Ultrathin, large area ß-Ni(OH)2 crystalline nanosheet as bifunctional electrode material for charge storage and oxygen evolution reaction.

Bifunctional electrode materials are highly desirable for meeting increasing global energy demands and mitigating environmental impact. However, improving the atom-efficiency, scalability, and cost-effectiveness of storage systems, as well as optimizing conversion processes to enhance overall energy utilization and sustainability, remains a significant challenge for their application. Herein, we devised an optimized, facile, economic, and scalable synthesis of large area (cm2), ultrathin (∼2.9 ± 0.3 nm) electroactive nanosheet of ß-Ni(OH)2, which acted as bifunctional electrode material for charge storage and oxygen evolution reaction (OER). The ß-Ni(OH)2 nanosheet electrode shows the volumetric capacity of 2.82 Ah.cm-3(0.82 µAh.cm-2) at the current density of 0.2 mA.cm-2. The device shows a high capacity of 820 mAh.cm-3 with an ultrahigh volumetric energy density of 0.33 Wh.cm-3 at 275.86 W.cm-3 along with promising stability (30,000 cycles). Furthermore, the OER activity of ultrathin ß-Ni(OH)2 exhibits an overpotential (η10) of 308 mV and a Tafel value of 42 mV dec-1 suggesting fast reaction kinetics. The mechanistic studies are enlightened through density functional theory (DFT), which reveals that additional electronic states near the Fermi level enhance activity for both capacitance and OER.

Transformative Dynamics: Self-Assembly of Iron Oxide Hydroxide Nanorods into Iron Oxide Microcubes for Enhanced Perfluoroalkyl Substance Remediation.

We report the controlled synthesis of iron oxide microcubes (IOMCs) through the self-assembly arrays of ferric oxide hydroxide nanorods (NRs). The formation of IOMCs involves a complex interplay of nucleation, self-assembly, and growth mechanisms influenced by time, thermal treatment, and surfactant dynamics. The self-assembly of vertically aligned NRs into IOMCs is controlled by dynamic magnetism properties and capping agents like cetyltrimethylammonium bromide (CTAB), whose concentration and temperature modulation dictate growth kinetics and structural uniformity. These controlled structural growths were obtained via a hydrothermal process at 120 °C at various intervals of 8, 16, 24, and 32 h in the presence of CTAB as the capping agent. In this hydrothermal method, the formation of vertically oriented NR arrays was observed without the presence of ligands, binders, harsh drying techniques, and solvent evaporation. The formation of the self-assembly of NRs to IOMCs is obtained with an increase in saturated magnetization to attain the most stable state. The synthesized IOMCs have a uniform size, quasi-shape, and excellent dispersion. Due to its excellent magnetic and catalytic properties, IOMCs were employed to remove the various emerging pollutants known as per- and polyfluorinated substances (PFAS). Various microscopic and spectroscopic techniques were employed for the characterization and interaction studies of IOMCs with various PFAS. The interaction between IOMCs and perfluoroalkyl substances (PFAS) was investigated, revealing strong adsorption tendencies facilitated by electrostatic interactions, as evidenced by UV-vis and FT-IR spectroscopic studies. Furthermore, the higher magnetic and positive surface charge of IOMCs is responsible for an effective remediation eliminating any secondary pollution with ease of recovery after the sorption interaction studies, thereby making it practically worthwhile.

Agri-waste derived electroactive carbon-iron oxide nanocomposite for oxygen reduction reaction: an experimental and theoretical study.

Herein, we have utilized agri-waste and amalgamating low Fe3+, to develop an economic iron oxide-carbon hybrid-based electrocatalyst for oxygen reduction reaction (ORR) with water as a main product following close to 4e- transfer process. The electrocatalytic activity is justified by electrochemical active surface area, synergetic effect, and density functional theory calculations.

All-Solid-State Supercapacitors Based on Cobalt Magnesium Telluride Microtubes Decorated with Tellurium Nanotubes.

Magnesium (Mg) has received very little exploration on its importance in the realm of battery-type energy storage technologies. They are abundantly present in seawater, and if successfully extracted and utilized in energy storage systems, it could lead to the long-term advancement of human civilization. Here, we fabricated an all-solid-state supercapacitor (ASSSC) using tellurium nanotubes decorated cobalt magnesium telluride microtubes (Te NTs@CoMgTe MTs) clad on nickel foam (NF). Owing to the unique mixed phase hierarchical structure, Te NTs@CoMgTe MTs showcases some advancement in energy storage performance. When tested in a three-electrode system, multiphasic hybrid of elemental Te and metal tellurides, Te NTs@CoMgTe MTs outperforms the monometallic telluride owing to the strong synergistic interaction effect triggered from conductive three components and delivers a long-life span performance up to 15,000 cycles. The fabricated Te NT@CoMgTe MT//AC solid-state device exhibits a maximum areal capacity of 59.2 µAh cm-2 (56.3 mAh g-1) at a current density of 6 mA cm-2 with a maximum energy density of 42.2 Wh kg-1 (46.5 µWh cm-2) at a power density of 6857.1 W kg-1 (7574.6 µW cm-2). The performance of the device is rigid even at different bending angles (0 to 180°) which validates the extensibility of the process for future applications.

Octahedral Pd3Cu7 Catalysts on Diverse Support Materials for Efficient Hydrogen Evolution: Theoretical Investigation and Mechanistic Perspective.

This work showcases a novel strategy for the synthesis of shape-dependent alloy nanostructures with the incorporation of solid substrates, leading to remarkable enhancements in the electrocatalytic performance. Herein, an aqueous medium approach has been used to synthesize an octahedral PdXCuY alloy of different Pd:Cu ratios to better comprehend their electrocatalytic potential. With the aim to outperform high activity and efficient stability, zirconium oxide (ZrO2), graphene oxide nanosheets (GONs), and hexagonal boron nitride nanosheets (hBNNs) solid substrates are occupied to decorate the optimized Pd3Cu7 catalyst with a minimum 5 wt % metal loading. When compared to the counterparts and different ratios, the Pd3Cu7@hBNNs catalyst exhibited an optimal activity for hydrogen evolution reaction (HER). The lower overpotential and Tafel values observed are 64 and 51 mV/dec for Pd3Cu7@hBNNs followed by Pd3Cu7@ZrO2, which showed a 171 mV overpotential and a 98 mV/dec Tafel value, respectively. Meanwhile, the Pd3Cu7@GONs were found to have a 202 mV overpotential and a 110 mV/dec Tafel value. The density functional theory, which achieves a lower free energy (ΔGH*) value for Pd3Cu7@hBNNs than the other catalysts for HER, further supports its excellent performance in achieving the Volmer-Heyrovsky mechanism path. Moreover, the superior HER activity and sturdier resilience after 8 h of stability may be due to the synergy between the metal atoms, monodisperse decoration, and the coordination effect of the support material.

2D Zinc Oxide - Synthesis, Methodologies, Reaction Mechanism, and Applications.

Zinc oxide (ZnO) is a thermally stable n-type semiconducting material. ZnO 2D nanosheets have mainly gained substantial attention due to their unique properties, such as direct bandgap and strong excitonic binding energy at room temperature. These are widely utilized in piezotronics, energy storage, photodetectors, light-emitting diodes, solar cells, gas sensors, and photocatalysis. Notably, the chemical properties and performances of ZnO nanosheets largely depend on the nano-structuring that can be regulated and controlled through modulating synthetic strategies. Two synthetic approaches, top-down and bottom-up, are mainly employed for preparing ZnO 2D nanomaterials. However, owing to better results in producing defect-free nanostructures, homogenous chemical composition, etc., the bottom-up approach is extensively used compared to the top-down method for preparing ZnO 2D nanosheets. This review presents a comprehensive study on designing and developing 2D ZnO nanomaterials, followed by accenting its potential applications. To begin with, various synthetic strategies and attributes of ZnO 2D nanosheets are discussed, followed by focusing on methodologies and reaction mechanisms. Then, their deliberation toward batteries, supercapacitors, electronics/optoelectronics, photocatalysis, sensing, and piezoelectronic platforms are further discussed. Finally, the challenges and future opportunities are featured based on its current development.

VO2 Nanostructures for Batteries and Supercapacitors: A Review.

Vanadium dioxide (VO2 ) received tremendous interest lately due to its unique structural, electronic, and optoelectronic properties. VO2 has been extensively used in electrochromic displays and memristors and its VO2 (B) polymorph is extensively utilized as electrode material in energy storage applications. More studies are focused on VO2 (B) nanostructures which displayed different energy storage behavior than the bulk VO2 . The present review provides a systematic overview of the progress in VO2 nanostructures syntheses and its application in energy storage devices. Herein, a general introduction, discussion about crystal structure, and syntheses of a variety of nanostructures such as nanowires, nanorods, nanobelts, nanotubes, carambola shaped, etc. are summarized. The energy storage application of VO2 nanostructure and its composites are also described in detail and categorically, e.g. Li-ion battery, Na-ion battery, and supercapacitors. The current status and challenges associated with VO2 nanostructures are reported. Finally, light has been shed for the overall performance improvement of VO2 nanostructure as potential electrode material for future application.

Gold Nanorods as an Efficient Substrate for the Detection and Degradation of Pesticides.

The rapid, ultralow detection, degradation, and complete removal of pesticides demand the design of potential substrates. Herein, we discussed gold nanorods (Au NRs) as the potential substrate for the naked eye detection and degradation of two common and broad-spectrum pesticides, chlorpyrifos (CPF) and malathion (MLT), up to 0.15 ppt concentration within 2 min. Under certain environmental conditions, both the pesticides degraded and adsorbed on the surface of Au NRs. The degraded moieties of CPF and MLT on the surface of Au NRs formed side-to-side and end-to-end interactions, respectively, leading to a long-range assembly. This shows that no external agent is required, and only CPF and MLT analytes are quite enough for the formation of assembly of Au NRs. Assembly of Au NRs is confirmed by transmission electron microscopy (TEM) analysis, and degradation is supported by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and gas chromatography-mass spectrometry (GC-MS) analyses. Au NRs were recovered and reused for four consecutive cycles. The fast and ultralow detection of pesticides demonstrates that Au NRs are a potential substrate for the detection and degradation of pesticides.

Modern Chemical Routes for the Controlled Synthesis of Anisotropic Bimetallic Nanostructures and Their Application in Catalysis.

Bimetallic nanoparticles (BNPs) have attracted greater attention compared to its monometallic counterpart because of their chemical/physical properties. The BNPs have a wide range of applications in the fields of health, energy, water, and environment. These properties could be tuned with a number of parameters such as compositions of the bimetallic systems, their preparation method, and morphology. Monodisperse and anisotropic BNPs have gained considerable interest and numerous efforts have been made for the controlled synthesis of bimetallic nanostructures (BNS) of different sizes and shapes. This review offers a brief summary of the various synthetic routes adopted for the synthesis of Palladium(Pd), Platinum(Pt), Nickel(Ni), Gold(Au), Silver(Ag), Iron(Fe), Cobalt(Co), Rhodium(Rh), and Copper(Cu) based transition metal bimetallic anisotropic nanostructures, growth mechanisms e.g., seed mediated co-reduction, hydrothermal, galvanic replacement reactions, and antigalvanic reaction, and their application in the field of catalysis. The effect of surfactant, reducing agent, metal precursors ratio, pH, and reaction temperature for the synthesis of anisotropic nanostructures has been explained with examples. This review further discusses how slight modifications in one of the parameters could alter the growth mechanism, resulting in different anisotropic nanostructures which highly influence the catalytic activity. The progress or modification implied in the synthesis techniques within recent years is focused on in this article. Furthermore, this article discussed the improved activity, stability, and catalytic performance of BNS compared to the monometallic performance. The synthetic strategies reported here established a deeper understanding of the mechanisms and development of sophisticated and controlled BNS for widespread application.

Chemically induced transformation of chemical vapour deposition grown bilayer graphene into fluorinated single-layer diamond.

Notwithstanding the numerous density functional studies on the chemically induced transformation of multilayer graphene into a diamond-like film carried out to date, a comprehensive convincing experimental proof of such a conversion is still lacking. We show that the fluorination of graphene sheets in Bernal (AB)-stacked bilayer graphene grown by chemical vapour deposition on a single-crystal CuNi(111) surface triggers the formation of interlayer carbon-carbon bonds, resulting in a fluorinated diamond monolayer ('F-diamane'). Induced by fluorine chemisorption, the phase transition from (AB)-stacked bilayer graphene to single-layer diamond was studied and verified by X-ray photoelectron, UV photoelectron, Raman, UV-Vis and electron energy loss spectroscopies, transmission electron microscopy and density functional theory calculations.

Paper based field deployable sensor for naked eye monitoring of copper (II) ions; elucidation of binding mechanism by DFT studies.

The study demonstrates the fabrication of test strips made from newly synthesized ortho-Vanillin based colorimetric chemosensor (probe P) that could be employed as field deployable tool for rapid and naked eye detection of Cu2+. Upon addition of Cu2+ to the chemosensor, it exhibits rapid pink color from colorless and can be easily seen through the naked eye. This probe exhibits a remarkable colorimetric "ON" response and the absorbance intensity of the probe enhances significantly in presence of Cu2+. The sensing mechanism has been deduced using FTIR, XPS, LCMS and DFT studies. The binding mechanism of the probe to Cu2+ was substantiated by DFT studies. HOMO of the probe suggests that a high electronic density resides on O, N atoms and thus these are the favorable binding site for the metal ions. Study revealed that the P + Cu2+ complex is -35.64 eV more stable than individual reactants. The Cu2+ binds to the probe in 1:1 stoichiometry with a binding constant of 2.6 × 104 M-1 as calculated by Job's plot and Benesi-Hildebrand plot. The chemosensor shows 1.8 × 10-8 M detection limit, which is considerably lesser than that of the WHO admissible limit of [Cu2+] in drinking water. Possible interfering ions namely Ca2+, Mg2+, Fe2+, Co2+, Ni2+, Cd2+, Hg2+, Mn2+, Al3+ and Cr3+ do not show any appreciable interference in the colorimetric response of the probe towards Cu2+. Particularly, the colorimetric "ON-OFF-ON" responses are proved to be repeated over 5 times by the sequential inclusion of Cu2+ and S2-. Sensitivity of the probe in real-time water and blood samples is found at par with results with AAS and ICP-OES techniques. Further, the reversibility of the probe and the easy fabrication of deployable strips for real-field naked eye detection of Cu2+ suggest importance of synthesized probe.

Remarkably selective biocompatible turn-on fluorescent probe for detection of Fe3+ in human blood samples and cells.

The robust nature of a biocompatible fluorescent probe is demonstrated, by its detection of Fe3+ even after repeated rounds of quenching (reversibility) by acetate in real human blood samples and cells in vitro. Significantly trace levels of Fe3+ ions up to 8.2 nM could be detected, remaining unaffected by the existence of various other metal ions. The obtained results are validated by AAS and ICP-OES methods. A portable test strip is also fabricated for quick on field detection of Fe3+. As iron is a ubiquitous metal in cells and plays a prominent role in biological processes, the use of this probe to image Fe3+ in cells is a substantial development towards biosensing. Cytotoxicity studies also proved the nontoxic nature of this probe.

Colossal grain growth yields single-crystal metal foils by contact-free annealing.

Single-crystal metals have distinctive properties owing to the absence of grain boundaries and strong anisotropy. Commercial single-crystal metals are usually synthesized by bulk crystal growth or by deposition of thin films onto substrates, and they are expensive and small. We prepared extremely large single-crystal metal foils by "contact-free annealing" from commercial polycrystalline foils. The colossal grain growth (up to 32 square centimeters) is achieved by minimizing contact stresses, resulting in a preferred in-plane and out-of-plane crystal orientation, and is driven by surface energy minimization during the rotation of the crystal lattice followed by "consumption" of neighboring grains. Industrial-scale production of single-crystal metal foils is possible as a result of this discovery.

Sodide and Organic Halides Effect Covalent Functionalization of Single-Layer and Bilayer Graphene.

The covalent functionalization of single and bilayer graphene on SiO2 (300 nm)/Si was effected through sequential treatment with the alkalide reductant [K(15-crown-5)2]Na and electrophilic aryl or alkyl halides, of which the iodides proved to be the most reactive. The condensation reactions proceeded at room temperature and afforded the corresponding aryl- or alkyl-appended graphenes. For each sample, Raman and X-ray photoelectron spectroscopies were used to evaluate the degrees and uniformities of functionalization. Statistical analyses of the Raman data revealed that the introduction of the organic moieties was accompanied by sp3-rehybridization of the basal plane atoms. When bilayers consisting of 13C and 12C layers were treated, both the top and bottom sheets were decorated with organic groups. The reaction was followed using Raman spectroscopy, and the mechanism was studied by theoretical calculations. Indicative of its structure and reactivity, 4-pyridyl-decorated single-layer graphene was readily benzylated and appears to be an ideal platform to develop functional materials.

Nanocerium oxide increases the survival of adult rod and cone photoreceptor in culture by abrogating hydrogen peroxide-induced oxidative stress.

In vitro cell culture system for adult rod and cone photoreceptor (PR) is an effective and economical model for screening drug candidates against all kinds of age related retinal blindness. Interestingly, adult PR cells have a limited survival in the culture system, thus preventing full exploitation of this in vitro approach for drug screening applications. The limited survival of the adult PR cells in culture is due to their inherently high oxidative stress and photic injury. Mixed valence-state ceria nanoparticles have the ability to scavenge free radicals and reduce oxidative stress. Here, ceria nanoparticles of 5-10 nm dimensions have been synthesized, possessing dual oxidation state (+3 and +4) as evident from x-ray photoelectron spectroscopy and exhibiting real time reduction of hydrogen peroxide (H2O2) as quantified by absorbance spectroscopy and cyclic voltammogram analysis. Using flow cytometry and cell culture assay, it has been shown that, upon one time addition of 10 nM of nanoceria in the PR culture of the 18 months old adult common carp (Cyprinus carpio) at the time of plating the cells, the oxidative stress caused due to hydrogen peroxide assault could be abrogated. A further single application of nanoceria significantly increases the survival of these fragile cells in the culture, thus paving way for developing a more robust photoreceptor culture model to study the aging photoreceptor cells in a defined condition.

Non-toxicity of water soluble multi-walled carbon nanotube on Escherichia-coli colonies.

Carboxylic acid functionalized water soluble carbon nanotube (wsCNT) shows no toxic effect against the growth of Escherichia-coli (E. coli), a gram-negative bacteria. Treatment up to 8 microg mL(-1) of wsCNT did not show any toxic effect on E. coli growth that was followed by using bacterial growth kinetics and Spread Plate Technique (SPT). The number of E-coli colonies counts with and without wsCNT showed nearly no change and the bacterial growth kinetics in both the cases showing no toxic effect of wsCNT on the growth of E. coli.

Carbon nano-onions for imaging the life cycle of Drosophila melanogaster.

Real-time X-ray or magnetic resonance imaging are known methods used for biomedical diagnosis. By the oral administration of barium meal, X-ray imaging can be extended for use in soft tissue imaging. The oral ingestion of a fluorescent probe is a new approach to imaging a living species. Here, water-soluble carbon nano-onions are introduced as a nontoxic, fluorescent reagent enabling Drosophila melanogaster (fruit flies) to be imaged alive. It is demonstrated that these water-soluble carbon nano-onions, synthesized from wood waste, colorfully image all the development phases of Drosophila melanogaster from its egg to adulthood. Oral ingestion of up to 4 ppm of soluble carbon nano-onions allows the optical fluorescence microscopy imaging of all the stages of the fruit fly life cycle without showing any toxic effects. The fluorescent Drosophila melanogaster excretes this fluorescing material upon the withdrawal of carbon nano-onions from its food.

Carbon nanocubes and nanobricks from pyrolysis of rice.

Carbon nanocubes and nanobricks were synthesized by pyrolyzing rice powder at 600 degrees C under nitrogen atmosphere. Purification with concentrated nitric acid introduced approximately 0.1 mol/g of carboxylic acid groups as found by acid-base titrimetric analysis. XRD pattern showed the 0.15 mol/g basic graphitic structure of these nano carbon materials. Their SEM and TEM images revealed cube or brick shaped nano crystals. These nanocrystals are further characterized by FT-IR, Raman, and EDAX analysis. High density wrapping of carboxylated acid groups introduces surface passivation of these nano carbon cubes and nano carbon bricks exhibiting photoluminescence. Solid state electronic spectrum showed several bands in the ultraviolet and visible region and excitation at 336 and 474 nm generates photoluminescence respectively in the ultraviolet and visible region.