Enhancing the stability of Ni Fe-layered double hydroxide nanosheet array for alkaline seawater oxidation by Ce doping

Electrocatalytic hydrogen production from seawater holds enormous promise for clean energy generation.Nevertheless,the direct electrolysis of seawater encounters significant challenges due to poor anodic stability caused by detrimental chlorine chemistry.Herein,we present our recent discovery that the incorporation of Ce into Ni Fe layered double hydroxide nanosheet array on Ni foam(Ce-Ni Fe LDH/NF)emerges as a robust electrocatalyst for seawater oxidation.During the seawater oxidation process,CeO_(2)is generated,effectively repelling Cl^(-)and inhibiting the formation of Cl O-,resulting in a notable enhancement in the oxidation activity and stability of alkaline seawater.The prepared Ce-Ni Fe LDH/NF requires only overpotential of 390 m V to achieve the current density of 1 A cm^(-2),while maintaining long-term stability for 500 h,outperforming the performance of Ni Fe LDH/NF(430 m V,150 h)by a significant margin.This study highlights the effectiveness of a Ce-doping strategy in augmenting the activity and stability of materials based on Ni Fe LDH in seawater electrolysis for oxygen evolution.

Defective Nickel-Iron Layered Double Hydroxide for Enhanced Photocatalytic NO Oxidation with Significant Alleviation of NO2 Production

Photocatalysis offers a sustainable means for the oxidative removal of low concentrations of NOx(NO,NO2,N2O,N2O5,etc.)from the atmosphere.Layered double hydroxides(LDHs)are promising candidate photocatalysts owing to their unique layered and tunable chemical structures and abundant surface hydroxide(OH)moieties,which are hydroxyl radical(OH)precursors.However,the practical applications of LDHs are limited by their poor charge-separation ability and insufficient active sites.Herein,we developed a facile N_(2)H_(4)-driven etching approach to introduce dual Ni^(2+)and OHvacancies(Niv and OHv,respectively)into NiFe-LDH nanosheets(hereafter referred to as NiFe-LDH-et)to facilitate improved charge-carrier separation and active Lewis acidic site(Fe^(3+)and Ni^(2+)exposed at OHv)formation.In contrast to inert pristine LDH,NiFe-LDH-et actively removed NO under visible-light illumination.Specifically,Ni_(76)Fe_(24)-LDH-et etched with 1.50 mmol·L^(-1)N_(2)H_(4)solution removed 32.8%of the NO in continuously flowing air(NO feed concentration:500 parts per billion(ppb))under visible-light illumination,thereby outperforming most reported catalysts.Experimental and theoretical data revealed that the dual vacancies promoted the production of reactive oxygen species(O_(2)·^(-)andOH)and the adsorption of NO on the LDH.In situ spectroscopy demonstrated that NO was preferentially adsorbed at Lewis acidic sites,particularly exposed Fe^(3+)sites,converted into NO+,and subsequently oxidized to NO3without the notable formation of the more toxic intermediate NO2,thereby alleviating risks associated with its production and emission.

In-depth analysis of VARTM-based solid-state supercapacitors utilizing CNT-dispersed cobalt-bismuth-samarium ternary hydroxide on woven carbon fiber for enhanced energy storage

Multi-metal hydroxides possess unique physical and chemical properties,making them promising candidates for supercapacitor working electrodes.Enhancing their electrochemical performance can be achieved through a combination with carbon materials.In this study,we synthesized a composite material by hydrothermally dispersed 4,6,and 10 wt%carbon nanotubes(CNT)into ternary cobaltbismuth-samarium hydroxide(CoBiSm-TOH).These nanocomposites were employed as the material for the working electrode in a supercapacitor.The findings reveal that at 1.5 A/g,the specific capacitance of CNT3@CoBiSm-TOH,using a three-electrode system,was found to be 852.91 F/g,higher than that of CoBi-BOH,CoBiSm-TOH,CNT1@CoBiSm-TOH and CNT5@CoBiSm-TOH-measuring 699.69,750.34,789.54 and 817.79 F/g,respectively.Moreover,CNT3@CoBiSm-TOH electrodes exhibited a capacitance retention of around 88%over 10,000 cycles.To demonstrate practical applicability,CNT3@CoBiSm-TOH was grown on woven carbon fiber(WCF),and a solid-state supercapacitor device was developed using the VARTM(vacuum-assisted resin transfer molding).This device displayed a specific capacitance of 272.67 F/g at 2.25 A/g.Notably,it achieved a maximum energy density of 53.01 Wh/kg at a power density of 750 W/kg and sustained excellent cycle stability over 50,000 cycles,maintaining 70%of its initial capacitance.These results underscore the importance of interfacial nanoengineering and provide crucial insights for the development of future energy storage devices.

Photo-promoted rapid reconstruction induced alterations in active site of Ag@amorphous NiFe hydroxides for enhanced oxygen evolution reaction

The dynamic surface self-reconstruction behavior in local structure correlates with oxygen evolution reaction(OER)performance,which has become an effective strategy for constructing the catalytic active phase.However,it remains a challenge to understand the mechanisms of reconstruction and to accomplish it fast and deeply.Here,we reported a photo-promoted rapid reconstruction(PRR)process on Ag nanoparticle-loaded amorphous Ni-Fe hydroxide nanosheets on carbon cloth for enhanced OER.The photogenerated holes generated by Ag in conjunction with the anodic potential contributed to a thorough reconstruction of the amorphous substrate.The valence state of unsaturated coordinated Fe atoms,which serve as active sites,is significantly increased,while the corresponding crystalline substrate shows little change.The different structural evolutions of amorphous and crystalline substrates during reconstruction lead to diverse pathways of OER.This PRR utilizing loaded noble metal nanoparticles can accelerate the generation of active species in the substrate and increase the electrical conductivity,which provides a new inspiration to develop efficient catalysts via reconstruction strategies.

Efficient C-N coupling in electrocatalytic urea generation on copper carbonate hydroxide electrocatalysts

Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen electrode.Our thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~*NHO.This work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.

Self-derivation and reconstruction of silver nanoparticle reinforced cobalt-nickel bimetallic hydroxides through interface engineering for overall water splitting

Designing efficient and long-lasting non-metal electrocatalysts is an urgent task for addressing the issue of kinetic hysteresis in electrochemical oxidation reactions.The bimetallic hydroxides,catalyzing the oxygen evolution reaction(OER),have significant research potential because hydroxide reconstruction to generate an active phase is a remarkable advantage.Herein,the complete reconstruction of ultrathin CoNi(OH)_(2) nanosheets was achieved by embedding Ag nanoparticles into the hydroxide to induce a spontaneous redox reaction(SRR),forming heterojunction Ag@CoNi(OH)_(2) for bifunctional hydrolysis.Theoretical calculations and in situ Raman and ex situ characterizations revealed that the inductive effect of the Ag cation redistributed the charge to promote phase transformation to highly activate Ag-modified hydroxides.The Co-Ni dual sites in Co/NiOOH serve as novel active sites for optimizing the intermediates,thereby weakening the barrier formed by OOH^*.Ag@CoNi(OH)_(2) required a potential of 1.55 V to drive water splitting at a current density of 10 mA cm^(-2),with nearly 98.6% Faraday efficiency.Through ion induction and triggering of electron regulation in the OER via the synergistic action of the heterogeneous interface and surface reconstruction,this strategic design can overcome the limited capacity of bimetallic hydroxides and bridge the gap between the basic theory and industrialization of water decomposition.

Heterostructural NiFeW disulfide and hydroxide dual‐trimetallic core‐shell nanosheets for synergistically effective water oxidatio

A stable and highly active core‐shell heterostructure electrocatalyst is essential for catalyzing oxygen evolution reaction(OER).Here,a dual‐trimetallic core‐shell heterostructure OER electrocatalyst that consists of a NiFeWS_(2)inner core and an amorphous NiFeW(OH)_(z)outer shell is designed and synthesized using in situ electrochemical tuning.The electrochemical measurements of different as‐synthesized catalysts with a similar mass loading suggest that the core‐shell Ni_(0.66)Fe_(0.17)W_(0.17)S_(2)@amorphous NiFeW(OH)_(z)nanosheets exhibit the highest overall performance compared with that of other bimetallic reference catalysts for the OER.Additionally,the nanosheet arrays were in situ grown on hydrophilic‐treated carbon paper to fabricate an integrated three‐dimensional electrode that affords a current density of 10 mA cm^(−2)at a small overpotential of 182 mV and a low Tafel slope of 35 mV decade^(−1)in basic media.The Faradaic efficiency of core‐shell Ni_(0.66)Fe_(0.17)W_(0.17)S_(2)@amorphous NiFeW(OH)_(z)is as high as 99.5%for OER.The scanning electron microscope,transmission electron microscope,and X‐ray photoelectron spectroscopy analyses confirm that this electrode has excellent stability in morphology and elementary composition after long‐term electrochemical measurements.Importantly,density functional theory calculations further indicate that the core‐shell heterojunction increased the conductivity of the catalyst,optimized the adsorption energy of the OER intermediates,and improved the OER activity.This study provides a universal strategy for designing more active core‐shell structure electrocatalysts based on the rule of coordinated regulation between electronic transport and active sites.

Recent advances in flat sheet mixed matrix membrane modified by Mg-based layered double hydroxides(LDHs)for salt and organic compound separations

Magnesium(Mg)is a widely used and attractive metal,known for its unique physical and chemical properties,and it has been employed in the manufacture of many practical materials.Layered Double Hydroxides(LDHs),particularly Mg-based LDHs,rank among the most prevalent two-dimensional materials utilized in separation processes,which include adsorption,extraction,and membrane technology.The high popularity of Mg-based LDHs in separation applications can be attributed to their properties,such as excellent hydrophilicity,high surface area,ion exchangeability,and adjustable interlayer space.Currently,polymer membranes play a pivotal role in semi-industrial and industrial separation processes.Consequently,the development of polymer membranes and the mitigation of their limitations have emerged as compelling topics for researchers.Several methods exist to enhance the separation performance and anti-fouling properties of polymer membranes.Among these,incorporating additives into the membrane polymer matrix stands out as a cost-effective,straightforward,readily available,and efficient approach.The use of Mg-based LDHs,either in combination with other materials or as a standalone additive in the polymer membrane matrix,represents a promising strategy to bolster the separation and anti-fouling efficacy of flat sheet mixed matrix polymer membranes.This review highlights Mg-based LDHs as high-potential additives designed to refine flat sheet mixed matrix polymer membranes for applications in wastewater treatment and brackish water desalination.

CO2 Transformation at Controlled Temperature with Lithium Hydroxide Solution and Metallic Lithium

This paper presents a study on CO2 atmospheric transformation which was reacted directly with lithium hydroxide solution and metallic lithium. This solution was obtained through the reaction between metallic lithium and deionized water where hydrogen is produced and by exposing the metal at ambient conditions. In the transformation process, atmospheric CO2 gas reacts directly with LiOH solution, in both cases, the CO2 transformation kinetics was different. For this purpose, reactions between CO2 and LiOH solution were carried out under controlled temperature and the second process only with metallic lithium, which was exposed at room temperature, however, in these two processes lithium carbonate oxide was formed and identified. According to the results, the efficiency in CO2 transformation is a function of temperature value which was variable until completely obtaining the by-product, its XRD characterization indicated the formation only of Li2CO3 in both procedures. Under laboratory conditions lithium compounds selectively reacted with CO2. In the same way, there is an alternative procedure to obtain LiOH and Li2CO3 for different applications in various areas.

Clinical Value of Endodontic Patients Treated with Calcium Hydroxide Preparations

Objective: To investigate the clinical value of endodontics patients treated with calcium hydroxide preparation. Methods: The study cases were selected from the endodontics patients who visited our hospital during the period from January 2022 to December 2023, and 97 cases were randomly selected according to the numerical table method and divided into two groups. There were 49 cases in the control group and 48 cases in the experimental group. The control group received conventional therapy, while the experimental group received treatment with calcium hydroxide preparation, and the clinical value of the two different treatment modalities was observed and analyzed. Results: In the experimental group, 45 out of 48 patients (93.75%) showed effectiveness, compared to 39 out of 49 patients (79.59%) in the control group. The effectiveness rate was significantly higher in the experimental group (P < 0.05). Initially, the VAS scores between the two groups were similar (P > 0.05), but after 1 and 3 months of treatment, the scores decreased in both groups. However, the experimental group had a greater decrease, indicating lower pain levels (P < 0.05). The experimental group had fewer complications (8.33%) compared to the control group (24.49%), with a significant difference (P < 0.05). Satisfaction with treatment was higher in the experimental group (95.83%) compared to the control group (95.83%), resulting in an overall higher satisfaction rate in the experimental group (83.67%;P < 0.05). Conclusion: The treatment effect of endodontics with calcium hydroxide preparation is remarkable, which not only can effectively help patients to relieve their pain and reduce the incidence of complications but also plays an important role in improving patients’ satisfaction with treatment, which is worthwhile to be vigorously promoted in the clinic and learn from it.

Ultrafast Synthesis of Metal-Layered Hydroxides in a Dozen Seconds for High-Performance Aqueous Zn(Micro-)Battery

Efficient synthesis of transition metal hydroxides on conductive substrate is essential for enhancing their merits in industrialization of energy storage field.However,most of the synthetic routes at present mainly rely on traditional bottom-up method,which involves tedious steps,time-consuming treatments,or additional alkaline media,and is unfavorable for high-efficiency production.Herein,we present a facile,ultrafast and general avenue to synthesize transition metal hydroxides on carbon substrate within 13 s by Joule-heating method.With high reaction kinetics caused by the instantaneous high temperature,seven kinds of transition metal-layered hydroxides(TM-LDHs)are formed on carbon cloth.Therein,the fastest synthesis rate reaches~0.46 cm^(2)s^(-1).Density functional theory calculations further demonstrate the nucleation energy barriers and potential mechanism for the formation of metal-based hydroxides on carbon substrates.This efficient approach avoids the use of extra agents,multiple steps,and long production time and endows the LDHs@carbon cloth with outstanding flexibility and machinability,showing practical advantages in both common and micro-zinc ion-based energy storage devices.To prove its utility,as a cathode in rechargeable aqueous alkaline Zn(micro-)battery,the NiCo LDH@carbon cloth exhibits a high energy density,superior to most transition metal LDH materials reported so far.

Design, synthesis, and nanoengineered modification of spherical graphene surface by layered double hydroxide (LDH) for removal of As (Ⅲ) from aqueous solutions

In this study, new nano spherical graphene modified with LDH(Layered Double Hydroxide) was prepared and used to remove As(Ⅲ) ion from aqueous solutions. At first, graphene oxide was synthesized from graphite using a well-known Hammer method. The obtained graphene oxide solution was sprayed in octanol solution under different temperatures and sprayed speed as influenced variables. The structure and physical characterization of synthesized spherical graphene oxide were determined by various techniques,including FT-IR, N_(2) adsorption–desorption, SEM, TEM, and EDX. In the next step, the hydrothermal method was applied to deposition LDH on the spherical graphene oxide. The synthesized spherical graphene modified by LDH was used to remove As(Ⅲ) as a toxic heavy metal ion. The effect of influenced variables including p H, contact time, amount of sorbent, and type eluent studied and the optimum values were as 8, 30, 50, and HCl(0.5 mol·L^(-1)), respectively. After optimization, the studied sorbent was shown a high adsorption capacity(149.3 mg·g^(-1)). The adsorption mechanism and kinetic models exhibited good agreement with the Langmuir isotherm and pseudo-second-order trends, respectively. Besides, the synthesized product was tested for seven times without significant loss in its sorption efficiency.

Layered double hydroxides as electrode materials for flexible energy storage devices

To prevent and mitigate environmental degradation,high-performance and cost-effective electrochemical flexible energy storage systems need to be urgently developed.This demand has led to an increase in research on electrode materials for high-capacity flexible supercapacitors and secondary batteries,which have greatly aided the development of contemporary digital communications and electric vehicles.The use of layered double hydroxides(LDHs)as electrode materials has shown productive results over the last decade,owing to their easy production,versatile composition,low cost,and excellent physicochemical features.This review highlights the distinctive 2D sheet-like structures and electrochemical characteristics of LDH materials,as well as current developments in their fabrication strategies for expanding the application scope of LDHs as electrode materials for flexible supercapacitors and alkali metal(Li,Na,K)ion batteries.

Zn-doped nickel iron(oxy)hydroxide nanocubes passivated by polyanions with high catalytic activity and corrosion resistance for seawater oxidation

Electrochemical water splitting to produce hydrogen fuel is a promising renewable energy-conversion technique.Large-scale electrolysis of freshwater may deplete water resources and cause water scarcity worldwide.Thus,seawater electrolysis is a potential solution to the future energy and water crisis.In seawater electrolysis,it is critical to develop cost-effective electrocatalysts to split seawater without chloride corrosion.Herein,we present zinc-doped nickel iron(oxy)hydroxide nanocubes passivated by negatively charged polyanions(NFZ-PBA-S)that exhibits outstanding catalytic activity,stability,and selectivity for seawater oxidation.Zn dopants and polyanion-rich passivated surface layers in NFZ-PBA-S could effectively repel chlorine ions and enhance corrosion resistance,enabling its excellent catalytic activity and stability for seawater oxidation.

Self-supported ultrathin NiCo layered double hydroxides nanosheets electrode for efficient electrosynthesis of formate

Electrochemical CO_(2)reduction into energy-carrying compounds,such as formate,is of great importance for carbon neutrality,which however suffers from high electrical energy input and liquid products crossover.Herein,we fabricated self-supported ultrathin NiCo layered double hydroxides(LDHs)electrodes as anode for methanol electrooxidation to achieve a high formate production rate(5.89 mmol h^(-1)cm^(-2))coupled with CO_(2)electro-reduction at the cathode.A total formate faradic efficiency of both anode for methanol oxidation and cathode for CO_(2)reduction can reach up to 188%driven by a low cell potential of only 2.06 V at 100 mA cm^(-2)in membrane-electrode assembly(MEA).Physical characterizations demonstrated that Ni^(3+)species,formed on the electrochemical oxidation of Ni-containing hydroxide,acted as catalytically active species for the oxidation of methanol to formate.Furthermore,DFT calculations revealed that ultrathin LDHs were beneficial for the formation of Ni^(3+)in hydroxides and introducing oxygen vacancy in NiCo-LDH could decrease the energy barrier of the rate-determining step for methanol oxidation.This work presents a promising approach for fabricating advanced electrodes towards electrocatalytic reactions.

Environmentally Friendly Room Temperature Synthesis of 1-Tetralone over Layered Double Hydroxide-Hosted Sulphonato-Salen-Nickel(II) Complex

1-Tetralone, a useful synthetic intermediate in the manufacture of pharmaceuticals, agrochemicals and dyes, can be prepared by liquid phase catalytic oxidation of tetralin. Selective oxidation of tetralin to 1-tetralone is still a big challenge with low-temperature processes using environmentally friendly routes even after decades of research. Herein, we demonstrate room-temperature oxidation of tetralin to 1-tetralone over layered double hydroxide-hosted sulphonato-salen-nickel(II) complex, LDH-[Ni-salen]. The layered double hydroxide-hosted sulphonato-salen-nickel(II) compound was characterized by powder X-ray diffraction, Fourier transform infrared spectrometer (FTIR), UV-Visible diffuse reflectance spectra, scanning electron microscopy (SEM) and elemental analysis. The theoretical calculations of free sulphonato-salen-nickel(II) complex using Density Functional Theory/CAM-B3LYP at the 6-311++ G(d,p) level of theory were also used to determine the orientation of the Ni-salen compound within the layered structure. The immobilized compound, LDH-[Ni-salen] was found to be an effective reusable catalyst for the oxidation of tetralin to 1-tetralone using a combination of trimethylacetaldehyde and molecular oxygen (14.5 psi) and at 25&deg;C. At 45.5% conversion, tetralin was converted to 1-tetralone with 77.2% selectivity at room temperature and atmospheric pressure after 24 h. The catalyst recycles test and hot filtration experiment showed that oxidation proceeded through Ni(II) sites in LDH-[Ni-salen]. The catalysts were reused several times without losing their catalytic activity and selectivity. The present results may provide a convenient strategy for the preparation of 1-tetralone using layered double hydroxide-based heterogeneous catalyst at ambient temperature for industrial application in near future.

Synthesis, Characterization, and Effects of Morphology on the Magnetic Application Base Properties of Pure Nickel Oxide (NiO) and Cobalt-Doped Nickel Oxide/Nickel Hydroxide (CoxNi1-xO/Ni(OH)2) Nanocomposites

Nano particle (NP) morphology is one of the material properties at the origin of potential application base properties exploited in several engineering and technology domains, such as fuel cell, electrodes, catalysis, sensing, electric, thermal, magnetic, and photovoltaic applications. The general properties and particle morphology of nickel oxide/Nickel hydroxide NPs can be modified by the introduction of impurity atoms or ions. Nano sized nickel oxide/nickel hydroxide nanocomposites were obtained from the thermal decomposition of single molecular precursors synthesized by a modified oxalate route using Carambola fruit juice as a precipitating agent. The compositional and morphological variations were studied by introducing cobalt as an impurity ion at different w/w% fractions (0%, 0.1%, 0.3%, 0.5%, 1%, 3%, 5.0%, 40.0% and 50.0%) into the microstructure of the nickel oxide/hydroxide. The precursors were characterized by FT-IR, while TGA/DTG analysis was carried out to decompose the precursors. The precursors decomposed at 400°C and were characterized by PXRD and SEM/TEM. The results revealed that Pure Nickel Oxide (NiO) and, Cobalt-doped Nickel Oxide/nickel hydroxide (CoxNi1-xO/Ni(OH)2) Nano composites have been synthesized and the synthesized samples have exhibited three distinct morphologies (porous face-centered cubic nano rods, rough and discontinuous CoxNi1-xO/Ni(OH)2) composite and, smooth and continuous mix spherical/cuboidal mixed morphological phase of (NiO/CoO). The morphology of the NPs varied with the introduction of the dopant atoms and with increase in the concentration of dopant atoms in the composite. Magnetic studies using vibrating sample magnetometry revealed superparamagnetic properties which correlated strongly with particle size, shape and morphology. Observed values of retention (4.50 × 10-3 emu/g) and coercivity (65.321 Oe) were found for 0.5 w/w% corresponding to impregnated porous nanorods of Co-doped NiO, and retention (9.03 × 10-3 emu/g) and coercivity (64.341 Oe), for X = 50.0%, corresponding to an aggregate network of a Nano spherical/cubic CoO/NiO mixed phase. Magnetic properties within this range are known to improve the magnetic memory and hardness of the magnetic materials. Therefore, the synthesized Cobalt-doped Nickel Oxide/nickel hydroxide (CoxNi1-xO/Ni(OH)2) Nano composites have potential applications in Magnetic memories and hardness of magnetic materials.

Advances in Mg-Al-layered double hydroxide steam coatings on Mg alloys:A review

Layered double hydroxide(LDH)coatings on magnesium(Mg)alloys shine brightly in the field of corrosion protection because of their special ion-exchange function.State-of-the-art steam coating as a type of LDH film preparation technique has emerged in recent years because only pure water is required as the steam source and its environmentally friendly LDH coating fits the current need for green development.Moreover,this coating can effectively inhibit the corrosion of the Mg alloy substrate due to the chemical bonding between the coating and the Mg alloy substrate.This review systematically explains cutting-edge advancements in the growth mechanism and corrosion behavior of LDH steam coatings,and analyzes the advantages and limitations of the steam-coating method.The influencing factors including pressure,CO_(2)/CO_(3)^(2-),aluminum content of the substrate alloy,solution type,and acid-pickling pretreatment,as well as the post-treatment of steam-coating defects,are comprehensively elucidated,providing new insights into the development of the in situ steam-coating technique.Finally,existing issues and future prospects are discussed to further accelerate the widespread application of Mg alloys.

Synthesis, Characterization, and Effects of Morphology on the Magnetic Application Base Properties of Pure Nickel Oxide (NiO) and Cobalt-Doped Nickel Oxide/Nickel Hydroxide (CoxNi1-xO/Ni(OH)2) Nanocomposites

Nano particle (NP) morphology is one of the material properties at the origin of potential application base properties exploited in several engineering and technology domains, such as fuel cell, electrodes, catalysis, sensing, electric, thermal, magnetic, and photovoltaic applications. The general properties and particle morphology of nickel oxide/Nickel hydroxide NPs can be modified by the introduction of impurity atoms or ions. Nano sized nickel oxide/nickel hydroxide nanocomposites were obtained from the thermal decomposition of single molecular precursors synthesized by a modified oxalate route using Carambola fruit juice as a precipitating agent. The compositional and morphological variations were studied by introducing cobalt as an impurity ion at different w/w% fractions (0%, 0.1%, 0.3%, 0.5%, 1%, 3%, 5.0%, 40.0% and 50.0%) into the microstructure of the nickel oxide/hydroxide. The precursors were characterized by FT-IR, while TGA/DTG analysis was carried out to decompose the precursors. The precursors decomposed at 400°C and were characterized by PXRD and SEM/TEM. The results revealed that Pure Nickel Oxide (NiO) and, Cobalt-doped Nickel Oxide/nickel hydroxide (CoxNi1-xO/Ni(OH)2) Nano composites have been synthesized and the synthesized samples have exhibited three distinct morphologies (porous face-centered cubic nano rods, rough and discontinuous CoxNi1-xO/Ni(OH)2) composite and, smooth and continuous mix spherical/cuboidal mixed morphological phase of (NiO/CoO). The morphology of the NPs varied with the introduction of the dopant atoms and with increase in the concentration of dopant atoms in the composite. Magnetic studies using vibrating sample magnetometry revealed superparamagnetic properties which correlated strongly with particle size, shape and morphology. Observed values of retention (4.50 × 10-3 emu/g) and coercivity (65.321 Oe) were found for 0.5 w/w% corresponding to impregnated porous nanorods of Co-doped NiO, and retention (9.03 × 10-3 emu/g) and coercivity (64.341 Oe), for X = 50.0%, corresponding to an aggregate network of a Nano spherical/cubic CoO/NiO mixed phase. Magnetic properties within this range are known to improve the magnetic memory and hardness of the magnetic materials. Therefore, the synthesized Cobalt-doped Nickel Oxide/nickel hydroxide (CoxNi1-xO/Ni(OH)2) Nano composites have potential applications in Magnetic memories and hardness of magnetic materials.

Improvement of Cemented Gangue Backfill Material with Barium Hydroxide in Acid Mine Water

As a kind of green concrete,the mechanical properties and durability of cemented gangue backfill material(CGBM)will be affected if they are in acid mine water with sulfate ions in the long term.To improve the performance of CGBM in acid mine water with sulfate ions,CGBM specimens with different doses of barium hydroxide were immersed in sulfuric acid solutions of different concentrations for 270 days.The changes of mass,ultrasonic pulse velocity(UPV)and compressive strength of the specimens at different ages were analyzed.Scanning electron microscopy(SEM)and X-ray diffraction(XRD)were used to analyze the microstructure and composition of the specimens.The results show that incorporation of barium hydroxide into CGBM specimen can promote the formation of barium sulfate precipitation and inhibit the generation of corrosion products such as ettringite.Meanwhile,barium sulfate precipitation blocks the pore channel invaded by sulfuric acid solution,delaying the progress of corrosion reaction and making the interior of CGBM specimen more complete.And the specimen with 2.0 kg/m^(3)barium hydroxide was more effective in improving performance.This study provides a basis for the ratio design of CGBM in acid mine water with sulfate ions.