Synthesis Conditions Research Articles

Stepwise Understanding on Hydrolysis Formation of the IrOx Nanoparticles as Highly Active Electrocatalyst for Oxygen Evolution Reaction

AbstractIn this study, we have investigated the synthesis of supported iridium oxide (IrOx) nanoparticles (NPs) through hydrolysis in a surfactant-free aqueous bath as a possible route for the large-scale production of highly active electrocatalyst for oxygen evolution reaction (OER) in acidic water electrolyzers. The process involves (i) formation of Ir-hydroxides complex from an Ir precursor in basic media followed by (ii) protonation in acidic media to form colloidal hydrated IrOx NPs and (iii) conversion and deposition of IrOx NPs on the surface of carbon or TiN support by probe sonication. The IrOx NPs produced through hydrolysis route form highly stable colloidal solution. Since it is essential to precipitate the catalyst NPs from the colloidal solution for their use in water electrolyzer electrode development, here, we investigate the optimal reaction conditions, e.g., pH, temperature, time, and presence of support, for efficient synthesis of the catalyst NPs. The reaction intermediates formed at different reaction steps are explored to get insights into the chemistry of the process. Under the optimal synthesis conditions, 100% precipitation of IrOx NPs was achieved. Further, the precipitated TiN supported IrOx NPs exhibited high OER activity, superior to that of the commercial benchmark IrO2 electrocatalyst. The study provides a scalable synthesis route for highly active, low Ir-content OER electrocatalysts for acidic water electrolyzers. Graphical Abstract

Surface-Enhanced Raman Spectroscopy Sensor Integrated with Ag@ZIF-8@Au Core-Shell-Shell Nanowire Membrane for Enrichment, Ultrasensitive Detection, and Inactivation of Bacteria in the Environment.

A core-shell-shell sandwich material is developed with silver nanowires as the core, ZIF-8 as an inner shell, and gold nanoparticles as the outer shell, namely, Ag@ZIF-8@Au nanowires (AZA-NW). Then, the synthesized AZA-NW is transformed into a surface-enhanced Raman spectroscopy (SERS) sensor (named M-AZA) by the vacuum filtration method and used to enrich, detect, and inactivate traces of bacteria in the environment. The M-AZA sensor has three main functions: (1) trace bacteria are effectively enriched, with an enrichment efficiency of 91.4%; (2) ultrasensitive detection of trace bacteria is realized, with a minimum detectable concentration of 1 × 101 CFU/mL; (3) bacteria are effectively killed up to 92.4%. The shell thickness of ZIF-8 (5-75 nm) is controlled by adjusting the synthesis conditions. At an optimum shell thickness of 15 nm, the effect of gold nanoparticles and ZIF-8 shell on the sensor's stability, SERS activity, and antibacterial performance is investigated. The simulation of the SERS sensor using the finite difference time domain (FDTD) method is consistent with the experimental results, theoretically demonstrating the role of the gold nanoparticles and the ZIF-8 shell. The sensor also shows excellent stability, safety, and generalizability. The campus water sample is then tested on-site by the M-AZA SERS sensor, indicating its potential for practical applications.

Optimization of preparation conditions and performance of a new degradable soil water retaining agent

Using polyaspartic acid (PAsp) and bentonite (BT) as the main raw materials, a new type of degradable soil water retaining agent (PAsp-AA/BT) was synthesized by microwave radiation. The optimum synthesis conditions and comprehensive properties of PAsp-AA/BT were discussed and the structure and surface characteristics of PAspsp-AA/BT were characterized by FTIR, SEM, XRD and TGA in the paper. The results showed that the optimum synthesis conditions of PAsp-AA/BT were as follows: the dosages of polyaspartic acid (PAsp), bentonite (BT), initiator potassium persulfate, crosslinking agent N,N′-methylene bisacrylamide was 5, 3, 0.3, 0.03%, respectively, the neutralization degree of acrylic acid was 75%, and the microwave power was 490W. Under this condition, the absorption ratio of the synthesized PAspsp-AA/BT in deionized water and 0.9% NaCl solution was 953 and 164 g/g, respectively. The synthesized PAsp-AA/BT had a high water absorption rate, good water retention and repeated water absorption, and the degradation rate in soil within 30 days reached 32.75%, with good degradation effect. The analysis of SEM, FT-IR, XRD and TGA showed that: the surface of PAsp-AA/BT was rough and had obvious pore structure, which was conducive to the diffusion of water molecules; polyaspartic acid, bentonite and acrylic acid were polymerized; the cross-linking structure was formed between polyaspartic acid, bentonite and acrylic acid; the product of PASP-AA/BT had good thermal stability. This study provides a new soil water retaining agent, which is helpful for the better development of soil water retaining agent research.

Improved Synthesis of Hollow Fiber SSZ-13 Zeolite Membranes for High-Pressure CO2/CH4 Separation.

High-silica CHA zeolite membranes are highly desired for natural gas upgrading because of their separation performance in combination with superior mechanical and chemical stability. However, the narrow synthesis conditions range significantly constrains scale-up preparation. Herein, we proposed a facile interzeolite conversion approach using FAU zeolite to prepare SSZ-13 zeolite seeds, featuring a shorter induction and a longer crystallization period of the membrane synthesis. The membrane thickness was constant at ~3 μm over a wide span of synthesis time (24 ~ 96 h), while the selectivity (separation efficiency) was easily improved by extending synthesis time without compromising permeance (throughput). At 0.2MPa feed pressure and 303 K, the membranes showed an average CO2 permeance of (5.2 ± 0.5) × 10-7 mol·m-2·s-1·Pa-1 (1530GPU), with an average CO2/CH4 mixture selectivity of 143 ± 7. Minimal defects ensure a high selectivity of 126 with a CO2 permeation flux of 0.4 mol·m-2·s-1 at 6.1MPa feed pressure, far surpassing requirements for industrial applications. The feasibility for successful scale-up of our approach was further demonstrated by the batch synthesis of 40 cm-long hollow fiber SSZ-13 zeolite membranes exhibiting CO2/CH4 mixture selectivity up to 400 (0.2 MPa feed pressure and 303 K) without using sweep gas.

Improved Synthesis of Hollow Fiber SSZ‐13 Zeolite Membranes for High‐Pressure CO2/CH4 Separation

High‐silica CHA zeolite membranes are highly desired for natural gas upgrading because of their separation performance in combination with superior mechanical and chemical stability. However, the narrow synthesis conditions range significantly constrains scale‐up preparation. Herein, we proposed a facile interzeolite conversion approach using FAU zeolite to prepare SSZ‐13 zeolite seeds, featuring a shorter induction and a longer crystallization period of the membrane synthesis. The membrane thickness was constant at ~3 μm over a wide span of synthesis time (24 ~ 96 h), while the selectivity (separation efficiency) was easily improved by extending synthesis time without compromising permeance (throughput). At 0.2 MPa feed pressure and 303 K, the membranes showed an average CO2 permeance of (5.2 ± 0.5) × 10‐7 mol·m‐2·s‐1·Pa‐1 (1530 GPU), with an average CO2/CH4 mixture selectivity of 143 ± 7. Minimal defects ensure a high selectivity of 126 with a CO2 permeation flux of 0.4 mol·m‐2·s‐1 at 6.1 MPa feed pressure, far surpassing requirements for industrial applications. The feasibility for successful scale‐up of our approach was further demonstrated by the batch synthesis of 40 cm‐long hollow fiber SSZ‐13 zeolite membranes exhibiting CO2/CH4 mixture selectivity up to 400 (0.2 MPa feed pressure and 303 K) without using sweep gas.

Instant green synthesis: obtaining stable nanoparticles and understanding the extract's behavior in the particle formation mechanism

Numerous plant extracts are abundant in biomolecules that can be employed in the biogenic synthesis of metallic nanoparticles owing to their potent reducing capabilities. The mechanism by which biomolecules act as reducers and expedite the reduction of silver ions remains poorly understood. This study presents an instantaneous and environmentally friendly synthesis of silver nanoparticles (AgNPs) using varying concentrations of commercially available green tea and concentrations of a dextrose-reducing solution. The AgNPs formed instantaneously, likely due to the competitive reaction between the polyphenols present in green tea and the dextrose. The best AgNPs produced using a diluted green tea solution at a concentration of 0.05 g of tea/ml and 100 μl of dextrose solution exhibited high stability over a period of 90 days, as confirmed by UV–vis spectroscopy and dynamic light scattering. The results of antioxidant properties from diluited tea showed 2,2-diphenyl-1-picrylhydrazyl (DPPH) 0.013 ± (0.1) μmol Trolox Equivalent Anyioxidant Capacity (TEAC) TEAC/g, Ferric Reducing Antioxidant Power (FRAP) 10.3 ± (0.1) μmol TEAC/g and Total Polyphenol Content (TPC) 0.12 ± (.001) μgGAE(Galic Acid Equivalent)/g). The resulting nanoparticles are extremely small, measuring approximately 30 to 50 nm in size, and exhibit a spherical morphology as evidenced by SEM imaging. The plasmon bandwidth is better in more diluted tea and higher proportions of dextrose added than the others condition of synthesis. Probably, the results of 2nd extraction of green tea diluted can be evidence that phenolic compounds, mainly, caffeine and gallic acid, are contributing to forming and stabilizing the silver nanoparticles. This fundamental knowledge showed the method employed is ecologically sound and adheres to green principles.

Uranium Oxide Hydrate Frameworks with Dy(III) or Lu(III) Ions: Insights Into the Framework Structures With Lanthanide Ions.

Two uranium oxide hydrate frameworks (UOHFs) with either Dy3+ or Lu3+ ions, Dy1.36(H2O)6[(UO2)10UO13(OH)4] (UOHF-Dy) or Lu2(H2O)8[(UO2)10UO14(OH)3] (UOHF-Lu), were synthesized hydrothermally and characterized with a range of structural and spectroscopic techniques. Although SEM-EDS analysis confirmed the same atomic ratio of ~5.5 for U : Dy and U : Lu, they displayed different crystal morphologies, needles for UOHF-Dy in the orthorhombic C2221 space group and plates for UOHF-Lu in the triclinic P-1 space group. Both frameworks are composed of β-U3O8 type layers linked by pentagonal bipyramidal uranium polyhedra, with the Dy3+/Lu3+ ions inside the channels. However, the arrangements of Dy3+/Lu3+ ions are different, with disordered Dy3+ ions well aligned at the centers of the channels and single Lu3+ ions well-separated in a zigzag pattern in the channels. While the characteristic vibrational modes were revealed by Raman spectroscopy, the presence of a pentavalent uranium center in UOHF-Lu was confirmed with diffuse reflectance spectroscopy. The formation of two types of UOHFs with lanthanide ions, high or low symmetry, and the structure trend were discussed regards to synthesis conditions and lanthanide ionic radius. This work highlights the complex chemistry driving the formation of UOHFs with lanthanide ions and has implications to the spent nuclear fuel under geological disposal.

Preparation and Characterization of Protein-Based Hydrogel: Cottonseed Protein Grafted with 2-Acrylamido-2-Methylpropanesulfonic Acid (AMPS)

Preparation and Characterization of Protein-Based Hydrogel: Cottonseed Protein Grafted with 2-Acrylamido-2-Methylpropanesulfonic Acid (AMPS)

Thiol Coordination Softens Liquid Metal Particles To Improve On-Demand Conductivity.

Achieving tunable rupturing of eutectic gallium indium (EGaIn) particles holds great significance in flexible electronic applications, particularly pressure sensors. We tune the mechanosensitivity of EGaIn particles by preparing them in toluene with thiol surfactants and demonstrate an improvement over typical preparations in ethanol. We observe, across multiple length scales, that thiol surfactants and the nonpolar solvent synergistically reduce the applied stress requirements for electromechanical actuation. At the nanoscale, dodecanethiol and propanethiol in toluene suppress gallium oxide growth, as characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. Quantitative AFM imaging produces force-indentation curves and height images, while conductive AFM measures current while probing individual EGaIn particles. As the applied force increases, thiolated particles demonstrate intensified softening, rupturing, and stress-induced electrical activation at forces 40% lower than those for bare particles in ethanol. To confirm that thiolation facilitates rupturing at the macroscale, a laser is used to ablate samples of EGaIn particles. Scanning electron microscopy and resistance measurements across macroscopic samples confirm that thiolated EGaIn particles coalesce to exhibit electrical activation at 0.1 W. Particles prepared in ethanol, however, require 3 times higher laser power to demonstrate a similar behavior. This unique collection of advanced techniques demonstrates that our particle synthesis conditions can facilitate on-demand functionality to benefit electronic applications.

Self-modification of Defective TiO2 under Controlled H2/Ar Gas Environment and Dynamics of Photoinduced Oxygen Vacancies.

In recent years, defective TiO2 has caught considerable research attention because of its potential to overcome the limits of low visible light absorption and fast charge recombination present in pristine TiO2 photocatalysts. Among the different synthesis conditions for defective TiO2, ambient pressure hydrogenation with the addition of Ar as inert gas for safety purposes has been established as an easy to realize process. Whether the Ar gas might still influence the resulting photocatalytic properties and defective surface layer remains an open question. Here, we reveal that the gas flow ratio between H2 and Ar has a crucial impact on the defective structure as well as the photocatalyic activity of TiO2. In particular, transmission electron microscopy (TEM) in combination with electron energy loss spectroscopy (EELS) revealed a larger width of the defective surface layer when using a H2/Ar (50%-50%) gas mixture over pure H2. Here, a possible reason could be the increase in dynamic viscosity of the gas mixture when Ar is added. Additionally, photoinduced enhanced Raman spectroscopy (PIERS) is implemented as a complementary approach to investigate the dynamics of the defective structures under ambient conditions which cannot be effortlessly realized by vacuum techniques like TEM.

On the formation and properties of amorphous and crystalline Li3-yBay/2OCl electrolytes

All-solid-state batteries (ASSBs) have potential to provide higher specific energy, higher power, and longer cycle life than Li-ion batteries (LIBs) for continuously increasing demands of high-performance rechargeable batteries with intrinsic safety. However, one of the barriers for successful design and fabrication of ASSBs is the lack of solid-state electrolytes (SSEs) that can meet multi-functional requirements for ASSBs. To address this issue, the present study investigates hydrothermal synthesis of amorphous and crystalline Ba-doped Li3OCl solid electrolytes and develops the understanding of the relationships between the synthesis conditions and electrochemical properties of the products. It is shown that the formation of an amorphous/crystalline Ba-doped Li3OCl mixture with little hydroxide impurities depends strongly on the hydrothermal reaction temperature, drying temperature, Ba concentration, and rate of removing OH− and H+ ions as steam from water solvated Ba-doped Li3OCl. The key to generate amorphous Li3OCl-based electrolytes with high ionic conductivities (7.65 × 10−3 S/cm) at room temperature is to create non-equilibrium synthesis conditions such as the one identified in this study. The understanding developed in this study will offer critical guidelines for synthesizing amorphous and crystalline Li3OCl-based electrolytes with superior electrochemical properties for ASSBs reliably and reproducibly in the near future.

The Influence of Variations in Synthesis Conditions on the Phase Composition, Strength and Shielding Characteristics of CuBi2O4 Films

The Influence of Variations in Synthesis Conditions on the Phase Composition, Strength and Shielding Characteristics of CuBi2O4 Films

Controlled synthesis of defective MOF-808 and its application in levulinic acid esterification

Defective MOF-808 (Def. MOF-808) plays a pivotal role in catalysis, offering the potential for optimizing catalytic reactions and enhancing reactivity. Through precise control of MOF-808 synthesis conditions, including time, temperature, zirconium (Zr) source, ligand ratio, defect agent type, and content, we systematically studied their effect on material properties. The results showed that by adjusting these conditions, we synthesized a series of MOF-808 materials with varying defect concentrations, referred to as Def. MOF-808. Shorter synthesis times, lower temperatures, defect agents with stronger coordination capabilities, and increased defect agent concentration or reduced organic ligand concentration effectively enhance Def. MOF-808’s defect concentration. The presence of defect sites facilitates the effective binding of the sulfate group, thereby amplifying the level of sulfation and augmenting its acid catalytic potential. Furthermore, this study unveiled a direct link between defect concentration and the catalytic activity observed in the levulinic acid esterification reaction. The Defect-engineered MOF-808 optimized through response surface design demonstrates exceptional heterogeneous acid catalysis performance, achieving impressive conversion rates of 97.5% and selectivity of 96.2%, coupled with remarkable catalytic stability. This study highlights defect engineering as a successful strategy to improve MOF-808 catalyst performance, offering insights for future enhancements.

Recent and Prospects of Synthesis and Application of Metal-Organic Frameworks (MOFs) in Water Treatment: A Review

AbstractWastewater treatment is designed to eradicate toxic pollutants emanating from the industrial effluent to the surface and underground water. The efficiency and limitations of most of the existing water treatment techniques such as coagulation/flocculation, photocatalysis, membrane technologies and adsorption in the remediation of toxic pollutants have been established. However, the success reported for each of these techniques is usually associated with the efficiency and environmental friendliness of water treatment products applied. MOFs-based products are one of the materials serving as an alternative to chemically synthesized products, and their application as water treatment products has been reported extensively but not systematically documented. In this review, authors endeavoured to comprehensively provide insights into the recent MOFs-based product synthesis for different applications, especially in water treatment. The key factors influencing the synthesis of MOFs, including choice of metal ions, organic linkers, and synthesis conditions, along with the latest developments in scalable and cost-effective fabrication techniques are discussed. The synthesis routes, their limitation and their performances as an adsorbent, photocatalyst and additives in membrane fabrication in the removal of toxic pollutants from water are elaborated. The prospects in the large-scale production of MOFs-based water treatment products for real industrial applications are critically reviewed in this study. Overall, a well-curated synthesis and application of MOFs in water treatment is hereby generated from the best resources accessible through the literature.

Design of experiment (DOE) and process optimisation of palladium catalysed biphenyl synthesis

ABSTRACT The effects of time, temperature and catalyst concentration were investigated for an optimised condition of biphenyl synthesis by Suzuki-Miyaura cross-coupling reactions by Neolyst catalysts. The optimisation process was analysed using Box Behnken Face-Centred Experimental Design in Response Surface Methodology (RSM). The design was employed to derive a statistical model for the effect of parameters studied on the yield of biphenyl. The coefficient of determination, r 2 was 0.9883% after model reduction. With an optimum time of 6.63 h, a temperature of 73°C and with minimum catalyst concentration of 0.013 mol% gives the optimum conditions for the maximum yield of biphenyl.

Enhancing wearable humidity sensing with conductive PANi-Coated polyurethane nanofibers

This study presents a flexible nanofibrous humidity sensor for wearable applications and smart textiles. The methodology involved fabricating polyurethane (PU) nanofibers via electrospinning, followed by polyaniline (PANi) coating under varied synthesis conditions. Scanning electron microscopy (SEM) analysis revealed consistent diameter uniformity in the prepared PU nanofibers. Moreover, an increase in average nanofiber diameter (305 to 539 nm) was observed with rising polymer solution concentration (7% to 9%). Fourier-transform infrared spectroscopy (FT-IR) confirmed the physical presence of PANi on PU nanofiber surfaces without inducing structural changes. Additionally, the strength of PU nanofibrous samples, with or without PANi coating, increased proportionally with higher PANi and PU polymer concentrations. Electrical conductivity was measured using a four-point device, and surface resistance was assessed across varying humidity levels to study humidity’s impact on samples. Results exhibited a linear relationship between surface electrical resistance and relative humidity changes. Furthermore, the PU and PU/PANi nanofibers exhibit contact angles of 113° and 133°, respectively. The PANi-coated sample is more hydrophobic compared to the uncoated sample. In conclusion, these findings underscore the potential of the developed sensor as a responsive tool for monitoring humidity fluctuations in diverse applications.

In situ cell-scale probing nucleation, growth and evolution of CsPbBr3 nanowires by optical absorption spectroscopy

The growth kinetics of colloidal lead halide perovskite nanomaterials are an integral part of their applications, remains poorly understood due to complex nucleation processes and lack of in situ size monitoring method. Here we demonstrated that absorption spectra can be used to observe in situ growth processes of ultrathin CsPbBr3 nanowires in solution with reference to the effective mass infinite deep square potential well model. By means of this method, we have found that the ultrathin nanowires, fabricated by hot injection method, were firstly formed within one minute. Subsequently, they merge with each other into a thicker structure with increasing reaction time. We revealed that the nucleation, growth, and merging of the CsPbBr3 nanowires are determined by the acid concentration and ligand chain length. At lower acidity, the critical nucleation size of the nanowire is smaller, while the shorter the ligand chain length, the faster the merging among the nanowires. Moreover, the merging mode between nanowires changed with their nucleation size. This growth kinetics of CsPbBr3 nanowires provides a reference for optimizing the synthesis conditions to obtain the one-dimensional CsPbBr3 with desired size, thus enabling accurate control of the nanowire shape.

Microwave‐Assisted Preparation of an Acidic Deep Eutectic Solvent: Green Analysis, Characterization and Application

AbstractMicrowave irradiation was postulated to reduce time and energy for deep eutectic solvent (DES) production which is in line with the principle of green chemistry. In this study, the choline chloride (ChCl)‐malic acid (MA) DES was prepared using microwave‐assisted (DES‐Mic) and conventional (DES‐Con) approaches. Microwave was a relatively greener approach as it was rapid (5 min) and consumed 92.8 % energy less than DES‐Con. Moreover, DES‐Mic and DES‐Con exhibited similar physicochemical profiles (pH, solubility, density) and rheological properties. Structural profiling through FTIR analysis suggested hydrogen bond formation between the functional groups of ChCl and MA. The FTIR spectra also did not show structural differences in the DES synthesized using different methods. DES‐Mic and DES‐Con exhibited superior 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) (80.8±0.1 and 83.2±0.3 %, respectively) free radical scavenging activities than ChCl (15.6±0.8 %), MA (20.0±1.4 %) and ChCl:MA aqueous mixture without subjected to DES synthesis conditions (ChCl:MAaq; 23.3±0.8 %). Both DES were also proven as more efficient solvents for the extraction of polysaccharides from ramie leaf, as they recorded higher yields (21.4±1.9 and 22.2±1.0 %, respectively) than equimolar of MA (17.7±2.6 %) and ChCl (6.4±0.2 %). Overall, microwave was proven as a more sustainable approach for DES preparation compared to conventional method, which could be further improvised for industrial applications.

Optimizing Green Synthesis of Hydrotalcite - Silver Nanoparticles using Syzygium Nervosum based Reducing Agent.

This work aimed to assess the effect of Syzygium nervosum leaf extract as a reducing agent for green synthesis of AgNPs on HT through an optimizing process using response surface methodology (RSM) and the Box-Benken model. The optimal conditions for synthesis of AgNPs on HT include reaction time of 6.15 hours, reaction temperature of 50 oC and the ratio of diluted Syzygium nervosum leaf extract to reduce AgNO3 of 50.37 mL/mg. Under the optimal conditions, the yield of reduction reaction reached 77.54 %, close to the theoretical value of 76.97 %.Besides, the morphology, density, and characteristics of AgNPs on the surface of HT layers have been determined by using Ultraviolet-visible spectroscopy, Field emission scanning electron microscopy, High resolution transmission electron microscopy, selected area diffraction, X-ray diffraction, Dynamic light scattering, Infraredspectroscopy, Fluorescence emission spectroscopy, Brunauer-Emmett-Teller methods. The spherical AgNPs were synthesized successfully on the surface of HT with the average particle size of 13.0 ± 1.1 nm. Interestingly, HT-Ag hybrid materials can inhibit strongly the growth of E. coli, S. aureus as well as two antibiotic resistance bacterial strains, P. stutzeri B27 and antibiotic resistance E. coli. Overall, the HT-Ag hybrid materials are very promising for application in practice.

Optimal conditions for nano-emulsified vegetable oil synthesis for the biostimulation of 1,1,2-trichloroethane and vinyl chloride contaminated groundwater in bioreactors

Contamination of groundwater with chlorinated aliphatic hydrocarbons (CAHs) has become increasingly widespread. Enhanced reductive dechlorination (ERD) by emulsified vegetable oil (EVO) is an environmentally friendly, low-carbon and sustainable technology that effectively eliminates the threat from CAHs. To improve the permeability and bioavailability of EVO in the low-permeability substratum, nano-emulsified vegetable oil (nanoEVO) can be synthesized using a modified phase inversion composition method (MPIC) by increasing the emulsification temperature that reduces the shear force required for the formation of nanodroplets and the interfacial tension between the mixed phase and water. The emulsification temperature of 60 °C, the water content of 40–70%, the droplet diameter (DD) of nanoEVO prepared by MPIC is ∼200 nm, and had good monodispersion (≤0.2). The high molecular weight and low solubility of vegetable oil, and similar size of droplet make nanoEVO remains homogeneous after storage for > one year. NanoEVO can effectively biostimulate indigenous bacteria in CAHs-contaminated groundwater to dechlorinate 1,1,2-trichloroethane (1,1,2-TCA) to ethene via vinyl chloride (VC). The maximum dihaloelimination rate of 1,1,2-TCA was ∼66.06 μM·Cl−·day−1 and the maximum hydrogenolysis rate of VC was ∼35.67 μM·Cl−·day−1. NanoEVO effectively increased the relative abundance of Dehalococcoides from <0.10 to 9.61%. The abundances of Dhc 16S rRNA gene and dehalogenase gene vcrA increased by 102 and 103, respectively. Biostimulation shaped the structure of microbial communities and promoted hydrolytic acidification and anaerobic fermentation. Moreover, the syntrophic VFA-oxidizing bacteria participated in secondary fermentation and were closely correlated with H2 consumption metabolism. By providing carbon sources and maintaining an anaerobic environment with stable pH and ORP, nanoEVO biostimulated the hydrolytic acidification led by fermentative bacteria, secondary fermentation with syntrophic VFA-oxidizing bacteria and reductive dechlorination carried out by dechlorinator, thus greatly increasing the CAH-dechlorinating ability of indigenous microbial communities.