Galvanic Replacement Reaction Research Articles

Redox transmetallation reaction mediated synthesis of Ni-Pd bimetallic nanocatalyst for pesticide degradation to value added product

In this work a wet-chemical recipe has been accounted for the synthesis of bimetallic Ni-Pd nanostructures at ambient condition involving pre-synthesized nickel nanoparticles and aqueous tetrachloropalladate, [PdCl4]2- solution. The Galvanic replacement reaction (GRR) starts instantaneously between less noble Ni0 nanoparticle i.e., zero valent nickel (ZVN) and more noble [PdCl4]2-. Thus ZVN is oxidatively etched out as soluble Ni2+ by more noble [PdCl4]2- depositing Pd0 onto the residual ZVN. Concurrently the Ni2+ ions move outwardly into the bulk solution and the Pd0enters into the inwardly fashion owing to their different diffusivities and results in the formation of hollow bimetallic nanostructures following diffusion limited nanoscale Kirkendall effect. Finally, the bimetallic nanomaterial was shown to be a competent heterogeneous catalyst for facile hydrolytic degradation of an organothiophosphate pesticide, methyl parathion (MP). After the completion of the degradation, the degraded product, 4-nitrophenolate (4-NP) was subsequently reduced to 4-aminophenolate (4-AP) in the same reaction pot in presence of the same catalyst using borohydride. 4-AP is the principal ingredient for the production of the medicine paracetamol. Hence the bimetallic Ni-Pd nanoparticles turn out to be a promising heterogeneous catalyst for water pollution abatement through pesticide degradation vis-à-vis generation of value added product out of the degraded product of the pesticide.

Controlling the composition and nanostructure of Au@Ag–Pt core@multi-shell nanoparticles prepared by co-reduction method

Three types of Au@Ag–Pt core@multi-shell nanoparticles (NPs) were synthesized via a co-reduction reaction from a galvanic replacement reaction (GRR) and a reducing agent, with different feeding ratios of Ag or Pt precursors. The morphology of the core-shell NPs showed a thin multi-shell with a mixture of Ag, void, and Pt granules, and their microstructure was investigated by scanning transmission electron microscopy. The effect of the Ag or Pt precursor feeding ratios on the competition of the two reduction reactions, and the subsequent impact on the nanostructure of Ag-void-Pt multi-shell were discussed. In the case of the sample with a reduced Ag precursor feeding ratio, the thickness of the Ag layer decreased significantly. The oxidation resistance of the Ag layer was improved due to the charge-transfer effect from Au to Ag, which suppressed galvanic replacement, and the reaction by the reducing agent was dominant. In the case of the sample with a reduced Pt precursor feeding ratio, the number of Pt granules was found to decrease while the volume of voids was maintained, suggesting that GRR was the dominant reaction in the co-reduction method. These results provide further insight into the co-reduction reaction mechanism and enable the control of noble trimetallic nanoparticles with complex shells.

The synergistic effect of Ir and oxygen vacancies on Enhancing the OER performance of Surface-Reconstructed FeCo LDH

The modification of Ir or oxygen vacancies (Vo) is a strategy to enhance the oxygen evolution reaction (OER) performance of heterogeneous nanocatalysts. However, it is crucial to further clarify the synergistic effect of Ir and Vo on the enhancement mechanism of OER performance after surface reconstruction. In this work, FeCo Layered double hydroxides (LDHs) co-modified by Ir and Vo were successfully prepared by the thermodynamically favorable galvanic replacement reaction. Electrochemical impedance spectroscopy confirmed that the synergistic effect of Ir and Vo enhanced the charge transfer of FeCo LDHs. XPS spectra reveal robust interactions between Ir and FeCo LDHs. Density-functional theory further reveals that the low-oxygen-coordinated Ir (III) acts as an active site to optimize the OER rate-determining step energy barrier. As a result, Ir and Vo co-modified FeCo LDH requires only a 203 mV overpotential to achieve a current density of 10 mA cm−2 and, more importantly, operates stably at an industrial current density of 250 mA cm−2 for 312 h without degradation. This work provides new insights and avenues for understanding the enhanced performance mechanism of catalysts after surface reconstruction and for industrial scale-up production.

An electrochemical aptasensor based on MOF-derived bimetallic carbon nanocomposites Au@Cu-C for ultrasensitive detection of homocysteine on portable potentiostat

Homocysteine (Hcy), a metabolic intermediate of methionine, is a biomarker for neurological, cardiovascular and cerebrovascular diseases. Timely measurement of Hcy acts as a significant role in disease prevention and diagnosis. Given the fast response of the electrochemical sensing method, herein, a sensitive electrochemical aptasensor was proposed for the detection of Hcy. The aptasensor was constructed by utilizing the MOF-derived bimetallic carbon nanocomposites (Au@Cu-C) plus multi-walled carbon nanotubes (MWCNTs) as electrode modification materials and methylene blue (MB) as the signal marker. The Au@Cu-C was synthesized through hydrothermal methods, calcination and simple galvanic replacement reactions. The prepared Au@Cu-C enhance the electrical signal due to the synergistic effect of bimetallic alloy, while the specific morphology facilitated the immobilization of the aptamer. MB, served as the signal marker, can reflect the current changes of the aptasensor caused by the conformational change of aptamer before and after binding Hcy. As a result, the constructed electrochemical aptasensor exhibited a high sensitivity of 0.415 μA μM−1, a low detection limit of 0.017 μM and an excellent recovery rate in the detection of human serum samples. Besides, the detection was performed on the portable potentiostat which demonstrated the potential application of the aptasensor in medical diagnosis and on-site analysis.

Interfacial galvanic replacement strategy for Pd-doped NiFe MOF nanosheets with highly efficient dopamine detection.

Aninterfacial galvanic replacement strategy to controllable synthesize palladium nanoparticles (Pd NPs)-modified NiFe MOF nanocomposite on nickel foam, which served as an efficient sensing platform for quantitative determination of dopamine (DA). Pd NPs grown in situ on the nanosheets of NiFe MOF via self-driven galvanic replacement reaction (GRR) and well uniform distribution was achieved. This method effectively reduced the aggregation of metallic nanoparticles and significantly promoted the electron transfer rate during the electrochemical process, leading to improved electrocatalytic activity for DA oxidation. Remarkably, the precisely constructed biosensor achieved a low detection limit (LOD) of 0.068µM and recovery of 94.1% (RSD 6.7%, N = 3) for simulated real sample detection and also exhibited superior selectivity and stability. The results confirmed that the as-fabricated Pd-NiFe/NF composite electrode could realize the quantitative determination of DA and showed promising prospects in real sample biosensing.

Effects of Antifoaming Agents on Manufacturing Silver Dendrites Through Fluoride-Assisted Galvanic Replacement Reaction

Abstract In fluoride-assisted galvanic replacement reaction (FAGRR), metallic dendrites are formed simultaneously with hydrogen gas. However, the presence of hydrogen bubbles impedes the reduction of metallic ions to form metallic dendrites. This study investigates the FAGRR approach to manufacturing Ag dendrites where ethanol is incorporated into an AgNO3 reaction solution. The findings of this study demonstrate the efficacy of ethanol as an antifoaming agent in enhancing the deposition of the Ag dendrites during the FAGRR process. The antifoaming effect of ethanol becomes more intense at higher concentrations of AgNO3. The introduction of ethanol into FAGRR can significantly improve processing efficiency and yield in the limited time for manufacturing science and engineering.

Galvanic Replacement Synthesis of VOx@EGaIn-PEG Core-Shell Nanohybrids for Peroxidase Mimics.

The development of high-performance biosensors is a key focus in the nanozyme field, but the current limitations in biocompatibility and recyclability hinder their broader applications. Herein, we address these challenges by constructing core-shell nanohybrids with biocompatible poly(ethylene glycol) (PEG) modification using a galvanic replacement reaction between orthovanadate ions and liquid metal (LM) (VOx@EGaIn-PEG). By leveraging the excellent charge transfer properties and the low band gap of the LM surface oxide, the VOx@EGaIn-PEG heterojunction can effectively convert hydrogen peroxide into hydroxyl radicals, demonstrating excellent peroxidase-like activity and stability (Km = 490 μM, vmax = 1.206 μM/s). The unique self-healing characteristics of LM further enable the recovery and regeneration of VOx@EGaIn-PEG nanozymes, thereby significantly reducing the cost of biological detection. Building upon this, we developed a nanozyme colorimetric sensor suitable for biological systems and integrated it with a smartphone to create an efficient quantitative detection platform. This platform allows for the convenient and sensitive detection of glucose in serum samples, exhibiting a good linear relationship in the range of 10-500 μM and a detection limit of 2.35 μM. The remarkable catalytic potential of LM, combined with its biocompatibility and regenerative properties, offers valuable insights for applications in catalysis and biomedical fields.

Modification of nickel wire electrodes with platinum in the presence of copper ions via galvanic replacement reactions

In the galvanic replacement reaction between Ni wire and PtCl42- in an aqueous solution, the deposition of Pt nanoparticles (PtNPs) on Ni wire is generally unfavorable. However, the addition of Cu2+ into an aqueous solution of PtCl42- was found to promote the deposition of PtNPs effectively for the immersion of Ni wire. This promoted deposition of PtNPs on Ni wire could be confirmed by observing the electrocatalytic responses for ethanol oxidation, electrochemical impedance and the surface images. In addition, the EDS analysis showed that the deposited PtNPs did not contain Cu. The formation of PtNPs without containing Cu was also verified by observing the electrocatalytic properties of other alcohols. Although we had previously reported the stepwise modification of Pt on Ag-deposited Ni wire, the Cu2O-modified Ni wire was useless to allow the deposition of PtNPs in a similar stepwise treatment. Hence, the simple preparation using aqueous solutions containing both PtCl42- and Cu2+ can be proposed as a useful approach to modify PtNPs on Ni materials via galvanic replacement reactions.

Pt-on-CoNi alloy nanoparticles supported on N and P co-doped graphene catalyst for highly efficient hydrogen evolution by acidic water electrolysis

The multimetallic catalysts with adjustable electronic structures and synergy effect between various metals compared to monometallic catalysts are widely applied in electrocatalysis. Herein, graphene is doped with N and P to prepare rGNP support, then a trimetallic PtCoNi/rGNP catalyst is prepared via simple impregnation and galvanic replacement reaction methods. Pt is highly dispersed on the CoNi alloy nanoparticles (NPs) on rGNP for PtCoNi/rGNP. Based on various characterization techniques and electrochemical testing results such as ICP-OES, XRD, XPS, TEM, HRTEM, STEM, STEM-EDX elemental mapping and line-scanning, it confirms the nanostructure of PtCoNi/rGNP (Pt-on-CoNi alloy). The overpotential of PtCoNi/rGNP for hydrogen evolution (HER) via acidic water electrolysis at 100 mA cm−2 is 15 mV, lower than commercial Pt/C (Pt/C) (66 mV). The Tafel slope of PtCoNi/rGNP is 6.46 mV dec−1, smaller than that of Pt/C (17.15 mV dec−1). The overpotential at 10 mA cm−2 only increases with 3.2 mV (reaching 13.2 mV) after a long time stability testing of 72 h, still lower than Pt/C (20 mV), indicating that it has high catalytic activity and stability. This work not only reveals the synergistic effect mechanism of noble metal-on-non-noble metal for the HER, but also provides a new strategy to develop efficient and highly stable catalysts for the HER.

An in-situ method for SERS substrate preparation and optimization based on galvanic replacement reaction

BackgroundVarious surface-enhanced Raman spectroscopy (SERS) substrate preparation methods have been reported, however, how to tune the “gap” between nanostructures to make more “hot spots” is still a barrier that restricts their application. The gap between nanostructures is usually fixed when the substrates are prepared. In other words, it is hard to tune interparticle distances for maximum electromagnetic coupling during substrate preparation process. Therefore, an in-situ substrate optimization method that could monitor the SERS signal intensity changes, i.e., to find the optimum gap width and particle size, during substrate preparation process is needed. ResultsA method based on the galvanic replacement reaction (GRR) is proposed for the in-situ gap width tuning between nanostructures as well as for the optimization of SERS substrates. Noble metal nanoparticles (NPs) form and grow on the sacrificial templates' surface while noble metal ions are reduced by sacrificial metal (oxides) in GRR. Along with the fresh and clean NPs’ surface generated, the gap between two noble metal NPs decreases with the growth of the NPs. To demonstrate this strategy, cuprous oxide/Ti (Cu2O/Ti) sacrificial templates were prepared, and then a GRR was carried out with HAuCl4. The real-time SERS detection during GRR show that the optimum reaction time (ORT) is 300 ± 30 s. Furthermore, SERS performance testing was conducted on the optimized substrate, revealing that the detection limit for crystal violet can reach 1.96 × 10−11 M, confirming the feasibility of this method. Significance and noveltyBy monitoring the in-situ SERS signal of probes during GRR will obtain an “optimal state” of the SERS substrate with optimal gap width and particle size. The SERS substrate preparation and optimization strategy proposed in this article not only provides a simple, efficient, and low-cost method to fabricate surface-clean noble NPs but also paves the way for the in-situ optimization of NPs size and gap width between NPs which could achieve wider applications of SERS.

Achieving Ni@(Pt/Ni(OH)2) ternary nanoflowers derived from Ni nanoflowers for electrochemical ammonia–nitrogen detection in the aqueous environment

In this work, Ni nanoflowers were electrodeposited on the Ni foam surface. And then, ternary Ni@(Pt/Ni(OH)2) nanoflowers were fabricated on the surface of Ni nanoflowers based on the sample and facile galvanic replacement reaction between Ni nanoflowers and H2PtCl6·6H2O. The electrocatalytic activities of all synthetic Ni@(Pt/Ni(OH)2) toward ammonia oxidation reaction have been measured via cyclic voltammetry (CV). As the potential sensing electrode, the abilities of ammonia–nitrogen detection have been evaluated via CV and differential pulse voltammetry (DPV) under optimum conditions of prepared Ni@(Pt/Ni(OH)2) nanoflowers. The limit of detection is 0.82 μM with high sensitivity of 0.075 mA µM−1 cm−2. The measured results indicated that the fabricated sensor has good anti-interference ability, reproducibility and stability in ammonia–nitrogen determination. This obtained Ni@(Pt/Ni(OH)2) sensor exhibited good recovery in detecting ammonia–nitrogen in real samples including lake water from 97.59 % to 100.61 % and sea water from 93.86 % to 97.31 %, indicating a great potential application for the detection of ammonia–nitrogen in water.

Nanoscale Kirkendall effect induced void formation in Au–Ag nanostructures and their application as SERS substrate

Triangular-shaped silver nanostructures were synthesized via a seed-mediated two-step method. A galvanic replacement reaction coupled with the Kirkendall effect was employed to transform Ag nanostructures into porous Au–Ag structures having voids at the nanoscale. Compared with previous reports, the medium and the binding agent used in the synthesis of silver nanoparticles employed as templates play a vital role in determining the extent of nanoscale voids formed due to the Kirkendall effect. Raman activity of these porous structures was tested with crystal violet as the probe molecule, and it was found that the Raman enhancement factor varies with cathode concentration.

Electrochemical sensor based on hollow Au/Pd/Ag dendrites prepared by galvanic replacement from a choline chloride-ethylene glycol deep eutectic solvent

This study presents a simple approach to fabricating a hollow dendritic Au/Pd/Ag electrode through a galvanic replacement reaction (GRR) in a choline chloride-ethylene glycol deep eutectic solvent. The resulting electrode's morphological, structural, and compositional features were characterized using SEM, TEM, XRD, and XPS techniques, with the XPS depth profile providing insights into metal content ratio variations along the electrode's depth. The results emphasize the significant impact of immersion time on both morphological evolution and composition. Cyclic voltammetry investigations revealed significantly enhanced current density in furaltadone (FTD) detection compared to bimetallic and single metallic electrodes. The proposed electrochemical sensor exhibited a dynamic linear range for FTD spanning 1.67–625 μM, accompanied by a low detection limit of 91.7 nM, as confirmed by differential pulse voltammetry (DPV) quantitative experiments. The selectivity, reproducibility, stability, and recovery of the as-prepared sensors were evaluated, particularly in aquaculture water samples, underscoring the practical applicability of the electrodes for furaltadone sensing. This innovative trimetallic electrode design opens avenues for advanced electrochemical sensors with enhanced performance characteristics.

Ag@Au yolk shells decorated onto silica spheres for enhanced plasmonic applications

Silica surfaces covered with a homogenous layer of metal nanoparticles exhibit superior plasmonic properties when compared with pristine colloidal counterparts, as they have higher scattering probability with enhanced potential utility. Precise galvanic replacement reactions performed on such sacrificial templates are of great interest. Herein, we demonstrate the robust formation of Ag@Au yolk shells decorated onto the dielectric silica spheres via a direct one-step galvanic replacement procedure, evidently initiating the deposition of Au onto low surface energy Ag facets (prefixed onto the silica spheres), resulting in a disjointed framework of compact dealloyed metal lobes, wherein their facets remain smooth enough with a high degree of crystallinity and exhibit maximal porosity. Our combined spectroscopic data analyses corroborate the plausible mechanism governing solely the formation of Ag@Au core-shell onto the silica spheres rather than their hollow counterparts. Furthermore, we made the respective monolayer films using the well-known air-water interface self-assembly technique, which allowed us to easily decorate different substrates with a uniform array of these surface-coupled metal nanoparticles. Enhanced refractive index (RI) sensing applications based on the sensitivity and FOM (figure of merit) calculations demonstrate the versatile nature of our synthetic protocol for direct synthesis of optical metamaterials along with their intriguing light-matter interactions, in general. Also, the plasmonic vector field of 2-D assembled nanoparticle monolayer displays intrigued SERS enhancement of crystal violet dye when compared with their respective drop-casted films, thus establishing a novel method for producing diverse meta-structures based efficient SERS substrates with promising applications in ultrasensitive chemical and biological sensing.

In situ epitaxial thickening of wafer-scale, highly oriented nanotwinned Ag on tailored polycrystalline Cu substrates

Highly (111)-oriented nanotwinned Ag (nt-Ag) is a promising candidate for a next-generation direct metal bonding material without a vacuum environment. However, conventional methods used for its preparation are costly, complex, and inefficient. Herein, we report an in-situ epitaxial thickening approach of wafer-scale (111) nt-Ag on tailored polycrystalline Cu substrates via a galvanic replacement reaction (GRR). The resultant Ag films replicate the crystallographic structure of the Cu substrate and exhibit local single crystallinity, which effectively protects the substrate from oxidation and achieves better bonding quality. Through detailed structural characterization and theoretical calculations, we provide insights on the counterintuitive thickening-corrosion mechanisms of GRR for the first time. We find that the interfacial interaction within the Ag/Cu becomes an additional driving force for the Ag ions to enter the lattice when the Cu substrate corrosion is inhibited. Our findings provide valuable insights into the formation and growth of nanotwin structures and can advance the future practical application of (111) nt-Ag in the microelectronics industry.

Corrigendum: Correction to “Hybrid Integration of Au Nanoplates and Ag Nanoparticles with Controlled Nanogaps via Cu2O‐mediated Galvanic Replacement Reaction: Plasmonic Catalysis and Photothermal Conversion”

Corrigendum: Correction to “Hybrid Integration of Au Nanoplates and Ag Nanoparticles with Controlled Nanogaps via Cu2O‐mediated Galvanic Replacement Reaction: Plasmonic Catalysis and Photothermal Conversion”

Ultrasound-assisted preparation of PdCo bimetallic nanoparticles loaded on beta zeolite for efficient catalytic hydrogen production from dodecahydro-N-ethylcarbazole

Research and development of high-performance catalysts is a key technology to realize hydrogen energy storage and transportation based on liquid organic hydrogen carriers. Co/beta was prepared using beta zeolite as a carrier via an electrostatic adsorption (ESA)-chemical reduction method, and it was used as the template and reducing agent to prepare bimetallic catalysts via an ultrasonic assisted galvanic replacement process (UGR). The fabricated PdCo/beta were characterized by TEM, XPS, FT-IR, XRD, H2-TPR, and H2-TPD. It was shown that the ultrafine PdCo nanoparticles (NPs) are evenly distributed on the surface of the beta zeolite. There is electron transfer between metal NPs and strong-metal-support-interaction (SMSI), which results in highly efficient catalytic dodecahydro-N-ethylcarbazole (12H-NEC) dehydrogenation performance of PdCo bimetallic catalysts. The dehydrogenation efficiency reached 100 % in 4 h at 180 °C and 95.3 % in 6 h at 160 °C. The TOF of 146.22 min−1 is 7 times that of Pd/beta. The apparent activation energy of the reaction is 66.6 kJ/mol, which is much lower than that of Pd/beta. Under the action of ultrasonic waves, the galvanic replacement reaction is accelerated, and the intermetal and metal-carrier interactions are enhanced, which improves the catalytic reaction performance.

Fabrication of robust superhydrophobic zinc-coated steel with anti-corrosion and self-cleaning behavior through a simple nickel galvanic replacement reaction

Zinc coating is a widely used coating for steel substrate as a galvanic protector but the corrosion rate of this coating increases when exposed to wet environment. In recent years, bioinspired superhydrophobic surfaces have received tremendous attention among various methods to enhance the corrosion resistance. In this study, superhydrophobic zinc-coated steel was fabricated based on nickel galvanic replacement reaction in NiCl2.6 H2O solution on zinc-coated steel and post modification to improve the corrosion resistance and create self-cleaning behavior. Based on the FESEM morphology and AFM topography images, galvanic replacement reaction created hierarchical micro/nanostructure that is key parameter for creating superhydrophobic surfaces. EDS, XRD, XPS and FTIR analysis confirmed the occurrence of galvanic replacement reaction and post modification of the surface with FAS- solution. The zinc-coated steel immersed in NiCl2.6 H2O solution with the concentration of 0.1 M for 10 min showed the highest water contact angle of 166.7° ± 1.6° and a contact angle hysteresis of 1.7°. In addition, it exhibited good long-term stability under various conditions, mechanical stability, self-cleaning capability, and robust adhesion which was not reported, previously. Corrosion study showed that the surface exhibit excellent charge transfer resistance and higher positive corrosion potential and a lower corrosion current density compared with the zinc coating. The results indicated that the galvanic replacement reaction is a simple, scalable, cost effective and promising method for creating multifunctional and robust superhydrophobic surfaces on zinc coatings to protect steel.

Bio-Inspired Superhydrophilic Self-Assembled Coronavirus-Like Pt-WC/CNT for Hydrogen Evolution Reaction.

This study presents a novel approach to enhance the catalytic activity of composite materials by promoting active surface exposure and improving hydrogen transfer performance. Through a self-assembly route involving tailored gas-solid and galvanic replacement reactions, Pt-WC/CNT catalysts with superhydrophilicity and coronavirus-like structure are synthesized. These unique structural features contribute to a remarkable enhancement in the electrocatalytic performance of the hydrogen evolution reaction (HER). Notably, the Pt-WC/CNT catalyst exhibits an outstanding intrinsic activity and efficient bubble transfer properties, leading to a high turnover frequency of 34.97 H2·s-1 at an overpotential of 100mV. This value is 4.8 times higher than that achieved by commercial Pt/C catalysts (7.30 H2·s-1), establishing Pt-WC/CNT as one of the most active catalysts reported to date. Moreover, the combination of gas-solid and galvanic replacement reactions in the synthesis process offers a scalable route for the production of Pt-loading controllable composite catalysts, thus challenging the dominance of commercial Pt/C catalysts.

Cellulose/GO monolith covered with Pd–Pt bimetallic nanocrystals for continuous-flow catalytic reduction of hexavalent chromium

Cellulose monolith materials have interconnected open porous structures with very high porosity, making them attractive structures for use as support materials in heterogeneous catalysis applications. In this study, we developed a highly efficient and reusable continuous-flow reactor for Cr(VI) remediation by combining the advantageous features of cellulose monoliths with suitable reinforcement techniques. We fabricated a porous monolithic cellulose/graphene oxide (GO) composite with a continuous three-dimensional skeletal framework using the thermally induced phase separation technique. Pd nanocrystals were synthesized in situ on the surface of the composite monolith, and then converted to porous Pd–Pt bimetallic nanocrystals through a galvanic replacement reaction. This approach eliminated the need for additional reductants and stabilizers, making the process simpler and more environmentally friendly. Under carefully optimized conditions, the cellulose/GO/Pd–Pt nanocomposite monolith exhibited outstanding performance in continuous-flow reactions for Cr(VI) reduction, achieving a maximum conversion rate of 98 %. Moreover, the nanocomposite monolith-based heterogeneous catalyst exhibited remarkable long-term stability, maintaining its catalytic activity even after extended periods of storage in the dried state. These findings highlight the potential of cellulose-based composite monoliths as versatile and robust support materials for heterogeneous catalysis.