Galvanic Displacement Reaction Research Articles

Development of ternary hybrid composites of transition metal and noble metal-based heterostructures: Ultrasensitive simultaneous electrochemical detection of bisphenol a and bisphenol S in food samples

Bisphenols threaten human health and sensitive detection is crucial. The present study aims to develop ternary composites of copper metal-organic framework (Cu-MOF) with AuAg microstructures. The composite structure was formed by a galvanic displacement reaction and confirmed using SEM. A binder-free catalyst was used to study the electrochemical redox reaction of bisphenol A (BPA) and bisphenol S (BPS); an irreversible cyclic voltammetric signal at +0.70 V and + 0.91 V (vs. Ag/AgCl), in the dynamic range of 20 nM to 2.0 mM, and 10 nM to 1.0 mM, with limits of detection of 2.9 nM, and 3.2 nM (S/N = 3) was obtained. Practical analysis was applied to frozen tomatoes, tuna fish, milk powder, PET bottles, raw milk, and urine samples with a recovery rate of 94.00–100.80% (n = 3). Voltammetric results were validated using HPLC detection with high precision. The sensor is a promising alternative platform for measuring BPA in food samples.

Driving inward growth of lithium metal in hollow microcapsule hosts by heteroatom‐controlled nucleation

AbstractThe application of Li metal anodes in rechargeable batteries is impeded by safety issues arising from the severe volume changes and formation of dendritic Li deposits. Three‐dimensional hollow carbon is receiving increasing attention as a host material capable of accommodating Li metal inside its cavity; however, uncontrollable and nonuniform deposition of Li remains a challenge. In this study, we synthesize metal–organic framework‐derived carbon microcapsules with heteroatom clusters (Zn and Ag) on the capsule walls and it is demonstrated that Ag‐assisted nucleation of Li metal alters the outward‐to‐inward growth in the microcapsule host. Zn‐incorporated microcapsules are prepared via chemical etching of zeolitic imidazole framework‐8 polyhedra and are subsequently decorated with Ag by a galvanic displacement reaction between Ag+ and metallic Zn. Galvanically introduced Ag significantly reduces the energy barrier and increases the reaction rate for Li nucleation in the microcapsule host upon Li plating. Through combined electrochemical, microstructural, and computational studies, we verify the beneficial role of Ag‐assisted Li nucleation in facilitating inward growth inside the cavity of the microcapsule host and, in turn, enhancing electrochemical performance. This study provides new insights into the design of reversible host materials for practical Li metal batteries.

Room temperature synthesis and hydrophobic surface protection of silver dendrites for hydrogel stretchable sensors

Hydrogel stretchable sensors have gained increasing popularity as essential components for next-generation flexible electronics. Stringent standards have been placed on the cost, conductivity, stability, and sensitivity of composites. In this work, highly conductive silver dendrites with uniform morphology were successfully synthesized by galvanic displacement reaction. Due to the more complex three-dimensional structure of the silver dendrites, the percolation threshold of the conductive composites was reduced to approximately 45 wt%. By decorating the as-prepared silver dendrites with a dense and hydrophobic dodecanethiol layer, the issue of hygrothermal stability in the hydrogel matrix has been successfully addressed. Silver dendrites conductive composites exhibited excellent electrical conductivity (8.57×10−4Ω∙cm for 65 wt% silver dendrites) and sensing properties. The stretchable conductors exhibited high sensitivity and linearity with F= 9.48 and R2= 0.9967. Therefore, human-computer interaction was successfully carried out by monitoring the movement of fingers, wrists, elbows, and knees of the human body.

Galvanic Displacement Reaction Enabled Specific and Sensitive Detection of Bacteria with a Digital Photocorrosion GaAs/AlGaAs Biosensor.

The conjugation of ionic gold with bacterial antibodies makes it possible to induce a specific interaction between targeted bacteria and the surface of a GaAs/AlGaAs biochip. The process of immobilization is based on a galvanic displacement reaction (GDR) involving electron transfer between GaAs and Au3+ ions that leads to the formation of a Au-Ga alloy anchoring bacteria to the biochip surface. The GDR-based immobilization of Escherichia coli on biochips comprising a stack of GaAs/AlGaAs nanolayers (dGaAs = 12 nm, dAlGaAs = 10 nm) was confirmed by X-ray photoelectron spectroscopy and atomic force microscopy-based infrared experiments. We report the successful application of this approach for highly sensitive detection of E. coli with a digital photocorrosion (DIP) biosensor. The photoluminescence (PL) monitored DIP of GaAs/AlGaAs nanolayers results in the formation of a PL intensity maximum whose temporal appearance depends on the electric charge transfer between bacteria and the biochip. The formation of a robust bacteria-biochip interface achieved with the GDR process allowed us to observe the role of bacteria on the temporal position of a PL intensity maximum related to the etching of two pairs of GaAs/AlGaAs nanolayers extending up to 24 nm below the biochip surface. We demonstrate the attractive detection of E. coli at 250 CFU/mL, and we discuss the potential of this approach for designing a family of biosensors addressing the quasi-continuous monitoring of a water environment for the presence of pathogenic bacteria.

Synthesis of bimetallic-nanocrystal-decorated rice bowl-shaped polymer particles for catalytic Cr(VI) remediation

Rice-bowl shaped polymer particles with convex and concave surfaces have emerged as promising noble metal catalyst supports. However, their synthesis and integration with catalytic materials using environmentally friendly methods have remained a challenge. This study presents a sustainable and efficient approach for synthesizing rice-bowl-shaped polystyrene (PS) particles and explores their potential as catalyst supports. The key to achieving this morphology lies in the utilization of anisotropic PS seeds, specifically hollow dimpled PS seeds. Uniform rice-bowl-shaped PS particles are obtained by dispersing these seeds in an oil-in-water (O/W) emulsion and allowing them to dry under ambient conditions. Non-toxic reducing agents and environmentally friendly solvents are employed for the in-situ chemical reduction process and galvanic displacement reaction to synthesize bimetallic (Ag/Pd) nanocrystals on the surfaces of the PS particles. The resulting Ag/Pd-coated PS particles exhibit excellent catalytic activity as microreactors for Cr(VI) reduction in water, while demonstrating remarkable stability during repeated use without significant loss of activity. Furthermore, the shape of the rice-bowl particles facilitates efficient packing and stacking, leading to enhanced catalytic performance not only in bulk solutions but also in confined spaces. This study highlights the potential of rice-bowl-shaped polymer particles as efficient and environmentally friendly catalyst supports, paving the way for the development of green catalytic applications.

Spatial Confinement of Li Metal in Hollow Microcapsule Hosts Enabled by Heteroatom-Driven Inward Growth

In recent years, the demand for advanced batteries with high energy densities has increased significantly, along with the growing demand for electric vehicles. Li metal has garnered considerable research attention as a promising anode material because of its high theoretical specific capacity (3860 mAh g−1) and low electrochemical equilibrium potential (−3.040 V vs. standard hydrogen electrode). However, Li metal batteries still have several hurdles in their practical application because Li metal anodes experience infinite volume expansion, which induces continuous rupture and formation of solid-electrolyte interphase (SEI) layers. This leads to electrolyte consumption and corrosion of Li metal, resulting in a low Coulombic efficiency and poor cycling performance. In addition, the uncontrollable dendrite growth of Li metal may cause early battery failure and safety issues. To address these problems, extensive research efforts have been made, including artificial SEI layers, optimized electrolyte formula, and rational design of three-dimensional (3D) host materials.Among the various 3D host materials under development, carbon-based materials with hollow structures have been investigated extensively because of their attractive features. The enlarged void space (cavity) of the hollow hosts can accommodate a significant amount of Li deposits, while inhibiting volume changes during plating–stripping cycles. In addition, hollow carbon possesses much lower density than metal-based materials, thereby increasing the specific capacity and energy density. However, the lithiophobic nature of carbon combined with its high resistance to Li+ transport through nanopores on the walls significantly hinders the formation of Li deposits inside the cavity. Li may nucleate on the outer surface of the carbon particles in a nonuniform manner, thereby causing the growth of Li dendrites and electrochemically inactive Li deposits.In this study, we synthesize metal-organic framework-derived carbon microcapsules with heteroatom clusters (Zn and Ag) on the capsule walls and demonstrate that Ag-assisted nucleation of Li metal alters the outward-to-inward growth in the microcapsule host. The cavity inside the microcapsule host, which was generated by etching with tannic acid, provides large void spaces for Li metal storage. Atomic Ag clusters decorated by a galvanic displacement reaction serve as preferential nucleation sites with a reduced energy barrier and promote the inward growth of Li metal in the cavity, while suppressing nonuniform Li plating on the outer surface. Through combined electrochemical, microstructural, and simulation studies, we verify the beneficial role of Ag-assisted Li nucleation in facilitating inward growth inside the cavity of the microcapsule host, resulting in enhanced electrochemical performance. This study provides new insights into the design of reversible host materials for practical Li-metal batteries.

Nanostructured Ir-based electrocatalysts for oxygen evolution prepared by galvanic displacement of Co and Ni

Proton exchange membrane (PEM) electrolysers are promising devices to produce hydrogen as a green fuel. Currently, this technology is limited by the sluggish kinetics of the oxygen evolution reaction (OER). In this work, we describe an environmentally safe method for the preparation of Ir oxide thin films (IrO2) for OER. Electrodeposition of Co and Ni was performed in the non-toxic choline chloride:urea deep eutectic solvent (ChCl:urea DES), followed by galvanic displacement reaction (GDR) of Co and Ni by Ir(IV). We evaluated how the GDR conditions, such as the metal replaced (Co or Ni), time and temperature affect both the activity and stability of the deposited IrO2 films on gold substrates. We observed that GDR of Ni at 90 °C induces morphological changes on the IrO2 nanostructures which resulted in higher activity and stability towards OER. We highlight that not only reducing mass loadings of Ir but also tuning the surface morphology and structure controlling the synthesis preparation, as well as investigating the role of the substrate, are key to design more active and stable OER electrocatalysts.

Compositional modulation through galvanic displacement in electrochemically deposited FeCoNiCuZn high entropy alloy thin films

After completing the aqueous electrodeposition of FeCoNiCuZn nanocrystalline high entropy (HEA) alloy system consisting of elements with significant differences in melting points and reduction potentials, unwanted galvanic displacement reactions (GDR) were observed on the alloy system when the film was held back in the electrolyte. This phenomenon, observed in alloys electroplated from aqueous baths containing a noble metal (currently Cu), leads to preferential deposition of the noble elements and changes the composition progressively at open circuit potential. A change in composition occurs in the electrodeposited alloy where Cu (from ∼13 to 58 at. %) was deposited on the alloy due to its nobler reduction potential causing displacement of Zn > Fe ∼ Co > Ni (order of displacement) from the deposited alloy with the Cu2+ ions present in the electrolyte. This work is the first observational report of galvanic displacement in HEAs composed of five elements. We categorically state that this GDR is crucial when designing/synthesizing HEAs alloys through electrodeposition.

In situ detection of natural dyes in archaeological textiles by SERS substrates immobilized on the fiber

Accurate detection of natural dyes in archaeological textiles is challenging due to limited sample availability. In situ detection of fibers by surface-enhanced Raman scattering (SERS) can overcome this challenge. In this study, we present two methods for the preparation of SERS substrates based on the laser photoreduction reaction and the galvanic displacement reaction, respectively. Our results show that the substrates prepared by these methods, including 450 nm-AgNPs, Cu-based Ag, and Zn-based Ag, offer several advantages such as rapid preparation, easy handling, low cost, high sensitivity and excellent reproducibility. Using these substrates, we successfully detected anthraquinones (alizarin, purpurin), indigoids (indigotin, indirubin), and protoberberine-type dyes in archaeological textiles from the Wei and Jin Dynasties. Notably, we were able to detect both indigo and protoberberine-type dyes in one archaeological fiber. The minimally invasive, in situ analytical approach developed provides a valuable tool for analytical applications where sampling is limited to microscopic amounts.

Fabrication of Silver Nanobowl Arrays on Patterned Sapphire Substrate for Surface-Enhanced Raman Scattering.

The current article discusses surface-enhanced Raman spectroscopy (SERS) as a powerful technique for detecting molecules or ions by analyzing their molecular vibration signals for fingerprint peak recognition. We utilized a patterned sapphire substrate (PSS) featuring periodic micron cone arrays. Subsequently, we prepared a three-dimensional (3D) PSS-loaded regular Ag nanobowls (AgNBs) array using self-assembly and surface galvanic displacement reactions based on polystyrene (PS) nanospheres. The SERS performance and structure of the nanobowl arrays were optimized by manipulating the reaction time. We discovered that the PSS substrates featuring periodic patterns exhibited superior light-trapping effects compared to the planar substrates. The SERS performance of the prepared AgNBs-PSS substrates was tested under the optimized experimental parameters with 4-mercaptobenzoic acid (4-MBA) as the probe molecule, and the enhancement factor (EF) was calculated to be 8.96 × 104. Finite-difference time-domain (FDTD) simulations were conducted to explain that the AgNBs arrays' hot spots were distributed at the bowl wall locations. Overall, the current research offers a potential route for developing high-performance, low-cost 3D SERS substrates.

Electroless-deposition of AuPd alloy on Prussian blue derived Hematite/AuPd catalyst: Synergistic effect and potent reusable catalyst for treating environment pollutants

Electroless-deposition of bi-metallic AuPd alloy nanoparticles (5–10 nm) on Prussian blue (PB) cubes with uniform composition and size are prepared using a galvanic displacement reaction. In this study, such galvanic displacement reaction routes deed the different redox potentials of three elements (Fe, Au, and Pd) to buoy up their deposition between each other. In comparison with the previous study for the PB/Au system, verdicts in this study enlighten the significant features, possessions, and etiquettes required to form exothermic bi-metallic AuPd alloy nanoparticles onto the PB surface. The Hematite/AuPd catalyst is derived by annealing PB/AuCN–PdCN in the presence of air. During heat treatment, AuPd alloy nanoparticles anchored over the PB surface were become embedded into the Hematite crystallites and led to a core–shell structure. Such core–shell; AuPd-Hematite particles in association with “AuPd composition dependent synergism” reflects an efficient catalytic activity toward the reduction of the hazardous organic pollutant; p-nitrophenol.

Role of Ir Decoration in Activating a Multiscale Fractal Surface in Porous Ni for the Oxygen Evolution Reaction

Interfacial engineering of electrocatalysts is a pivotal approach for promoting the energy conversion efficiency of water electrolysis systems. Anchoring clusters or even single atoms of a foreign element on the surface of a support, usually 3D structured, can alter its local electronic structure leading to superior electrocatalytic activity. Herein, we report a method to decorate a 3D fractal Ni electrode with Ir atoms via a galvanic displacement reaction. The resulting electrode has a very low Ir loading of 1.6 μmole cmgeo–2, with iridium atoms present as 4–5 nm diameter nanoclusters on the electrode surface. The activity for the electrochemical oxygen evolution reaction (OER) of the 3D fractal Ni electrode was improved by decoration with Ir, resulting in an overpotential of 195 mV at 10 mA cm–2 and a Tafel slope of 44 mV dec–1. Apart from increasing the electrocatalytic activity for the OER due to the very presence of more active iridium atoms, the galvanic displacement reaction resulted in a factor 8–10 increase of the electrochemically active surface area due to the creation/activation of a secondary pore structure that contributes also to the better electrocatalytic performance of the resulting electrode. Using operando acoustic emission, it is demonstrated that the galvanic displacement reaction and the presence of Ir nanoclusters have the additional effect of reducing the average O2 bubble size formed during the OER. As a result, the blocking effect of O2 bubbles at high current density is less drastic than on the 3D fractal Ni electrode, resulting in a less severe decrease of the electrochemically active area at large current density. All three effects contribute toward improving the OER performance of the Ir-decorated 3D fractal Ni electrode.

Ga-Pt supported catalytically active liquid metal solutions (SCALMS) prepared by ultrasonication - influence of synthesis conditions on n-heptane dehydrogenation performance.

Supported catalytically active liquid metal solution (SCALMS) materials represent a recently developed class of heterogeneous catalysts, where the catalytic reaction takes place at the highly dynamic interface of supported liquid alloys. Ga nuggets were dispersed into nano-droplets in propan-2-ol using ultrasonication followed by the addition of Pt in a galvanic displacement reaction - either directly into the Ga/propan-2-ol dispersion (in situ) or consecutively onto the supported Ga droplets (ex situ). The in situ galvanic displacement reaction between Ga and Pt was studied in three different reaction media, namely propan-2-ol, water, and 20 vol% water containing propan-2-ol. TEM investigations reveal that the Ga-Pt reaction in propan-2-ol resulted in the formation of Pt aggregates on top of Ga nano-droplets. In the water/propan-2-ol mixture, the desired incorporation of Pt into the Ga matrix was achieved. The ex situ prepared Ga-Pt SCALMS were tested in n-heptane dehydrogenation. Ga-Pt SCALMS synthesized in pure alcoholic solution showed equal dehydrogenation and cracking activity. Ga-Pt SCALMS prepared in pure water, in contrast, showed mainly cracking activity due to oxidation of Ga droplets. The Ga-Pt SCALMS material prepared in water/propan-2-ol resulted in high activity, n-heptene selectivity of 63%, and only low cracking tendency. This can be attributed to the supported liquid Ga-Pt alloy where Pt atoms are present in the liquid Ga matrix at the highly dynamic catalytic interface.

Preparation of silver nanosheet-assembled film as a surface-enhanced Raman scattering substrate

Abstract In this work, we demonstrate a simple method for the fabrication of silver (Ag) nanosheet-assembled film on aluminum (Al) foil based on the galvanic displacement reaction between Al and Ag+. In order to obtain Ag nanosheets with large area and high aggregation density, both F− and H+ ions were introduced into the reaction system to etch the barrier layer Al2O3 on Al foils and promote the increase of the number of Ag nuclei. Therefore, Ag nuclei grew into nanosheets with citrate ions as the shape control agent. By varying the reaction parameters, Ag nanosheet film was optimized for surface-enhanced Raman scattering (SERS) measurements. The Ag nanosheet film prepared by the presented method exhibit the advantages of controllable morphology, good SERS activity, and distribution in large area, which could be utilized as a promising SERS-active candidate substrate for analytical applications.

Rational Design of 3-Dimensional Carbon Architectures with Controlled Interfacial Activity for Reversible Li Metal Storage

Three-dimensional (3D) host architectures for Li metal storage have emerged as promising strategies for resolving the critical issues of Li metal anodes: severe volume changes and dendritic growth of Li during charge–discharge processes. However, the ionic resistance of electrolyte-filled pores causes the preferential deposition of Li on top of the 3D architecture (i.e., top plating), resulting in early cell failure. To realize Li metal anodes with high capacity and cyclability, herein, we report 3D-architectured electrodes with controlled interfacial activity based on metal–organic framework (MOF)-derived carbon hosts. Electrochemical simulations of Li plating processes in the 3D-architectured electrode suggest that the top plating can be effectively suppressed by increasing the interfacial activity across the thickness toward bottom of the electrode. MOF nanoparticles are pyrolyzed to form highly porous carbon hosts, and then, atomic Ag clusters are incorporated into the host by a galvanic displacement reaction to enhance the interfacial activity. A bi-layered carbon electrode with controlled interfacial activity is fabricated via sequential electrophoretic deposition of the host materials: i.e., as-pyrolyzed carbon on top and Ag-incorporated carbon on bottom. In comparison with the conventional electrode with uniform interfacial activity, the bi-layered electrode exhibits reduced overpotentials for Li plating and enhanced cyclability during galvanostatic Li plating–stripping. The combined computational and experimental studies further demonstrate that the bottom layer with atomic Ag clusters acts as a preferential site for Li nucleation even in the presence of kinetic limitations of ionic transport. As a result, Li deposits are confined in the bi-layered carbon electrode, thereby enhancing the reversibility of Li metal storage. This work provides an effective strategy to develop long-cycling, high-capacity Li metal anodes by controlling the interfacial activity of 3D carbon architectures.

Morphology and Electrochemistry Drive Corrosion of Electroless Nickel Immersion Gold Films: A Multi-Technique Analysis

Electroless nickel immersion gold (ENIG) is a common surface finish for high-reliability microelectronics circuitry due to its good solderability, corrosion resistance, layer thickness uniformity and applicability for fine pitch applications1. ENIG deposition is a multistep process in which a 3 to 6 micron (118-236 μ-in) layer of electroless nickel (i.e. Ni-P) is deposited onto the substrate material (typically copper), followed by a galvanic displacement reaction replacing the surface layer of Ni with 0.04 to 0.1 microns (1.6 to 4 μ-in) of gold (Au). Despite ENIG’s widespread use, it continues to suffer from a failure mode known as “black pad” or Ni hypercorrosion during immersion gold deposition2. A cohesive mechanistic explanation for the occurrence of Ni hypercorrosion is not yet established despite extensive study. Recent approaches have attempted to characterize in-situ the influence of bath chemistry; however, the competing influence of all variables of the ENIG process (e.g. temperature, pH, solution chemistry, volume mixing, surface morphology, etc.) make global mechanistic conclusions challenging if not impossible experimentally3. Instead, the work here aims to develop tools to assess an ENIG film of unknown origin or deposition conditions for the risk of corrosion. Therefore, this study utilizes a combination of surface characterization via x-ray photoelectron spectroscopy (XPS) depth profiling and transmission electron microscopy (TEM) imaging and electrochemical characterization via cyclic polarization (CP) and scanning vibrating electrode technique (SVET) to build a multi-technique analysis of ENIG failures.ENIG samples with identical geometries and plating requirements from two domestic vendors (A & B) were obtained. XPS with argon ion sputtering allows for comparison of atomic concentration of Ni, Au and P in ENIG films through their depth as a function of the number of sputter cycles. XPS results show that Vendor A films have a high concentration of Ni in the Au layer and a lower concentration of P near the Au-Ni interface, whereas Vendor B films have a low concentration of Ni in the Au layer and a higher concentration of P near the Au-Ni interface. This indicates a more porous morphology in Vendor A versus B films. SVET is an electrochemical scanning probe tool which allows for real-time observation of cathodic and anodic currents (in a 0.35% NaCl solution) representing existing and developing defect sites on ENIG surfaces. SVET experiments show that Vendor A and B samples exhibit preferential anodic currents on ENIG surfaces corresponding to Ni hypercorrosion defects. Focused ion beam (FIB) lift-outs from SVET samples viewed in TEM give ex-situ confirmation that SVET observations align with the real metal layer structure and chemistry as well as confirming the presence and location of corrosion products. CP curves for samples of each film in a 0.35% NaCl solution demonstrate that both Vendor A and Vendor B films exhibit effective corrosion rates above 1.0 mil per year which is on the order of bare Cu wire in the same electrolyte. Overall, a distinct difference in film morphology between Vendor A and B samples exists; however, both films exhibit substantial electrochemical activity in solution indicating corrosion susceptibility. Taken together, these results show that Ni hypercorrosion can be driven by at least two distinct mechanisms: high porosity in the Au film leading to enhanced Ni migration and reaction at the Au surface; or, P enrichment at the Au-Ni interface leading to enhanced P migration and a more electronegative surface composition. Future work will build out characterization of additional ENIG samples to establish a failure matrix for ENIG films, encompassing a wider variety of unique mechanisms. D. Goyal, T. Lane, P. Kinzie, C. Panichas, K. M. Chong, and O. Villalobos, in "52nd Electronic Components and Technology Conference 2002.(Cat. No. 02CH37345)", p. 732-739. IEEE, 2002.R. Ramanauskas, A. Selskis, J. Juodkazyte, and V. Jasulaitiene, Circuit World, (2013).A. Accogli, E. Gibertini, G. Panzeri, A. Lucotti, and L. Magagnin, Journal of The Electrochemical Society, 167 (8), 082507 (2020). SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525

Sandwich structure confined gold as highly sensitive and stable electrochemical non-enzymatic glucose sensor with low oxidation potential

• Fe 3 O 4 @Au@CoFe-LDH is prepared through a spontaneous galvanic displacement reaction. • In Fe 3 O 4 @Au@CoFe-LDH, the metallic Au intercalates between Fe 3 O 4 and LDH forming the sandwich structure. • Fe 3 O 4 @Au@CoFe-LDH possesses high sensitivity of 6342 μA mM −1 cm −2 , broad linear detection range of 0.0375 to 15.64 mM and low limit of detection of 12.7 μM, with an extremely low oxidation potential of 0.82 V vs. RHE. • The small quantity of Au laying between LDH and Fe 3 O 4 is the active part of glucose oxidation and the existence of Fe 3 O 4 nanoparticles significantly improves the stability of the electrocatalyst. The preparation of highly sensitive and stable non-enzymatic glucose sensors is critical to the prevention and treatment of diabetes. Fe 3 O 4 @Au@CoFe-LDH is prepared through a spontaneous galvanic displacement reaction. A series of structural characterizations testify the successful formation of Fe 3 O 4 @Au@CoFe-LDH electrocatalyst, with the Au intercalating between Fe 3 O 4 and LDH to form the sandwich structure. Cyclic voltammetry tests indicate that Au is responsible for the electrocatalytic oxidation of glucose. The characterizations of the electrochemical sensor for glucose detection indicate that Fe 3 O 4 @Au@CoFe-LDH possesses high sensitivity of 6342 μA mM −1 cm −2 , with an extremely low oxidation potential of 0.82 V vs. RHE. Even with the high glucose concentration of 15 mM, the sensitivity remains at 4359 μA mM −1 cm −2 . Due to the broad linear detection range (0.0375 to 15.64 mM) and the low limit of detection (12.7 μM), Fe 3 O 4 @Au@CoFe-LDH is applicable towards practical application. Thanks to the sandwich structure, which confines the Au in between Fe 3 O 4 and CoFe-LDH, the Fe 3 O 4 @Au@CoFe-LDH glucose sensor shows high long-term stability and satisfactory selectivity. The successful synthesis of the sandwich-structured Fe 3 O 4 @Au@CoFe-LDH provides a new conception for the design of highly sensitive and stable non-enzymatic glucose electrodes.

Mechanistic Insight into Li–Host Interactions in Carbon Hosts for Reversible Li Metal Storage

In recent years, the industrial requirements for rechargeable batteries in terms of energy density have continuously increased owing to the widespread adoption of portable electronic devices and electric vehicles. Li metal has been identified as a promising anode material to meet the ever-increasing demand for rechargeable batteries with high energy densities because of its low redox potential (−3.04 V vs. standard hydrogen electrode)and high specific capacity (3860 mAh g−1) [1]. Despite these advantages, the commercial use of Li metal anodes has been hindered by unresolved critical issues, such as the uncontrollable growth of Li dendrites and the severe volume changes during cycling. In practice, the dendritic growth of Li deposits causes the formation of dead Li species and triggers internal short-circuiting of batteries during cycling, leading to a significant loss of reversibility and raising safety concerns. Moreover, large volume changes in the Li metal anode during Li plating–stripping, which originate from the “hostless” character of the Li metal, impose severe stresses on the solid–electrolyte interphase (SEI) layers, and thus reducing the mechanical stability of SEIs. Once the SEI layers are cracked or fractured, bare Li metal is exposed to the electrolyte, leading to the continuous formation of thick SEI layers on the anode surface. This is mainly responsible for the continuous, irreversible loss of active Li, i.e., low Coulombic efficiency and short cycle lifetimes.3D “host” architectures are beneficial for securing the dimensional stability of Li metal anodes by utilizing internal pores (i.e., free-spaces) as reservoirs for Li storage. Moreover, they provide large active surface areas and hence reduce the effective current densities, suppressing uneven Li plating (dendritic growth) during high-rate operations. Metal-organic framework (MOF)-derived carbon offers many advantages over conventional carbon materials in terms of specific surface area, pore volume, and structural tunability. Furthermore, the critical role of atomically dispersed heteroatoms has been verified in reducing the energy barriers for the nucleation and growth of Li [2].Herein, we report MOF-derived porous carbon hosts with strong Li–host interactions achieved by galvanically displaced lithiophilic seeds. Owing to the distinctive chemical and structural nature of zeolitic imidazolate frameworks (ZIF-8), atomically dispersed Zn can be spontaneously replaced by Ag with a strong lithiophilicity via a galvanic displacement (GD) reaction. Based on a comparative study of carbon hosts with different sizes, morphologies, and distributions of Ag, in particular, we assess the efficacy of lithiophilic Ag in promoting reversible Li storage inside porous carbon hosts. The strong Li–host interactions enabled by lithiophilic Ag effectively reduce the overpotentials for nucleation and growth of Li, and more importantly, the role of lithiophilic Ag in governing the reversibility of Li plating–stripping is discussed in terms of the spatial distribution characteristics of Ag. The atomically dispersed Ag triggers the outward growth of Li from the internal pores of the carbon host, showing a stable cycling performance (>745 cycles). Contrarily, the surface-anchored Ag nanoparticles induce uneven Li plating on the outer surface of the carbon host, resulting in a rapid performance drop (~305 cycles) during cycling. This work provides new insights into the development of advanced 3D host materials for reversible Li metal anodes by utilizing strong Li–host interactions.

Nucleation and Growth of Copper on Cobalt in Advanced Interconnect Metallization

Copper was implemented as a conductor for advanced back-end-of-line (BEOL) interconnects based on its low electrical resistivity and improved electromigration life relative to the aluminum baseline.1, 2 Over the past two decades, the smallest dimension of Cu interconnects has decreased from about 300 to the range of 10-20 nanometers.3 Until recently, damascene Cu electroplating on PVD Cu seed has been optimized to provide void-free Cu metallization using a process relying on inorganic and organic additives toenable bottom-up growth from the base of vias and trenches.1,2,4 With ever-decreasing feature size, the conventional damascene process is becoming increasingly limited by the inability to deposit a sufficiently continuous Cu seed on a barrier/Co liner stack without resulting in pinch-off of the PVD seed.In this talk we will report on the development of direct Cu plating on Co using a range of deposition processes to illustrate the challenges and possible direction for improvement of the nucleation and subsequent growth of Cu on the Co seed. One challenge is to create a Cu layer without significantly etching the Co in the plating bath. This can be achieved by reducing the electrode potential difference between Cu electrodeposition and Co corrosion using proper additives in the plating bath to increase suppression (Figure 1). Such a large overpotential translates into improved nucleation density, which effectively inhibits the complete dissolution of the ultrathin Co layers. This effect is also illustrated by measuring the galvanic displacement reaction between Cu ions and Co at open circuit potential (OCP). Figure 2 reveals quick deposition of a monolayer equivalent of Cu followed by a slight increase in Cu thickness over time.A second challenge involves generation of dense nucleation which results in a smooth initially plated Cu film. The number of protrusions is reduced noticeably when a potential-controlled entry is replaced by leaving the electrode at OCP for a short time before any current is applied (Figures 3a and 3b). A short OCP time allows Co oxides to first dissolve, thereby making more surface sites available for nucleation. The smoothness can be further enhanced by increasing the acidity of the bath (Figure 3c). Higher acid could have modulated the reactivities of additive(s) to promote lateral growth. Improved nucleation can also be attained through substrate engineering. This is shown in Figure 4(a-c), where the morphology/continuity of the electroless film exhibits a strong dependency on Co thickness. Furthermore, agglomeration caused by diffusion of Cu across the substrate during deposition can have a large effect on the final film morphology. This can be seen in figure 4 (d-f), in which differences in deposition morphology across a range of conditions are captured in a simple lateral diffusion simulation.We will discuss the mechanisms leading to these effects and their impact on the design of systems to produce improved film morphology.References(1) P.C. Andricacos, C. Uzoh, J. O. Dukovic, J. Horkans, H. Deligianni, IBM J. Res. Develop. 42, 567 (1998)(2) J. Reid, Jpn. J. Appl. Phys. 40, 2650 (2001)(3) I. Ciofi, P. J. Roussel, R. Baert, A. Contino, A. Gupta, K. Croes, C. J. Wilson, D. Mocuta, Z. Tokei, IEEE Trans. Electron. Devices, 66, 2339 (2019).(4) T.P. Moffat, D. Wheeler, S. K. Kim, D. Josell, J. Electrochem. Soc. 153, C127, (2006) Figure 1

A new promising Pt(Mo2C) catalyst for hydrogen evolution reaction prepared by galvanic displacement reaction

A new promising Pt(Mo2C) catalyst for hydrogen evolution reaction prepared by galvanic displacement reaction