A positive threshold voltage Vthof 0.68 V is obtained for the enhancement-mode EP-HEMT. In addition, a traditional HEMT based on thermal-evaporation gate is compared for the demonstration of the studied EP-HEMT with the improved performance, such as a higher maximum drain saturation current of 228.9 mA/mm, a higher maximum transconductance of 107.2 mS/mm, a lower gate leakage current of 1.2 × 10–7 mA/mm, and a higher ON/OFF drain current ratio of 4.57 × 105.

Facile Synthesis of Highly Oxidation Stable Nanosilver-Coated Copper Nanowires for Transparent Flexible Electrodes

This study reports an efficient electroless plating approach using an amino-alcohol precursor to synthesize the oxidation stable copper@silver (Cu@Ag) core–shell nanowires. The synthesized nanowires were characterized by different techniques. The as-synthesized nanowires were used to fabricate transparent flexible electrodes (TFEs) and transparent stretchable heaters (TSHs). The nanowire network on the substrates was sintered using the 5% aqueous solution of H2O2, which welded the nanowires at their junction and strongly attached to the substrate. Therefore, the optical-electrical performance (∼13 Ω sq–1 @ 89% transmittance), oxidation stability, and mechanical flexibility of as-prepared TFEs and TSHs were improved to a large extent. In addition, the performance of the TSHs in terms of high-saturation temperature and stability against repeated stretching cycles upon 20% mechanical strain temperature are also enhanced. The overall processing strategy was suitable to synthesize the Cu@Ag core–shell nanowires and to fabricate the stable TFEs and TSHs for modern electronic and thermoelectric devices.

Investigation of Pd|HfO2|AlGaN|GaN Enhancement-Mode High Electron Mobility Transistor with Sensitization, Activation, and Electroless-Plating Approaches

A new Pd|HfO2|AlGaN|GaN metal-oxide-semiconductor (MOS) enhancement-mode high electron mobility transistor (HEMT) is fabricated with low-temperature sensitization, activation, electroless-plating, and two-step gate-recess approaches. Experimentally, a high positive threshold voltage Vth of 1.96 V, a very low gate leakage IG of 6.3 × 10–8 mA/mm, a high maximum extrinsic transconductance gm, max of 75.3 mS/mm, a high maximum drain saturation current ID, max of 266.9 mA/mm, and a high ON/OFF current ratio of 7.6 × 107 are obtained at 300 K. Moreover, the related temperature-dependent characteristics, over temperature ranges from 300 to 500 K, are comprehensively studied. The very low temperature coefficients on gate current, drain saturation current, transconductance, and threshold voltage confirm the thermal-stable capability of the studied device. Therefore, based on these advantages, the studied Pd|HfO2|AlGaN|GaN MOS structure is suitable for the development of high-performance HEMTs.

Investigation of Pd|HfO-=SUB=-2-=/SUB=-|AlGaN|GaN Enhancement-Mode High Electron Mobility Transistor with Sensitization, Activation, and Electroless-Plating Approaches

A new Pd|HfO2|AlGaN|GaN metal-oxide-semiconductor (MOS) enhancement-mode high electron mobility transistor (HEMT) is fabricated with low-temperature sensitization, activation, electroless-plating, and two-step gate-recess approaches. Experimentally, a high positive threshold voltage Vth of 1.96 V, a very low gate leakage IG of 6.3·10-8 mA/mm, a high maximum extrinsic transconductance gm,max of 75.3 mS/mm, a high maximum drain saturation current ID,max of 266.9 mA/mm, and a high ON/OFF current ratio of 7.6·107 are obtained at 300 K. Moreover, the related temperature-dependent characteristics, over temperature ranges from 300 to 500 K, are comprehensively studied. The very low temperature coefficients on gate current, drain saturation current, transconductance, and threshold voltage confirm the thermal-stable capability of the studied device. Therefore, based on these advantages, the studied Pd|HfO2|AlGaN|GaN MOS structure is suitable for the development of high-performance HEMTs. Keywords: HfO2, AlGaN|GaN, metal-oxide-semiconductor, high electron mobility transistor, electroless plating, gate recess, threshold voltage.

Hydrogen sensing performance of a GaN-based Schottky diode with an H2O2 treatment and electroless plating approach

A new electroless plating (EP)-Pd/GaOx/GaN Schottky diode-type hydrogen sensor is fabricated and comprehensively studied herein. The GaOx dielectric is formed as a result of a proper H2O2 treatment on the GaN surface. In addition, a 20-period sensitization/activation process and an appropriate EP approach of the Pd catalytic layer are employed to facilitate a high-performance metal-semiconductor (M-S) Schottky contact. Experimentally, an extremely high hydrogen sensing response of 5.5 × 106 (under 1% H2/air gas) and a relatively low detection limit of 5 ppm H2/air are obtained at 300 K. The corresponding response and recovery times are 22 s and 21 s at 300 K, respectively. A new data transmission algorithm based on the Kalman algorithm is also proposed in this work. According to the simulation results, the data transmission volume can be reduced by 90%. The average recovery error rate is less than 0.38%. Furthermore, our developed reduced redundancy method can pre-warn the user of sensor failure. Based on the advantages mentioned above, therefore, the studied device is promising for high-performance hydrogen sensing and Internet of Things (IoT) applications.

Electroless Plating of Highly Efficient Bifunctional Boride‐Based Electrodes toward Practical Overall Water Splitting

AbstractExploring highly‐efficient and low‐cost electrodes for both hydrogen and oxygen evolution reaction (HER and OER) is of primary importance to economical water splitting. Herein, a series of novel and robust bifunctional boride‐based electrodes are successfully fabricated using a versatile Et2NHBH3‐involved electroless plating (EP) approach via deposition of nonprecious boride‐based catalysts on various substrates. Owing to the unique binder‐free porous nodule structure induced by the hydrogen release EP reaction, most of the nonprecious boride‐based electrodes are highly efficient for overall water splitting. As a distinctive example, the Co‐B/Ni electrode can afford 10 mA cm−2 at overpotentials of only 70 mV for HER and 140 mV for OER, and can also survive at large current density of 1000 mA cm−2 for over 20 h without performance degradation in 1.0 m KOH. Several boride‐based two‐electrode electrolyzers can achieve 10 mA cm−2 at low voltages of around 1.4 V. Moreover, the facile EP approach is economically viable for flexible and large size electrode production.

Rate dependent behaviors of nickel-based microcapsules

In this work, nickel-based microcapsules with liquid core were fabricated through an electroless plating approach. The quasi-static and high speed impact behaviors of microcapsules were examined by in-house assembled setups which are able to evaluate properties of materials and structures in microlevel accurately. Results indicated that the fabricated microcapsules showed strong rate sensitivity and the nominal strength of the capsule increased (up to 62.1%) with the increase in loading rates (up to 8200 s−1). The reduced modulus of nickel-based microcapsules was three orders of magnitude larger than that of the traditional microcapsules. The findings revealed that the fabricated nickel-based microcapsules produced remarkable performances for both static and dynamic loading applications. A high speed camera with stereo microscope was used to observe the failure mode of the microcapsule during the impact, which is of great importance to study the mechanical behaviours of materials and structures. Different failure modes were identified as multi-cracks with more rough and tortuous fracture surfaces and debris were observed for the samples subject to impact loading. Finite element method was employed to further understand the physical phenomenon which fitted well with the experimental results. These results could inspire more fundamental studies on the core-shell microstructures and potential applications in multifunctional materials.

Low-Overhead Thin-Film Approaches and Platforms for Spectroscopic Fingerprinting and Electronic Single-Molecule Sensing

Nanopores are nanochannels formed through thin insulating membranes such as silicon nitride, and are powerful, yet conceptually and structurally simple, single-molecule sensor elements. When immersed in an electrolyte and with a cross-membrane applied voltage, the presence of a target species is indicated, in a resistive-pulse-sensing mode, by a perturbation of the ionic current through the pore whose frequency is correlated to the analyte concentration, and whose characteristics relate to the analyte, solution, and nanopore properties. It is important to be able to tune the nanopore size and surface properties; we present low-overhead routes based on electroless plating to fabricated customized nanopores. Those fabrication strategies can augment the performance capabilities of channel-through-membrane devices, but are also useful in combination with other structures and applications. In particular, we have used the same core electroless plating approach to turn a wide variety of materials into substrates for surface-enhanced Raman spectroscopy (SERS). These materials span from conventional micro- and nanofabrication-compatible materials, whether native or highly structured, to consumer-scale materials such as paper. These materials can, by their properties and construction, offer chemical analysis capabilities that complement the added SERS performance. In the case of paper-based SERS, an added benefit is the natural compatibility with the demands of low-cost diagnostics, including ease of disposability. Details of nanofabrication strategies will provide context for discussion of prospects of, and concrete biosensing applications using, tailored nanopore single-molecule sensors and multifunctional SERS substrates. Practical issues affecting device ease of use and sensing performance will be outlined, extending to disposable devices.

A general route to the synthesis of PS/metal composites and their conversion to metal hollow microspheres

In this work, we put forward a simple and universal electroless plating approach to synthesize polystyrene/metal (PS/M) composite spheres, and hollow metal (e.g. Ni, Co, Cu) structures were also obtained after removing the PS core. Monodisperse PS microspheres were initially synthesized via a dispersion polymerization, and then these PS spheres activated with Pd served as templates for the synthesis of PS/M core–shell composite. The parameter of temperature was investigated in details, which strongly influenced the quality and morphology of metal coatings. Based on the above core–shell structures, the PS core template could be removed by ethyl acetate, and metal hollow spheres were formed finally. X-ray diffraction and scanning electron microscopy characterizations indicated that elemental Ni, Co, and Cu coatings with highly pure phase were successfully deposited onto the surfaces of PS microspheres. Such PS/M composites with low density would have wide applications in electromagnetic shielding fields.

Hydrogen sensing characteristics of a Pt/AlGaN/GaN heterostructure field-effect transistor (HFET) prepared by sensitization, activation, and electroless plating (EP) approaches

A Pt/AlGaN/GaN heterostructure field-effect transistor (HFET), based on sensitization, activation, and electroless plating (EP) deposition approaches, is fabricated and studied. Utilizing the sensitization and activation processes, a dense and uniform Pd seed layer could be implanted on the AlGaN layer prior to Pt-gate formation. In addition, a dense Pt-gate morphology and excellent Schottky contact properties are obtained. This causes significant improvement in DC performance and thermal stabilities as compared with a thermal evaporation (TE)-based one. For a used gate dimension of 1×100μm2, the lower gate leakage current of 0.9 (8.4)nA, higher maximum extrinsic transconductance of 90.1 (52.1)mS/mm, and maximum drain saturation current of 325 (178)mA/mm are found for an EP Pt-gate HFET at 300 (600)K. Moreover, as a hydrogen gas sensor, the maximum drain current response (13.7%), high on/off ratio (8×105), and fast response (28s) and recovery (36s) time constants in 10,000, 50, and 5ppm H2/air gases are obtained at 400K, respectively. Therefore, the studied EP Pt-gate HFET shows promise for a high-performance electronic device and hydrogen gas sensing applications.

An enhancement-mode pseudomorphic high electron mobility transistor prepared by an Electroless Plating (EP) and a gate-sinking approaches

An enhancement-mode PHEMT (EPHEMT), fabricated by Electroless Plating (EP) and gate-sinking approaches, is comprehensively studied under high-temperature ambiences (300–475K). The interdiffusion at Pd/AlGaAs interface confirmed by Auger depth spectroscopy (AES) profile analysis leads to the modulation of threshold voltage. In addition, the corresponding Pd-gate morphologies are examined through atomic force microscopy (AFM) and scanning electron microscopy (SEM). By gate-sinking (525K), an EP-based PHEMT with threshold voltage shifting of +0.33V is converted to an E-mode operation. Based on inherent advantages of EP-gate formation, the studied EPHEMT shows excellent DC performance and well thermal stability. With a gate dimension of 1×100μm2, the studied EPHEMT presents low gate current of 6.5 (74.5)μA/mm, maximum extrinsic transconductance of 185.2 (150.6)mS/mm, maximum drain saturation current of 219.9 (98.8)mA/mm, and threshold voltage of 0.203 (0.196)V at 300 (475)K. In addition, the thermal stabilities on gate current, extrinsic transconductance, and drain current are found for the studied EPHEMT. Furthermore, a designed direct-coupled FET logic (DCFL) inverter, combined with an EP-gate and a thermal evaporated (TE)-gate PHEMT, is achieved and characterized.

Nano-SiC effect on wood electroless Ni–P composite coatings

In this research, Ni–P/nano-SiC composite coatings were prepared on wood surface by simple electroless plating approach. The flatness, porosity, and crystallinity of Ni–P/nano-SiC composite coatings were investigated. The flatness and porosity of the composite coatings enhanced with the increase in nano-SiC content of the coatings, and the composite coatings were obtained within the range of 0.5–1.5 g (1.8 g/L) nano-SiC in the solution bath. The full width at half maximum values of Ni X-ray diffraction peaks in the composite coatings broadened and strengthened with the increment of nano-SiC content in the coatings, which triggered preferred growth direction of diffraction peaks. The composite structure was characterized with scanning electron microscopy images. The uniformity of particles in the composite coatings could be improved obviously with the increase in the nano-SiC content of the coatings because an amorphous phase of SiC hindered the movement of dislocations and declined the size of Ni–P crystallite. Besides, the flatness, porosity, and crystallinity of composite coatings depended on the P content in the composite coatings. P content can be decreased by increasing SiC content of plating solutions. The flatness, porosity, crystallinity, and wear resistance of composite coatings exhibited excellent properties as the content of nano-SiC in the composite coatings reached 1.0 g (1.8 g/L).

Large area uniform deposition of silver nanoparticles through bio-inspired polydopamine coating on silicon nanowire arrays for practical SERS applications.

Despite the significant progress, the controlled deposition of nanoparticles onto the support materials having 3-D nano-morphologies is still facing challenges due to the limited diffusion of metal ions into the nanostructures and uncontrolled aggregation of nanoparticles. In this study, a simple yet versatile alternative is demonstrated to control the silver nanoparticle (AgNP) density and morphology onto the 3-D silicon nanowire (SiNW) arrays based on bio-inspired polydopamine (PDOP) coating and electroless plating approaches for practical Surface-Enhanced Raman Spectroscopy (SERS) applications. In order to control silver deposition and its morphology and to optimize the SERS performance of AgNP decorated SiNW arrays, the effect of some key experimental parameters including SiNW length and morphology, silver reduction time and PDOP thickness are investigated in detail. The optimized samples demonstrate remarkable surface-enhancement ability in Raman signals with high reproducibility (lower than ∼10% spot-to-spot and sample-to-sample). Interestingly, it is found that PDOP coating not only serves as a reducing agent for the deposition of AgNPs on SiNW arrays in a controlled manner, but also contributes to the observed SERS enhancements in terms of improving photon scattering and promoting electron transfer processes due to its organic semiconductor nature.

Fabrication of silver nanosheets on quartz glass substrates through electroless plating approach

Silver nanosheets (NSs) have been synthesized by an electroless plating approach using a complexation mechanism of triethanolamine (TEA) and Ag+ to reduce the oxidation–reduction potential difference and slow down the deposition speed of Ag on quartz glass substrates. The synthesized Ag NSs with 500 nm in edge length and 30 nm in thickness stand on the substrates and are dispersed uniformly. The formation mechanism of Ag NSs is proposed. The formation of Ag NSs is attributed to the molar ratio of AgNO3 to TEA, the concentration of AgNO3 and the influence of reaction temperature. This study is important in vertical immobilization Ag NSs on solid substrates, which could provide substrates for catalysis or surface-enhanced Raman scattering.

Characteristics of a Pd/AlGaN/GaN Transistor Processed Using the Sensitization, Activation, and Electroless Plating (EP) Approaches

The characteristics of a Pd/AlGaN/GaN high electron mobility transistor (HEMT) processed using the sensitization, activation, and electroless plating (EP) deposition approach are studied and demonstrated. A dense and uniform Pd seed layer is achieved by using the additional sensitization and activation processes. Therefore, the superior characteristics in turn-on voltage (1.79 V), gate leakage current (9 nA), maximum extrinsic transconductance (95.8 mS/mm), and maximum drain saturation current (373.8 mA/mm) are obtained for a 1 μm gate HEMT at 300 K. As increasing the temperature from 300 to 600 K, the reduced variation and degradation rates are also found for the studied EP-gate device. Furthermore, superior hydrogen gas sensing performance, including large drain current change (34.1 mA/mm) and high sensing response (3469%), is observed under 1% H2/air ambience. Consequently, the studied EP-gate AlGaN/GaN HEMT shows the promise for high-performance electronic device and hydrogen sensor applications.

Microwire formation based on dielectrophoresis of electroless gold plated polystyrene microspheres

Microspheres coated with a perfectly conductive surface have many advantages in the applications of biosensors and micro-electromechanical systems. Polystyrene microspheres with the diameter of 10 μm were coated with a 50 nm-thick gold layer using an electroless gold plating approach. Dielectrophoresis (DEP) for bare microspheres and shelled microspheres was theoretically analysed and the real part of the Clausius—Mossotti factor was calculated for the two kinds of microspheres. The experiments on the dielectrophoretic characterisation of the uncoated polystyrene microspheres and gold coated polystyrene microspheres (GCPMs) were carried out. Experimental results showed that the gold coated polystyrene microspheres were only acted by a positive dielectrophoretic force when the frequency was below 40M Hz, while the uncoated polystyrene microspheres were governed by a negative dielectrophoretic force in this frequency range. The gold coated polystyrene microspheres were exploited to form the microwire automatically according to their stable dielectrophoretic and electric characterisations.

Manipulation of gold coated microspheres using electrorotation

The electrorotation of microspheres coated with conductive surface is a novel and important technology for label-free biosensors. Using the electroless plating approach, the polystyrene microspheres with 15 μm and 25 μm in diameters were coated with 50 nm gold layer in thickness. The electrorotation experiments on those gold coated polystyrene microspheres (GCPMs) were carried out. The results showed that they rotated in the opposite direction of the electric field in a low frequency range (100–100 kHz), and the maximum rotation speed was higher than that of uncoated microspheres. Based on the theory of traveling wave electroosmosis(TWEO) and induced charge electroosmosis (ICEO), the electrorotation of GCPMs was quantitively analyzed and confirmed by observing the fluid flow around GCPM. The equations describing the electroration speed of GCPMs were proposed, which are consistent with the experiment results.