High Double Layer Capacitance Research Articles

Bimetallic FeCu-MOF derivatives as heterogeneous catalysts with enhanced stability for electro-Fenton degradation of lisinopril

A bimetallic FeCu/NC core-shell catalyst, consisting in nanoparticles where zero-valent Fe and Cu atoms, slightly oxidized on their surface, are encapsulated by carbon has been successfully prepared by modifying the synthesis route of MIL(Fe)-88B. FeCu/NC possessed well-balanced textural and electrochemical properties. According to voltammetric responses, in-situ Fe(III) reduction to Fe(II) by low-valent Cu was feasible, whereas the high double-layer capacitance confirmed the presence of a great number of electroactive sites that was essential for continuous H2O2 activation to •OH via Fenton's reaction. Electrochemical impedance and distribution of relaxation times (DRT) analysis informed about the strong leaching resistance of FeCu/NC. To validate the promising features of this catalyst, the advanced oxidation of the antihypertensive lisinopril (LSN) was investigated for the first time. The heterogeneous electro-Fenton (HEF) treatment of 16.1 mg L−1 LSN solutions was carried out in a DSA/air-diffusion cell. At pH 3, complete degradation was achieved within 6 min using only 0.05 g L−1 FeCu/NC; at near-neutral pH, 100 % removal was also feasible even in actual urban wastewater, requiring 60–75 min. The FeCu/NC catalyst demonstrated high stability, still maintaining 86.5 % of degradation efficiency after 5 cycles and undergoing low iron leaching. It outperformed the monometallic (Fe/NC and Cu/NC) catalysts, which is explained by the Cu(0)/Cu(I)-catalyzed Fe(II) regeneration mechanism that maintains the Fenton's cycle. LC-MS/MS analysis allowed the identification of two main primary LSN by-products. It can then be concluded that the FeCu/NC-based HEF process merits to be further scaled up for wastewater treatment.

Boosting HER performance of ZIF-67 via optimizing synthesis parameters in alkaline medium

Electrochemical water splitting offers a promising route to sustainable hydrogen production. Metal-Organic Frameworks (MOFs) have emerged as potential electrocatalysts due to their tunable structure and composition. We investigated the electrocatalytic activity of ZIF-67 for the hydrogen evolution reaction (HER) in alkaline media. Synthesis parameters, including temperature, reaction time, acidity, molar ratio of 2-methylimidazole (2-MIM) to cobalt source, cobalt source type, addition method of 2-MIM, and solvent type, were systematically varied to optimize the electrocatalytic properties of ZIF-67. The synthesized ZIF-67 electrocatalysts were characterized using BET, FESEM, EDS, TEM, XRD, FTIR, and UV–vis spectroscopy. The electrocatalytic properties were evaluated by cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and chronoamperometry methods. The optimized ZIF-67 electrocatalyst exhibited remarkable performance, with a low overpotential of 171 mV, a small Tafel slope of 82 mV.dec−1, a low charge transfer resistance of 97 Ω, a high double-layer capacitance of 13.5 mF cm−2, and high stability for 15 h at the current density of 10 mA cm−2. The enhanced electrocatalytic activity of the optimized ZIF-67 was attributed to its high surface area, tunable pore structure, and the presence of active cobalt sites.

High-Performance Bidirectional Microelectrode Array for Assessing Sevoflurane Anesthesia Effects and In Situ Electrical Stimulation in Deep Brain Regions.

Precise assessment of wakefulness states during sevoflurane anesthesia and timely arousal are of paramount importance to refine the control of anesthesia. To tackle this issue, a bidirectional implantable microelectrode array (MEA) is designed with the capability to detect electrophysiological signal and perform in situ deep brain stimulation (DBS) within the dorsomedial hypothalamus (DMH) of mice. The MEA, modified with platinum nanoparticles/IrOx nanocomposites, exhibits exceptional characteristics, featuring low impedance, minimal phase delay, substantial charge storage capacity, high double-layer capacitance, and longer in vivo lifetime, thereby enhancing the sensitivity of spike firing detection and electrical stimulation (ES) effectiveness. Using this MEA, sevoflurane-inhibited neurons and sevoflurane-excited neurons, together with changes in the oscillation characteristics of the local field potential within the DMH, are revealed as indicative markers of arousal states. During the arousal period, varying-frequency ESs are applied to the DMH, eliciting distinct arousal effects. Through in situ detection and stimulation, the disparity between these outcomes can be attributed to the influence of DBS on different neurons. These advancements may further our understanding of neural circuits and their potential applications in clinical contexts.

Electro-assisted sorption behavior and mechanism of low-concentration rare earth elements on carbon based materials

With increasing demands for rare earth elements (REEs) in high-tech and futuristic applications, developing efficient methods for recovering low-concentration REEs is necessary. Here, electro-assisted sorption of low-concentration REEs, La(III), Gd(III) and Y(III) (as symbol of light, medium, and heavy REEs) on carbon-based materials, activated carbon (AC), graphene, and graphite by a facile method was reported. Recovery of La(III), Gd(III) and Y(III) could reach ∼100 % under low-concentration condition where the maximum adsorption capacity was up to 342.38 mg/(g·dm2). Variants including applied voltage, electrodes-distance, pH, impurities, and concentration were considered to study the effects on REEs recovery. Interestingly, adsorption capacity and recovery under low voltage were respectively almost 20 and 14 folds than that without voltage, because voltage promoted REEs transfer and strengthened electrostatic interaction between electrodes and REEs. The mechanism for enhancing REEs recovery on carbon-based electrodes was resulted from high electric double layer (EDL) capacitance and low charge transfer resistance. Total desorption of REEs from electrodes could be quickly realized using NH4Cl or HCl solution. Overall, the study gave a new insight of low-concentration REEs recovery using carbon-based materials, and provided an efficient route using electric method with porous materials for REEs recovery.

Co3O4/activated carbon nanocomposites as electrocatalysts for the oxygen evolution reaction.

The Oxygen Evolution Reaction (OER) is crucial in various processes such as hydrogen production via water splitting. Several electrocatalysts, including metal oxides, have been evaluated to enhance the reaction efficiency. Zeolitic Imidazolate Framework-67 (ZIF-67) has been employed as a precursor to produce Co3O4, showing high OER activity. Additionally, the formation of composites with carbon-based materials improves the activity of these materials. Thus, this work focuses on synthesizing ZIF-67 and commercial activated carbon (AC) composites, which were used as precursors to obtain Co3O4/C electrocatalysts by calculating ZIF-67/CX (X = 10, 30, and 50, the mass percentage of AC). The obtained materials were thoroughly characterized by employing X-ray powder diffraction (XRD), confirming the cobalt oxide structure with a sphere-like morphology as observed in the TEM images. The presence of oxygen vacancies was confirmed by infrared spectroscopy and EPR measurements. The electrocatalytic performance in the OER was investigated by linear sweep voltammetry (LSV), which revealed an overpotential of 325 mV at 10 mA cm-2 and a Tafel slope value of 65.32 mV dec-1 for Co3O4/C10, superior in activity to several previously reported studies in the literature and electrochemical stability of up to 8 hours. The reduced value of charge transfer resistance, high double-layer capacitance, and the presence of Co3+ ions justify the superior performance of the Co3O4/C10 electrocatalyst.

Flexible Manganese Oxide Electrode Fabricated with Heat‐Treated Buckypaper for Supercapacitor

With the emergence of new technologies, wearable and portable devices become essential tools for various applications, which are flexibly designed. In this situation, flexible supercapacitors with fast charge and discharge cycles are needed as their power source. This study introduces the flexible pseudocapacitor electrode fabricated by electrodeposition of manganese oxide (MnO2) onto heat‐treated hydrophilic buckypaper (BP) molded on polydimethylsiloxane (PDMS). Here, the heat treatment of BP that is optimized by a proper adoption of thermogravimetric analysis is performed to enhance the electrodeposition efficiency of MnO2. Then, proper hydrophilicity of the heat‐treated BP (H‐BP) and successful preparation of MnO2/H‐BP@PDMS electrode is well confirmed by electrochemical, spectroscopical, and optical measurements. In their evaluations, it is found that heat treatment of BP is more important factor than electrodeposition time to improve the electrodeposition efficiency of MnO2 under the same aqueous electrolyte. With that, such optimally prepared MnO2/H‐BP@PDMS electrode shows a high electrical double layer and excellent specific capacitance of 1.31 F/cm2 at 1 mA/cm2, which are better results than those of other electrodes.

Theoretical and Experimental Investigations of Oxygen Activation Effect of Carbon Nanofibers Interacting with Polypyrrole

Theoretical modeling calculations and experimental measurements were adopted to investigate the oxygen activation effect of carbon nanofibers (CNFs) interacting with polypyrrole (PPY). The CNF undergoes a hydrothermal oxidation process to form epoxy and hydroxyl groups containing carbon nanofibers (CNF-O). The oxygen activation effect of CNF on the electronic and electrochemical properties was investigated through the interfacial interaction between CNF-O and PPY. Theoretical modeling calculation discloses that CNF-O/PPY exhibits lower electronic bandgaps (0.64 eV), a higher density of states (10.039 states/eV), and a lower HOMO–LUMO molecular orbital energy gap (0.077 eV) than CNF/PPY (1.56 eV, 7.946 states/eV and 0.112 eV), presenting its superior electronic conductivity and electroactivity. The Mulliken population and charge density difference analysis disclose the stronger interface interaction of CNF-O/PPY caused by epoxy and hydroxyl groups. Cyclic voltammogram measurements reveal that CNF-O/PPY exhibits a higher response current and a higher specific capacitance (221.1–112.2 mF g−1) than CNF/PPY (57.6–24.2 mF g−1) at scan rates of 5–200 mV s−1. Electrochemical impendence spectrum measurements disclose that CNF-O/PPY exhibits a lower charge transfer resistance (0.097 Ω), a lower ohmic resistance (0.336 Ω), a lower Warburg impedance (317 Ω), and a higher double-layer capacitance (0.113 mF) than CNF/PPY (1.419 Ω, 9.668 Ω, 7865 Ω, and 0.015 mF). Both theoretical and experimental investigations prove that CNF-O/PPY presents an intensified intermolecular interaction rather than CNF/PPY. The promotive oxygen activation effect of CNF could contribute to improving the electronic and electrochemical properties of CNF-O/PPY.

Facile synthesis of surface oxygen vacancy and Ti3+ defects in SrTiO3 perovskite coupled g-C3N4 decorated with Au ternary nanocomposites for enhancing electrocatalytic activity from acidic and natural seawater conditions

The development of efficient electrocatalysts became vital to resolving the ongoing clean energy crises and environmental issues, wherein high-performance catalysts for the improved electrocatalytic hydrogen evolution reaction (EHER) are demanded. To meet this goal, an advanced and green ultrasonic-assisted pulsed laser ablation in liquid technique was used to prepare surface oxygen vacancy and Ti3+ defects in perovskite-based ternary nanocomposites (PTNCs) decorated with Au@SrTiO3/g-C3N4. An effective cathode was designed using Au@SrTiO3/g–C3N4–decorated PTNCs for EHER that operated in an acidic media of 0.5 M H2SO4. The optimized Au@SrTiO3/g-C3N4 PTNCs revealed an improved EHER at a very low over-potential of 0.082 V at a cathodic current density (J) of −10 mA/cm2, high double-layer capacitance (679.8 μF/cm2), large electrochemical surface area (19.4 cm2), high mass activity (198.35 A/g), high specific activity (2.91 mA/cm2), high surface charge density (0.0404 C/cm2), high catalytic active sites (4.19 × 10−7 mol/cm2), and exceptional long-term stability at 50 h, respectively. The Tafel slope of 45.36 mV/dec confirmed the presence of the Volmer-Heyrovsky mechanism to explain the enhanced EHER cycle of the prepared PTNCs. The improved electrocatalytic EHER performance was attributed to the induced synergistic strong metal-support interaction (SMSI) effect of the surface oxygen vacancy and Ti3+ defects in PTNCs that increased electrochemical surface area, high exposure of abundant active sites, improved intrinsic kinetics, and fast charge transport, respectively. Moreover, Au@SrTiO3/g–C3N4–decorated PTNCs exhibit excellent natural seawater electrolysis in terms of EHER at a low over-potential of 0.300 V at a J = −10 mA/cm2 and long-term stability at 10 h, respectively. It is demonstrated that the proposed novel surface oxygen vacancy and Ti3+ defects in Au@SrTiO3/g-C3N4 PTNCs are effective electrocatalysts can be beneficial for producing hydrogen from green technologies in future energy applications via interface engineering.

Highly Efficient Cobalt Sulfide Heterostructures Fabricated on Nickel Foam Electrodes for Oxygen Evolution Reaction in Alkaline Water Electrolysis Cells

Non-noble metal electrocatalysts for the oxygen evolution reaction (OER) have recently gained particular attention. In the present work, a facile one-step electrodeposition method is applied in situ to synthesize cobalt sulfide nanostructures on nickel foam (NF) electrodes. For the first time, a systematic study is carried out on the impact of the Co/S molar ratio on the structural, morphological, and electrochemical characteristics of Ni-based OER electrodes by employing Co(NO3)2·6 H2O and CH4N2S as Co and S precursors, respectively. The optimum performance was obtained for an equimolar Co:S ratio (1:1), whereas sulfur-rich or Co-rich electrodes resulted in an inferior behavior. In particular, the CoxSy@NF electrode with Co/S (1:1) exhibited the lowest overpotential value at 10 mA cm−2 (0.28 V) and a Tafel slope of 95 mV dec−1, offering, in addition, a high double-layer capacitance (CDL) of 10.7 mF cm−2. Electrochemical impedance spectroscopy (EIS) measurements confirmed the crucial effect of the Co/S ratio on the charge-transfer reaction rate, which is maximized for a Co:S molar ratio of 1:1. Moreover, field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) were conducted to gain insights into the impact of the Co/S ratio on the structural and morphological characteristics of the electrodes. Notably, the CoxSy@NF electrocatalyst with an equimolar Co:S ratio presented a 3D flower-like nanosheet morphology, offering an increased electrochemically active surface area (ESCA) and improved OER kinetics.

Synthesis of defect-engineered molybdenum sulfides on reduced graphene oxide for enhanced hydrogen evolution reaction kinetics

Amorphous molybdenum sulfide (a-MoS3) is a promising non-precious electrocatalyst for hydrogen evolution reaction owing to the abundant defective active sites. Here in, we show a rapid microwave-assisted synthesis method to produce a-MoS3 catalysts on reduced graphene oxide (rGO) substrates. The a-MoS3 reported in this study comprise of two possible 1D chain-like structures, i.e., with molybdenum (IV) in Weber's model and molybdenum (V) in Hibble's model, unlike the polymeric cluster type a-MoS3 structures reported in literature. Thermal annealing of the microwave-prepared a-MoS3 produced a family of defect-engineered MoSx/rGO hybrids, from a-MoS3 to crystalline MoS2, which showed tunable HER activities. XPS analysis provided in-depth understanding of the compositional changes in MoSx/rGO with thermal annealing. The a-MoS3/rGO 250 (annealed at 250 °C) exhibited the highest HER catalytic activity among all the MoSx/rGO hybrids, with an overpotential of 208 mV at 10 mA/cm2, a low Tafel slope of 52 mV/decade, a high double layer capacitance of 3.7 mF/cm2 and a high TOF value of 0.43 H2/s per site at the HER overpotential of 208 mV. The excellent HER activity is attributed to both MoV and sulfur active sites. This study provides a controllable, scalable and rapid synthesis method to produce 1D chain-like a-MoS3 structures for HER electrocatalysis.

One-step electrodeposition of NiS heterostructures on nickel foam electrodes for hydrogen evolution reaction: on the impact of thiourea content

Herein, we report on the one-step growth of nickel sulfide (NiS) heterostructures on nickel foam (NF) substrate via a facile electrodeposition method, employing Ni(NO3)2.6H2O and CH4N2S as Ni and S precursors, respectively. For the first time, a systematic study was carried out on the impact of the Ni/S molar ratio on the electrochemical performance of as-prepared electrodes for water splitting. The optimum performance was obtained for a Ni:S ratio equal to 2:1, whereas lower or higher ratios resulted in much inferior performance. The NiS@NF electrode with a Ni:S ratio of 2:1 exhibited the lowest overpotentials |η10| = 136 mV, |η100| = 209 mV, extremely low Tafel slope (60 mV dec-1), and very high double layer capacitance value (2.78 mF cm-2). Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), and X-ray photoelectron spectroscopy (XPS) revealed the formation of coral-like nanoarchitecture, resulting in enhanced HER activity.

Improved supercapacitor and oxygen evolution reaction performances of morphology-controlled cobalt molybdate

Herein, various morphologies (Bundle of rods, rods, nanoparticles, and umbra) of cobalt molybdate (CoMoO4) were obtained by changing the pH (6, 7, 8, and 9) of the solutions during hydrothermal synthesis. The evolution mechanism of different morphologies was explained. These samples were used for supercapacitors and oxygen evolution reaction (OER) catalysts. The higher double-layer capacitance (464 mF cm−2) was observed in CoMoO4 nanoparticles. It demonstrated high specific capacitance (191 F/g at a current density of 1 A/g) and excellent cyclic stability performance (98 % retention capability after 2000 cycles) in the 3 M KOH solution. Furthermore, CoMoO4 nanoparticles showed the lowest overpotential (200 mV at 10 mA/cm2) and onset potential in linear sweep voltammetry polarization curves, superior turnover frequency (0.0095 s−1), and low Tafel slopes (149 mV/dec) compared to other morphologies. According to chronoamperometry test, good electrochemical stability was noted in nanoparticles for 10 h towards OER. The higher energy storage and OER performances of CoMoO4 nanoparticles were related to excellent oxidation/reduction/electron transfer abilities, great surface area, and rich active sites. Thus, these findings suggest that morphology controlled CoMoO4 could be a great candidate for efficient supercapacitor electrode materials and OER catalysts.

Cu2CoSnS4 electrocatalyst embedded paper working electrodes for efficient, stable, pH universal, and large-current-density hydrogen evolution reaction

In this study, practical application for the industrial-scale hydrogen evolution reaction (HER) process is established using sustainable Cu2CoSnS4 embedded in paper-working electrodes. The Cu2CoSnS4 is produced using a solvent-free solid-phase approach. The effect of a wide pH range of electrolytes on working electrodes for hydrogen evolution reactions is also investigated. The Cu 2CoSnS4 embedded paper-working electrodes exhibit goodelectrocatalytic activity for hydrogen evolution reaction with low overpotential values of 233, 310, and 261 mV vs RHE at 10 mA/cm 2 in 0.5 M H2SO4,1 M KOH, and 1 M PBS, respectively. These designed electrodes exhibit high double-layer capacitance and electrochemical surface area for a wide pH range. In acidic, alkaline and neutral environments, the catalyst-embedded paper electrodes explicit high turnover frequencies of 2.15 s−1, 2.75 s−1, and 2.11 s−1, respectively. The temperature-dependent hydrogen evolution reaction is studied to calculate the activation energy of the cathodic electrode. Utilising chrono-amperometry for about 118 h in an acidic media, which shows that electrodes have a high degree of stability. In comparison to other previously reported work on catalyst-embedded electrodes, the Cu2CoSnS4 embedded paper-working electrodes offer excellentpotential for HER activity across a wide pH range and are suitable for industrial application.

Metal-organic framework-derived boron-doped iron-cobalt tannate nanoparticles as a high-efficiency electrocatalyst for oxygen evolution reaction

Electrocatalytic oxygen evolution reaction (OER) is an important half reaction for energy conversion and storage, which possesses low OER efficiency due to the multistep proton-coupled electron transfer. Herein, B-doped iron-cobalt tannate nanoparticles (B-doped FeCoTA) are synthesized by one-step hydrothermal method. It is proved that the optimized B-doped FeCoTA exhibits excellent electrocatalytic performance for OER with a low overpotential of 306 mV at a current density of 10 mA cm−2, a small Tafel slope of 28 mV dec−1, a high double-layer capacitance of 6.31 mF cm−2 and excellent OER stability with a low potential of 1.55 V (vs RHE) at 10 mA cm−2, which is ascribed to the synergistic effect between bimetallic and heteroatom doping. The B incorporation can greatly enhance the electrical conductivity between metals, facilitate electron transfer and material exchange, thus greatly reducing reaction dynamics and strengthening OER performance. This work can provide a good strategy for the design and development of new efficient and stable OER electrocatalysts.

Energy Storage Mechanism in Supercapacitors with Porous Graphdiynes: Effects of Pore Topology and Electrode Metallicity.

Porous graphdiynes are a new class of porous two-dimensional materials with tunable electronic structures and various pore structures. They have potential applications as well-defined nanostructured electrodes and could provide ideal platforms for understanding energy storage mechanisms underlying supercapacitors. Herein, we investigate the effect of stacking structure and metallicity on energy storage with such electrodes. Simulations revealed that supercapacitors based on porous graphdiynes of AB stacking structure could achieve both higher double-layer capacitance and ionic conductivity than AA stacking. This phenomenon is ascribed to more intense image forces in AB stacking, leading to a breakdown of ionic ordering and the formation of effective "free ions". Macroscale analysis shows that doped porous graphdiynes could deliver both outstanding gravimetric and volumetric energy and power densities due to their enhanced quantum capacitance. These findings pave the way for designing high-performance supercapacitors by regulating pore topology and metallicity of electrode materials. This article is protected by copyright. All rights reserved.

Hybrid Nanostructured Compounds of Mo2C on Vertical Graphene Nanoflakes for a Highly Efficient Hydrogen Evolution Reaction.

Organizing a post-fossil fuel economy requires the development of sustainable energy carriers. Hydrogen is expected to play a significant role as an alternative fuel as it is among the most efficient energy carriers. Therefore, nowadays, the demand for hydrogen production is increasing. Green hydrogen produced by water splitting produces zero carbon emissions but requires the use of expensive catalysts. Therefore, the demand for efficient and economical catalysts is constantly growing. Transition-metal carbides, and especially Mo2C, have attracted great attention from the scientific community since they are abundantly available and hold great promises for efficient performance toward the hydrogen evolution reaction (HER). This study presents a bottom-up approach for depositing Mo carbide nanostructures on vertical graphene nanowall templates via chemical vapor deposition, magnetron sputtering, and thermal annealing processes. Electrochemical results highlight the importance of adequate loading of graphene templates with the optimum amount of Mo carbides, controlled by both deposition and annealing time, to enrich the available active sites. The resulting compounds exhibit exceptional activities toward the HER in acidic media, requiring overpotentials of 82 mV at -10 mA/cm2 and demonstrating a Tafel slope of 56 mV/dec. The high double-layer capacitance and low charge transfer resistance of these Mo2C on GNW hybrid compounds are the main causes of the enhanced HER activity. This study is expected to pave the way for the design of hybrid nanostructures based on nanocatalyst deposition on three-dimensional graphene templates.

Construct of an Electrodeposited Cobalt-Molybdenum Film and Evaluation of Its Efficiency in Hydrogen Evolution.

Hydrogen is a valuable clean energy source, and electrolysis to produce hydrogen from water is a crucial component. However, a major problem of hydrogen generation by electrolysis is its large overpotential and poor economics. To reduce the overpotential, we mainly use nickel foam and Co-Mo ions as feedstock and create an efficient catalytic material by electrodeposition. The Co-Mo interaction improves the current efficiency. In 1 mol/L NaOH solution, the overpotential of the Co-Mo-NF composites was low when the current density is -10 mA/cm2, with the best value reaching 45.3 mV, which is less than those of Co-NF (94.4 mV) and Mo-NF (88.2 mV). All deposits had similar Tafel slopes in the 77.9 mV/decade range. The catalyst does not just have a favorable effect on hydrogen formation but also has a surprisingly high double-layer capacitance (up to 180 mF/cm2) and good stability. This research provides an impactful approach for developing a non-precious metal HER catalyst for industrial hydrogen production.

Facile route for synthesizing WS2/W2C nano hollow flowers and their application for hydrogen evolution reaction

Recently, catalysts based on tungsten disulfide nanoflowers (WS2 NFs) and tungsten carbide (W2C) materials have been intensively investigated for hydrogen evolution reaction (HER). In this study, a facile and scalable route was utilized to synthesize a nano hollow flowers catalyst based on heterostructure of WS2 and W2C (WS2/W2C NHFs). Besides that, other structures of tungsten compounds including WS2–WO3 flower particles (FPs) and pure WS2 NFs were also prepared by the similar route with slight modification, to compare the differences in their structures and HER activities. Materials properties were comprehensively studied via X-ray diffraction analysis, field emission scanning microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Then, the HER catalytic activities of synthesized materials were also carefully studied. The results indicate that WS2/W2C NHFs exhibits the HER activities much better than that of prepared WS2–WO3 FPs and pure WS2 NFs. The HER performance of WS2/W2C NHFs exhibits a low Tafel slope of about 61 mV.dec−1, an overpotential of − 280 mV at − 10 mA.cm-2, high double-layer capacitance (11.9 mF cm-2) and the superstability in acid media. This improvement is attributed to the synergistic effect of the WS2 and W2C heterostructure as well as the special structure of WS2/W2C NHFs catalyst.

A Microelectrode Array Modified by PtNPs/PB Nanocomposites Used for the Detection and Analysis of Glucose-Sensitive Neurons under Different Blood Glucose States.

Hypoglycemia state damages the organism, and glucose-excited and glucose-inhibited neurons from the ventral medial hypothalamus can regulate this state. Therefore, it is crucial to understand the functional mechanism between blood glucose and electrophysiology of glucose-excited and glucose-inhibited neurons. To better detect and analyze this mechanism, a PtNPs/PB nanomaterials modified 32-channel microelectrode array with low impedance (21.91 ± 6.80 kΩ), slight phase delay (-12.7° ± 2.7°), high double layer capacitance (0.606 μF), and biocompatibility was developed to realize in vivo real-time detection of the electrophysiology activities of glucose-excited and glucose-inhibited neurons. The phase-locking level of some glucose-inhibited neurons elevated during fasting (low blood glucose state) and showed theta rhythms after glucose injection (high blood glucose state). With an independent oscillating ability, glucose-inhibited neurons can provide an essential indicator to prevent severe hypoglycemia. The results reveal a mechanism for glucose-sensitive neurons to respond to blood glucose. Some glucose-inhibited neurons can integrate glucose information input and convert it into theta oscillating or phase lock output. It helps in enhancing the interaction between neurons and glucose. Therefore, the research can provide a basis for further controlling blood glucose by modulating the characteristics of neuronal electrophysiology. This helps reduce the damage of organisms under energy-limiting conditions, such as prolonged manned spaceflight or metabolic disorders.

Application of Potassium Ion Conducting KTiOPO4 as Effective Inner Solid-Contact Layer in All-Solid-State Potassium Ion-Selective Electrode

Solid electrolytes used in all-solid-state batteries electronically separate the positive and negative electrodes in the battery and only allow the carrier ions to pass through. KTiOPO4 (KTP), a potassium ion-conducting solid electrolyte, was first applied as the inner solid contact layer of an all-solid-state potassium ion-selective electrode (ISE) to stabilize the membrane potential. Application of the KTP layer improved the long-term potential stability of the ISE by stabilizing the membrane potential. This can be further improved by adding acetylene black (AB) to the KTP layer which reduced the electrode resistance owing to its high double-layer capacitance.