Hydroxide Composites Research Articles

Magneto-electrochemical water splitting performance of graphene oxide/nickel aluminum-layered double hydroxide nanocomposites

Designing efficient, cheap catalysts for oxygen production is very important for water electrolysis and green hydrogen production. Here, synthesis and electrocatalytic performance of graphene oxide (GO)/nickel-aluminum layered double hydroxide (NiAl-LDH) composites were investigated for water-splitting applications. The composition, microstructure, and morphology of the nanocomposites were confirmed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and field emission scanning electron microscopy (FE-SEM), and their water oxidation performance was examined in 0.1 M potassium hydroxide solution in the presence and absence of magnetic field. The results show that optimized GO/NiAl-LDH nanocomposite (GO-1 %/NiAl-LDH) exhibits the lowest overpotential compared with other prepared nanocomposites. This performance demonstrates comparable electroactivity to well-developed electrocatalysts like the perovskite-based electrodes, it also shows an improved electrocatalytic activity compared to NiAl-LDHs due to the presence of graphene oxide in the composite. We interpreted this significant performance to improve electron transform and high active site at the synthesized GO/NiAl-LDH composites. The best electrocatalytic activity with an overpotential of 443 and 473 mV at the current density 10 mA.cm−2 were evidenced for GO-1 %/NiAl-LDH nanocomposite in the presence and absence of external magnetic field, respectively. Furthermore, the tafel slope were reported about 54 and 162 mV.dec−1 in the presence and absence of magnetic field, respectively. This improved water oxidation can be attributed to the magneto-hydrodynamic effect and the increased number of metal sites on LDHs under the magnetic field.

Thin film synthesis and photovoltaic performance of polypyrrole@cobalt hydroxide composites for solar cells and optoelectronic devices

Mono-nanocomposites (MNCs) comprising polypyrrole (PPy) and cobalt hydroxide nanoparticles (Co(OH)2 NPs) are emerging as highly favorable contenders for applications in solar cells and optoelectronic devices, owing to their distinctive attributes encompassing robust light absorption, elevated conductivity, and commendable chemical stability. This investigation delves into the production of a thin film [PPy@Co(OH)2]MNC utilizing the physical vapor deposition (PVD) method. The structural and morphological characteristics of the [PPy@Co(OH)2]MNC thin film were scrutinized through X-ray diffraction (XRD) and scanning electron microscopy (SEM). Optical properties, namely reflectance (R), absorbance (Abs), and transmittance (T) within the UV–vis–NIR spectrum, were precisely gauged at room temperature. Time-dependent density functional theory (TD-DFT) calculations and optimizations were conducted to analyze the geometric parameters, while the refractive index dispersion was probed using the single oscillator Wemple-Didomenico (WD) model. Additionally, the energy of a single oscillator and the energy of dispersion were quantified. The [PPy@Co(OH)2]MNC thin film exhibited pronounced light absorption across the UV–vis–NIR spectrum, characterized by a bandgap of 1.6 eV. The Au/[PPy@Co(OH)2]MNC/p-Si/Al heterojunction device demonstrated a power conversion efficiency and fill factor (FF) of 2.6 % and 55.07 %, respectively, under an irradiance of 100 W/cm2. The findings of this investigation underscore the potential of [PPy@Co(OH)2]MNC-based thin films as auspicious candidates for deployment in solar cells and optoelectronic devices.

Composite hydroxide mediated synthesis of barium-doped strontium oxide nanostructures for energy storage applications

Composite hydroxide mediated synthesis of barium-doped strontium oxide nanostructures for energy storage applications

Synergistic Effects of ZnO@NiM′-Layered Double Hydroxide (M′ = Mn, Co, and Fe) Composites on Supercapacitor Performance: A Comparative Evaluation

Synergistic Effects of ZnO@NiM′-Layered Double Hydroxide (M′ = Mn, Co, and Fe) Composites on Supercapacitor Performance: A Comparative Evaluation

Synthesis and Performance of ZnAl@Layered Double Hydroxide Composites with Eucheuma cottonii for Adsorption and Regeneration of Congo Red Dye

Synthesis and Performance of ZnAl@Layered Double Hydroxide Composites with Eucheuma cottonii for Adsorption and Regeneration of Congo Red Dye

Ingeniously construction of industrial carbon fiber/nickel-iron layered double hydroxide heterostructure composite for high-efficient microwave absorption in aircraft

To enhance the survivability of military aircraft in electromagnetic warfare, carbon fiber/nickel-iron layered double hydroxide (CF/NiFe-LDH) composites with heterogeneous structure were constructed starting from the raw industrial carbon fiber (CF) by electrostatic self-assembly. By reasonably adjusting the mass ratio of CF and NiFe-LDH, the voids formed by LDH arrays stacked on the fiber surface are utilized to promote reflection and scattering of electromagnetic wave (EMW), optimizing impedance matching, as well as synergize dielectric-magnetic dual loss mechanism. Moreover, interfacial polarization effect induced by the abundant heterogeneous interfaces significantly enhance the ability of EMW dissipation. The optimized CF/NiFe-LDH heterostructure composite exhibits the minimum reflection loss (RLmin) value of −52.48 dB at mere 1.77 mm thickness and an expansive maximum effective bandwidth (EABmax) of 7.29 GHz at 2.14 mm. In addition, the computer simulation technology (CST) revealed that the radar scattering cross section (RCS) reduction of composites reaches up to 26.92 dBm2 at an incidence angle of 90°, demonstrating their excellent radar attenuation capability. Tremendously, the heterogeneous composites achieve an SRL1 value of 524.8, which is appreciably better than most of the EMW absorbing materials. The wondrous characteristics including lightweight, ultra-thin, high-efficient microwave absorbing ability of CF/NiFe-LDH heterostructure composites display potential application in fighter aircraft.

Fire-safe and multifunctional epoxy/layered double hydroxide composites via an interfacial catalysis

Aiming to impart epoxy with a phosphorous-free super-efficient fire safety and multifunctions via a facile interface-manipulation protocol, we innovatively proposed a proof of concept of a two-in-one catalytic function via covalently inducing an interfacial supramolecular assembly of Salen-Fe complex on organic layered double hydroxide (LDH-DBS). Various characterizations confirmed the target LDH-DBS@Salen-Fe with a surface-located uniform and ultrathin deposition of Salen-Fe complex, which was conducive to a better nanodispersion in epoxy matrix. An exceptionally low loading of 2 wt% LDH-DBS@Salen-Fe (i.e., 0.6 % Salen-Fe) endowed epoxy with a UL-94 V-0 level and intensive fire protection with a suppressed peak heat release rate by 45.0 %. An insightful mechanism investigation demonstrated that the interface-located Salen-Fe rapidly catalyzed a charring reaction with an ultrafast formation of protective fire chars to resist an early-stage fire attack. Additionally, relative to EP/2LDH-DBS, a mere 0.6 % Salen-Fe increased the tensile, flexural and impact strength by 39.6 %, 31.5 % and 37.0 %, respectively based on the optimized interface compatibilization. Interestingly, an ultralow loading of Salen-Fe significantly contributed to a degradation recycling of epoxy under a mild condition with mass loss after 7 h treatment 392.8 % higher than its counterpart via catalytically promoting the generation of CHCOO∙ and HO∙ at the interface. In perspective, an interfacial supramolecular assembly of two-in-one catalysts exploits a novel route towards a phosphorous-free fire-safe and multifunctionally reinforced polymers.

Effect of annealing treatment on impact toughness and crystallization behaviors of polypropylene/ethylene vinyl acetate copolymer/layered double hydroxide composites

Effect of annealing treatment on impact toughness and crystallization behaviors of polypropylene/ethylene vinyl acetate copolymer/layered double hydroxide composites

Ti3C2 MXene nanosheets integrated cobalt-doped nickel hydroxide heterostructured composite: An efficient electrocatalyst for overall water-splitting

Developing an efficient electrocatalyst for superior electrochemical water splitting (EWS) is crucial for achieving comprehensive hydrogen production. A heterostructured electrocatalyst, free of noble metals, Ti3C2 MXene nanosheet-integrated cobalt-doped nickel hydroxide (NHCoMX) composite was synthesized via a hydrothermal method. The abundant pores in the Ti3C2 MXene nanosheet (MX)–integrated microarchitecture increased the number of active sites and facilitated charge transfer, thus enhancing electrocatalysis. Specifically, the MX-enhanced charge transfer considerably transformed the microelectronic structure of cobalt-doped Ni(OH)2 (NHCo), which promoted its hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Hence, as an EWS catalyst, NHCoMX exhibited an exceptional electrocatalytic activity, demonstrating OER and HER overpotentials of 310 mV and 73 mV, respectively, with low Tafel slopes of 65 mV dec−1 and 85 mV dec−1, respectively; it exhibited a current density of 10 mV cm−2 in 1.0 mol L−1 KOH, representing the closest efficiency to the noble state-of-the-art RuO2 and Pt/C catalyst. Furthermore, the developed electrocatalyst improved the activities of both HER and OER, leading to an overall EWS current density of 10 mA cm−2 at 1.72 V in an alkaline electrolyte with two electrodes. This study describes an efficient heterostructured NHCoMX composite electrocatalyst. It is significantly comparable to the noble state-of-the-art electrocatalysts and can be extended to fabricate resourceful catalysts for large-scale EWS applications.

Ni/Hierarchical Zeolites Derived from Zeolites@Layered Double Hydroxides (LDHs) Composites for Furfural Hydrogenation

AbstractFurfural hydrogenation is one of the most important reactions for the transformation of biomass‐derived resources into high value‐added chemicals. To achieve a highly efficient catalytic activity of the reaction, catalysts with a high dispersion of metal nanoparticles (NPs) on solid supports are required. However, the development of highly efficient and stable catalysts is still challenging. Herein, the highly dispersed nickel nanoparticles (Ni NPs) supported on the hierarchical ZSM‐5 nanosheets (Z5‐NS) derived from the hierarchical ZSM‐5 nanosheets@NiAl‐layered double hydroxides (LDHs) composites were successfully fabricated. Remarkably, the fabricated Z5‐NS/Ni catalyst exhibited a high furfural conversion of 85 % with a yield of furfuryl alcohol of 60 %. This work illustrates the fabrication of highly metal dispersed on solid supports with high metal loading, which can enhance the catalytic performances in the hydrogenation of biomass‐derived compounds.

MOF derived tri-metallic CoNiMn hydroxide assembled on carbon cloth for hybrid supercapacitor and hydrogen evolution

Polymetallic hydroxides are promising electrode materials for supercapacitors and electrocatalysis due to their unique physical and chemical properties. Herein, carbon cloth self-supported cobalt‑nickel‑manganese hydroxide (CoNiMn-OH/CC) composites were synthesized by a facile hydrothermal method with zeolite imidazolate framework-67 (ZIF-67) as a template. The results indicate that the hydroxides maintain the morphology of ZIF-67 template, while the addition of Mn can affect the redox behavior and enhance the electrochemical activity of metal hydroxides. Therefore, the prepared CoNiMn-OH with ultrathin edge-surface stacked nanosheets structure can promote electron/ion transfer, which induces to better charge storage kinetics and activity for supercapacitors and hydrogen evolution reaction (HER). In-situ Raman spectra combined density functional theory calculations co-revealed the reaction mechanism. The optimized CoNi3Mn1-OH nanosheets has a high specific capacity of 955.7C g−1 at 1 A g−1 and excellent rate performance with 91.1 % capacitance retention (870.7C g−1 at 10 A g−1). The hybrid supercapacitor device with CoNi3Mn1-OH as the positive electrode and activated carbon (AC) as the negative electrode has an energy density of up to 30 Wh kg−1, a power density of 0.8 kW kg−1, and excellent cycling stability (78.5 % capacity retention after 10000 cycles at 5 A g−1). In addition, the CoNi3Mn1-OH composite with tuned Ni and Mn metal ratios has a low HER overpotential of 202 mV at 10 mA cm−2.

Enhanced peroxymonosulfate activation for effective norfloxacin degradation by sepiolite-based FeCo layered double hydroxide composite

In this study, the FeCo layered double hydroxide/Sepiolite composite was successfully synthesized by a water bath approach which exhibited outstanding norfloxacin (NOR) degradation performance in presence of peroxymonosulfate (PMS). The reaction rate constant in the FeCo-LDH/Sepiolite/PMS system was 0.1644 min−1, which was around 1.78 times greater than that in the FeCo-LDH/PMS system. The introduction of the sepiolite carrier, which led to an increase in specific surface area and pore volume, was principally responsible for the considerable improvement in PMS activation efficiency. Moreover, the composite presented good stability and reusability. According to the results of the electron paramagnetic resonance (EPR) and quenching tests, the predominant reactive species in the FeCo-LDH/Sepiolite/PMS/NOR system were SO4•- and 1O2. Furthermore, possible NOR degradation pathways and catalytic mechanism were proposed. In summary, our research provised new ideas in the synthesis of promising mineral based PMS catalyst for wastewater treatment.

The potential of chitosan intercalated nickel/iron layered double hydroxide composites as extraction adsorbent for phthalates

In this research, the potential utility of chitosan-nickel/iron LDHs (CS-Ni/Fe LDHs) has been examined for the separation and pre-concentration of five phthalates (PAEs: diethylphthalate (DEP), dipropylphthalate (DPP), dibutylphthalate (DBP), benzylbutylphthalate (BBP), and dioctylphthalate (DOP)). The extraction efficiency of CS-Ni/Fe LDH composites against the target phthalates is studied through the control of the key variables (e.g., eluent type, elution volume, flow rate, adsorbent amount, solution pH, and salt addition effect). Under the optimal conditions, the method detection limit towards target PAEs is estimated as 0.023–0.033 ng/mL over a 0.1–100 ng/mL range (R2>0.999). The CS-Ni/Fe LDH composites are utilized successfully to extract PAEs in real samples such as perfume, cream, bottled water, and bottled milk (recovery: 97.3–136.8%). The spent CS-Ni/Fe LDH composites can be regenerated at least over 30 cycles. The good agreement in adsorption isotherms with the non-linear Langmuir model indicates the formation of monolayered PAE molecules over CS-Ni/Fe LDH composites. The computed partition coefficients (mg g−1μM−1) for CS-Ni/Fe LDH are found as follows: DOP (802) > DBP (491) > DPP (355) > DEP (248) > BBP (247). The thermodynamic analysis reveals the exothermic and spontaneous behavior of the adsorption process. The CS-Ni/Fe LDHs are thus identified as efficient sorbent media for PAEs through hydrogen bonding and hydrophobic interactions. Accordingly, CS-Ni/Fe LDH composites are recommended as a useful option for capturing PAEs under real-world conditions.

Crystalline CdS/Amorphous Cd(OH)2 Composite for Electrochemical CO2 Reduction to CO in a Wide Potential Window.

Electrochemical CO2 reduction is a promising method for converting atmospheric CO2 into valuable low-carbon chemicals. In this study, a crystalline cadmium sulfide/amorphous cadmium hydroxide composite was successfully deposited on the carbon paper substrate surface by in-situ chemical bath deposition (named as c-CdS/a-Cd(OH)2/CP electrodes) for the efficient electrochemical CO2 reduction to produce CO. The c-CdS/a-Cd(OH)2/CP electrode exhibited high CO Faradaic efficiencies (>90 %) under a wide potential window of 1.0 V, with the highest value reaching ~100 % at the applied potential ranging from -2.16 V to -2.46 V vs. ferrocene/ferrocenium (Fc/Fc+), superior to the crystalline counterpart c-CdS/CP and c-CdS/c-Cd(OH)2@CP electrodes. Meanwhile, the CO partial current density reached up to 154.7 mA cm-2 at -2.76 V vs. Fc/Fc+ on the c-CdS/a-Cd(OH)2/CP electrode. The excellent performance of this electrode was mainly ascribed to its special three-dimensional structure and the introduction of a-Cd(OH)2. These structures could provide more active sites, accelerate the charge transfer, and enhance adsorption of *COOH intermediates, thereby improving the CO selectivity. Moreover, the electrolytes consisting of 1-butyl-3-methylimidazolium tetrafluoroborate and acetonitrile also enhanced the reaction kinetics of electrochemical CO2 reduction to CO.

Photocatalytic degradation of p-aminobenzoic acid on N-biomass charcoal etched with Fe-Al-bilayer hydroxide: New insights through spectroscopic investigation

We investigated the photocatalytic property of etched iron‑aluminum layered double hydroxide (LDH) composites using urea-modified biochar (N-BC) carrier to degrade para-aminobenzoic acid (PABA), a refractory organic pollutant. The prepared FeAl-LDH@FeSx-N-BC composite exhibited excellent photocatalytic performance, attributed to the enhanced photogenerated charge-carrier separation by the etched LDH and the improved comparative surface areas by the doped N-BC. The composite photocatalytically degraded 96 % of PABA. The performance was affected by solute concentration, pH and photocatalyst dose. Adding p-benzoquinone and EDTA-2Na significantly decreased the degradation rate, suggesting that superoxide radicals and holes were co-involved in PABA degradation. The excellent PABA removal efficiency was consistent for three consecutive runs. The samples' reactive oxygen species was confirmed, as electron paramagnetic reverberation explained the photodegradation mechanism. Under xenon lamp irradiation, two PABA photocatalytic degradation pathways were proposed using Liquid Chromatograph Mass Spectrometer (LCMS) and density functional theory. As expected, FeAl-LDH@FeSx-N-BC showed excellent photocatalytic performance, expanding a new direction and possibility for future photocatalytic treatment of water pollutants.

Ultrasound assisted synthesis of CoFe-LDH for the simultaneous electrochemical detection of dopamine and acetaminophen

Herein, CoFe layered double hydroxide composites (CoFe-LDH) were synthesised by a simple ultrasound assisted synthesis method. It has been characterized by scanning electron microscopy (SEM), X-ray diffraction and X-ray photoelectron spectroscopy. CoFe-LDH modified glass carbon electrode was used as dual-function sensors for DA and AP detection. The sensor exhibits a wide detection linear range for DA and AP (2 μM-900 μM), low detection limits (DA: 0.08 μM; AP: 0.37 μM) (S/N = 3). The sensitivity of CoFe-LDH/GCE for DA and AP were 0.54 μA μM−1 cm−2 and 0.55 μA μM−1 cm−2. And it shows good reproducibility, selectivity, and stability. In addition, the sensor demonstrated good recovery rates for the detection of DA and AP in human serum samples.

EDTA-interlayer modified Mg/Fe layered double hydroxides for enhanced adsorption of methyl orange: Adsorption performance and mechanism study

Herein, we explored the efficacy of ethylenediaminetetraacetic acid (EDTA) intercalation modified layered double hydroxides (LDHs) composites for removing the anionic dye methyl orange (MO) from aqueous solutions. EDTA intercalated layered hydroxides (EDTA-Mg/Fe LDHs) with a 4:1 Mg/Fe molar ratio have been successfully prepared and thoroughly characterized using SEM-EDS, FTIR, XRD, XPS, UV-Vis and Zeta potential analysis. Batch adsorption experiments were conducted to evaluate the adsorption performance of the innovative adsorbent on MO. The results indicated successful EDTA loading into Mg/Fe LDHs, exhibiting excellent adsorption performance for MO. At pH 6.0, with a 0.03 g adsorbent dose, MO removal exceeded 91.10% within 90 min, following a pseudo second order kinetic model. The maximum adsorption capacity reached 1207.43 mg/g, fitting well with the Redlich Peterson model. Thermodynamic parameters suggested a spontaneous and favorable adsorption process. Furthermore, we assessed the desorption and regeneration effectiveness of EDTA-Mg/Fe LDHs, emphasizing the importance of developing cost-effective and environmentally friendly adsorbents with practical applications and scientific significance.

The role of Ag ions incorporation on the Magnetic, and Antimicrobial Properties of NiO Nanoparticles

Ni1-xAgxO nanoparticles (NPs) with x = 0.00, 0.02, 0.04, 0.06, and 0.08) were fabricated using the composite hydroxide mediated (CHM) method. The effects of Ag doping on the structural, magnetic, and antimicrobial characteristics of NiO NPs have been reported. The stretching mode of the Ni–O molecules was identified at 443 cm−1 in the Fourier transform infrared spectra. The aggregation of nanoparticles with different sizes and shapes is seen under transmission and scanning electron microscopes. The blocking temperature (TB) peak in zero-field cooled (ZFC) magnetization curves display the magnetization from the core of NPs. This peak is absent for the samples with x=0.00 and 0.02, which show instead a small net magnetization from the antiferromagnetic core of these NPs. However, a TB peak was found for the samples with x=0.04,0.06and0.08, at 22, 72, and 65 K, respectively, which indicates that the magnetization is induced from the AFM core of NiO NPs for higher Ag doping. With an increasing concentration of Ag in the NiO NPs, the net magnetization did increase and a maximum was found for x = 0.04 at 300 K. For a higher doping concentration of 8 % Ag, a sharp decrease in magnetization was observed. Furthermore, the efficacy and synergistic effect of Ag doping had been analyzed for the effective improvement of the antibacterial properties of NiO NPs. Pure and Ag-doped NiO NPs were exploited to assess their anti-microbial activity against Enterobacter sp., E. coli, P. aeruginosa, and S. pyrogens. The study revealed that anti-bacterial or anti-biofouling properties were introduced as an additional attribute to NiO NPs by incorporation of Ag ions due to its inherent nature as an antimicrobial agent and enhanced its capability to sterilize microbial pathogens.

Self‐emulsification synthesis of epoxy phosphate ester and its flame‐retardant mechanism in flexible poly(vinyl chloride)/magnesium hydroxide composites

AbstractA trade‐off dilemma exists for simultaneously improving the mechanical properties and flame resistance of flexible polyvinyl chloride (fPVC)/magnesium hydroxide (MH) composites. In this study, epoxy phosphate ester (EPE), a hydrophobic surface modifier of MH, was synthesized using a self‐emulsification method. After modification, EPE was bonded to the surface of MH (MHEPE) without altering its morphology. The results of limiting oxygen index and cone calorimetry tests indicated that fPVC/MHEPE exhibited better flame retardancy and smoke suppression effects than did fPVC/MH. The peak of the heat release rate, total heat release, peak of the smoke production rate, and total smoke production of the fPVC/MHEPE composite were 206.0 kJ m−2, 45.90 MJ m−2, 0.0729 m2 s−1, and 9.88 m2, which were 8.64%, 14.00%, 27.61%, and 9.02% lower than those of the fPVC/MH composite, respectively. For the fPVC/MHEPE composite, a compact and continuous char residue formed, which could inhibit heat and flammable volatile migration between the matrix and burning zones. In the gas phase, the dilution effect of H2O vapor reduced the concentrations of O2 and flammable volatiles. The free‐radical quenching effect of ·PO and ·PO2 also played a vital role in extinguishing flame and terminating combustion. Further, the introduction of EPE improved the tensile and impact strengths of the fPVC/MH composites because of the excellent interfacial compatibility between MHEPE and the fPVC matrix. This study provides a simple and workable solution for the trade‐off dilemma, and the remarkable flame retardancy and mechanical properties of the fPVC/MHEPE composite render it a promising cable material.

Effective Detection of Cu(II) Ions Based on Carbon Dots@Exfoliated Layered Double Hydroxides Composites Fluorescence Probe.

A series of carbon dots@exfoliated layered double hydroxides (CDs@LDH) composites were hydrothermally fabricated by Mg/Al LDH and formamide. The results of FTIR, UV-vis, and XPS spectra in company with HRTEM images showed that crystalline nano CDs formed on the single layer of LDH by Mg-C bond. With the increase of solvothermal reaction time from 2 to 6h, the band gap and the binding energy of aminic and graphitic N species of CDs@LDH composites decreased, whereas the crystallinity increased. The fluorescence peaks of CDs@LDH composites could be deconvoluted into short-wavelength (416nm) and large-wavelength (443nm) components by Gaussian function, and the fluorescence intensities of both components enhanced with the extension of the solvothermal reaction time. The simultaneous enhancements of fluorescence lifetime and quantum yield resulted from the relatively high electron density in graphitic nitrogen of CDs@LDH, whereas the reduction of nonradiative rate was due to the high crystallinity in the carbon core of CDs@LDH. A strong exciton-lattice interaction also has been validated based on the excitation and emission spectra of CDs@LDH, so the fluorescence emission of CDs@LDH composite was heavily related to its crystalline carbon core and nitrogen-containing groups. CDs@LDH with high nitrogen-containing exhibited a superior detection property for Cu2+ ion sensing with the linear range of 26.90 ~ 192.20μM and a limit of detection of 0.1957μM. The photo-induced electron transfer (PET) process dominated the fluorescence quenching of CDs@LDH by Cu2+ ion since the fluorescence lifetime decreased with the increase of Cu2+ ion concentration.