High-Performance Memristive Synapse Composed of Ferroelectric ZnVO-Based Schottky Junction.

In pursuit of realizing neuromorphic computing devices, we demonstrated the high-performance synaptic functions on the top-to-bottom Au/ZnVO/Pt two-terminal ferroelectric Schottky junction (FSJ) device architecture. The active layer of ZnVO exhibited the ferroelectric characteristics because of the broken lattice-translational symmetry, arising from the incorporation of smaller V5+ ions into smaller Zn2+ host lattice sites. The fabricated FSJ devices displayed an asymmetric hysteresis behavior attributed to the ferroelectric polarization-dependent Schottky field-emission rate difference in between positive and negative bias voltage regions. Additionally, it was observed that the magnitude of the on-state current could be systematically controlled by changing either the amplitude or the width of the applied voltage pulses. Owing to these voltage pulse-tunable multi-state memory characteristics, the device revealed diverse synaptic functions such as short-term memory, dynamic range-tunable long-term memory, and versatile rules in spike time-dependent synaptic plasticity. For the pattern-recognition simulation, furthermore, more than 95% accuracy was recorded when using the optimized experimental device parameters. These findings suggest the ZnVO-based FSJ device holds significant promise for application in next-generation brain-inspired neuromorphic computing systems.

Nitrogen-Doped CuO@CuS Core-Shell Structure for Highly Efficient Catalytic OER Application.

Water electrolysis is a highly efficient route to produce ideally clean H2 fuel with excellent energy conversion efficiency and high gravimetric energy density, without producing carbon traces, unlike steam methane reforming, and it resolves the issues of environmental contamination via replacing the conventional fossil fuel. Particular importance lies in the advancement of highly effective non-precious catalysts for the oxygen evolution reaction (OER). The electrocatalytic activity of an active catalyst mainly depends on the material conductivity, accessible catalytically active sites, and intrinsic OER reaction kinetics, which can be tuned via introducing N heteroatoms in the catalyst structure. Herein, the efficacious nitrogenation of CuS was accomplished, synthesized using a hydrothermal procedure, and characterized for its electrocatalytic activity towards OER. The nitrogen-doped CuO@CuS (N,CuO@CuS) electrocatalyst exhibited superior OER activity compared to pristine CuS (268 and 602 mV), achieving a low overpotential of 240 and 392 mV at a current density of 10 and 100 mA/cm2, respectively, ascribed to the favorable electronic structural modification triggered by nitrogen incorporation. The N,CuO@CuS also exhibits excellent endurance under varied current rates and a static potential response over 25 h with stability measured at 10 and 100 mA/cm2.

Ultrasonic processing of WO3 nanosheets integrated Ti3C2 MXene 2D-2D based heterojunctions with synergistic effects for enhanced water splitting and environmental remediation.

This article describes a straightforward chemical procedure that involves hydrothermal and ultrasonic treatments to create a new 2D/2D ultrathin WO3/Ti3C2 heterojunctions. The features of the fabricated heterojunctions were characterized and examined by field emission electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), optical absorption spectroscopy (UV-Vis). By photodegrading an organic dye under the influence of visible light, the photocatalytic degradation capabilities of the heterojunctions were also investigated. The performance of WO3/Ti3C2 was superior to that of bare WO3, with a removal rate of 94% and a kinetic rate constant (k) that was approximately 3 times that of WO3. The creation of 2D/2D heterojunction was observed to encourage the spatial charge separation and increase the surface reactive sites, to result with the increased photocatalytic activity in WO3/Ti3C2 heterojunction. The photocurrent values discovered through photoelectrochemical studies further indicated Ti3C2's active function in enhancing water-splitting performance. The impedance analysis examined by an electrochemical method revealed that heterojunctions might be helpful in accelerating the migration of charges quickly to get the outcomes seen.

Metal-free electrocatalytic nanocomposites of poly azovan blue-decorated graphitic carbon nitride for simultaneously sensing paracetamol and 4-aminophenol.

Excessive consumption of paracetamol (PA) and 4-aminophenol (4-AP) can have harmful effects on the human body. This study developed a novel electroanalytical technique that utilizes the nanocomposites of poly azovan blue (PAB)-decorated graphitic carbon nitride (g-C3N4), deposited onto a screen-printed carbon electrode (SPCE), for the concurrent sensing of PA and 4-AP. The fabricated g-C3N4@PAB/SPCE exhibited exceptional synergistic effects, such as a high active electrochemical surface area and excellent electron transfer properties. The electrochemical behavior of g-C3N4@PAB/SPCE for simultaneous PA and 4-AP sensing was evaluated in the linear dynamic ranges of 0.08-75 and 0.05-90 µM, with the detection limits (S/N = 3) of 0.011 and 0.016 µM and sensitivities of 2.974 and 2.857 µA/µM/cm-2 for PA and 4-AP, respectively. Additionally, g-C3N4@PAB/SPCE showed long-term stability, high reproducibility (RSD = 2.17%, n = 4), and superior anti-interference capabilities. Finally, when g-C3N4@PAB/SPCE was tested for simultaneously sensing both PA and 4-AP in tap water and artificial urine models, it exhibited satisfactory recoveries, demonstrating its potential use for various industrial and clinical applications.

Fabrication of Ru loaded MgB2 with guar gum hybrid for photocatalytic degradation of crystal violet.

Today, dyes/pigment-based materials are confronting a serious issue in harming marine ecology. Annihilate these serious water pollutants using photoactive 2D nanohybrid catalysts showed promising comparativeness over available photocatalysts. In the present work, a facile route to decorate Ruthenium (Ru) on 2D MgB2 flower-like nanostructures was developed via ecofriendly guar gum biopolymer substantial template (MgB2/GG@Ru NFS) and its photocatalytic performance was reported. Synthesis of MgB2@Ru, MgB2/GG@Ru NFS and commercial MgB2, was studied by FTIR, XRD, FE-SEM, EDX, AFM, TEM, UV-vis spectra, and XPS analysis. From the results, the MgB2/GG@Ru NFS exhibited a superior photocatalytic performance (99.7 %) than its precursors MgB2@Ru (79.7 %), and MgB2 (53.7 %), with the degradation efficiency of the crystal violet (CV) within 100 min under visible light irradiation. The proposed photo-catalyst MgB2/GG@Ru NFS showed negligible loss of photocatalytic activity even after five successive cycles, revealing its reusability and enhanced stability due to the network structure. The photocatalytic mechanism for MgB2/GG@Ru NFS was evaluated by trapping experiment of active species, verifying that superoxide (O2-) and electron (e-) contributed significant role in the dye degradation.

Self-Assembly of Copper Oxide Interfaced MnO2 for Oxygen Evolution Reaction.

Designing efficient electrocatalytic systems through facile synthesis remains a formidable task. To address this issue, this paper presents the design of a combination material comprising two transition metal oxides (copper oxide and manganese oxide (CuO/MnO2)), synthesized using a conventional microwave technique to efficiently engage as an active oxygen evolution reaction (OER) catalyst. The structural and morphological properties of the composite were confirmed by the aid of X-ray diffraction (XRD) studies, field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive spectrometry (EDS). FESEM clearly indicated well-aligned interlacing of CuO with MnO2. The OER performance was carried out in 1 M KOH. The assembled CuO/MnO2 delivered a benchmark current density (j = 10 mA cm-2) at a minimal overpotential (η = 294 mV), while pristine CuO required a high η (316 mV). Additionally, the CuO/MnO2 electrocatalyst exhibited stability for more than 15 h. These enhanced electrochemical performances were attributed to the large volume and expanded diameter of the pores, which offer ample surface area for catalytic reactions to boost OER. Furthermore, the rate kinetics of the OER are favored in composite due to low Tafel slope (77 mV/dec) compared to CuO (80 mV/dec).

Mechanochemically interlocked cubane copper complex interface for WOLED.

In the rapid development of organic light-emitting diodes (OLEDs), phosphorescent transition metal complexes have played a crucial role as the most promising candidates for next generation display and lighting applications. However, most devices are fabricated using iridium and platinum-based complexes which are expensive and available in very limited quantities, whereas using relatively abundant organometallic complexes for fabrication results mostly in inefficient performance results. To overcome these issues, we have synthesized tetra copper iodide with tetra triphenyl cage like structure (denoted as CIPh) as an emerging class of luminescent material by mechanochemical grinding followed by thermal treatment for application in white OLED. The CIPh complex exhibits considerable quantum yield and a millisecond decay lifetime. Phosphorescent OLEDs were fabricated using CIPh complex as emitter shows a remarkable performance with external quantum efficiency and current efficiency of 5.28 % and 22.76 cd/A, with a high brightness of 4200 cd m-2, respectively. White OLEDs were also fabricated with a fluorescent blue and phosphorescent red emitted with (CIPh) as green emitter and achieved an impressive CRI of 82 with an EQE of over 3 %. This is the first ever attempt at fabricating WOLEDs using organocopper complex.

In Situ Facile Synthesis of Low-Cost Biogenic Eggshell-Derived Nanohydroxyapatite/Chitosan Biocomposites for Orthopedic Implant Applications.

In situ facile synthesis and the characterization of nanohydroxyapatite/chitosan (nHAP/CS) biocomposites were investigated for examining their potential applications in orthopedic implant technology. Firstly, the bare nHAP, europium-doped hydroxyapatite (Eu-nHAP), yttrium-doped hydroxyapatite (Y-nHAP), and Eu- and Y-codoped hydroxyapatite (Eu,Y-nHAP) nanoparticles were synthesized by the wet precipitation technique using biowaste-eggshell-derived calcium oxide powders. Then, through ultrasonication using the nanohydroxyapatite/chitosan mixtures (molar ratio = 1:2), the nHAP/CS, Eu-nHAP/CS, Y-nHAP/CS, and Eu,Y-nHAP/CS biocomposites were fabricated. Among them, Eu,Y-nHAP/CS showed higher cell viability (94.9%), higher solubility (pH = 7.6 after 21 days), and greater antibacterial activity than those of the other composites. In addition, Eu,Y-nHAP/CS exhibited improved mechanical properties compared with the other composites. For example, the nanoindentation test displayed the Eu,Y-nHAP/CS-coated 316L stainless steel implant to possess a higher Young's modulus value (9.24 GPa) and greater hardness value (300.71 MPa) than those of the others. The results indicate that the biomass-eggshell-derived Eu,Y-doped nHAP is of good use for orthopedic implant applications.

Enhanced photocatalytic crystal-violet degradation performances of sonochemically-synthesized AC-CeO2 nanocomposites.

Semiconductor-based photocatalysis is one of the favorable techniques for the wastewater treatment. Herein, we synthesized the activated carbon-decorated cerium dioxide (AC-CeO2) nanocomposites via the facile ultrasonication method by using the biomass-derived AC nanoflakes and the sonochemically-synthesized CeO2 nanoparticles. The AC-CeO2 nanocomposites exhibited the aggregated morphology with the AC nanoflakes-anchored CeO2 nanoparticles. Since the hybridization of conductive AC and semiconductive CeO2 would lead to the increased photocarrier transport and the reduced photocarrier recombination, during the photocatalytic reaction, the AC-CeO2 nanocomposites showed the enhanced crystal violet dye-degradation efficiency up to 97.9 % within 135 min. The results suggest that the AC-CeO2 nanocomposites hold promise as a prominent photocatalyst for future green environmental technology.

Excellent Electrocatalytic Hydrogen Evolution Reaction Performances of Partially Graphitized Activated-Carbon Nanobundles Derived from Biomass Human Hair Wastes.

Carbonaceous materials play a vital role as an appropriate catalyst for electrocatalytic hydrogen production. Aiming at realizing the highly efficient hydrogen evolution reaction (HER), the partially graphitized activated-carbon nanobundles were synthesized as a high-performance HER electrocatalyst by using biomass human hair ashes through the high-temperature KOH activation at two different temperatures of 600 and 700 °C. Due to the partial graphitization, the 700 °C KOH-activated partially graphitized activated-carbon nanobundles exhibited higher electrical conductivity as well as higher textural porosity than those of the amorphous activated-carbon nanobundles that had been prepared by the KOH activation at 600 °C. As a consequence, the 700 °C-activated partially graphitized activated-carbon nanobundles showed the extraordinarily high HER activity with the very low overpotential (≈16 mV at 10 mA/cm2 in 0.5 M H2SO4) and the small Tafel slope (≈51 mV/dec). These results suggest that the human hair-derived partially graphitized activated-carbon nanobundles can be effectively utilized as a high-performance HER electrocatalyst in future hydrogen-energy technology.

Graphitic carbon-encapsulated V2O5 nanocomposites as a superb photocatalyst for crystal violet degradation.

To materialize the excellent photocatalyst for crystal violet dye-degradation, the graphitic carbon-encapsulated vanadium pentoxide (GC-V2O5) nanocomposites were synthesized through the simple sonication method by using the green tea waste-derived GC nanoflakes and the sonochemically synthesized V2O5 nanorods. The nanocomposites were confirmed to comprise an aggregated morphology, in which the orthorhombic V2O5 nanorods were well anchored with the intertwingled GC nanoflakes. Owing to the encapsulation of defective V2O5 by conductive GC, the GC-V2O5 nanocomposites exhibited the enhanced photocatalytic dye-degradation efficiency up to 98.4% within 105 min. Namely, the encapsulated GC nanosheets might compensate the native defects (i.e., charge traps) on the V2O5 surface; hence, the charge transport could be enhanced during the dye-degradation process while the photocarrier recombination could be suppressed. The results suggest the conducting layer-encapsulated semiconducting oxide nanocomposites (e.g., GC-V2O5) to be of good use for future green environmental technology, particularly, as a superb photocatalyst for dye degradation.

TriMOF synergized on the surface of activated carbon produced from pineapple leaves for the environmental pollutant reduction and oxygen evolution process.

Facile and modest synthesis of significantly effective and less-cost catalysts for environmental pollutant degradation and oxygen evolution holds substantial potential in environmental and energy fields. Hereby, Trimetallic organic frameworks (TriMOF) consisting of Fe, Co, and Zn synergized on the surface of activated carbon (AC) from pineapple leaves tend to show exponential catalytic activity due to the more excellent ionic conductivity, catalytic stability and multiple active sites provided by different metal precursors. Furthermore, the developed nanocomposite was coated on the stainless-steel electrode substrate at room temperature, delivering greater electrocatalytic surface area and numerous active sites. The oxidation reaction kinetics drives the catalytic reduction of 4-nitrophenol to 4-aminophenol with a minimal time of 12 min @ >97 % efficiency. Furthermore, on electrocatalytic oxidation of water splitting process due to the presence of multiple metallic, active sites, the overpotential is at 370 mV having Tafel slope of 40 mV/dec and electrochemically active surface area of is 9.9 mF/cm2. This superior catalytic reduction of 4-nitrophenol and electrocatalytic water oxidation process is attributed to the developed composite's active centre and conductivity.

Excellent photocatalytic performances of Co3O4-AC nanocomposites for H2 production via wastewater splitting.

Natural sunlight-driven photocatalytic hydrogen production from wastewater is one of the most desirable techniques that can realize future green energy technology. Herein, we report the synthesis and the characterization of the biomass activated carbon (AC)-decorated cobalt oxide (Co3O4) nanocomposites for solar-stimulated photocatalytic hydrogen production from sulphide wastewater. The Co3O4-AC nanocomposites were ultrasonically synthesized by using hydrothermally-grown spinel Co3O4 nanoflakes and biomass-derived AC nanoflakes. Co3O4-AC showed a nanobundle-like aggregated morphology, and exhibited a large specific surface area (~133 m2/g). Through utilizing Co3O4-AC as a photocatalyst for photocatalytic splitting of sulphide wastewater (0.2 M) under solar irradiance with 730 W/m2, an enhanced H2 production efficiency (~70 mL/h) was achieved owing to the synergic effects from 2-dimentionally configured Co3O4 and AC microstructures; i.e., large surface area of Co3O4 and high electrical conductivity of AC. These findings suggest the nanocomposites of Co3O4-AC to hold great promise for the green approach of photocatalytic wastewater splitting.

Derivation of Luminescent Mesoporous Silicon Nanocrystals from Biomass Rice Husks by Facile Magnesiothermic Reduction.

High-quality silicon (Si) nanocrystals that simultaneously had superior mesoporous and luminescent characteristics were derived from sticky, red, and brown rice husks via the facile and cost-effective magnesiothermic reduction method. The Si nanocrystals were confirmed to comprise an aggregated morphology with spherical nanocrystals (e.g., average sizes of 15-50 nm). Due to the surface functional groups formed at the nanocrystalline Si surfaces, the Si nanocrystals clearly exhibited multiple luminescence peaks in visible-wavelength regions (i.e., blue, green, and yellow light). Among the synthesized Si nanocrystals, additionally, the brown rice husk (BRH)-derived Si nanocrystals showed to have a strong UV absorption and a high porosity (i.e., large specific surface area: 265.6 m2/g, small average pore diameter: 1.91 nm, and large total pore volume: 0.5389 cm3/g). These are indicative of the excellent optical and textural characteristics of the BRH-derived Si nanocrystals, compared to previously reported biomass-derived Si nanocrystals. The results suggest that the biomass BRH-derived Si nanocrystals hold great potential as an active source material for optoelectronic devices as well as a highly efficient catalyst or photocatalyst for energy conversion devices.

One-Pot Synthesized Biomass C-Si Nanocomposites as an Anodic Material for High-Performance Sodium-Ion Battery.

Aiming at materializing an excellent anodic source material of the high-performance sodium-ion battery (SIB), we fabricated the biomass carbon-silicon (C-Si) nanocomposites by the one-pot synthesis of facile magnesiothermic reduction using brown rice husk ashes. The C-Si nanocomposites displayed an aggregated morphology, where the spherical Si nanoparticles (9 nm on average) and the C nanoflakes were encapsulated and decorated with each other. When utilizing the nanocomposites as an SIB anode, a high initial discharge capacity (i.e., 378 mAh/g at 100 mA/g) and a high reversible capacity (i.e., 122 mAh/g at 200 mA/g) were achieved owing to their enhanced electronic and ionic conductivities. Moreover, the SIB device exhibited a high cyclic stability in its Coulombic efficiency (i.e., 98% after 100 charge-discharge cycles at 200 mA/g). These outstanding results depict that the one-pot synthesized biomass C-Si nanocomposites are beneficial for future green energy-storage technology.

Upcycling of Wastewater via Effective Photocatalytic Hydrogen Production Using MnO2 Nanoparticles-Decorated Activated Carbon Nanoflakes.

In the present work, we demonstrated the upcycling technique of effective wastewater treatment via photocatalytic hydrogen production by using the nanocomposites of manganese oxide-decorated activated carbon (MnO2-AC). The nanocomposites were sonochemically synthesized in pure water by utilizing MnO2 nanoparticles and AC nanoflakes that had been prepared through green routes using the extracts of Brassica oleracea and Azadirachta indica, respectively. MnO2-AC nanocomposites were confirmed to exist in the form of nanopebbles with a high specific surface area of ~109 m2/g. When using the MnO2-AC nanocomposites as a photocatalyst for the wastewater treatment, they exhibited highly efficient hydrogen production activity. Namely, the high hydrogen production rate (395 mL/h) was achieved when splitting the synthetic sulphide effluent (S2- = 0.2 M) via the photocatalytic reaction by using MnO2-AC. The results stand for the excellent energy-conversion capability of the MnO2-AC nanocomposites, particularly, for photocatalytic splitting of hydrogen from sulphide wastewater.

Excellent Oxygen Evolution Reaction of Activated Carbon-Anchored NiO Nanotablets Prepared by Green Routes.

A sustainable and efficient electrocatalyst for the oxygen evolution reaction (OER) is vital to realize green and clean hydrogen production technology. Herein, we synthesized the nanocomposites of activated carbon-anchored nickel oxide (AC-NiO) via fully green routes, and characterized their excellent OER performances. The AC-NiO nanocomposites were prepared by the facile sonication method using sonochemically prepared NiO nanoparticles and biomass-derived AC nanosponges. The nanocomposites exhibited an aggregated structure of the AC-NiO nanotablets with an average size of 40 nm. When using the nanotablets as an OER catalyst in 1 M KOH, the sample displayed superb electrocatalytic performances, i.e., a substantially low value of overpotential (320 mV at 10 mA/cm2), a significantly small Tafel slope (49 mV/dec), and a good OER stability (4% decrease of overpotential after 10 h). These outstanding OER characteristics are considered as attributing to the synergetic effects from both the ample surface area of the electrochemically active NiO nanoparticles and the high electrical conductivity of the AC nanosponges. The results pronounce that the fully ecofriendly synthesized AC-NiO nanotablets can play a splendid role as high-performance electrocatalysts for future green energy technology.

Bacterial Compatibility/Toxicity of Biogenic Silica (b-SiO2) Nanoparticles Synthesized from Biomass Rice Husk Ash.

Biogenic silica (b-SiO2) nanopowders from rice husk ash (RHA) were prepared by chemical method and their bacterial compatibility/toxicity was analyzed. The X-ray diffractometry (XRD) patterns of the b-SiO2 nanopowders indicated an amorphous feature due to the absence of any sharp peaks. Micrographs of the b-SiO2 revealed that sticky RHA synthesized SiO2 nanopowder (S1) had clustered spherical nanoparticles (70 nm diameter), while b-SiO2 nanopowder synthesized from red RHA (S2) and b-SiO2 nanopowder synthesized from brown RHA (S3) were purely spherical (20 nm and 10 nm diameter, respectively). Compared to the S1 (11.36 m2g-1) and S2 (234.93 m2g-1) nanopowders, the S3 nanopowders showed the highest surface area (280.16 m2g-1) due to the small particle size and high porosity. The core level of the X-ray photoelectron spectroscopy (XPS) spectra showed that Si was constituted by two components, Si 2p (102.2 eV) and Si 2s (153.8 eV), while Oxygen 1s was observed at 531.8 eV, confirming the formation of SiO2. The anti-bacterial activity of the b-SiO2 nanopowders was investigated using both gram-positive (Escherichia coli) and gram-negative (Staphylococcus aureus) microorganisms. Compared to S2 and S3 silica nanopowders, S1 demonstrated enhanced antibacterial activity. This study signifies the medical, biomedical, clinical, and biological importance and application of RHA-mediated synthesized b-SiO2.

Activated Carbon-Decorated Spherical Silicon Nanocrystal Composites Synchronously-Derived from Rice Husks for Anodic Source of Lithium-Ion Battery.

The nanocomposites of activated-carbon-decorated silicon nanocrystals (ACAC) were synchronously derived in a single step from biomass rice husks, through the simple route of the calcination method together with the magnesiothermic reduction process. The final product, ACAC, exhibited an aggregated structure of activated-carbon-encapsulated nanocrystalline silicon spheres, and reveals a high specific surface area (498.5 m2/g). Owing to the mutualization of advantages from both silicon nanocrystals (i.e., low discharge potential and high specific capacity) and activated carbon (i.e., high porosity and good electrical conductivity), the ACAC nanocomposites are able to play a substantial role as an anodic source material for the lithium-ion battery (LIB). Namely, a high coulombic efficiency (97.5%), a high discharge capacity (716 mAh/g), and a high reversible specific capacity (429 mAh/g after 100 cycles) were accomplished when using ACAC as an LIB anode. The results advocate that the simultaneous synthesis of biomass-derived ACAC is beneficial for green energy-storage device applications.

Substantial LIB Anode Performance of Graphitic Carbon Nanoflakes Derived from Biomass Green-Tea Waste.

Biomass-derived carbonaceous constituents constitute fascinating green technology for electrochemical energy-storage devices. In light of this, interconnected mesoporous graphitic carbon nanoflakes were synthesized by utilizing waste green-tea powders through the sequential steps of air-assisted carbonization, followed by potassium hydroxide activation and water treatment. Green-tea waste-derived graphitic carbon displays an interconnected network of aggregated mesoporous nanoflakes. When using the mesoporous graphitic carbon nanoflakes as an anode material for the lithium-ion battery, an initial capacity of ~706 mAh/g and a reversible discharge capacity of ~400 mAh/g are achieved. Furthermore, the device sustains a large coulombic efficiency up to 96% during 100 operation cycles under the applied current density of 0.1 A/g. These findings depict that the bio-generated mesoporous graphitic carbon nanoflakes could be effectively utilized as a high-quality anode material in lithium-ion battery devices.