Ni Metal Ions Research Articles

Electronic interaction between d electron-poor and d electron-rich transition metal ions promoted the CO2 capture performance of calcium-based adsorbent

The investigation of intrinsic principles for the more precise design CaO adsorbent with excellent CO2 capture performance by doping metal oxides is of great significance, but has not yet been explored. Herein, we address the critical challenge by systematical evaluation on a series of magnetic bimetallic oxides doped calcium-based adsorbents from the perspective of electronic interaction between d electron-poor and d electron-rich transition metal ions promoting the CO2 capture performance. The Mn, Co, Mo and Ni metal ions with varied d-electron numbers are doped into calcium-based adsorbent, and the results show that the introduction of magnetic bimetallic oxides with d electron-poor and d electron-rich transition metal ions into CaO at the same time can significantly promote the stability of CO2 capture. Taking the (Mn-Co)-codoped samples as an example, the relationship of d electron-poor and d electron-rich transition metal ions synergistic interaction and promoted CO2 adsorption performance is elucidated. The loose flake nanostructures favor the diffusion of CO2 inside the particles, and the uniform distribution of each component effectively ensures the double-exchange interactions. The generation of more oxygen vacancies significantly improves the CO2 affinity for the calcium-based sample. Furthermore, the results of kinetic analysis reveal that the synergistic interaction can reduce the apparent activation energy of carbonation reaction. These insights into the systematical regulation of the double-exchange interaction are expected to provide guidance for the relatively more precise design of the calcium-based adsorbent with high performance of CO2 adsorption.

Creation of Metal-Complex-Integrated Tensegrity Triangle DNA Crystals.

Structural DNA nanotechnology is an emerging field and is expected to be used for various applications in materials science. In this study, we designed a DNA tensegrity triangle to accommodate the bipyridine complexes with metal ions (Ni2+ and Fe2+) at the center of the space within the triangle. A metal-bipyridine-incorporated DNA tensegrity triangle was crystalized, and the presence of metals within it was confirmed through X-ray crystal structure analysis. A signal of the anomalous dispersion effect derived from metal was observed in the center of the DNA triangle.

A self-supporting nanoflower-like film of 3D walnut shell derived carbon/NiCo2S4 for supercapacitors and zinc-ion batteries with high energy density

Nanocomposites with special structures can generally provide more efficient electron and ion transfer kinetics during electrochemical charge storage, resulting in satisfactory energy densities. Herein, we adopted a simple hydrothermal method to prepare a nanoflower-like NiCo2S4 growing on hierarchical porous N, O co-doped walnut shell-derived carbon (10-WSC-N/O@NiCo2S4). Metal ions (Ni2+, Co2+) enhanced the active site to obtain better electrochemical activity, as well as the porous carbon framework helped achieve better ion transport and electron conduction. Importantly, 10-WSC-N/O@NiCo2S4 exhibits 1176 F g−1 at 0.5 A g−1, the prepared 10-WSC-N/O@NiCo2S4//WSC-N/O displays a remarkable energy density of 68.6 Wh kg−1 at 375 W kg−1 and only decreases a 12 % in capacitance after 8000 cycles at 3.0 A g−1. Additionally, the 10-N/O@NiCo2S4//Zn device achieves a high energy density of 88.54 Wh kg−1 at 750 W kg−1. Overall, this work provides an efficient strategy for fabricating high-performance electrode materials.

The novel α-TiO2@g-C3N4 heterostructure for ultra rapid ionic pumping and effective capacitive deionization

Anatase titanium dioxide (α-TiO2) has been widely identified as an efficient electrode material for capacitive deionization (CDI). However, this material usually suffers from limited exposure of active sites, poor electrical conductivity and significant obstacles in ion movement due to its tendency to severely aggregate during its preparation. A novel approach to fabricate α-TiO2@g-C3N4 composite materials was proposed in this work. In detail, the 2D material g-C3N4 serves as a high-speed electron-conducting scaffold, allowing uniform loading of nanoscale α-TiO2 and exposing abundant active sites. Furthermore, g-C3N4 facilitates electron transport to nanoscale α-TiO2, enhancing charge transfer and activating previously underutilized electrochemical centers. As a result, α-TiO2@g-C3N4 composites were synthesized for the first time. Through these improvements, the prepared α-TiO2@g-C3N4 exhibits excellent desalination performance, with a high degree of efficiency in water purification. It shows an improved salt adsorption capacity (SAC) of 50.4 mg g-1 and a salt adsorption rate (SAR) of 2.7 mg g-1 min−1 in a 1.2 V, 1 mm electrode spacing, and 500 mg L-1 NaCl solution. This outstanding CDI performance surpasses most recently reported electrode materials. More importantly, this electrode showed remarkable removal efficiencies for various heavy metal ions (Ni2+, Cr3+, Cu2+, Pb2+, Fe3+ and Cd2+), indicating its significant potential for wastewater purification. The superior CDI performance of the α-TiO2@g-C3N4 composite material endows it with practical application in future.

MXene-based conductive hydrogels with toughness and self-healing enhancement by metal coordination for flexible electronic devices

MXene-based conductive hydrogels have emerged as a new type of soft materials in flexible electronics. Herein, metal coordination is introduced into MXene-based conductive hydrogels to synchronously enhance the mechanical and self-healing properties. MXene-based conductive hydrogels are made up of polyacrylic acid (PAA), sium carboxymethyl cellulose (SCMC), Ti3C2TX and metal ions (Ni2+, Al3+ or Sn4+). PAA/SCMC/Ti3C2TX/Sn4+ hydrogel is found to have excellent mechanical (stress: 122 kPa; strain: 1688 %; toughness: 0.95 ± 0.12 MJ m−3) and self-healing (self-healing efficiency: 99.27 % (conductivity); 81.16 % (stress); and 83.13 % (strain)) properties due to the metal coordination and H-bonding. The hydrogel has also good conductivity of 0.82 S m−1 and adhesion of 38.94 kPa. The flexible sensors based on this hydrogel can efficiently detect human motions, electromyography (EMG), electrocardiography (ECG) and handwriting signals. Furthermore, a supercapacitor assembled from this hydrogel has a high specific capacitance of 118.66 F g−1 and good stability (15000 charge-discharge cycles). This work provides an effective strategy for exploiting mechanically tough and self-healing MXene-based conductive hydrogels with prospective applications in flexible electronics.

2-Propyl-1H-imidazole-4,5-dicarboxylate acid supported cu/ni/fe/co complexes: synthesis, biological and catalytic evaluation

Herein, we report 2-propyl-1H-imidazole-4,5-dicarboxylate complexes of Cu/Co/Fe/Ni metal ions. The complexes have been characterized using powder X-ray diffraction, FTIR, and mass spectrometry. Thermal gravimetric analysis (TGA) established their thermal stability, enduring temperatures of up to 650 °C. The interaction of Bovine Serum Albumin (BSA) and DNA with these complexes was examined, revealing a significant binding affinity up to 70%. Fluorescence quenching experiments also showed the binding of complexes with biomolecules. These interactions were substantiated by molecular docking studies against the proteins 3v03 (BSA) and 1d28 (DNA), shedding light on the essential interactions driving their potential medicinal activity. The Cu complex displayed a notably high GSC score and a substantial area as determined through the Patch Dock server. Free radical interaction with 2,2-diphenylpicrylhydrazyl (DPPH) shows their antioxidant activity where Cu and Fe complexes expressed greater activity as compared to others. The catalytic properties of the compounds were assessed using p-nitrophenol (PNP) where the complexes exhibited reducing activity, leading to a conversion of over 90% of PNP into p-aminophenol. Analysis revealed a pseudo-second-order model closely aligned with experimental values, indicating second-order reduction kinetics.

Elucidating the Transition of 3D Morphological Evolution of Binary Alloys in Molten Salts with Metal Ion Additives.

Molten salts serve as effective high-temperature heat transfer fluids and thermal storage media used in a wide range of energy generation and storage facilities, including concentrated solar power plants, molten salt reactors and high-temperature batteries. However, at the salt-metal interfaces, a complex interplay of charge-transfer reactions involving various metal ions, generated either as fission products or through corrosion of structural materials, takes place. Simultaneously, there is a mass transport of ions or atoms within the molten salt and the parent alloys. The precise physical and chemical mechanisms leading to the diverse morphological changes in these materials remain unclear. To address this knowledge gap, this work employed a combination of synchrotron X-ray nanotomography and electron microscopy to study the morphological and chemical evolution of Ni-20Cr in molten KCl-MgCl2, while considering the influence of metal ions (Ni2+, Ce3+, and Eu3+) and variations in salt composition. Our research suggests that the interplay between interfacial diffusivity and reactivity determines the morphological evolution. The summary of the associated mass transport and reaction processes presented in this work is a step forward toward achieving a fundamental comprehension of the interactions between molten salts and alloys. Overall, the findings offer valuable insights for predicting the diverse chemical and structural alterations experienced by alloys in molten salt environments, thus aiding in the development of protective strategies for future applications involving molten salts.

Enhancing nanoplastics removal by metal ion-catalyzed ozonation

Nanoplastics (NPs), characterized by sizes < 1 µm, are not completely removed in conventional drinking water treatment plants affecting human health. Catalytic ozonation appears as a promising alternative due to its ability to oxidize emerging pollutants by generating hydroxyl radicals with higher removal rate and mineralization than single ozonation. In this work, catalytic ozonation was investigated for the removal of polystyrene nanoplastics (PSNPs) by employing transition metal ion catalysts, Fe3+, Co2+, Ni2+, and Zn2+. The single ozonation of PSNPs, in the absence of catalyst, led to low turbidity reduction (33 %) and low mineralization rate (16 %) even after 2 h reaction time. Nevertheless, the rapid size reduction of PSNPs by >99 % in less than 5 min of ozonation (TOD: 30 mg L−1) was confirmed. This fact could imply a new issue under the ozone disinfection conditions by the formation of smaller-size particles. However, in the presence of Co2+ (1 mM), the highest PSNPs ozonation performance was achieved, decreasing the turbidity up to 65 % and achieving 70 % of mineralization in the same ozonation time. The scavenger experiments with methanol confirmed that direct ozonation and catalyst role were responsible for PSNPs degradation, with the generation of •OH being the most dominant catalytic mechanism. Therefore, although single ozonation at disinfection doses reduced the particle size of PSNPs, the catalytic process demonstrated greater efficacy in the total removal of PSNPs. These results highlight the need to further investigate ozonation of NPs intermediates, and the synergic improvements of catalytic ozonation for their mineralization.

Modification of Coal Fly Ash Waste into Manganese-Oxide-Coated-Zeolite (MOCZ) to Adsorb Heavy Metal Ions Ni2+

High consumption of coal as a source of electrical energy in Indonesia has resulted in piles of waste from coal burning, namely fly ash, which can damage the environment and harm health. Fly ash contains main oxides, namely silica (SiO2) and alumina (Al2O3), whose components are similar to zeolite, so they can be synthesized into zeolite-like material (ZLM) which can be used as an adsorbent for heavy metal Ni2+. Therefore, this research discussed the characterization of manganese-oxide-coated-zeolite (MOCZ) from fly ash waste as a heavy metal adsorbent. The research procedure consisted of preparation, purification, and activation stage of fly ash to obtain fly ash that is free from impurities, the stage of making sodium silicate and sodium aluminate, and zeolite synthesis. The resulting zeolite was then coated with manganese oxide to expand the surface area of the zeolite and increase the ability of zeolite to adsorb heavy metal Ni2+. The research results showed that fly ash waste that was coated with manganese oxide can adsorb heavy metal Ni2+. The adsorption of the Ni2+ metal ion solution by zeolite with MOCZ modification is in line with the pseudo-second-order kinetic and Langmuir isotherm.

Valorization of battery manufacturing wastewater: Recovery of high-value metal ions through reaction-enhanced membrane cascade

Leveraging the latent value within battery manufacturing wastewater holds considerable potential for promoting the sustainability of the water-energy nexus. This study presents an efficient method for recovering transition metal ions (Ni2+, Co2+, Cu2+, and Cd2+) from highly saline battery wastewater (Na+, Li+, K+, or Mg2+). Our approach involves the effective utilization of a reaction-enhanced membrane cascade (REMC), comprising a meticulously orchestrated series of selective complexation-decomplexation steps involving polyethyleneimine (PEI) and various transition metal ions. This strategic intervention effectively segregates transition metal ions from salt ions during the fractionation process using an ultrafiltration membrane in a diafiltration process, overcoming osmotic pressure limitations. The ensuing concentration step via nanofiltration achieves an impressive 99 % yield and an extraordinary 215-fold concentration of transition metal ions (>99.8 % purity). The proposed method was validated with 16 different ion pairs to demonstrate its versatility, offering a pragmatic pathway for recycling various transition metal ions from industrial wastewater.

Non-Pigmented Antarctic Yeasts and Their Resistance to Toxic Metals

Despite the key role in biogeochemical processes and in the functioning of terrestrial ecosystems, yeasts of Antarctic regions still remain insufficiently studied. The study and analysis of the composition of Antarctic microbial communities remains relevant and is carried out using molecular biological approaches. The investigation of their resistance to toxic metal ions is essential to select industrially promising strains that can contribute to the development of new methods of metals detoxification via microorganisms. Aim. To determine the taxonomic position of non-pigmented Antarctic yeasts and investigate their resistance to toxic metal ions. Methods. The objects of the research are yeasts isolated from Antarctic phytocenoses. They were grown on malt wort (pH 5.0–5.5, temperature 18–20 °C). Isolation of genomic DNA was performed via the commercial DNA-sorb kit. Amplification of DNA was carried out using primers NL1 and NL4. Phylogenetic analysis was conducted by construction of trees (dendrograms) showing the position of the studied strains among closely related and typical species. The resistance of yeasts to toxic metal ions was established by cultivation in the concentration gradient of Ni2+, Co2+, CrO42-, and Сu2+. The ecophysiological traits of the isolated yeast strains including psychro- and halotolerance were determined. Results. Phylogenetic analysis showed a high percentage of similarity (99.5–99.6 %) of sequences of 18S rRNA genes of Antarctic yeast strains with the yeast sequences from the GenBank database. Psychrotolerant and halotolerant Antarctic yeast strains S11 and S12 were identified as Leucosporidium scottii and Debaryomyces hansenii, respectively. The studied yeast strains were found to be the most resistant to metal ions Ni2+ and Co2+. Strain of L. scottii S11 grew at 800 mg/L of Co2+, and D. hansenii S12 – at 750 mg/L of Ni2+. The yeasts were the least resistant to CrO42-: the L. scottii S11 and D. hansenii S12 strains grew at concentrations of 25 mg/L and 150 mg/L, respectively. In the presence of Cu2+, they grew at the same concentration – 600 mg/L. The combined action of toxic metal ions resulted in the increased toxic effects on the studied yeasts. Conclusions. The nucleotide sequences of 18S rRNA gene fragment of yeast strains S11 and S12 were included in the GenBank database under the numbers LT220858 and LT220859. Metal-resistant psychrotolerant yeast strains can be used to evaluate the metals content in polar regions as well as to bioremediate metal-contaminated ecosystems. However, further research is needed to develop and optimize bioremediation processes.

Neutralizing anti-diphtheria toxin scFv produced by phage display.

Diphtheria can be prevented by vaccination, but some epidemics occur in several places, and diphtheria's threat is considerable. Administration of diphtheria antitoxin (DAT) produced from hyperimmunized animals is the most common treatment. Recombinant human antibody fragments such as single-chain variable fragments (scFv) produced by phage display library may introduce an interesting approach to overcome the limitations of the traditional antibody therapy. In the present study, B cells of immunized volunteers were used to construct a human single-chain fragment (HuscFv) library. The library was constructed with the maximum combination of heavy and light chains. As an antigen, Diphtheria toxoid (DTd) was used in four-round phage bio-panning to select phage clones that display DTd bound HuscFv from the library. After panning, individual scFv clones were selected. Clones that were able to detect DTd in an initial screening assay were transferred to Escherichia coli HB2151 to express the scFvs and purification was followed by Ni metal ion affinity chromatography. Toxin neutralization test was performed on Vero cells. The reactivity of the soluble scFv with diphtheria toxin were done and affinity calculation based on Beatty method was calculated. The size of the constructed scFv library was calculated to be 1.3×106 members. Following four rounds of selection, 40 antibody clones were isolated which showed positive reactivity with DTd in an ELISA assay. Five clones were able to neutralize DTd in Vero cell assay. These neutralizing clones were used for soluble expression and purification of scFv fragments. Some of these soluble scFv fragments show neutralizing activity ranging from 0.6 to 1.2µg against twofold cytotoxic dose of diphtheria toxin. The affinity constant of the selected scFv antibody was determined almost 107M-1. This study describes the prosperous construction and isolation of scFv from the immune library, which specifically neutralizes diphtheria toxin. The HuscFv produced in this study can be a potential candidate to substitute the animal antibody for treating diphtheria and detecting toxins.

Uncovering the influence of Ni-doping in CuBi2O4 photocatalyst on its visible-light-responsiveness for the efficient removal of toxic Alizarin yellow R dye from wastewater

In recent years, wastewater pollution has a significant huge impact on both human life and aquatic animals. Wastewater treatment has become a challenging task for researchers due to the presence of complex organic pollutants. In the present work, we report the investigation of the influence of Ni-doping on photocatalytic activity of CuBi2O4 to effectively removal of complex organic pollutants. For this, we synthesized the various photocatalysts, including CuBi2O4, Ni0.05Cu0.95Bi2O4, Ni0.10Cu0.90Bi2O4, and Ni0.15Cu0.85Bi2O4 using a facile hydrothermal method. The photocatalytic efficiency of the synthesized photocatalysts was evaluated for degradation of Alizarin yellow R (AYR) dye under visible-light illumination. The experimental results revealed an 85.78% degradation of AYR dye in the presence of a CuBi2O4 photocatalyst. In constrast, the degradation rate increased to 98.43% for Ni0.10Cu0.90Bi2O4 photocatalyst within 70 min. Similarly, the rate constant also increased from 0.0286 min−1 to 0.0633 min−1, affirming the photocatalytic efficacy of the Ni0.10Cu0.90Bi2O4 photocatalyst. The increased photocatalytic efficiency of the Ni0.10Cu0.90Bi2O4 photocatalyst was attributed to its increased surface area (98.27 m2 g−1) and reduced the optical bandgap energy due to the incorporation of Ni metal ions into the basic framework of CuBi2O4. Furthermore, the investigation into the effect of various reaction parameters revealed a significant influence on the removal of AYR dye. It can be perceived that the formation of •OH and O2•− radicals on the surface of the catalyst resulted in the degradation of AYR. Notably, the synthesized Ni0.10Cu0.90Bi2O4 photocatalyst displayed exceptional photostability. This work provides a cost-effective method of developing efficient photocatalyst for wastewater remediation.

Adsorptive removal of heavy metal ions from model aqueous media using titanium metal-organic framework and its polyvinyl chloride functionalized composite

The present study was conducted on Ti-MOF and its PVC functionalized composite with the objective of toxic heavy metal ions removal from aqueous media. For achieving this purpose, the solvothermal method was used to synthesis Ti-MOF which was then functionalized with PVC for composite synthesis. The synthesized adsorbent materials were then analyzed via different techniques that include the FTIR, XRD, SEM and EDX analysis along with TGA and point of zero charge (PZC). Batch experiments were conducted for nickel (Ni) and copper (Cu) metal ions sorption from water, using the synthesized adsorbents, under different experimental conditions like initial metal ions concentration, pH, adsorbent’s dosage, time of contact and temperature. The sorption of heavy metal ions by the adsorbents was increased with increasing the media dosage and concentration. Whereas, increasing the pH of the system, from pH-2 to pH-10, also enhanced the sorption phenomenon, because of the pronounced forces of attraction between the positively charged adsorbate ions and the adsorbent’s negatively charged surface, accompanied by precipitation at a much higher pH. It was observed that the adsorption on the functionalized adsorbent surface was greater than the parent MOF material because of the availability of a greater number of adsorption sites, increasing the adsorption capacity of Ni ions from 6.436 to 29.2 mg/g and that of Cu ions from 21.414 to 41.616 mg/g. In addition, the composite material was found to have greater affinity towards Cu metal ions as compared to Ni metal ions, which is attributed to the smaller size of Cu metal ions as compared to Ni ions. To determine the adsorption mechanism, various adsorption isotherms were examined. The results concluded that the Langmuir adsorption isotherm was the suitable model to explain the adsorption mechanism.Moreover, thermodynamic parameters like Gibbs free energy (, change in enthalpy, along with the change in entropy, were determined. The sorption process was found to be more spontaneous at lower temperatures, with the exothermic nature of adsorption, in the case of Ni metal ions and the endothermic nature in the case of Cu metal ions.Also, the negative value of ΔS in case of Ni ions adsorption accounts for the decreased disorderliness of the system which is also the opposite tothat of Cu ions adsorption onto the surface of Ti-PVC composite.The PVC functionalized Ti-MOF was thus found to be an effective, durable, and environmentally friendly adsorbent, for the sorption of heavy metal ions from wastewater.

Plastic response of macrophages to metal ions and nanoparticles in time mimicking metal implant body environment.

The paradigm of using metal biomaterials could be viewed from two sides - treatment of wide spectrum of degenerative diseases, and debris release from materials. After implant insertion, metal nanoparticles (NPs) and ions are released not only upon the first contact with cells/tissues, but in continual manner, which is immediately recognized by immune cells. In this work, the effects of metal nanoparticles (TiO2, Ni) and ions (Ni2+, Co2+, Cr3+, Mo6+) on primary human M0 macrophages from the blood samples of osteoarthritic patients undergoing total arthroplasty were studied in order to monitor immunomodulatory effects on the cells in a real-time format. Thehighest NiNPs concentration of 10µg/ml had no effect on any of macrophage parameters, while the Ni2+ ions cytotoxicity limit for the cells is 0.5mM. The cytotoxic effects of higher Ni2+ concentration revealed mitochondrial network fragmentation leading to mitochondrial dysfunction, accompanied by increased lysosomal activity and changes in pro-apoptotic markers. The suppression of M2 cell formation ability was connected to presence of Ni2+ ions (0.5mM) and TiO2NPs (10µg/ml). The immunomodulatory effect of Mo6+ ions, controversially, inhibit the formation of the cells with M1 phenotype and potentiate the thread-like shape M2s with increased chaotic cell movement. To summarize, metal toxicity depends on the debris form. Both, metal ions and nanoparticles affect macrophage size, morphological and functional parameters, but the effect of ions is more complex and likely more harmful, which has potential impact on healing and determines post-implantation reactions.

Four Anderson– and isopolymolybdate–viologen photochromic materials for UV detection, inkless erasable printing, and ammonia detection

In this work, four POMs-based compounds are devised and synthesized by employing viologen organic ligand under hydrothermal and solvothermal conditions, namely [M2(H2O)6(Cpmbpy)2(TeMo6O24)] M = Ni (1); Co (2)), {[M(Cpmbpy)2(DMF)2(β-Mo8O26)][H4(β-Mo8O26)]}·4C2H7N (M = Cu (3); Co (4)), (Cpmbpy = 1–Cyclopropylmethyl–[4,4′]bipyridinyl–1–ium·chloride). Compound 1 or 2 exhibits one–dimensional (1D) POMs-Ni chain constructed from the [TeMo6O24]6− POMs and Ni metal ions. For compound 3 or 4, two 4,4′–bipyridine groups and two DMF molecules coordinate with a CuII ion to form a {Cu(Cpmbpy)2(DMF)2}4− subunit. And the two [β-Mo8O26]4− are directly connected the {Cu(Cpmbpy)2(DMF)2}4+ subunit to form a 1D chain structure. Compounds 1–4 exhibits photochromic properties under irradiation with a filtered Xe lamp (300–400 nm), showing rapid light response and varying degrees of color change. Four compounds can also be utilized as visible UV detectors and inkless erasable printing materials. In addition, compounds 1 and 2 exhibits a significant NH3 response.

NiCo‐glycolate‐derived porous spherical NiCo2S4 for high‐performance asymmetric supercapacitors

The construction of electrode materials with high rate and excellent cycling stability is the key to supercapacitors. Due to their remarkable high conductivity and great electrochemical activity, transition bimetallic sulfides are extremely appealing electrode materials for supercapacitors, but their synthesis is still challenging. In this study, a NiCo bimetallic sulfide (NiCo2S4) microspheres with porous structure were prepared via direct vulcanization of NiCo‐EG complexes followed by a thermal treatment, which were pre‐synthesized via coordination of ethylene glycol (EG) with transition metal ions (Ni2+, Co2+) under hydrothermal condition. Some experimental parameters were investigated, including the control of NiCo2S4 microspheres produced by the ratio of precursor NiCo‐EG to different masses of sulfur sources, which in turn affects the electrochemical properties. When applied as electrode for supercapacitor, the NiCo2S4 microspheres obtained under optimal condition delivered a high capacitance (1386 F g−1 at 1 A g−1), excellent rate capability (845 F g−1 at 10 A g−1) and stable cycling performance (80.05% after 5000 cycles at 10 A/g). Furthermore, for checking the practicality of the produced NiCo2S4 microspheres, an asymmetric supercapacitor device was built using activated carbon (AC) as the negative electrode and NiCo2S4 microspheres as the positive electrode. The assembled NiCo2S4//AC cell had a power density of 799.9 W kg−1 and an energy density of 30.5 Wh kg−1, confirming that the structurally optimized NiCo2S4 porous nanomicrospheres have excellent electrochemical properties and have a wide range of application prospects.

Self-assembled superhydrophilic MOF-decorated membrane for highly efficient treatment and separation mechanism of multi-component emulsions

Complex multi-component pollutant-oil-water emulsions have caused serious environmental problems and increased the difficulty of purification treatment in the last few decades. The membrane based on two-dimensional (2D) materials can rationally control the interlayer distance, thus improved the separation performance of the membrane for complex wastewater. We herein reported a composite membrane, in which 2D metal-organic frameworks (MOFs) Co-CAT-1 with super-hydrophilicity cross-linked by polyethylene imine (PEI) was integrated into graphene oxide (GO) and then coated on polyvinylidene fluoride (PVDF) membrane (CPG membrane). The CPG membrane exhibited highly efficient in separating oil-water (including crude oil) emulsions, achieving a flux of 219 L∙m−2∙h−1∙bar−1 and a separation efficiency of 99.2 %. Moreover, the separation efficiency for complex emulsions after several cycles was maintained >99 % for dyes and 76 % for heavy metal ions (Ni2+, Pb2+, Zn2+). The remarkable fouling resistance and reusability of CPG membrane in purifying complex oil-in-water emulsions can be attributed to their internal cross-linking, electrostatic interactions, hydrogen bonding attraction, and π-π stacking. Molecular dynamics simulations were employed for in-depth studies on the separation processes of dye- and heavy metal ions-emulsions, revealing the mechanisms of mass transfer within the membrane. This work aims to construct stable and multifunctional membranes for separating pollutant-oil-water emulsions with multi-component.

Nano-composite rGO-Ag-Cu-Ni mediated photocatalytic degradation of anthracene and benzene

Polycyclic aromatic hydrocarbons (PAHs) are omnipresent, persistent, and carcinogenic pollutants continuously released in the atmosphere due to the rapid increase in population and industrialization worldwide. Hence, there is an ultimate rise in concern about eliminating the toxic PAHs and their related aromatic hydrocarbons from the air, water, and soil environment by employing efficient removal technologies using nanoparticles as a catalyst. Here, the degradation of selective PAHs viz., anthracene and benzene using laboratory synthesized rGO-Ag-Cu-Ni nanocomposite (catalyst) was studied. Characterization studies revealed the nanocomposites exhibited surface plasma resonance at 350 - 450 nm, confirming the presence of Ag, Cu, and Ni metal ions embedded on the reduced graphene substrate. It was found that the nanocomposites synthesized were spherical, amorphous in nature, and aggregated together with measurements ranging from 423 to 477 nm. An SEM-EDX analysis of the nanocomposite demonstrated that it contained 25.13% O, 14.24% Ni, 27.79% Cu, and 32.84% Ag, which confirms the synthesis of the nanocomposite. Crystalline, sharp nanocomposites of average size 17–41 nm with an average diameter of 118.5 nm (X-ray diffraction and DLS) were observed. FTIR spectra showed that the nanocomposites had the functional groups alkanes, alkenes, alkynes, carboxylic acids, and halogen derivatives. Batch adsorption studies revealed that the maximum degradation achieved at optimum nano-composite concentration of 10 μg/mL, pH value of 5, PAHs concentration of 2 μg/mL and effective irradiation source being UV radiations in the case of both benzene and anthracene pollutants. The degradation of benzene and anthracene followed Freundlich & Langmuir isotherm with the highest R2 value of 0.9894 & 0.9885, respectively. Adsorption kinetic studies under optimum conditions revealed that the adsorption of both benzene and anthracene followed Pseudo-second order kinetics. Antimicrobial studies revealed that the synthesized nano-composite exhibited potential antimicrobial activity against Gram positive bacterium (Bacillus subtilis, Staphylococcus aureus), Gram negative bacterium (Klebsiella pneumonia, Escherichia coli) and fungal strain (Aspergillus niger) respectively. Thus, the synthesized rGO-Ag-Cu-Ni nano-composite acts as an effective antimicrobial agent as well as a PAHs degrading agent, helping to overcome antibiotics resistance and to mitigate the overgrowing PAHs pollution in the environment.

Trace tiny NiCo alloy nanoparticles encapsulated on hierarchical porous peanut-like carbon walls for robust oxygen evolution reaction

The fine regulation of the porous structure and morphology of biomass-like carbon is a promising strategy to realize rapid catalytic reaction kinetics. Herein, we report a universal hydrothermal method to manipulate metal ions (Ni2+, Co2+, and Fe3+) into peanut-like carbon (pC) derived from sucrose. Furthermore, a simple pyrolysis strategy is developed to finely manipulate the porous structure of pC to realize the hierarchical porous structure, large specific surface area, and abundant defects of NiCo@mpNC catalyst, in which highly dispersed trace NiCo alloy nanoparticles are encapsulated with N-doped pC. Particularly, N-doped porous pC consists of massive ultrathin carbon walls, which restrict the growth of tiny NiCo alloy nanoparticles. Therefore, the fabricated NiCo@mpNC inherits superior oxygen evolution reaction (OER) activity with a low overpotential of 278 mV (vs. RHE) at a current density of 10 mA cm−2. Moreover, NiCo@mpNC enables robust electrocatalytic stability (≥ 20 h) at a multi-scale current density of 10, 20, and 50 mA cm−2. The potential decays by only 8 mV after 3000 cyclic voltammetry (CV) cycles. This work opens up a feasible way for the fine design of biomimetic carbon matrix with hierarchical porous structure as typical carriers for high-efficient OER catalysts.