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When a magnetic moment is embedded in a metal, it captures itinerant electrons to form the Kondo cloud1,2, which can spread out over a few micrometres3,4. For a metal with dense magnetic impurities such that Kondo clouds overlap with each other, correlated ground states are formed. When the impurities form a regular lattice, the result is a heavy fermion or anti-ferromagnetic order depending on the dominant interaction5,6. Even in the case of random impurities, overlapping Kondo clouds are expected to form a coherent ground state. Here, we examine this issue by performing electrical transport and high-precision tunnelling density-of-states (DOS) spectroscopy measurements in a highly P-doped crystalline silicon metal where disorder-induced localized magnetic moments exist7. We detect the Kondo effect in the resistivity of the Si metal below 2 K and an exotic pseudogap in the DOS with gap edge peaks at a Fermi energy below 100 mK. The DOS gap and peaks are tuned by applying an external magnetic field and transformed into a metallic Altshuler-Aronov gap8 in the paramagnetic disordered Fermi liquid (DFL) phase. We interpret this phenomenon as the Kondo condensation, the formation of a correlated ground state of overlapping Kondo clouds, and its transition to a DFL. The boundary between the Kondo condensation and DFL phases is identified by analysing distinct DOS spectra in the magnetic field-temperature plane. A detailed theoretical analysis using a holographic method 9 , 10 , 11 reproduces the unusual DOS spectra, 1, supporting our scenario. Our work demonstrates the observation of the magnetic version of Bardeen-Cooper-Shrieffer (BCS) pair condensation and will be useful for understanding complex Kondo systems., Comment: 34 pages,5+6 figures, accepted in nature physics

The layer-by-layer mesoporous nanohybrids of Ni-Cr-layered double hydroxide (Ni-Cr-LDH) and polyoxotungstate nanoclusters (Ni-Cr-LDH-POW) are prepared via exfoliation reassembling strategy. The intercalative hybridization of Ni-Cr-LDH with POW nanoclusters leads to forming a layer-by-layer stacking framework with significant expansion of the interplanar spacing and surface area. The aqueous hybrid supercapacitor (AHSC) and all-solid-state hybrid supercapacitor (SSHSC) devices are fabricated using Ni-Cr-LDH-POW nanohybrid as a cathode and reduced graphene oxide (rGO) as an anode material. Notably, the NCW-2//rGO AHSC device delivers an ED of 43 Wh kg

Utilizing zeolitic imidazolate frameworks (ZIFs) poses a significant challenge that demands a facile synthesis method to produce uniform and nanometer-scale materials with high surface areas while achieving high yields. Herein, we demonstrate a facile and cost-effective strategy to systematically produce ZIF8 nanocrystals. Typically, ZIF8 nanocrystal synthesis involves a wet chemical route. As the reaction time decreased (150, 120, and 90 min), the size of the ZIF8 crystals decreased with uniform morphology, and productivity reached as high as 89%. The composition of the product was confirmed through XRD, FE-SEM, TEM, EDS, and Raman spectroscopy. The ZIF8 synthesized with different reaction time was finally employed for catalyzing the electrochemical hydrogen evaluation reaction (HER). The optimized ZIF8-3 obtained at 90 min of reaction time exhibited a superior catalytic action on the HER in alkaline medium, along with a remarkably long-term stability for 24 h compared with the other ZIF8 nanocrystals obtained at different reaction times. Specifically, the optimized ZIF8-3 sample revealed an HER overpotential of 172 mV and a Tafel slope of 104.15 mV·dec−1. This finding, thus, demonstrates ZIF8 as a promising electrocatalyst for the production of high-value-added green and sustainable hydrogen energy.

NixFeyMoz layered double hydroxide (LDH) electrocatalysts fabricated via a simple hydrothermal technique for overall water splitting in an alkaline medium are reported.

In everyday life superior lithium-ion batteries (LIB) with fast charging ability have become a valuable asset. The LIB performance of anode composite copper cobalt tin sulphide (Cu2CoSnS4; CCTS) electrodes, which were fabricated using a simple and easy hydrothermal method, was investigated. The electrochemical charge storage performance of the CCTS anode demonstrated sustainability, high-rate capability and efficiency. The CCTS anode exhibited a first discharge capacity of 914.5 mAhg−1 and an average specific capacity of 198.7 mAhg−1 in consecutive cycles at a current density of 0.1 Ag−1. It had a capacity retention of ~62.0% and a coulombic efficiency of more than 83% after over 100 cycles, demonstrating its excellent cycling performance and reversibility. It can be an alternative anode to other established electrode materials for real battery applications.

Kesterite Cu2ZnSnS4 (CZTS)-based solar devices have become a popular alternative to copper indium gallium selenide (CIGS) due to its outstanding properties such as high efficiency, non-toxicity, cost-effectiveness, suitable optoelectrical properties, and earth-abundancy. In this study, we directly fabricated CZTS films via a single-step spray pyrolysis technique, in contrast to conventional techniques where post sulfurization is required. The spray deposited CZTS films are investigated for their optical, structural, and electrical properties. The X-ray diffraction (XRD) and Raman analysis study revealed the synthesis of the phase-pure kesterite CZTS films without impurity phases. Large crystallites of CZTS are obtained at a deposition temperature of 400 °C, exhibiting a porous granular morphology with different grain sizes upon temperature variation. The size-dependent optical properties revealed that the CZTS films exhibited admirable visible light absorption of 105 cm−1 and an electronic bandgap ranging between 1.42 and 1.58 eV. The minimum dielectric loss obtained for optimized CZTS due to fewer intrinsic defects confirmed the materials’ applicability. Thus, the study provides a simple, viable route to fabricate CZTS without post-treatment to build affordable solar cells.

A simple and scalable immersion-based corrosion induced strategy to integrate rGO nanosheets and Ni–Fe-based hydroxide nanocatalysts on nickel foam at 25 °C, demonstrating an efficient electrocatalysis for low-cost hydrogen generation.

Water-stable, lead-free zero-dimensional (0D) organic–inorganic hybrid colloidal tin(IV) perovskite, A2SnX6 (A is a monocationic organic ion and X is a halide) nanocrystals (NCs) with high photoluminescence (PL) quantum yield (QY) have rarely been explored. Herein, we report solution-processed colloidal NCs of blue light-emitting T2SnCl6 and orange light-emitting T2Sn1-xSbxCl6 [T+ = tetramethylammonium cation] from their corresponding single crystals (SCs). These colloidal NCs are well-dispersible in non-polar solvents, thereby maintaining their bright emission. This paves the way for fabricating homogeneous thin films of these NCs. Due to organic cation (T+)-controlled large spin–orbit coupling (SOC), the T2Sn1-xSbxCl6 NCs exhibit bright orange emission with an enhancement in PL QY of 41% compared to their bulk counterpart. Furthermore, we explore T2Sn1-xBixCl6 and T2Sn1-x-yBixSbyCl6 SCs, which show blue and green emission, respectively; the latter is attributed to the newly formed Sb 5p and Sb 5 s orbital-driven band structures confirmed by applying density functional theory (DFT) calculations. The SCs and NCs exhibit excellent stability in water under ambient conditions because of the in-situ generation of a hydrophobic and oxygen-resistant passivating layer of oxychloride in the presence of water. Our findings open a pathway for designing lead-free perovskites materials for thin-film-based optoelectronic devices.

An efficient and sustainable gas diffusible OER anode toward industrial alkaline water-splitting is fabricated by simply immersing Ni foam in ethanolic FeCl3 etchant, which produces a microporous Ni backbone decorated with nanocatalysts.

Facile template–free controllable growth of freestanding polyhedron–like CoS onto microporous Ni foam with three-dimensional architecture via a mild hydrothermal technique is reported. The as-obtained CoS catalyst phase was first tailored to N-Co9S8 (nitrogen doped Co9S8), and its inherent reaction kinetics and conductivity were then enhanced through sulfur incorporation via a hydrothermal process. The electrochemical performance of the pristine CoS and a sulfur-enriched N-Co9S8 (S, N-Co9S8) electrode in alkaline 1.0 M KOH was examined. The optimized polyhedral S, N-Co9S8 structured catalyst exhibits significantly enhanced electrocatalytic activity for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). As a result, low overpotentials of 244 and −92 mV is required to achieve the current density of 10 mA cm−2 for the OER and HER, respectively. Furthermore, when the polyhedral S, N-Co9S8 catalyst was employed as a bifunctional catalyst in a two-electrode electrolyzer cell exhibiting a cell voltage of 1.549 V at 10 mA cm−2 and demonstrates excellent long-term (50 hrs.) chronopotentiometric electrolysis at various current rate, reveals excellent bifunctional OER and HER activities at different applied current densities. The superior OER and HER activities of the S, N-Co9S8 catalyst is result of the improved electronic conductivity and enhanced intrinsic reaction kinetics, which led to the enhanced electrocatalytically active sites after the incorporation of heteroatoms in the catalyst structure.

The oxygen evolution reaction (OER) plays a key role in determining the performance of overall water splitting, while a core technological consideration is the development of cost-effective, efficient, and durable catalysts. Here, we demonstrate a robust reduced Fe-oxide@NiCo2O4 bilayered non-precious-metal oxide composite as a highly efficient OER catalyst in an alkaline medium. A bilayered oxide composite film with an interconnected nanoflake morphology (Fe2O3@NiCo2O4) is reduced in an aqueous NaBH4 solution, which results in a mosslike Fe3O4@NiCo2O4 (reduced Fe-oxide@NiCo2O4; rFNCO) nanostructured film with an enhanced electrochemical surface area. The rFNCO film demonstrates an outstanding OER activity with an extraordinary low overpotential of 189 mV at 10 mA cm–2 (246 mV at 100 mA cm–2) and a remarkably small Tafel slope of 32 mV dec–1. The film also shows excellent durability for more than 50 h of continuous operation, even at 100 mA cm–2. Furthermore, density functional theory calculations suggest that the unintentionally in situ doped Ni during the reduction reaction possibly improves the OER performance of the rFNCO catalyst shifting d-band centers of both Fe and Ni active sites.

Halide perovskites (HPs) are used in various applications, including solar cells, light-emitting diodes, lasers, and photodetectors. These materials have recently received a great deal of attention as high-energy radiation detectors and scintillators due to their excellent light yield, mobility-lifetime product (µτ), and X-ray sensitivity. In addition, due to their solution-processability and low cost, perovskite materials could be used to produce thick perovskite films across wide areas, allowing for low-dose X-ray imaging. Perovskite-based scintillators and detectors could eventually replace commercialized products like thallium‐doped cesium iodide (CsI:Tl) and amorphous silicon (Si). Here, we review all of the key properties of HPs, the relevant terminology necessary for radiation detection and scintillation, the physical mechanisms underlying their operation, the fabrication process, and perovskite crystals and thin-films of varying dimensionality used for high-energy radiation detection. We also cover the critical issues and solutions that HPs as detectors, scintillators, and imagers face.

In everyday life, superior lithium-ion batteries (LIBs), with fast charging ability, have become valuable assets. The LIB performance of an anode composite copper cobalt tin sulphide (Cu

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

We have developed chelator-free copper-64-incorporated iron oxide (IO) nanoparticle (NPs) which have both magnetic and radioactive properties being applied to positron emission tomography (PET)-magnetic resonance imaging (MRI). We have found that the IO nanoparticles composed of radioactive isotope 64Cu may act as a contrast agent being a diagnostic tool for PET as well as a good T2 MRI nanoprobe due to their good r2/r1 ratio. Furthermore, we demonstrate that the 64Cu incorporation at the core of core-shell-structured IO NPs exhibits a good in vivo stability, giving us an insightful strategy for the design of a contrast agent for the PET-MRI system.

Developing efficient electrocatalysts for urea oxidation reaction (UOR) can be a promising alternative strategy to substitute the sluggish oxygen evolution reaction (OER), thereby producing hydrogen at a lower cell-voltage. Herein, we synthesized a binder-free thin film of ultrathin sheets of bimetallic Cu-Fe-based metal–organic frameworks (Cu/Fe-MOFs) on a nickel foam via a drop-casting route. In addition to the scalable route, the drop-casted film-electrode demonstrates the lower UOR potentials of 1.59, 1.58, 1.54, 1.51, 1.43 and 1.37 V vs. RHE to achieve the current densities of 2500, 2000, 1000, 500, 100 and 10 mA cm−2, respectively. These UOR potentials are relatively lower than that acquired by the pristine Fe-MOF-based film-electrode synthesized via a similar route. For example, at 1.59 V vs. RHE, the Cu/Fe-MOF electrode exhibits a remarkably ultra-high anodic current density of 2500 mA cm−2, while the pristine Fe-MOF electrode exhibits only 949.10 mA cm−2. It is worth noting that the Cu/Fe-MOF electrode at this potential exhibits an OER current density of only 725 mA cm−2, which is far inconsequential as compared to the UOR current densities, implying the profound impact of the bimetallic cores of the MOFs on catalyzing UOR. In addition, the Cu/Fe-MOF electrode also exhibits a long-term electrochemical robustness during UOR.

Ruddlesden-Popper (RP) phases (An+1BnO3n+1, n = 1, 2,···) have attracted intensive research with diverse functionalities for device applications. However, the realization of a high-quality RP-phase film is hindered by the formation of out-of-phase boundaries (OPBs) that occur at terrace edges, originating from lattice mismatch in the c-axis direction with the A'B'O3 (n = ∞) substrate. Here, using strontium ruthenate RP-phase Sr2RuO4 (n = 1) as a model system, an experimental approach for suppressing OPBs was developed. By tuning the growth parameters, the Sr3Ru2O7 (n = 2) phase was formed in a controlled manner near the film-substrate interface. This higher-order RP-phase then blocked the subsequent formation of OPBs, resulting in nearly defect-free Sr2RuO4 layer at the upper region of the film. Consequently, the Sr2RuO4 thin films exhibited superconductivity up to 1.15 K, which is the highest among Sr2RuO4 films grown by pulsed laser deposition. This work paves the way for synthesizing pristine RP-phase heterostructures and exploring their unique physical properties.

A metal–organic framework (MOF) is a highly porous material with abundant redox capacitive sites for intercalation/de-intercalation of charges and, hence, is considered promising for electrode materials in supercapacitors. In addition, dopants can introduce defects and alter the electronic structure of the MOF, which can affect its surface reactivity and electrochemical properties. Herein, we report a copper-doped iron-based MOF (Cu@Fe-MOF/NF) thin film obtained via a simple drop-cast route on a 3D-nickel foam (NF) substrate for the supercapacitor application. The as-deposited Cu@Fe-MOF/NF electrodes exhibit a unique micro-sized bipyramidal structure composited with nanoparticles, revealing a high specific capacitance of 420.54 F g−1 at 3 A g−1 which is twice compared to the nano-cuboidal Fe-MOF/NF (210 F g−1). Furthermore, the asymmetric solid-state (ASSSC) supercapacitor device, derived from the assembly of Cu@Fe-MOF/NFǁrGO/NF electrodes, demonstrates superior performance in terms of energy density (44.20 Wh.kg−1) and electrochemical charge–discharge cycling durability with 88% capacitance retention after 5000 cycles. This work, thus, demonstrates a high potentiality of the Cu@Fe-MOF/NF film electrodes in electrochemical energy-storing devices.

Hydrogen generation during wastewater treatment has remained a long-standing challenge for the environment preservation welfare. In the present work, we have fabricated a promising bifunctional thin film-based catalyst for hydrogen generation with concurrent wastewater treatment. The prepared catalyst film is a vertically oriented thin SnS (tin monosulfide) nanosheet array on a Ni-foam (SnS/NF) obtained via a solution process, demonstrating a promising electrocatalytic activity towards the generation of green H2 fuel at the cathodic side and the decomposition of urea waste at the anodic side. Notably, while assembling two identical electrodes as cathode and anode together with a reference electrode (i.e., SnS/NF∥SnS/NF vs. RHE assembly) in 1 M KOH aqueous electrolyte containing 0.33 M urea, the electrolyzer electrolyzed urea at a lower cell potential of 1.37 and 1.43 V (vs. RHE) to deliver a current density of 10 mA cm−2 and 50 mA cm−2, respectively, for the decomposition of urea at the anodic SnS/NF electrode and green hydrogen fuel generation at the cathodic SnS/NF electrode. This activity on electrocatalytic urea decomposition lies within the best performance to those of the previously reported sulfide-based and other catalytic materials. The promising catalytic activities of the SnS catalyst film are attributed to its combined effect of self-standing nanosheet array morphology and high crystallinity, which provides abundant active sites and a facile charge transfer path between the nanosheet arrays and the electrolyte. Thus, the present work offers a green avenue to the waste-urea treatment in water and sustainable hydrogen energy production.

Lead-free, non-toxic transition metal-based phosphorescent organic–inorganic hybrid (OIH) compounds are promising for next-generation flat-panel displays and solid-state light-emitting devices. In the present study, we fabricate highly efficient phosphorescent green-light-emitting diodes (PHOLEDs) using the lead-free, non-toxic, zero-dimensional OIH compound [(H2CCHCH2)(C6H5)3P]2MnBr4 (1), which exhibits an emission peak at 516 nm and a long lifetime of 441 μs. The long lifetime indicates the phosphorescent emissive nature of 1. Density functional theory calculations confirm that the narrow green emission from 1 is due to the highly localized electronic states of the valence and conduction bands. A flexible green-light-emitting phosphorescent substrate is successfully fabricated from 1 using a nylon membrane, indicating that 1 has a significant potential for use in flexible optoelectronic devices. By engineering the organic hole and electron transport layers, we achieve a highly efficient all-vacuum-deposited PHOLED with a current efficiency of 24.71 cd A−1, a power efficiency of 20.61 lm W−1, and an external quantum efficiency of 7.12%. Together, our findings will pave the way for the development of high-performance Mn(II)-based LEDs.

Green hydrogen derived from the water-electrolysis route is emerging as a game changer for achieving global carbon neutrality. Economically producing hydrogen through water electrolysis, however, requires the development of low-cost and highly efficient electrocatalysts

Ammonium toxicity is a significant source of pollution from industrial civilization that is disrupting the balance of natural systems, adversely affecting soil and water quality, and causing several environmental problems that affect aquatic and human life, including the strong promotion of eutrophication and increased dissolved oxygen consumption. Thus, a cheap catalyst is required for power generation and detoxification. Herein, compost soil is employed as a novel electrocatalyst for ammonium degradation and high-power generation. Moreover, its effect on catalytic activity and material performances is systematically optimized and compared by treating it with various reducing agents, including potassium ferricyanide, ferrocyanide, and manganese dioxide. Ammonium fuel was supplied to the compost soil ammonium fuel cell (CS-AFC) at concentrations of 0.1, 0.2, and 0.3 g/mL. The overall results show that ferricyanide affords a maximum power density of 1785.20 mW/m2 at 0.2 g/mL fuel concentration. This study focuses on high-power generation for CS-AFC. CS-AFCs are sustainable for many hours without any catalyst deactivation; however, they need to be refueled at regular intervals (every 12 h). Moreover, CS-AFCs afford the best performance when ferricyanide is used as the electron acceptor at the cathode. This study proposes a cheap electrocatalyst and possible solutions to the more serious energy generation problems. This study will help in recycling ammonium-rich wastewaters as free fuel for running CS-AFC devices to yield high-power generation with reducing agents for ammonium fuel cell power applications.

Despite the considerable efforts in advancing nonprecious-metal candidates as oxygen evolution reaction (OER) electrocatalysts, cost-effective production of efficient and stable catalysts via simple synthesis routes remains to be realized. We report on the experimental and density functional theory (DFT) guidelines of nickel (Ni)–vanadium (V) layered double hydroxides (LDHs) to prepare an optimal electrocatalyst by changing its composition ratio. The optimized Ni0.75V0.25 LDH exhibits the ultralow overpotentials of 200 and 292 mV at the current densities of 10 and 400 mA cm–2, respectively, a long-term durability of more than 100 h at 10 mA cm–2, and an extremely low Tafel slope of 48.3 mV dec–1. These findings can provide guidance for the facile optimal design of state-of-the-art water oxidation catalysts by using LDHs for large-scale practical applications. The enhanced catalytic performance can be attributed to a lower hydrogen desorption energy and the presence of many open O sites, which can promote the initiation of the OER reaction.

Developing multicomponent superlattices (SLs) using lead halide perovskite nanocrystals (NCs) is challenging due to weak ionic bonding and the high ionic mobility of halide ions. Recently, Kovalenko et al. developed multicomponent SLs, including binary cubic SLs, binary perovskite-like SLs, ternary perovskite-like SLs, and columnar binary SLs.

Commercial lithium–ion batteries (LIBs) are insufficient to bridge the energy density gap between demand and supply in advanced heavy and portable electronic devices because of graphite anodes (poor theoretical capacity: 372 mAh g−1). Ternary chalcogenide metal‐sulfides are promising as alternative anode materials in high power and energy densities but suffer from capacity fading with poor long‐term cycling stability due to the dissolution of polysulfide species created during the lithium‐ion insertion/de‐insertion process. Here, we report the hydrothermal synthesis of graphene integrated CuCo2S4 microparticles as a high‐capacity and sustainable anode material for LIBs. We solve the concentration gradient of lithium polysulfide at the interface of electrode/electrolyte via integrating graphene into the active metal sulfide anode material. The mechanically flexible and highly conductive nature of graphene helps relieve undesirable elongation and shrinkage during battery cycling, suppressing active material dissolution and enhancing electron/ion transport through the electrochemical double‐layer (EDL). Our one step approach demonstrates towards the practical application of advanced metal sulfide anodes for LIBs.

Herein a method is proposed for engineering the electronic properties (including the band structure) of diamond via surface hybridization with graphene. Graphene layers (5–50 nm in thickness) were grown vertically onto a polished 〈110〉 textured polycrystalline diamond plate (1 × 1 cm2) (vGr-diamond) at ∼1300 °C via hydrogen plasma etching in a chemical vapor deposition (CVD) chamber. Due to the crystallographic relationship, the graphene layers embed at an angle of 30° to the diamond surface comprising the (110) planes. The epitaxial relationship is demonstrated via low angle X-ray diffraction (XRD), the XRD rocking curve, Raman and scanning electron microscopy. With hybridization, the diamond sample reveals a strong photoluminescent (PL) signal at ∼2.78 eV (∼450 nm). The peak was assigned to the ‘interface defects’ of the vGr-diamond hybrid structure, which are a type of ‘surface defect’ of the CVD diamond that generates a peak at ∼2.69 eV. The blue shift (∼90 meV) of the interface defects is due to the compressive strain of ∼3% applied to the interface atoms. Simulations indicate that the hybrid structures possess a finite band gap of 1.85–0.25 eV, which decreases upon increasing the thickness of the graphene layers to ∼1.4 nm. The appearance of a small band gap was attributed to the compressive strain. These findings may provide a route for diamond to become a platform for next generation and extreme electronic devices.

Synthesizing binder-free metal–organic frameworks (MOF) as thin films on a large scale to serve directly as electrodes for water electrolysis is challenging. Here, we report a simple and readily scalable strategy for fabricating binder-free Cu–Fe–NH2 based MOF thin film-electrodes directly applicable as a catalyst for water electrolysis. Films composed of thin 2D-nanosheets of the MOF were deposited by dropping ink obtained from solvothermally synthesised bulk MOFs onto nickel foam substrates, or simply immersing the substrates in the ink. The Cu–Fe–NH2 MOF electrodes demonstrated excellent oxygen evolution reaction (OER) performance, comparable or superior to recently reported state-of-the-art MOFs. Strikingly, the MOF electrodes exhibited a remarkably low OER overpotential of 330 mV at a high current density of 500 mA cm−2, and excellent durability with a very minor chronopotentiometric decay loss of 1.26% at the end of a 24 h test at a high bias current of 500 mA cm−2.

This work reports the fabrication of vanadium sulfide (VS2) microflower via one-step solvo-/hydro-thermal process. The impact of ethylene glycol on the VS2 morphology and crystal structure as well as the ensuing influences on electrocatalytic hydrogen evolution reaction (HER) and supercapacitor performance are explored and compared with those of the VS2 obtained from the standard pure-aqueous and pure-ethylene glycol solvents. The optimized VS2 obtained from the ethylene glycol and water mixed solvents exhibits a highly ordered unique assembly of petals resulting a highly open microflower structure. The electrode based on the optimized VS2 and exhibits a promising HER electrocatalysis in 0.5 M H2SO4 and 1 M KOH electrolytes, attaining a low overpotential of 161 and 197 mV, respectively, at 10 mA.cm−2 with a small Tafel slope 83 and 139 mVdec−1. In addition, the optimized VS2 based electrode exhibits an excellent electrochemical durability over 13 h. Furthermore, the superior VS2 electrode based symmetric supercapacitor delivers a specific capacitance of 139 Fg−1 at a discharging current density of 0.7 Ag−1 and exhibits an enhanced energy density of 15.63 Whkg−1 at a power density 0.304 kWkg−1. Notably, the device exhibits the capacity retention of 86.8% after 7000 charge/discharge cycles, demonstrating a high stability of the VS2 electrode.

A very simple, as well as sensitive and selective, sensing protocol was developed on a pre-anodized graphite pencil electrode surface coated using poly(thionine) (APGE/PTH). The poly(thionine) coated graphite pencil was then used for simultaneous sensing of 3-nitrophenol (3-NP) and 4-nitrophenol (4-NP). The poly(thionine) coated electrode exhibited an enhanced electrocatalytic property towards nitrophenol (3-NP and 4-NP) reduction. Redox peak potential and current of both nitrophenols were found well resolved and their simultaneous analysis was studied. Under optimized experimental conditions, APGE/PTH showed a long linear concentration range from 20 to 230 nM and 15 nM to 280 nM with a calculated limit of detection (LOD) of 4.5 and 4 nM and a sensitivity of 22.45 µA/nM and 27.12 µA/nM for 3-NP and 4-NP, respectively. Real sample analysis using the prepared sensor was tested with different environmental water samples and the sensors exhibited excellent recovery results in the range from 98.16 to 103.43%. Finally, the sensor exposed an promising selectivity, stability, and reproducibility towards sensing of 3-NP and 4-NP.