Flower-like Nanostructures Research Articles

Robust carbon dots-wrapped NiCo flower-like nanostructures for enhanced triiodide reduction

Replacing traditional counter electrodes (CEs) with Pt-free electrodes is one of the challenges for developing dye-sensitized solar cells (DSCs). Herein, we successfully synthesized carbon dots-wrapped NiCo flower-like nanostructure (NiCo/Cdots) and evaluated its application as CEs for DSCs. To characterize as-prepared materials, we conducted FESEM and TEM-EDS. Cyclic Voltammetry (CV), electrochemical Impedance Spectroscopy (EIS), Bode, and Tafel plots were then used to investigate the electrocatalytic properties of NiCo/Cdots CE. As a result, the as-prepared sample exhibited high electrocatalytic activity, low charger-transfer resistance, and large exchange current density. DSC based on NiCo/Cdots CE was assembled and showed a slightly lower PCE than Pt CE-based DSCs (8.27 and 8.52 %, respectively). However, it provided excellent stability during a long-term performance. These results indicated that CoNi/Cdots is a low-cost, easy-to-fabricate material with high potential as a CE of DSCs.

Fabrication of binary metal–organic frameworks of Ni–Mn@ZIFs(Cox·Zn1−xO) decorated on CF/CuO nanowire for high-performance electrochemical pseudocapacitors

Herein, metal–organic frameworks (MOFs) derived nanoflower-like based binary transition metal (Ni–Mn) are successfully fabricated by a simple synthesis method. The fabricated nanoflower-like structure displays a unique nanoflower-like architecture and internal porous channels constructed by MOF coated on CuO/CF/ZIFs (Cox·Zn1−xO) substrate, which is beneficial for the penetration of electrolyte and electron/ion transportation. The as-prepared CF/CuO/ZIFs (Cox·Zn1−xO)@BMOF(Ni–Mn) electrode materials present significant synergy among transition metal ions, contributing to enhanced electrochemical performances. The as-prepared CF/CuO/ZIFs (Cox·Zn1−xO)@BMOF(Ni–Mn) hybrid nanoflower-like display a high specific capacity of 1249.99 C g−1 at 1 A g−1 and the specific capacitance retention is about 91.74% after 5000 cycles. In addition, the as-assembled CF/CuO/ZIFs (Cox·Zn1−xO)@BMOF(Ni–Mn)//AC asymmetric supercapacitor (ASC) device exhibited a maximum energy density of 21.77 Wh·kg−1 at a power density of 799 W kg−1, and the capacity retention rate after 5000 charge and discharge cycles was 88.52%.

Environmentally-friendly calcite scale mitigation: encapsulation of CDs@ MS composite within membranes framework for nanofiltration

Scale formation caused by the precipitation of sparingly soluble salts such as CaCO3 is a major challenge in membrane-based desalination technologies, leading to flux decline and increased energy costs. Surface modification using nanoscale coatings is a promising approach to mitigate membrane fouling. In this work, we demonstrate the antiscalant properties of a MoS2-carbon quantum dot (CDs@MS-NF) composite with a nanoflower-like structure coating for suppressing calcite scale formation. The CDs@ MS-NF coating was synthesized via a solvothermal method and applied to a polyamide reverse osmosis membrane surface using an in-situ growth technique. Characterization revealed uniform coverage of MoS2 nanosheets decorated with CDs@MS-NF on the membrane surface. Static fouling tests simulating calcium sulfate scaling conditions were conducted to evaluate the antifouling performance. The CDs@MS-NF coated membrane exhibited a flux reduction of only 11 %, compared to 34 % for the unmodified membrane after 24 hours. Further analyses showed a calcite nucleation induction time of 5.2 hours and a critical scaling threshold of 1.8 times the solubility for the CDs@ MS-NF coated membrane, indicating significant inhibition of scale formation. We hypothesize that the CDs@ MS-NF nanocomposite layer alters surface charge and wettability while also catalyzing redox reactions to hinder calcite crystal growth. This work demonstrates that multifunctional two-dimensional nanocomposite coatings can effectively mitigate membrane scaling through multiple synergistic mechanisms.

Dimensional Reduction of Metal-Organic Frameworks for Photocatalytic Synthesis of Fused Tetracyclic Heterocycles.

Heterogeneous palladium catalysts with high efficiency, high Pd atom utilization, simplified separation, and recycle have attracted considerable attention in the field of synthetic chemistry. Herein, we reported a zirconium-based two-dimensional metal-organic framework (2D-MOF)-based Pd(II) photocatalyst (Zr-Ir-Pd) by merging the Ir photosensitizers and Pd(II) species into the skeletons of the 2D-MOF for the Pd(II)-catalyzed oxidation reaction. Morphological and structural characterization identified that Zr-Ir-Pd with a specific nanoflower-like structure consists of ultrathin 2D-MOF nanosheets (3.85 nm). Due to its excellent visible-light response and absorption capability, faster transfer and separation of photogenerated carriers, more accessible Pd active sites, and low mass transfer resistance, Zr-Ir-Pd exhibited boosted photocatalytic activity in catalyzing sterically hindered isocyanide insertion of diarylalkynes for the construction of fused tetracyclic heterocycles, with up to 12 times the Pd catalyst turnover number than the existing catalytic systems. In addition, Zr-Ir-Pd inhibited the competitive agglomeration of Pd(0) species and could be reused at least five times, owing to the stabilization of 2D-MOF on the single-site Pd and Ir sites. Finally, a possible mechanism of the photocatalytic synthesis of fused tetracyclic heterocycles catalyzed by Zr-Ir-Pd was proposed.

Examination of structural and spectrophotometric optical characteristics of nano-like flower quinolinyl carbonyl pyrazole-1-carbodithioate films: a new trend for optoelectronic applications

The current investigation entailed the synthesis of benzyl 5-amino-4-[(1-ethyl-4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)carbonyl]-1H-pyrazole-1-carbodithioate (referred as BAEHQP, compound 2) from 6-ethyl-4,5-dioxo-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carbonitrile (compound 1), followed by its characterization in nanocrystalline thin films produced through thermal evaporation in a high vacuum. Computational and experimental methodologies were employed for this purpose. Density functional theory (DFT) calculations using the B3LYP/6-311++G(d,p) basis set were utilized to predict the HOMO-LUMO gap and evaluate the global reactivity descriptors, elucidating the chemical hardness, kinetic stability, and electron-donating capabilities. X-ray diffraction (XRD) analysis verified the presence of a polycrystalline structure in the BAEHQP powder and indicated an amorphous nature in the thin film. Utilizing the Williamson-Hall formula, the mean crystallite size and microstrain were determined to be 63.36 nm and 0.00667, respectively. Scanning electron microscopy corroborated the nanoflower-like structure, and particle size analysis was conducted to determine the size distribution. The optical properties, encompassing both linear and nonlinear aspects, of BAEHQP thin film were investigated using spectrophotometric methods, delineating band transitions and identifying a fundamental direct energy gap of 2.2 eV. The distinct attributes of thin-film absorption and dispersion were outlined, and the unanticipated findings hold potential implications for advancing the industrialization of photodiode device manufacturing.

Exploring the gas sensing potential of BiOBr0.9I0.1: A highly responsive sensor for ammonia detection at room temperature

Bismuth halide oxides (BiOX, where X = Cl, Br, I) are renowned in photocatalysis for their distinct layered structure, modifiable band gap, and affordability. However, their application in gas sensing has garnered comparatively less research attention. Notably, solid solutions of BiOX demonstrate superior attributes over pure BiOX compounds. BiOBrxI1-x solid solution was successfully synthesized using in situ precipitation method and used as a gas-sensitive material for ammonia (NH3) gas sensor. The structural and compositional integrity of the synthesized samples was meticulously confirmed by X-ray diffraction (XRD), which revealed the coexistence of different BiOBr and BiOI phases. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) provided insights into the morphology, revealing a flower-like nanostructure, which favors the surface reaction rate. The electronic and optical properties of the material were further elucidated by photoluminescence (PL) spectroscopy and ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), which revealed that the band gap is tailored to facilitate the sensitivity and selectivity of ammonia detection. Key properties including surface area and porosity were quantitatively evaluated by Bruner-Emmett-Taylor (BET) analysis and found BiOBr0.9I0.1 sensor to have a specific surface area of 13.08 m2/g. Specifically, the BiOBr0.9I0.1 sensor's response ratio (Ra/Rg) to 100 ppm of ammonia reaches 8, approximately fourfold higher than that of the pure BiOBr sensor. The flower-like morphology of BiOBr0.9I0.1 enhances surface activity and charge transfer efficiency, thereby facilitating greater gas adsorption and elevating sensor performance. The rapid response and recovery times (12/24 s at 30 ppm), low detection threshold (LOD, 0.75 ppm), along with its selectivity and reproducibility at room temperature, position the BiOBr0.9I0.1 material as a promising candidate for ammonia gas detection.

Outstanding performance of flower-like NiO nanostructures in epoxied soybean oil-based polyurethane nanocomposite coatings: Investigation of anticorrosion and antibacterial properties

Nowadays, nanocomposite coatings have gained much attention from both academic and industrial aspects mainly because of the outstanding properties which they can offer simultaneously. Specifically, anti-corrosion properties can make them one of the best choices to solve destructive corrosion problems. Nickel oxide (NiO) nanoparticles have been synthesized to create these outstanding properties in vegetable oil-based polyurethane coatings. To this end, epoxidized soyabean oil was utilized to synthesize polyol and produce polyurethane coatings, and NiO nanoparticles were incorporated into the obtained coatings. The obtained coatings were evaluated through the FTIR, H NMR, and FESEM techniques and their performance in terms of water uptake, anticorrosion and antibacterial properties were investigated. The obtained results clearly showed that the presence of NiO nanoparticles has had an undeniable effect on the performance of the coating in protecting mild steel substrate against corrosion. Moreover, using these nanoparticles has created remarkable antibacterial properties in the coating besides improved mechanical performance compared to pure polyurethane coating.

Zn doping induces rich oxygen vacancies in δ-MnO2 flower-like nanostructures for impressive energy density coin cell supercapacitor

In this work, Zn-doped δ-MnO2 (ZnMO) flower-like nanostructures on carbon fibers are synthesized by one-pot hydrothermal method. It is found that insertion of Zn ions induces oxygen vacancy defects, increase in active sites and conductivity of δ-MnO2 (MO) structure. These features making ZnMO structure an excellent candidate for the fabrication of electrode material for supercapacitors. It has been revealed that ZnMO@CC electrode delivered an enhanced specific capacitance of 667 F g−1 at a current density of 1 A g−1 as compared to the pristine δ-MnO2 and previously reported nanostructures. The developed asymmetric coin cell supercapacitor (ZnMO//AC) obtained a specific capacitance of 116 F g−1 at 1 A g−1 and achieved an outstanding energy density of 71.5 Wh kg−1 at a power density of 1067.1 W kg−1. Moreover, the device retains its initial capacitance of 92 % after 8000 cycles at 8 A g−1. These results suggest that ZnMO could be an emerging electrode material for the fabrication of high-performance supercapacitors for practical applications. This research hunts for new visions for the preparation of MnO2-based material by doping strategy for energy storage applications, especially supercapacitor.

Microwave-Assisted Synthesis of Flower-like MnMoO4 Nanostructures and Their Photocatalytic Performance.

This article describes an affordable method for the synthesis of MnMoO4 nanoflowers through the microwave synthesis approach. By manipulating the reaction parameters like solvent, pH, microwave power, and irradiation duration along this pathway, various nanostructures can be acquired. The synthesized nanoflowers were analyzed by using a powder X-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and UV-vis diffuse reflectance spectroscopy (UV-DRS) to determine their crystalline nature, morphological and functional group, and optical properties, respectively. X-ray photoelectron spectroscopy (XPS) was performed for the examination of elemental composition and chemical states by qualitative and quantitative analysis. The results of the investigations demonstrated that the MnMoO4 nanostructures with good crystallinity and distinct shape were formed successfully. The synthesized MnMoO4 nanoflowers were tested for their efficiency as a photocatalyst in the degradation studies of methylene blue (MB) as model organic contaminants in an aqueous medium under visible light, which showed their photocatalytic activity with a degradation of 85%. Through the band position calculations using the electronegative value of MnMoO4, the photocatalytic mechanism of the nanostructures was proposed. The results indicated that the effective charge separation, and transfer mechanisms, in addition to the flower-like shape, were responsible for the photocatalytic performance. The stability of the recovered photocatalyst was examined through its recyclability in the degradation of MB. Leveraging MnMoO4's photocatalytic properties, future studies may focus on scaling up these processes for practical and large-scale environmental remediation.

Study of Cation Distribution and Photocatalytic Activity of Nonthermal Plasma-Modified NiZnFe2O4 Magnetic Nanocomposites.

In this study, NiZnFe2O4 composite was synthesized using a sol-gel route and subjected to nonthermal plasma treatment for tailoring their cations' distribution and physicochemical, magnetic, and photocatalytic properties. Microwave plasma treatment was given to the composites for 60 min in support of postsynthesis sintering at 700 °C for 5 h. X-ray diffraction (XRD) analysis was conducted on pre- and postplasma-modified ferrite composites to identify phase-pure cubic spinel structure and cations' distribution. The cation distributions were measured from the ratio of XRD intensity peaks corresponding to (220), (311), (422) and (440) planes. The intensity ratio of plasma-treated ferrite composites decreased compared to that of pristine composites. The crystallite size and lattice constant were increased on plasma treatment of the composite. The morphological analysis showed nanoflower-like structures of the particles with an increased surface area in the plasma-treated composites. The plasma oxidation and sputtering effects caused a reduction in the nanoflower size. The energy bandgap increased with a decrease in particle size due to plasma treatment. The rhodamine B dye solution was then irradiated with a light source in the presence of the nanocomposites. The dye degradation efficiency of the composite photocatalyst increased from 80 to 96% after plasma treatment.

Binderless synthesis of hierarchical, marigold flower-like NiCo2O4 films for high-performance symmetric supercapacitor

The facile and cost-effective chemical bath deposition method is employed for the binder-free synthesis of NiCo2O4 marigold flower-like nanostructures on a flexible stainless-steel substrate. Binderless and surfactant-free synthesis of NiCo2O4 films for supercapacitor application is a crucial part of this synthesis process. The effect of reaction times on the deposition of NiCo2O4 nanostructured films has been discussed briefly based on the electrochemical performance and surface morphology of films. The reaction time is varied as 2, 4, 6, and 8 h. The prepared films were analyzed by structural and morphological characterizations. The time-dependent significant change in morphology of NiCo2O4 films is discussed in detail. The development of the Marigold-like flowers from wheat grain-like nanostructures has been observed for increasing reaction time. The film deposited at 6 h reaction time (NCO-6 electrode) showed better specific capacitance of 1277 F/g at 5 mA/cm2, which retained about 95 % after 10,000 cycles. The NiCo2O4 film exhibited a 0.7 V potential window with the maximum energy and power density of 86 Wh/kg and 2333 W/kg, respectively. The fabricated aqueous symmetric device i.e., NCO//NCO showed energy density and power density of 16.4 Wh/kg and 275.5 W/kg, respectively. The fabricated device shows 90.5 % retention in performance after 5000 cycles. These results revealed that NiCo2O4 can be a better electrode material for energy storage devices.

Nanoflower-like NiCo2O4 Composite Graphene Oxide as a Bifunctional Catalyst for Zinc-Air Battery Cathode.

Developing efficient bifunctional catalysts for nonprecious metal-based oxygen reduction (ORR) and oxygen evolution (OER) is crucial to enhance the practical application of zinc-air batteries. The study harnessed electrostatic forces to anchor the nanoflower-like NiCo2O4 onto graphene oxide, mitigating the poor inherent conductivity in NiCo2O4 as a transition metal oxide and preventing excessive agglomeration of the nanoflower-like structures during catalysis. Consequently, the resulting composite, NiCo2O4-GO/C, exhibited notably superior ORR and OER catalytic performance compared to pure nanoflower-like NiCo2O4. Notably, it excelled in OER catalytic activity of the OER relative to the precious metal RuO2. As a bifunctional catalyst for ORR and OER, NiCo2O4-GO/C displayed a potential difference of 0.88 V between the ORR half-wave potential and the OER potential at 10 mA·cm-2, significantly lower than the 1.08 V observed for pure flower-like NiCo2O4 and comparable to the 0.88 V exhibited by precious metal catalysts Pt/C + RuO2. The NiCo2O4-GO/C-based zinc-air battery demonstrated a discharge capacity of 817.3 mA h·g-1, surpassing that of precious metal-based zinc-air batteries. Moreover, charge-discharge cycling tests indicated the superior stability of the NiCo2O4-GO/C-based zinc-air battery compared to its precious metal-based counterparts.

Doping effect of Europium (Eu3+) on flower-like ZnO nanostructures: shape variations, optical properties and its applicability in electrochemical sensing of heavy metal (Lead) ion detection

Doping effect of Europium (Eu3+) on flower-like ZnO nanostructures: shape variations, optical properties and its applicability in electrochemical sensing of heavy metal (Lead) ion detection

P-Ni co-doped Mo2C embedded in carbon-fiber paper as a highly efficient electrocatalyst for hydrogen evolution in alkaline media

The development of noble-metal-free electrocatalysts with high electrocatalytic performance and stability by adopting a scalable route is key to solving the energy crisis. We report a PNi co-doped Mo2C-based electrocatalyst with high hydrogen evolution reaction (HER) catalytic activity prepared by a molten-salt method. Using phosphating times of 2 h and 4 h yielded P-Ni-Mo2C-2h and P-Ni-Mo2C-4h, respectively, both of which exhibited nanoflower-like structures that provided abundant active sites for the reaction. P-Ni-Mo2C-2h possessed good electrocatalytic properties with a low overpotential of only 140.5 mV at j = 10 mA cm−2 and a small Tafel slope of 50.7 mV dec−1 in an alkaline environment. P-Ni-Mo2C-2h exhibited excellent stability after 20 h of continuous hydrogen production. The use of an excessively long phosphating time caused a narrow down of spaces formed by nanoflakes, thereby reducing the HER performance of the electrocatalyst. The results of this study provide guidelines for the preparation of high-efficiency PNi co-doped electrocatalysts.

PEG-PVP-Assisted Hydrothermal Synthesis and Electrochemical Performance of N-Doped MoS2/C Composites as Anode Material for Lithium-Ion Batteries.

Molybdenum disulfide shows promise as an anode material for lithium-ion batteries. However, its commercial potential has been constrained due to the poor conductivity and significant volume expansion during the charge/discharge cycles. To address these issues, in this study, N-doped MoS2/C composites (NMC) were prepared via an enhanced hydrothermal method, using ammonium molybdate and thiourea as molybdenum and sulfur sources, respectively. Polyethylene glycol 400 (PEG400) and polyvinylpyrrolidone (PVP) were added in the hydrothermal procedure as soft template surfactants and nitrogen/carbon sources. The crystal structure, morphology, elemental composition, and surface valence state of the N-doped MoS2/C composites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS), respectively. The results indicate that the NMC prepared by this method are spherical particles with a nanoflower-like structure composed of MoS2 flakes, having an average particle size of about 500 nm. XPS analysis shows the existence of C and N elements in the samples as C-N, C-C, and pyrrolic N. As anodes for LIBs, the NMC without annealing deliver an initial discharge capacity of 548.2 mAh·g-1 at a current density of 500 mA·g-1. However, this capacity decays in the following cycles with a discharge capacity of 66.4 mAh·g-1 and a capacity retention rate of only 12% after 50 cycles. In contrast, the electrochemical properties of the counterparts are enhanced after annealing, which exhibits an initial discharge capacity of 575.9 mAh·g-1 and an ultimate discharge capacity of 669.2 mAh·g-1 after 70 cycles. The capacity retention rate decreases initially but later increases and elevated afterward to reach 116% at the 70th cycle, indicating an improvement in charge-discharge performance. The specimens after annealing have a smaller impedance, which indicates better charge transport and lithium-ion diffusion performance.

Synthesis and Characterization of Flower-Like Cobalt-Doped ZnO Nanostructures for Ammonia Sensing Applications

Abstract The present study uses the co-precipitation method to explore the synthesis of zinc oxide and cobalt-doped ZnO sensors, encompassing a range of cobalt concentrations from 1 to 4 wt.%. The synthesized samples undergo comprehensive analysis to evaluate their structural, morphological, optical, and gas-sensing properties. X-ray diffraction revealed a hexagonal Wurtzite structure, and the crystallite size decreased from 16.92 to 15.39 nm. Energy-dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy collectively affirmed the presence of cobalt. Scanning electron microscopy was used to analyze the morphological characteristics. The Tauc-plot was used to determine the optical bandgap via diffuse reflectance spectroscopy. As cobalt doping increased, the band gap increased from 3.18 to 3.23 eV. Further, atomic force microscopy and Brunauer-Emmett-Teller analysis were used to assess the surface topography and pore size distribution. The AFM measurements indicated roughness within 435-700 nm. The BET analysis revealed mesoporous properties, with surface area ranging between 18.657 to 21.962 m2/g. Subsequently, the gas-sensing capabilities of the Co-doped ZnO sensors were examined for various volatile organic compounds at room temperature. The sensor with 4% Cobalt doping exhibited a fast response and recovery time of 21 and 20 seconds for 2 ppm of NH3

Effect of Precursor and Calcination Time on the Morphological Structure and Catalytic Activity of Co3O4 Film in the Oxygen Evolution Reaction

This research investigates the effect of cobalt precursor and calcination time on the morphology and catalytic activity of Co3O4 films in the oxygen evolution reaction (OER). Co3O4 films with porous flower-like nanostructures were obtained using cobalt nitrate as a cobalt precursor, while cobalt chlorides were used to produce porous nanoneedle structures Co3O4 film. Extended annealing time at temperatures 350°C caused structural fractures in the films. Among the samples, the synthesized Co3O4 films were then evaluated as catalyst materials for the OER in alkaline 1M KOH electrolyte. Among synthesized films, the Co3O4-2-1h, synthesized using the cobalt chlorides as Co precursor and annealed at 350°C for 1 hour, exhibited better OER catalytic activity. With its porous nanoneedle structure, the Co3O4-2-1h demonstrated superior performance comparable to the state-of-the-art 20% Ir/C catalyst. Moreover, the Co3O4-2-1h film demonstrates remarkable stability for the OER in a 1M KOH alkaline electrolyte.

Insights into dehydration of layered cobalt hydroxide for gas sensor application with low-temperature response behavior

Dehydration of layer metal hydroxides at controlled annealing temperatures is an efficient strategy for regulating the material properties. In this work, we studied the dehydration process of α-Co(OH)2 with flower-like nanostructure under various conditions and explored their gas sensing application. Stable dehydrated α-Co(OH)2 obtained by solidification in air at 140 °C, exhibits specific selective low-temperature gas-sensing behavior for Et3N. The response to 50 ppm Et3N was up to 9.52 at 140 °C operating temperature with short response and recovery time. The sensor is the high reversibility and the excellent reproducibility with ppb level detection limit. The partial oxidation of the dehydration α-Co(OH)2 in the air has a significant impact on the sensing performance. The large specific surface area of the dehydration α-Co(OH)2 affords rich reactive sites for both reaction and adsorption of Et3N molecules. This research provides a new solution for building low-temperature high-performance amine sensor.

Controllable Synthesis of Flower-like Hierarchical CuCo2S4 Nanostructure Arrays for High-Performance Hybrid Supercapacitors

Transition metal sulfides (TMSs) are considered as attractive materials in the areas of energy storage because of their unique redox properties, excellent electronic conductivity, as well as environmental friendliness. However, poor cyclic stability and limited electrochemical active sites hinder their further application. To address this issue, a flower-like hierarchical CuCo2S4 structure is constructed by a two-step hydrothermal method. In this nanostructure, CuCo2S4 grows outward to form a tightly bound hierarchical structure on the nickel foams (NFs). This oriented structure can provide more laminar gaps for electrolyte ion diffusion, exposing more reaction sites to increase the ion transport efficiency between the layers, reducing the ion transport resistance and improving the reaction kinetics. Thus, the CuCo2S4 electrode exhibits excellent energy storage performance, exhibiting a high specific capacity of 1415.6 F g−1 at 1 A g−1. After 10,000 cycles of 10 A g−1, it still has 91.9% of the initial performance. In addition, an asymmetrical supercapacitor (ASC) was constructed by choosing CuCo2S4 as the anode and RGO as the cathode, which has the maximum energy density (61.8 Wh Kg−1) at 812.1 W Kg−1 and significant cycling endurance (92.05% retention) at 10,000 turns. Briefly, the researchers successfully constructed an array of CuCo2S4 flower-like hierarchical nanostructures and confirmed their potential application in supercapacitors.

Transition metal Co induce CoSe2/NiWSe2 interface structural reorganization for efficient oxygen evolution reaction and urea oxidation reaction

Urea-containing wastewater has become an increasingly serious environmental and energy problem. The use of electrochemical urea oxidation reaction (UOR) technology to treat wastewater containing urea has gained considerable significance. The regulation of the composition and electronic properties of the catalyst by doping transition metal elements is crucial for the development of oxygen evolution reaction (OER) and UOR catalysts with high catalytic activity. In this paper, WSe2, CoSe2, NiWSe2 and CoSe2/NiWSe2 were synthesized by hydrothermal method combined with annealing treatment. Compared with WSe2, CoSe2, and NiWSe2, the OER and UOR catalytic activity of CoSe2/NiWSe2 are significantly improved. For OER, a low overpotential of 1.44 V is all that is needed to reach a current density of 10 mA cm−2. The overpotential of UOR is only 1.32 @ 10 mA cm−2, and it can still maintain excellent electrochemical stability after 30 h. The electronic structure of CoSe2/NiWSe2 is changed by the incorporation of Co, thereby improving the conductivity and accelerating the reaction kinetics. CoSe2 particles are uniformly distributed on the layered NiWSe2 nanosheets, which promotes the charge transfer and synergistic effect at the interface between CoSe2 and NiWSe2. The nanoflower-like structure with thin edges enriches the active sites of CoSe2/NiWSe2. Therefore, the transition metal element doping technology can provide a new method for the development of efficient OER and UOR electrocatalysts and provide a new way to reduce the overall energy consumption during urea degradation.