Phase evolution in calcium molybdate nanoparticles as a function of synthesis temperature and its electrochemical effect on energy storage

Modulating nanostructures with polyvinylpyrrolidone: Design and development of a porous, biocompatible, and pH-Stable core-shell magnetic microrobot for demonstrating drug absorption from wastewater

Increased antineoplastic drug concentrations in wastewater stem from ineffective treatment plants and increased usage. Although microrobots are promising for pollutant removal, they face hurdles in developing a superstructure with superior adsorption capabilities, biocompatibility, porosity, and pH stability. This study focused on adjusting the PVP concentration from 0.05 to 0.375 mM during synthesis to create a favorable CMOC structure for drug absorption. Lower PVP concentrations (0.05 mM) yielded a three-dimensional nanoflower structure of CaMoO4 and CuS nanostructures, whereas five-fold concentrations (0.25 mM) produced a porous structure with a dense CuS core encased in a transparent CaMoO4 shell. The magnetically movable and pH-stable COF@CMOC microrobot, achieved by attaching CMOC to cobalt ferrite (CoF) NPs, captured doxorubicin efficiently, with up to 57 % efficiency at 200 ng/mL concentration for 30 min, facilitated by electrostatic interaction, hydrogen bonding, and pore filling of DOX. The results demonstrated that DOX removal through magnetic motion showed superior performance, with an estimated improvement of 57% compared to stirring conditions (17 %). A prototype PDMS microchannel system was developed to study drug absorption and microrobot recovery. The CaMoO4 shell of the microrobots exhibited remarkable robustness, ensuring long-lasting functionality in harsh wastewater environments and improving biocompatibility while safeguarding the CuS core from degradation. Therefore, microrobots are a promising eco-friendly solution for drug extraction. These microrobots show promise for the selective removal of doxorubicin from contaminated wastewater.

One-Dimensional Nickel Molybdate Nanostructures with Enhanced Supercapacitor Performance

One-dimensional NiMoO4 nanofibers were successfully prepared by electrospinning and high-temperature calcination. The supercapacitor performance tests were conducted on the prepared materials in a three-electrode system, and it was found that the calcination temperature during the preparation of the fibers seriously affects the final morphology and electrochemical performance of the obtained samples. The sample with a calcination temperature of 500 °C has better performance, its specific capacitance can reach 1947 F g-1, and the retention rate is 82.35% after 3000 cycles of constant current charging-discharging. The improvement of electrochemical performance is primarily on account of the unique one-dimensional nanostructure of the material, which can both enhance the charge transfer efficiency and effectively increase the speed of electrolyte ion diffusion.

Synthesis, characterization and antifungal potential of titanium dioxide nanoparticles against fungal disease (Ustilago tritici) of wheat (Triticum aestivum L.)

Nanoparticles (NPs) preparation using a green as well as environmentally acceptable processes has achieved a lot of attention in recent decade. The current study compared the synthesis of titania (TiO₂) nanoparticles synthesized from leaf extracts of two plant species (Trianthema portulacastrum, Chenopodium quinoa) and traditional approach by chemical preparation. The effects of no calcination on the physical characteristics of TiO₂ NPs as well as their antifungal effects were examined and compared with the already reported calcinated TiO₂ NPs. The produced TiO₂ NPs were evaluated using high-tech techniques such as X-ray diffraction (XRD), scanning electron microscope, energy dispersive spectroscopy (EDX), and elemental mapping. TiO₂ NPs prepared by sol-gel technique (T1) and prepared from extractions from leaves of T. portulacastrum (T2), and C. quinoa (T3) were either calcinated or non calcinated and tested against fungal disease (Ustilago tritici) of wheat for antifungal efficacy. The -peak (2θ) at 25.3 was confirmed by XRD to be connected with the anatase (101) form in both cases but before calcination, NPs were lacking the rutile and brookite peaks. The results showed that all types of TiO₂ NPs examined had good antifungal activity against U. tritici, but those made from C. quinoa plant extract have good antifungal activity against disease. TiO₂ NPs which are produced by the green methods (T2, T3) have the highest antifungal activity (58%, 57% respectively), while minimal activity (19%) was recorded when NPs were synthesized using the sol-gel method (T1) with 25 μl/mL. Non calcinated TiO₂ NPs have less antifungal potential than calcined TiO₂ NPs. It can be concluded that calcination may be preferred for efficient antifungal activity when using titania nanoparticles. The green technology may be used on a larger scale with less damaging TiO₂ NP production and can be utilized against fungal disease on wheat crop to reduce crop losses worldwide.

Ultrahigh energy-storage density of a lead-free 0.85Bi0.5Na0.5TiO3–0.15Ca(Nb0.5Al0.5)O3 ceramic under low electric fields

Ultrahigh recoverable energy storage density (Wrec = 4.41 J cm−3) and efficiency (η = 88%) at low electric field (210 kV cm−1), over wide frequency (10–100 Hz) and temperature (20–200 °C) were achieved simultaneously for 0.85Bi0.5Na0.5TiO3-0.15Ca(Nb0.5Al0.5)O3 ceramics.

Solution combustion synthesis: the relevant metrics for producing advanced and nanostructured photocatalysts

The current developments and progress in energy and environment-related areas pay special attention to the fabrication of advanced nanomaterials via green and sustainable paths to accomplish chemical circularity. The design and preparation methods of photocatalysts play a prime role in determining the structural, surface characteristics and optoelectronic properties of the final products. The solution combustion synthesis (SCS) technique is a relatively novel, cost-effective, and efficient method for the bulk production of nanostructured materials. SCS-fabricated metal oxides are of great technological importance in photocatalytic, environmental and energy applications. To date, the SCS route has been employed to produce a large variety of solid materials such as metals, sulfides, carbides, nitrides and single or complex metal oxides. This review intends to provide a holistic perspective of the different steps involved in the chemistry of SCS of advanced photocatalysts, and pursues several SCS metrics that influence their photocatalytic performances to establish a feasible approach to design advanced photocatalysts. The study highlights the fundamentals of SCS and the importance of various combustion parameters in the characteristics of the fabricated photocatalysts. Consequently, this work deals with the design of a concise framework to link the fine adjustment of SCS parameters for the development of efficient metal oxide photocatalysts for energy and environmental applications.

A Review of Cobalt-Containing Nanomaterials, Carbon Nanomaterials and Their Composites in Preparation Methods and Application

With the increasing demand for sustainable and green energy, electric energy storage technologies have received enough attention and extensive research. Among them, Li-ion batteries (LIBs) are widely used because of their excellent performance, but in practical applications, the electrochemical performance of electrode materials is not satisfactory. Carbon-based materials with high chemical stability, strong conductivity, high specific surface area, and good capacity retention are traditional anode materials in electrochemical energy storage devices, while cobalt-based nano-materials have been widely used in LIBs anodes because of their high theoretical specific capacity. This paper gives a systematic summary of the state of research of cobalt-containing nanomaterials, carbon nanomaterials, and their composites in LIBs anodes. Moreover, the preparation methods of electrode materials and measures to improve electrochemical performance are also summarized. The electrochemical performance of anode materials can be significantly improved by compounding carbon nanomaterials with cobalt nanomaterials. Composite materials have better electrical conductivity, as well as higher cycle ability and reversibility than single materials, and the synergistic effect between them can explain this phenomenon. In addition, the electrochemical performance of materials can be significantly improved by adjusting the microstructure of materials (especially preparing them into porous structures). Among the different microscopic morphologies of materials, porous structure can provide more positions for chimerism of lithium ions, shorten the diffusion distance between electrons and ions, and thus promote the transfer of lithium ions and the diffusion of electrolytes.

Enhanced NaFe0.5Mn0.5O2/C Nanocomposite as a Cathode for Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have emerged as an alternative candidate in the field of energy storage applications. To achieve the commercial success of SIBs, the designing of active materials is highly important. O3-type layered-NaFe0.5Mn0.5O2 (NFM) materials provide higher specific capacity along with Earth-abundance and low cost. Nevertheless, the material possesses some disadvantages, such as a low rate capability and severe capacity fading during cycling. To overcome such drawbacks, composite O3-type layered NFM with carbon has been prepared for the cathode electrode of SIBs through a facile solution combustion method followed by calcination process. The introduction of carbon sources into NFM material provides excellent electrochemical performances; moreover, the practical limitations of NFM material such as low electrical conductivity, structural degradation, and cycle life are effectively controlled by introducing carbon sources into the host material. The NFM/C-2 material delivers the specific charge capacities of 171, 178, and 166 mA h g-1; and specific discharge capacities of 188, 169, and 162 mA h g-1, in the first 3 cycles, respectively.

Zirconia Toughened Alumina-Based Separator Membrane for Advanced Alkaline Water Electrolyzer

Hydrogen is nowadays considered a favorable and attractive energy carrier fuel to replace other fuels that cause global warming problems. Water electrolysis has attracted the attention of researchers to produce green hydrogen mainly for the accumulation of renewable energy. Hydrogen can be safely used as a bridge to successfully connect the energy demand and supply divisions. An alkaline water electrolysis system owing to its low cost can efficiently use renewable energy sources on large scale. Normally organic/inorganic composite porous separator membranes have been employed as a membrane for alkaline water electrolyzers. However, the separator membranes exhibit high ionic resistance and low gas resistance values, resulting in lower efficiency and raised safety issues as well. Here, in this study, we report that zirconia toughened alumina (ZTA)-based separator membrane exhibits less ohmic resistance 0.15 Ω·cm2 and low hydrogen gas permeability 10.7 × 10-12 mol cm-1 s-1 bar-1 in 30 wt.% KOH solution, which outperforms the commercial, state-of-the-art Zirfon® PERL separator. The cell containing ZTA and advanced catalysts exhibit an excellent performance of 2.1 V at 2000 mA/cm2 at 30 wt.% KOH and 80 °C, which is comparable with PEM electrolysis. These improved results show that AWEs equipped with ZTA separators could be superior in performance to PEM electrolysis.

A green low-temperature preparation of iron molybdate with durable electrochemical performances

Herein, nano-Fe2(MoO4)3 (FMO) has been prepared by a green sol–gel route at a low temperature (350 °C), which is far below the conventional value (above 650 °C).

Elucidating the electronic structures of β-Ag2MoO4 and Ag2O nanocrystals via theoretical and experimental approaches towards electrochemical water splitting and CO2 reduction

In this paper, we demonstrate a combined theoretical and experimental study on the electronic structure, and the optical and electrochemical properties of β-Ag2MoO4 and Ag2O. These crystals were synthesized using the hydrothermal method and were characterized using X-ray diffraction (XRD), Rietveld refinement, and TEM techniques. XRD and Rietveld results confirmed that β-Ag2MoO4 has a spinel-type cubic structure. The optical properties were investigated by UV-Vis spectroscopy. DFT+U formalism, via on-site Coulomb corrections for the d orbital electrons of Ag and Mo atoms (Ud) and the 2p orbital electrons of O atoms (Up) provided an improved band gap for β-Ag2MoO4. Examination of the density of states revealed the energy states in the valence and conduction bands of the β-Ag2MoO4 and Ag2O. The theoretical band structure indicated an indirect band gap of approximately 3.41 eV. Furthermore, CO2 electroreduction, and hydrogen and oxygen evolution reactions on the surface of β-Ag2MoO4 and Ag2O were studied and a comparative investigation on molybdate-derived silver and oxide-derived silver was performed. The electrochemical results demonstrate that β-Ag2MoO4 and Ag2O can be good electrocatalysts for water splitting and CO2 reduction. The CO2 electroreduction results also indicate that CO2 reduction intermediates adsorbed strongly on the surface of Ag2O, which increased the overpotential for the hydrogen evolution reaction on the surface of Ag2O by as much as 0.68 V against the value of 0.6 V for Ag2MoO4, at a current density of -1.0 mA cm-2.

Phase transformation in tungsten oxide nanoplates as a function of post-annealing temperature and its electrochemical influence on energy storage

The morphology and crystal structure of electrode materials have an enormous impact on their electrochemical properties for employment in supercapacitors for various applications. In this study, the transformations of the crystal structure of WO3·H2O nanoplates were conducted by post-annealing at 200 °C and 400 °C. The morphological and structural evolution of the electrodes was studied via FEG-SEM, HRTEM, FTIR, XRD, and Raman spectroscopy. The phase transition and enhanced degree of crystallinity were observed with increasing temperature. The orthorhombic structures of the hydrate WO3·H2O (W80), the mixed-phase with mesoporous structure (W200), and finally the monoclinic phase of WO3 structures (W400) were achieved at annealing temperatures of 80 °C, 200 °C, and 400 °C respectively. The electrochemical performance of electrode W200 showed the highest specific capacitance of 606 F g-1 as compared to electrode W80 (361 F g-1), and was two-fold greater than electrode W400 (302 F g-1) at a current density of 1 A g-1. Moreover, electrode W200 exhibited excellent cyclic stability of 89% at an ultrahigh scan rate of 100 mV s-1 after 4000 cycles. The results highlight that the mixed-phase WO3 nanoplates would make a suitable electrode material for supercapacitors with desired electrochemical features.

Synthesis, Characterization, and Analysis of Hybrid Carbon Nanotubes by Chemical Vapor Deposition: Application for Aluminum Removal

Hybrid carbon nanotubes (CNTs) are grown on biomass powder-activated carbon (bio-PAC) by loading iron nanoparticles (Fe) as catalyst templates using chemical vapor deposition (CVD) and using acetylene as carbon source, under specific conditions as reaction temperature, time, and gas ratio that are 550 °C, 47 min, and 1, respectively. Specifications of hybrid CNTs were analyzed and characterized using field emission scanning electron microscope (FESEM) with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopic (TEM), Fourier-transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area Brunauer-Emmett-Teller (BET), and zeta potential. The results revealed the high quality and unique morphologies of hybrid CNTs. Furthermore, removal and capacity of Al3+ were optimized by response surface methodology (RSM). However, the results revealed that the pseudo-second-order model well represented adsorption kinetic data, while the isotherm data were effectively fitted using a Freundlich model. The maximum adsorption capacity was 347.88 mg/g. It could be concluded that synthesized hybrid CNTs are a new cost-effective and promising adsorbent for removing Al3+ ion from wastewater.

Coupling Magnetic Single-Crystal Co2 Mo3 O8 with Ultrathin Nitrogen-Rich Carbon Layer for Oxygen Evolution Reaction

Transition-metal oxides as electrocatalysts for the oxygen evolution reaction (OER) provide a promising route to face the energy and environmental crisis issues. Although palmeirite oxide A₂ Mo₃ O₈ as OER catalyst has been explored, the correlation between its active sites (tetrahedral or octahedral) and OER performance has been elusive. Now, magnetic Co₂ Mo₃ O₈ @NC-800 composed of highly crystallized Co₂ Mo₃ O₈ nanosheets and ultrathin N-rich carbon layer is shown to be an efficient OER catalyst. The catalyst exhibits favorable performance with an overpotential of 331 mV@10 mA cm^-2 and 422 mV@40 mA cm^-2 , and a full water-splitting electrolyzer with it as anode catalyst shows a cell voltage of 1.67 V@10 mA cm^-2 in alkaline. Combined HAADFSTEM, magnetic, and computational results show that factors influencing the OER performance can be attributed to the tetrahedral Co sites (high spin, t₂ ³ e⁴ ), which improve the OER kinetics of rate-determining step to form *OOH.

Traditional salt-in-water electrolyte vs. water-in-salt electrolyte with binary metal oxide for symmetric supercapacitors: capacitive vs. faradaic

The electrochemical energy storage of lithium and sodium ions from aqueous solutions in binary metal oxides is of great interest for renewable energy storage applications. Binary metal oxides are of interest for aqueous energy storage due to their better structural stability and electronic conductivity and tunability of redox potentials. They have also been widely studied as novel electrodes for supercapacitors. The interactions between water and lithium/sodium ions, and water and binary metal oxide surface determine the electrochemical reactions and their long-term stability. Our results indicate that the aqueous sodium electrolyte has a stronger influence on the capacitance and cycling stability of the binary (Ca and Mo) metal oxide electrode than its lithium cousin. The symmetric cell in a two-electrode configuration was assembled with the proposed binary metal oxide, which shows an average discharge voltage of 1.2 V, delivering a specific capacitance of 72 F g-1 at a specific energy density of 32 W h kg-1 based on the total mass of the active materials. The development of highly concentrated aqueous electrolytes such as the "water-in-salt" electrolyte showed a larger electrochemical (voltage) window with enhanced storage capacitance for increasing the salt concentrations has also been discussed.

Ab Initio-Based Structural and Thermodynamic Aspects of the Electrochemical Lithiation of Silicon Nanoparticles

We reported the theoretical understandings of the detailed structural and thermodynamic mechanism of the actual lithiation process of silicon nanoparticle systems based on atomistic simulation approaches. We found that the rearrangement of the Si bonding network is the key mechanism of the lithiation process, and that it is less frequently broken by lithiation in the smaller sizes of Si nanoparticles. The decreased lithiation ability of the Si nanoparticles results in the lithiation potential being significantly lower than that of crystalline silicon phases, which impedes the full usage of the theoretical maximum capacity. Thus, nanosized Si materials could have a negative effect on performance if they become too fine-sized. These findings provide a detailed view of the electrochemical lithiation process of silicon nanoparticles (Si NPs) and engineering guidelines for designing new Si-based nanostructured materials.

Seaweed-Liked WS₂/rGO Enabling Ultralong Cycling Life and Enhanced Rate Capability for Lithium-Ion Batteries

WS₂ is considered as a potential anode material for lithium ion batteries (LIBs) with superior theoretical capacity and stable structure with two-dimensional which facilitates to the transportation and storage of lithium ion. Nevertheless, the commercial recognition of WS₂ has been impeded by the intrinsic properties of WS₂, including poor electrical conductivity and large volume expansion. Herein, a seaweed-liked WS₂/reduced graphene oxide (rGO) composites has been fabricated through a procedure involving the self-assembling of WO₄2-, hexadecyl trimethyl ammonium ion with graphene oxide (GO) and the subsequent thermal treatment. The WS₂/rGO nanocomposite exhibited the outstanding electrochemical property with a stable and remarkable capacity (507.7 mAh·g-1) at 1.0 A·g-1 even after 1000 cycles. This advanced electrochemical property is due to its seaweed-liked feature which can bring in plentiful active sites, ameliorate the stresses arisen from volume variations and increase charge transfer rate.