Hydrolysis Of Zn Research Articles

Hydrogen Evolution Atomic Cluster Catalysts-Decorated Hierarchical Nanoporous Zinc for on-Demand Hydrogen Generation By Metal Hydrolysis

In recent years, there has been an increasing interest in nanoporous metals due to their wide range of applications, including catalysis, electrocatalysis, energy storage, actuation, and plasmonics. However, considerable attention has been given to precious nanoporous metals such as nanoporous Au, Pd, Pt, Ag, and Cu due to their low chemical reactivity, which makes them relatively easy to synthesize and characterize. Less precious nanoporous metals such as nanoporous Zn, Al, and Mg have been rarely fabricated and characterized because of their relatively high chemical reactivity 1. In this talk, I will present a novel, highly scalable approach to making hierarchical nanoporous zinc (NP-Zn) decorated with atomic clusters of hydrogen evolution catalysts for on-demand hydrogen generation by metal hydrolysis. Our approach involves selective etching in combination with galvanic replacement reactions. The conventional selective etching method requires several days to create a monolithic piece of NP-Zn 2. Our approach creates the same amount of hierarchical NP-Zn in less than 5 minutes, instead of several days. In our work, we used focused ion beam/scanning electron microscopy techniques to reveal the internal nanoscale morphology of the hierarchical NP-Zn, and small-angle X-ray scattering to analyze the pore size distribution. In general, when NP-Zn is used for hydrogen generation by metal hydrolysis, the hydrogen generation yield is low, typically around 20%. This is because zinc is naturally a poor hydrogen evolution material. Our process overcomes this issue by creating NP-Zn with its interface decorated with clusters of hydrogen evolution catalysts, which enables hydrogen generation yield exceeding 90% depending on the catalyst loading. References (1) Fu, J.; Welborn, S. S.; Detsi, E. Dealloyed Air- and Water-Sensitive Nanoporous Metals and Metalloids for Emerging Energy Applications. ACS Appl. Energy Mater. 2022, 5 (6), 6516–6544. https://doi.org/10.1021/acsaem.2c00405.(2) Fu, J.; Deng, Z.; Lee, T.; Corsi, J. S.; Wang, Z.; Zhang, D.; Detsi, E. pH-Controlled Dealloying Route to Hierarchical Bulk Nanoporous Zn Derived from Metastable Alloy for Hydrogen Generation by Hydrolysis of Zn in Neutral Water. ACS Appl. Energy Mater. 2018, 1 (7), 3198–3205. https://doi.org/10.1021/acsaem.8b00419.

EFFECT OF REACTION CONDITIONS ON PARTICLE SIZE OF ZNO NANOPARTICLES VIA CONTROLLED PRECIPITATION METHOD AND IN-VITRO ANTIBACTERIAL CAPACITY

High-yield ZnO spheroidal nanoparticles with an average diameter around 23 nm (≈ 25% frequency) and 30 nm (≈ 28% frequency) were obtained by controlled semicontinuous precipitation at low temperatures. This synthesis was obtained from hydrozincite (Zn5(CO3)2(OH)6) as primary nanoparticles. The Zn5(CO3)2(OH)6 nanoparticles were synthesized by hydrolysis of Zn(NO3)2 in aqueous solution of (NH4)2CO3 and later, the precipitation becomes. Two temperatures of 60 and 70 °C in combination with three times of reaction were tested; followed by calcination of the precipitate at 400 °C. This range of sizes of nanoparticles is comparable with those obtained by other methods reported in the literature, such as microemulsions, however, here the advantage was not using solvents or surfactants. The ZnO nanoparticles were characterized by energy dispersive X-ray spectroscopy coupled to a scanning electron microscopy (SEM-EDS), transmission electronic microscopy (TEM), and X-ray diffraction. The antibacterial activity of the films against Gram-positive (S. aureus) and Gram-negative (E. coli.) bacteria was investigated using the disc diffusion method. The best results were found in the inhibition zone for Gram-positive bacteria, when the concentration of ZnO NPs incorporated was 3 mg disc-1.

Effects of hydrogen bubbles on deformation of zinc anodes at high depth of discharge

The effects of hydrogen evolution reaction on the deformation of zinc anode which cycles at nearly 100% depth of discharge (DOD) are studied. Results show that the generated hydrogen bubbles during charging process will gather on the surface of the middle of the anode and will cover the ZnO which is produced by the hydrolysis of Zn (OH)42− and prevent ZnO participation in the charging process. Since the charge-discharge reaction only occurs at the edges of the bubbles, the multiple dissolution and redeposition of the active material results in the formation of a massive ZnO and a very low specific discharge capacity. This finding provides a new perspective for the deformation of zinc anodes of the secondary alkaline zinc-based batteries.

NANOPARTÍCULAS ESFÉRICAS DE ÓXIDO DE ZINC SINTETIZADAS POR UN MÉTODO DE PRECIPITACIÓN SEMICONTINUA A BAJAS TEMPERATURAS

The synthesis of spheroidal high purity zinc oxide (ZnO) and crystal size in a range of 20 and 45 nm, using the semicontinuous precipitation method is reported in this work. The ZnO nanoparticles (ZnO-NPs) were made by hydrolysis of Zn(NO3)2 with NaOH aqueous solution and precipitation at temperatures below 90 °C. The ultrafine powder of ZnO was analyzed by X-ray diffraction (XRD), where the formation of ZnO nanoparticles and hexagonal crystal structure (wurtzite) was corroborated. Spheroidal nanoparticles were observed by transmission electron microscopy (TEM) and energy dispersive aX-ray (EDX) spectra confirming the presence of high purity ZnO-NPs. A factorial experimental model 23 was performed to grant statistical validity of the experimental procedure. The antibacterial activity of ZnO-NPs was tested by the agar disk diffusion method, against S. aureus and E. coli.

PH-Controlled Dealloying Route to Hierarchical Bulk Nanoporous Zn Derived from Metastable Alloy for Hydrogen Generation by Hydrolysis of Zn in Neutral Water

Dealloyed nanoporous metals made of very-reactive elements have rarely been reported. Instead, reactive materials are used as sacrificial components in dealloying. The high chemical reactivity of nonprecious nanostructured metals makes them suitable for a broad range of applications such as splitting water into H2 gas and metal hydroxide. On the other hand, the same high chemical reactivity hinders the synthesis of nanostructured metals. Here we use a pH-controlled dealloying strategy to fabricate bulk nanoporous Zn with bulk dimensions in the centimeter range via the selective removal of Al from metastable face-centered cubic bulk Zn20Al80 at. % parent alloys. The corresponding bulk nanoporous Zn exhibits a hierarchical ligament/pore architecture characterized by primary ligaments and pores with an average feature size in the submicrometer range. These primary structures are made of ultrafine secondary ligaments and pores with a characteristic feature size in the range of 10–20 nm. Our bulk nanoporous Zn can split water into H2 and Zn(OH)2 at ambient temperature and pressure and continuously produce H2 at a constant rate of 0.08 mL/min per gram of Zn over 8 h. We anticipate that in this hierarchical bulk architecture, the macropores facilitate the flow of water in the bulk of the material, while the mesopores and ultrafine ligaments provide a high surface area for the reaction of water with Zn. The bulk nanoporous Zn/water system can be used for on-board or on-demand H2 applications, during which H2 is produced when needed, without prior storage of this gas compressed in cylinders as it is currently the case.

Effect of steam and CO2 on ethane activation over Zn-ZSM-5

Hydrolysis of Zn(ii) sites in Zn-ZSM-5 suppresses ethane oligomerization and aromatization.

Synthesis of ZnO nanoparticles and a composite with polyacrylamide in acrylamide solutions

The use of solutions of acrylamide (AAm) opens up new ways for easy one-step synthesis of ZnO nanoparticles (NPs) and their composites with polyacrylamide (PAAm). To obtain a nanocrystalline product in which the composition of NPs is close to {(ZnO) m (Zn2+) n }(CH3COO−)2n with n/m = 0.292, the hydrolysis of Zn(CH3COO)2·2H2O should be carried out in 96% ethanol. In this process, AAm plays the role of an organic base that accepts protons and does not act as a protective ligand. The ZnO NPs/PAAm composite is formed as a viscous transparent colorless hydrogel if the same reaction is carried out in an aqueous medium simultaneously with the radical polymerization of AAm initiated by (NH4)2S2O8. A solid composite can be isolated due to the destruction of the hydrogel by the addition of ethanol. In the composite, PAAm acts as a polymeric matrix in which ZnO NPs are distributed. The synthesis products were characterized by XRD, TEM, SEM, EDX, DLS, IR, Raman scattering, photoluminescence, and chemical analysis. The particles in both products were nanocrystals of hexagonal ZnO about a few nanometers in size. The powder of {(ZnO) m (Zn2+) n }(CH3COO−)2n NPs had a yellow photoluminescence with emission maximum at λ em = 590 nm. The photoluminescence band of the ZnO NPs/PAAm hydrogel had a maximum at λ em = 449 nm.

Competition between the reaction medium and nanostructured ZnO in the photocatalytic degradation of anthracene. Toward an optimal process for polycyclic aromatic hydrocarbons remediation

Contamination with polycyclic aromatic hydrocarbons (PAHs) is considered an important health issue due to the toxicity of these compounds. Photocatalytic degradation of anthracene, a representative molecule of PAHs, using the high quantum yield semiconductor ZnO, has been reported. The solubility of anthracene in water makes necessary to use mixtures with organic solvents in fundamental degradation studies. It is well known that some organic solvents participate in the photochemical transformation of this molecule. In the PAHs photocatalysis, the competition between a semiconductor and solvents has not reported. Therefore, in this work, we decided to study the photocatalytic degradation of anthracene with two common reaction media and nanostructured ZnO. The semiconductor was obtained by a one pot method which consists in an alkaline hydrolysis of Zn(CH3COO)2⋅2H2O in ethanol. Nanoparticles size in colloidal dispersion was calculated using UV-Vis spectroscopy and High Resolution Transmission Electron Microcopy (HR-TEM). ZnO powder was isolated and characterized by X-ray diffraction to be used in photocatalytic experiments. Surface area determination and photocurrent spectroscopic experiments were also carried out. Linear sweep voltammetries under darkness and UV-Vis irradiation indicate a charge separation due to photoexcitation. Photocatalytic experiments in ethanol:water pH 12 (1:1) and acetone:water pH 12 (1:1), with and without ZnO was explored. The results demonstrated that ethanol:water and acetone:water promotes the photo-transformation of anthracene to 9,10-anthraquinone. Meanwhile, ZnO transformed anthracene to benzoic acid and to 9,10-anthraquinone in ethanol:water and acetone:water, respectively. A faster photochemical kinetic is observed when acetone was used as solvent in the presence and in the absence of ZnO.

Glutathione-functionalized Mn:ZnS/ZnO core/shell quantum dots as potential time-resolved FRET bioprobes

High-quality glutathione-capped Mn:ZnS/ZnO core/shell quantum dots were prepared in aqueous solution through the nucleation-doping method by using low-cost inorganic salts as precursors. Remarkable improvements of photoluminescence (PL) were achieved by introduction of a ZnO shell around the Mn:ZnS QDs through basic hydrolysis of Zn(NO3)2. The Mn:ZnS/ZnO quantum dots have been demonstrated to be sensitive time-resolved Förster resonance energy transfer (TR-FRET) bioprobes for the detection of a trace amount of biomolecules such as avidin at a concentration of 3 nM with a linear response ranging from 10 to 100 nM. We anticipate that the QDs may have great potential for versatile applications in biodetection and bioimaging.

Photocatalytic Characterization of Fe‐ and Cu‐Doped ZnO Nanorods Synthesized by Cohydrolysis

Fe‐ and Cu‐doped ZnO nanorods have been synthesized by a novel process employing a hydrolysis of metal powders. Zn, Fe, and Cu nanopowders were used as starting materials and incorporated into distilled water. The solution was refluxed at 60°C for 24 h to obtain the precipitates from the hydrolysis of Zn and dopants (Cu and Fe). The TEM results for ZnO with and without metal doping showed that the produced powders had a rod‐like shape. The rod shape was attributable to the zinc oxide from the hydrolysis of Zn. With an increasing doping content, the UV‐vis spectra were shifted to a long wavelength and this result indicates that the band gap was changed by the metal doping. The values of phenol degrading Fe‐ and Cu‐doped ZnO by a solar simulator were measured to be 60 and 75%, respectively.

Fluid Dynamics of a Transverse Jet Reactor for Zinc Aerosol Hydrolysis

A new concept for control of the flow field, and thus particle yield, in an aerosol reactor designed for the hydrolysis of Zn in the two-step Zn/ZnO solar thermochemical cycle for hydrogen production is described and evaluated. For the hydrolysis step, much attention has been given to Zn nanoscale reacting aerosols for their potential to increase conversion to ZnO and because they enable a continuous, controllable process. The success of this continuous process depends on achieving high particle yields in the reactor. A key challenge is to control the flow field in aerosol reactors to keep the particles entrained in the flow without deposition on the reactor wall. The ability of a new reactor concept based on transverse jet fluid dynamics to control the flow field and rapidly cool the Zn vapor is investigated. In the transverse jet reactor, evaporated Zn entrained in an Ar carrier gas issues vertically into the horizontal tubular reactor through which cooler H2O and Ar flow. Particles are formed in the presence of steam at ~450 K. The trajectory of the jet is controlled via the effective velocity ratio, R, which is the square root of the ratio of the kinetic energy of the jet to that of the cross-flow. A computational fluid dynamics (CFD) model indicates that the trajectory of the jet can be controlled so that the majority of the Zn mass is directed down the center of the reactor, not near the reactor walls for R = 4.25 to R = 4.5. Experimentally, maximum particle yields of 93% of the mass entering the reactor are obtained at R = 4.5.

Physicochemical properties and cellular toxicity of (poly)aminoalkoxysilanes-functionalized ZnO quantum dots

Luminescent ZnO nanocrystals were synthesized by basic hydrolysis of Zn(OAc)2 in the presence of oleic acid and then functionalized with (poly)aminotrimethoxysilanes in the presence of tetramethylammonium hydroxide to render the QDs water-dispersible. The highest photoluminescence quantum yield (17%) was achieved using N1-(2-aminoethyl)-N2-[3-(trimethoxysilyl)propyl]-1,2-ethanediamine as surface ligand. Transmission electron microscopy and powder x-ray diffraction showed highly crystalline materials with a ZnO nanoparticle diameter of about 4 nm. The cytotoxicity of the different siloxane-capped ZnO QDs towards growing Escherichia coli bacterial cells was evaluated in MOPS-minimal medium. Although concentrations of 5 mM in QDs caused a complete growth arrest in E. coli, siloxane-capped ZnO QDs appeared weakly toxic at lower doses (0.5 or 1 mM). The concentration of bioavailable Zn 2+ ions leaked from ZnO QDs was evaluated using the biosensor bacteria Cupriavidus metallidurans AE1433. The results obtained clearly demonstrate that concentrations of bioavailable Zn2+ are too low to explain the inhibitory effects of the ZnO QDs against bacteria cells at 1 mM and that the siloxane shell prevents ZnO QDs from dissolution contrary to uncapped ZnO nanoparticles. Because of their low cytotoxicity, good biocompatibility, low cost and large number of functional amine end groups, which makes them easy to tailor for end-user purposes, siloxane-capped ZnO QDs offer a high potential as fluorescent probes and as biosensors.

Facile Fabrication and Efficient Photocatalytic Activity of 3D-Ordered Macroporous ZnO Film

Three-dimensionally (3D) ordered macroporous ZnO film was fabricated on a glass slide by layer-by-layer depositing and hydrolysis of Zn(CH3COO)2using 3D-ordered latex film as template followed by calcination at 450 °C for 2 h to remove the organic template. The as-prepared 3D-ordered macroporous ZnO film was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), diffusive reflectance UV-visible absorption spectra (DRUV-VIS), photoluminescence (PL), and photoelectrochemical measurement. Its photocatalytic activity was evaluated by the photocatalytic degradation of crystal violet (CV) aqueous solution at ambient temperature under the irradiation of simulated solar light. It was found that the 3D-ordered ZnO film exhibits efficient photocatalytic activity for photodegradation of CV under the irradiation of simulated solar light.

Aqueous Route to Biocompatible ZnSe:Mn/ZnO Core/Shell Quantum Dots Using 1-Thioglycerol As Stabilizer

Water-dispersible 1-thioglycerol-capped Mn-doped ZnSe quantum dots (QDs) were prepared in aqueous solution through the nucleation-doping method by using safe and low-cost inorganic salts as precursors. Influence of the Zn/Se ratio, precursors concentrations and reaction pH on the particle size, colloidal stability, and photoluminescence (PL) were investigated. Under optimal conditions, thioglycerol-capped ZnSe:Mn QDs with an average diameter of 3.5 nm and a PL quantum yield of 3.5% in water at neutral pH were produced. X-ray powder diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, UV–visible spectroscopy and spectrofluorometry have been used to characterize the crystal structure and the optical properties of the dots. Remarkable improvements of stability in biological medium and PL were achieved by introduction of a ZnO shell through basic hydrolysis of Zn(NO3)2. ZnO was found to eliminate the surface-trap state from Mn2+-doped ZnSe cores and enhance their PL quantum yield to 12%. Growth inhibition tests showed that core/shell ZnSe:Mn/ZnO@TG QDs do not exhibit any cytotoxicity toward E. coli bacterial cells up to a concentration of 0.14 mg/mL, indicating that these nanocrystals can be considered as building blocks for the synthesis of bioprobes for cells and tissues imaging.

Enhanced Photostability from CdSe(S)/ZnO Core/Shell Quantum Dots and Their Use in Biolabeling

AbstractWe report on the preparation and on the photophysical and structural characterization of alloyed CdSe(S) nanocrystals, which are covered by a ZnO shell. CdSe(S) QDs were prepared by reaction of CdCl2 with NaHSe in the presence of 3‐mercaptopropionic acid (MPA) under hydrothermal conditions. The incorporation of sulfur arises from the surface‐mediated MPA hydrolysis on the growing QD surface. Water‐dispersible CdSe(S) QDs were successfully capped with a ZnO shell obtained by basic hydrolysis of Zn(OAc)2. The experimental results from transmission electron microscopy (TEM) imaging and powder X‐ray diffractometry (XRD) analyses indicate that the core/shell CdSe(S)/ZnO QDs have a very small diameter (ca. 2.8 nm) and exhibit a face‐centered cubic crystal structure. Our results show that core/shell CdSe(S)/ZnO QDs have a higher photostability than CdSe(S) cores. CdSe(S)/ZnO QDs have potential applications asfluorescent biological labels and were successfully used for imaging Schewanella oneidensis bacterial biofilms.

High-Yield Synthesis of Zinc Oxide Nanoparticles from Bicontinuous Microemulsions

The high-yield synthesis of zinc oxide (ZnO) primary nanoparticles with high purity and with diameters between 6 and 22 nm using bicontinuous microemulsions is reported in this work. The ZnO nanoparticles were made by hydrolysis of Zn(NO3)2with NaOH aqueous solution and precipitation, followed by calcination of the precipitate. Higher yields and productivities of ZnO nanoparticles were obtained compared to values produced with w/o micremulsions reported in the literature. Particles were characterized by transmission electronic microscopy (TEM), X-ray diffraction, and atomic absorption spectroscopy.

Physical facets of ultrasonic cavitational synthesis of zinc ferrite particles

This paper addresses the physical features of the ultrasonic cavitational synthesis of zinc ferrite particles and tries to establish the relationship between cavitation physics and sonochemistry of the zinc ferrite synthesis. A dual approach of coupling experimental results with simulations of radial motion of cavitation bubbles has been adopted. The precursors for the zinc ferrite, viz. ZnO and Fe 3O 4 are produced in situ by the hydrolysis of Zn and Fe(II) acetates stimulated by OH radicals produced from the transient collapse of the cavitation bubbles. Experiments performed under different conditions create significant variation in the production of OH radicals, and hence, the rate of acetate hydrolysis. Correlation of the results of experiments and simulations sheds light on the important facets of the physical mechanism of ultrasonic cavitational zinc ferrite synthesis. It is revealed that too much or too little rate of acetate hydrolysis results in smaller particle size of zinc ferrite. The first effect of a higher rate of hydrolysis leads to excessively large growth of particles, due to which they become susceptible to the disruptive action of cavitation bubbles. Whereas, the second effect of too small rate of hydrolysis of Zn and Fe(II) acetates restricts the growth of particles. It has been observed that the initial reactant concentration does not influence the mean particle size or the size distribution of zinc ferrite particles. The present investigation clearly confirms that the rate-controlling step of zinc ferrite synthesis through ultrasonic cavitational route is the rate of formation of OH radicals from cavitation bubbles.

Kinetics of the thermal dissociation of ZnO exposed to concentrated solar irradiation using a solar‐driven thermogravimeter in the 1800–2100 K range

AbstractThe two‐step H2O‐splitting thermochemical cycle based on the Zn/ZnO redox reactions is considered for solar H2 production, comprising the endothermal dissociation of ZnO followed by the exothermal hydrolysis of Zn. A solar‐driven thermogravimeter, in which a packed‐bed of ZnO particles is directly exposed to concentrated solar radiation at a peak solar concentration ratio of 2400 suns while its weight loss is continuously monitored, was applied to measure the thermal dissociation rate in a set‐up closely approximating the heat and mass transfer characteristics of solar reactors. Isothermal thermogravimetric runs were performed in the range 1834–2109 K and fitted to a zero‐order Arrhenius rate law with apparent activation energy 361 ± 53 kJ mol−1 K−1 and frequency factor 14.03 × 106 ± 2.73 × 106 kg m−2 s−1. Application of L‘vov’s kinetic expression for solid decomposition along with a convective mass transport correlation yielded kinetic parameters in close agreement with those derived from experimental data. © 2009 American Institute of Chemical Engineers AIChE J, 2009

Effects of NH 3·H 2O pretreatment on the fabrication of uniform titania nanocoating in an aqueous solution

An investigation is reported of the TiO 2 nanocoating on the ZnS-based phosphor via a sol–gel method in an aqueous solution using titanium diethanolamine complex as the precursor. The pretreatment of ZnS phosphors with NH 3·H 2O is important to the coating process. When NH 3·H 2O was added into the ZnS phosphor suspension, OH − promoted the hydrolysis of Zn 2+ on the surface of ZnS phosphors, which resulted in the formation of Zn–OH. Zn–OH reacted with the hydrolysis product of titanium diethanolamine complex, thus the titania coatings were obtained. The coating morphology was strongly dependant on the pH of the pretreated ZnS phosphor suspension and the weight ratio of ZnS to TiO 2.

Growth, Structural, and Optical Characterization of ZnO-Coated Cellulosic Fibers

Rod-shaped ZnO particles were grown over wood cellulose fibers using a two-step process. In the first step, the formation of ZnO seeds at cellulose fibers surfaces was induced by the alkaline hydrolysis of aqueous Zn(II); in the second step, the growth of the ZnO seeds into larger nanoparticles was promoted by the controlled hydrolysis of Zn(II)−amine complexes. In particular, we will report the use of hexamethylenetetramine (C6H12N4) and triethanolamine (C6H15NO3) to grow, respectively, ZnO nanorods and microrods at the cellulose fibers surfaces. Photoluminescence measurements performed on the nanocomposite materials showed the typical excitonic ZnO recombination peaked between 3.38 and 3.34 eV, at low temperature. The full width at half-maximum of the excitonic line is dependent on the ZnO particles morphology and can be as narrow as 30 meV for some of the materials investigated.