Storage Capability Research Articles

Effective CO2 Thermocatalytic Hydrogenation with High Coke Resistance on Ni-CZ/Attapulgite Composite

Converting CO2 into methane is considered a promising and economically viable technology for global transportation and utilization of this greenhouse gas. This study involves the preparation of a Ni-CZ (CeO2-ZrO2)/ATP (attapulgite) catalyst through the co-precipitation and impregnation methods. XRD, SEM, TEM, N2 absorption-desorption isotherms, XPS, H2-TPR, CO2-TPD, TG/DSC, and Raman were adapted to characterize the obtained samples. Real-time GC was used to measure the catalytic performances and to intensively study the impact of Ni loading content and ATP to CZ ratio on the catalytic performance of the products. DRIFTs was used to monitor the interstitial radicals in the catalytic reactions and to deduce the catalytic mechanisms. The results indicate that the composite catalytic matrix composed of CZ assembled on ATP demonstrated higher CO2 methanation stability and better carbon deposition resistance ability than the single CZ or ATP as the carrier, which should be attributed to the improved specific surface area and pore volume of the ATP assembled matrix and the enhanced dispersibility of the CZ and Ni species. The adoption of CZ solid solutions improves the oxygen storage capability of the catalyst, thereby providing continued mobile O2− in the matrix and accelerating the molecular exchange rate in the catalytic reactions. The ideal loading quantity of nickel contents on the CZA matrix is 15%, as the CO2 conversion decreases at elevated temperatures when the Ni loading content reaches 20%. Among the tested samples, the 15Ni-0.8CZA sample showed the best catalytic performance of 75% CO2 conversion and 100% CH4 selectivity at 400 °C. After 50 h of stability tests, the CO2 conversion rate still remained 70.84%, and the CH4 selectivity obtained 97.46%. No obvious coke was detected according to the Raman spectra of the used catalyst. The in situ DRIFTS experiment showed that formate is the main intermediate of the CO2 hydrogenation reaction on the 15Ni-0.8CZA catalyst.

Electrospray deposition of starch-containing laccase: A green technique for low-cost and eco-friendly biosensors

Recently a laccase-based biosensors with unprecedented reuse and storage capabilities in the detection of catechol compound has been manufactured using ambient Electrospray Deposition (ESD) technique. These biosensors showed to be reused up to 63 measurements on the same electrode just prepared at room temperature and pressure. In this new work the reasons behind such a high-performance functioning have been investigated by analysing the commercial sample of laccase with different chemical physics methods: Electrophoresis, Fourier Transform Infrared Spectroscopy, X-ray Fluorescence and Nuclear Magnetic Resonance Spectroscopy. The analyses reveal the presence of the starch in the sample and its essential role as stabilizing agent. Indeed, comparing the performance of starch/laccase-based biosensors with starch-free/laccase-based biosensors, both produced via ESD, showed that the starch-free biosensors lost about 40% of their performance after just the first wash. This suggests that the presence of starch in the laccase sample is a key factor in providing the high wash and storage resistance, which are essential for the fabrication of such devices.

Impact of Ca2+ and Zr4+ substitution on mechanical energy harvesting response of lead-free BaTiO3 piezoceramics with thermally stable storage density and efficiency

The Ba1-xCaxZryTi1-yO3 (BCZT; x = 0.18, y = 0.08; x = 0.15, y = 0.10; x = 0.12, y = 0.12; x = 0.09, y = 0.14; both x and y are in mol. %) piezoceramics were prepared by solid-state reaction method and investigated their energy storage and harvesting responses. The composition x = 0.15, y = 0.10 ( i.e. BCZT-2) reveals the morphotropic phase boundary (MPB) near room temperature with enhanced piezoelectric properties such as piezoelectric charge coefficient (d33) ∼ 380 pC/N, piezoelectric strain coefficient (d33*) ∼ 583.71 pm/V, piezoelectric voltage coefficient (g33) ∼ 14.09 ×10−3Vm/N, figure of merits (d33×g33) ∼ 5.35 ×10−12m2/N and the electromechanical coupling coefficient (kp) ∼ 0.291. The harvested peak-to-peak open circuit AC voltage is 30 V and the calculated current is in the range of 0.02–0.14 mA with varied load resistance and the maximum obtained power density is 13.38 μW/mm3 for BCZT-2 ceramics. The DC output signal of BCZT-2 ceramics successfully lit up the 'FCLNT' panel consisting of 53 red LEDs. At room temperature, BCZT ceramics have a recoverable energy storage density (Wrec) and storage efficiency (η) in the range between 506.46 and 257.49 mJ/cm3 and 50.53 – 64.93 % respectively. The composition x = 0.12, y = 0.12 (i.e. BCZT-3) revealed the highest energy storage efficiency (η) ∼ 64.93 % at room temperature. Nonetheless, the temperature-dependent (till its Curie temperature) maximum obtained Wrec of all BCZT ceramics is found in the range between 238.41 and 446.49 mJ/cm3 with an η of 66.98–79.67 %. Thus, compositionally tuned BCZT ceramics exhibit considerable piezoelectric properties, including energy storage and harvesting capabilities.

A unique solar pond system integrated with chlor-alkali electrolyser for heat storage and hydrogen production

Solar ponds are recognized as a simple, but a unique solution for renewable heat storage to use later. A freshwater feed to solar ponds is considered a crucial requirement to maintain the salinity gradient accordingly for heat storage purposes. This study aims to benefit from this specific requirement for solar ponds by integrating chlor-alkali electrolysers to produce hydrogen along with heat storage, which is a common purpose of a solar pond. Therefore, the proposed system establishes a desirable synergy, as per the sustainable development goals, between a conventional solar pond and an innovative high-tech hydrogen production system. In order to produce hydrogen, the saline water withdrawn from the upper convective zone is used in a chlor-alkali electrolyser powered by solar PV in order to produce green hydrogen. Thus, a conventional solar pond is converted into an integrated energy system that produces hydrogen and chlorine for useful purposes, along with heat storage capability. The system’s performance has been assessed in terms of the energy and exergy efficiencies for five distinct cities located in different countries that are grappling with poverty. The system’s performance, which is assessed in five cities, demonstrates the energy and exergy efficiencies ranging from 11.66 % to 14.56 % and 6.84 % to 8.60 % for the solar pond. They vary from 21.95 % to 24.22 % and from 14.23 % to 14.66 % for the overall system, respectively. Furthermore, the system effectively captures and stores solar energy, and it reaches temperatures up to 89.1°C. Moreover, the proposed system is expected to contribute to the United Nations’ Sustainable Development Goals by addressing energy poverty, promoting clean energy, and fostering economic growth.

Two-dimensional heterostructure of MXene-derived V2O5·H2O and graphene with enhanced Zn-ion storage capability

Aqueous rechargeable zinc-ion batteries (ZIBs) are promising candidates for gird-scale energy storage with economic and environmental advantages. Layered hydrated vanadium oxides with multivalent and “lubricating” effect receive much attention in ZIBs. However, the application of them is suffering from the poor intrinsic conductivity and the unstable structure. Herein, a unique 2D/2D heterostructure of δ-V2O5·H2O nanobelts (VO) and reduced graphene oxide (rGO) is designed as cathode for ZIBs (denoted as VOG). The stronger interface coupling and the shorter ion transport pathways impart the VOG electrode impressive stability and fast ions diffusion kinetics. Specifically, the VOG cathode delivers a superior capacity of 342 mAh g−1 at 1 A g−1 and a remarkable rate capability of 280 mAh g−1 at a quite high rate of 10 A g−1. The energy storage mechanism involved is investigated by systematical characterizations. The exploration of such 2D/2D heterostructure materials with strong synergy sheds light on the rational design of high performanced AZIBs.

Effects of Co-doping on the microstructure and electrochemical performance of nickel vanadate (Ni3V2O8) electrode material for aqueous symmetric supercapacitor

Recently, there has been an increased focus on supercapacitors due to their reliable electrochemical energy storage capabilities. This study utilized an environmentally friendly facile hydrothermal method to prepare the nickel vanadate (NiVO) and cobalt-doped nickel vanadate (Co-doped Ni3V2O8) composite for supercapacitor applications. The prepared materials of pure and Co-doped Ni3V2O8 with different concentrations of Co (10 % and 15 %) were evaluated through three electrode assemblies. It is significant to note that although Co smoothed the surface of NiVO, most of the nickel vanadate crystals broke apart into tiny particles and increased the number of electroactive sites. Pure NiVO has a specific capacitance (Cs) of 1638.06 F/g at 5 mV/s. It has been observed that the electrochemical performance has been improved by adding Co 10 % and 15 % in NiVO. The 15 % Co-doped NiVO exhibits an outstanding Cs of 2641.99 F/g at a scan rate of 5 mV/s with a high capacitance retention of 98.14 % after 1k charge-discharges cycles. This excellent performance of the material is due to more electroactive sites and synergistic effects among Co and Ni in the composite. To further elaborate the electrochemical performance of 15 % Co-doped NiVO, it is employed for the fabrication of a symmetries supercapacitor (SSC) device, which shows that the fabricated device has a capacitance of 286 F/g at a current density (CD) of 0.5 A/g and high energy density of 39.7 Wh/kg at a power density of 333.33 W/kg. The symmetric device maintains a cyclic stability of 93.8 % while undergoing 5000 consecutive charge–discharge cycles at a current density of 10 A/g. Based on rigorous testing and analysis, these findings suggest that the prepared electrode material is reliable and suitable for implementation in forthcoming wearable electronic systems.

Attaining superior performance in an aqueous hybrid supercapacitor based on N-Doped highly porous carbon spheres and N-S dual doped Co3O4

Cobalt oxide (Co3O4) has seen a significant interest for its application as an electrode for supercapacitors, due to its cost-effectiveness, high theoretical capacitance and outstanding redox activity. However, Co3O4 exhibits poor electrical conductivity and cycle life restricting its high-power energy storage applications. High porosity carbons are materials of choice for applications in electric double layer charge storage but suffer from poor energy densities due to limited charge storage capabilities. Here we propose a hierarchical functionalization strategy to develop N, S co-doped Co3O4 and N doped high porosity carbon micro-spheres for efficient and durable hybrid supercapacitor. Benefiting from the structural eminence, improved electrical conductivity and high quantity of N content, the heteroatom enriched N, S co-doped Co3O4 and N doped porous carbon spheres demonstrates superior electrochemical performance. Moreover, hybrid supercapacitor cell with N, S co-doped Co3O4 as a cathode and N doped porous carbon spheres as anode deliver a high specific energy of 52 Wh kg-1 at power density of 1462 W kg-1 coupled with the capacity retention of 95 % after 5,000 charge-discharge cycles.Therefore, by improving both anode and cathode simultaneously can be considered an effective approach to enhance energy storage capabilities of hybrid supercapacitors while maintain exceptionally high-power densities.

High performance potassium/sodium-ion storage enabled by anchoring cobalt atoms on sulfur vacancies in WS2 nanosheets

Transition metal dichalcogenides (TMDs) as anodes have presented significant potential in alkali-ion batteries. Nevertheless, they are generally vulnerable to low conductivity and sluggish ion diffusion as well as severe volume variation. Here, a strategy of filling metal atoms into anion vacancies is proposed and applied to the example of WS2. More specifically, sulfur vacancies are produced and partially filled by Co atoms simultaneously in WS2 (denoted as Co@WS2-SV), creating a highly reactive micro-structure composed of Co-W-S, which can not only effectively provide more active sites, but also boost the charge transfer and reaction kinetics. Consequently, the as-prepared Co@WS2-SV exhibits superior K+ storage performance, which includes an ultrahigh reversible capacity of 382.9 mAh g−1 at 0.05 A g−1. Besides, Co@WS2-SV still maintain a capacity of 112.6 mAh g−1 after 1100 cycles at 2 A g−1 while the capacity fades to ∼0 mAh g−1 after only 800 cycles for WS2. Simultaneously, Co@WS2-SV also displays outstanding rate capability (338.7 mA h g−1 at 2 A g−1) and acceptable cycling performance (264.2 mA h g−1 at 1 A g−1 after 100 cycles) for sodium storage. The strategy in our study provides new way of precisely designing the other TMDs anodes for metal-ion batteries.

Collaborative Optimization for Active Distribution Network with Soft Open Point and Energy Storage

Background: The increasing use of high-penetration distributed clean energy has led to voltage fluctuations in the distribution network that surpass safety limits and pose challenges to economic and low-carbon operation. Traditional voltage regulation devices are unable to meet the real-time high-precision voltage control needs when encountering frequent fluctuations due to physical limitations. The Soft Open Point (SOP) can provide continuous reactive power to achieve rapid voltage regulation. Objective: We propose a collaborative optimization approach that fully considers the regulatory capabilities of SOP and energy storage to eliminate voltage violations and reduce network losses. Methods: This study introduces an active distribution network reactive power voltage optimization approach that incorporates intelligent SOP and energy storage, combining conventional devices (such as on-load tap changers and capacitor banks) with contemporary devices (such as SOP, distributed generators, and energy storage) to establish synergy. A coordinated optimization model was developed, considering various operational constraints to minimize network losses and regulate the voltage of distribution network nodes. By using linearization and quadratic relaxation, the original non-convex mixed-integer non-linear optimization model was transformed into a Mixed-Integer Second-Order Cone Programming (MISOCP) model to meet the requirements of rapid voltage regulation. Results: A case study was conducted on the IEEE 33-node test system, showing that the proposed approach effectively reduces network losses and eliminates voltage violations. Conclusion: The feasibility and effectiveness of the proposed methodology have been validated, confirming its ability to ensure the safe and economic operation of active distribution networks.

Exergo and enviro-economic analysis of thermal energy storage assisted finned solar still

The current investigation focuses on improving the performance of a single slope solar still integrated with Phase Change Material as energy storage media. The problem of low thermal conductivity of PCM which hinders the energy storage capability has been addressed by incorporating fins with different profiles into the energy storage unit. Initially, an experimental investigation was conducted and analyzed to assess the effective performance of a Conventional Single Slope Solar Still (CSS) using various water depth levels: 1–4 cm. The optimal basin water depth for testing solar still with energy storage material along with fins was identified as 2 cm. Subsequently, the CSS was subjected to performance enhancement investigation under three different conditions: Case 1 – Solar Still (SS) with PCM storage unit, Case 2 – SS with fins at the PCM storage unit, and Case 3 – SS with fins at the storage unit and a parallel plate attached to the other end of the fins. The experimental results demonstrated the production of fresh water and efficiency improvements are as follows 26.95%, 55.86%, 69.14% and 24.34%, 52.83%, 68.83% for cases I, II, and III, respectively. Further, it was observed that Case III exhibited a lower cost of water production and a shorter payback period compared to CSS. The enviro-economic analysis revealed that the net CO2 emissions (NCEM) and Carbon Credits Earned (CCE) for Case III were 15.60 tons and 312.07 USD respectively against 9.22 tons and 184.31 USD for CSS.

Intrinsically microporous polyimide-based metal-free catalysts for round-the-clock photodegradation of organic pollutants

Photocatalytic degradation of organic pollutants is an essential technology for various environmental applications. However, the effectiveness of most photocatalysts is restricted to light. Herein, we report metal-free catalysts derived from intrinsically microporous polyimide for persistence in photocatalytic degradation of dyes. We systematically investigate the effect of porosity and functionality on photocatalytic efficiency. Both the pristine 4,4′-(hexafluoroisopropylidene)diphthalic anhydride-3,3′-dimethylnaphthidine and its thermally annealed counterpart at 530 °C exhibit high charge storage capabilities, enabling continuous photodegradation in the absence of light. The pre-irradiated catalyst exhibits an approximately 99% degradation of the dye, with a ~40% improvement relative to the non-pre-irradiated sample. We studied the influence of the chemical structure and porosity on the photocatalytic degradation efficiency in darkness by varying the polyimide chemical structure using different diamines. This research underscores the potential of polymers with intrinsic microporosity for application in the continuous degradation of dyes, contributing to the pursuit of cleaner water.

An Experimental Study Analysis of The Suitability of Sensible Heat Storage Materials for Solar Cooking Under Algerian Sahara Conditions

Solar power stands as a crucially sustainable energy source, primarily harnessed for heating and generating power. Various energy storage materials exist, enabling the improvement of diverse solar heating systems' performance. In this study, we've experimentally examined the thermal storage capabilities of small masonry brick pieces within a box-type solar cooker. This material was utilized atop the cooking plate in the tested cooker. The authors focused on making box cookers more efficient without breaking the bank, particularly benefiting those in remote areas. They explored using cost-effective heat storage materials, making it accessible even to those with limited education. Cooking trials showed promising results, indicating the practicality of affordable energy storage materials. These findings hint at the possibility of widespread adoption of the tested model. The cooker boasts a thermal efficiency of approximately 36.8%, a cooking power of around 61.10 W, and a thermal storage capacity of roughly 7 hours per day. The estimated cost for the cooker tested comes in at about $75.

Porous structural battery composite for coordinated integration of mechanical and electrical functionalities

AbstractStructural battery composites (SBCs) represent an emerging multifunctional technology in which materials functionalized with energy storage capabilities are used to build load‐bearing structural components. However, due to the liquid electrolyte contamination in structural battery electrolyte (SBE) and the large volume expansion of active battery materials, the poor interlayer interfacial in multilayer SBCs often causes difficulties in practical use. In this study, a new porous LiFePO4‐graphite SBC is designed and fabricated by independently distributing battery materials and resin matrix on carbon fiber fabric in pattern lattice form to prepare electrodes prepreg. The cured porous composite framework supports the load‐bearing function while limiting the electrochemical reaction in liquid electrolyte within lattices. The electrodes show reversible electric resistance after 3000 bending cycles with radius as small as 10 mm. The mechanical properties enhance significantly with tensile strength of 486.1 MPa and Young's modulus of 9.1 GPa compared to that with a liquid–solid biphasic mixed SBE structure. The SBC also exhibits a favorable capacity of 27.8 mAh/g at 0.1C. This straightforward integration path of mechanical and electrical functionalities is compatible with the manufacturing process of aerospace composite structures, which will provide an efficient and convenient energy supply solution for distributed electronics.Highlights A porous full‐cell structural battery composite (SBC) was designed and fabricated with prepregs. A suspension deposition and volatilization method was developed for robust battery material coating. Electrodes layer exhibited reversible electric resistance after 3000 tensile/bending cycles. The tensile strength and modulus increased significantly compared to the SBC with liquid–solid biphasic mixed structural battery electrolyte. Coordinated integration path was completely compatible with the manufacturing process of aerospace composite structures.

DONGLE 2.0: Direct FPGA-Orchestrated NVMe Storage for HLS

Rapid growth in data size poses significant computational and memory challenges to data processing. FPGA accelerators and near-storage processing have emerged as compelling solutions for tackling the growing computational and memory requirements. Many FPGA-based accelerators have shown to be effective in processing large data sets by leveraging the storage capability of either host-attached or FPGA-attached storage devices. However, the current HLS development environment does not allow direct access to host-or FPGA-attached NVMe storage from the HLS code. As such, users must frequently hand off between HLS and host code to access data in storage, and such a process requires tedious programming to ensure functional correctness. Moreover, since the HLS code uses radically different methods to access storage compared to DRAM, the HLS codebase targeting DRAM-based platforms cannot be easily ported to NVMe-based platforms, resulting in limited code portability and reusability. Furthermore, frequent suspension of HLS kernel and synchronization between CPU and FPGA introduce significant latency overhead and require sophisticated scheduling mechanisms to hide latency. To address these challenges, we propose a new HLS storage interface named DONGLE 2.0 that enables direct FPGA-orchestrated NVMe storage access. By providing a unified interface for storage and memory access, DONGLE 2.0 allows a single-source HLS program to target multiple memory/storage devices, thus making the codebase cleaner, portable, and more efficient. DONGLE 2.0 is an extension to DONGLE 1.0 [ 1 ] but adds support for host-attached storage. While its primary focus is still on FPGA NVMe access in near-storage configurations, the added host storage support ensures its compatibility with platforms that lack native support for FPGA-attached NVMe storage. We implemented a prototype of DONGLE 2.0 using an AMD/Xilinx Alveo U200 FPGA and Solidigm DC-P4610 SSD. Our evaluation on various workloads showed a geometric mean speed-up of 2.3× and a reduction in lines of code (LoC) by 2.4× compared to the state-of-the-art commercial platform when using FPGA-attached NVMe storage. Moreover, DONGLE 2.0 demonstrated a geometric mean speed-up of 1.5× and a reduction in LoC by 2.4× compared to the state-of-the-art commercial platform when using host-attached NVMe storage.

Simultaneous Tailoring of Chemical Composition and Morphology Configuration in Metal Hexacyanoferrate for Ultrafast and Durable Sodium‐ion Storage

Metal hexacyanoferrates (MHCFs) with adjustable composition and open framework structures have been considered as intriguing cathode materials for sodium‐ion batteries (SIBs). Exploiting MHCFs with ultrafast and durable sodium storage capability as well as comparable capacity is always a goal that many investigators pursue, but remains challenging. Herein, simultaneous tailoring of chemical composition and morphology configuration is carried out to design a hollow monoclinic high‐entropy MHCF (HMHE‐HCF) assembled by nanocubes for the first time to realize the objective. The “cocktail effect” of high‐entropy construction, rich sodium content of monoclinic phase, and unique hollow structure endow HMHE‐HCF cathode with fast reaction kinetics and energetically stable performance during continuous charging/discharging processes. As a result, the HMHE‐HCF cathode demonstrates superior rate performance up to an ultra‐high rate of 100 C (71.1% retention to 0.1 C), and remarkable cycling stability with a capacity retention of 77.8% over 25,000 cycles at 100 C, outperforming most reported sodium‐ion cathodes. Further, the HMHE‐HCF//hard carbon full‐cell delivers capacities of 99.0 and 82.3 mAh g–1 at 0.1 C and 10 C, respectively, and retains 98.1% of the initial capacity after 1,600 cycles at 5C, demonstrating its potential application for sodium‐ion storage.

Simultaneous Tailoring of Chemical Composition and Morphology Configuration in Metal Hexacyanoferrate for Ultrafast and Durable Sodium-Ion Storage.

Metal hexacyanoferrates (MHCFs) with adjustable composition and open framework structures have been considered as intriguing cathode materials for sodium-ion batteries (SIBs). Exploiting MHCFs with ultrafast and durable sodium storage capability as well as comparable capacity is always a goal that many investigators pursue, but remains challenging. Herein, simultaneous tailoring of chemical composition and morphology configuration is carried out to design a hollow monoclinic high-entropy MHCF (HMHE-HCF) assembled by nanocubes for the first time to realize the objective. The "cocktail effect" of high-entropy construction, rich sodium content of monoclinic phase, and unique hollow structure endow HMHE-HCF cathode with fast reaction kinetics and energetically stable performance during continuous charging/discharging processes. As a result, the HMHE-HCF cathode demonstrates superior rate performance up to an ultra-high rate of 100 C (71.1 % retention to 0.1 C), and remarkable cycling stability with a capacity retention of 77.8 % over 25,000 cycles at 100 C, outperforming most reported sodium-ion cathodes. Further, the HMHE-HCF//hard carbon full-cell delivers capacities of 99.0 and 82.3 mAh g-1 at 0.1 C and 10 C, respectively, and retains 98.1 % of the initial capacity after 1,600 cycles at 5 C, demonstrating its potential application for sodium-ion storage.

Adoption of lib (Lithium Batteries) for hybrid propulsion on small passenger vessel and consequences on damage stability

Nowadays the Hybrid Propulsion is a reality, increasing its diffusion. The main principle is the storing of energy in battery packs to provide energy for the propulsion system of the vessel, aiming the fundament of hybrid propulsion is the use of Li-Ion or Li-Po batteries, with high capability of energy storage (MWh). This good capability has the disadvantage of the explosion risk if exposed to heat. The solutions adopted can impact on damage stability. This paper will analyze the aspects connected with hybrid propulsion in small passenger vessels, considering the State of Art of Rules regarding the fire safety and the possible solutions adopted regarding Lithium batteries. The paper refers to the consequences of adoption of new technology of Lithium batteries developed to be used in maritime application, batteries indicated as “LiB”. The paper is not referring to Lithium metal batteries with the Lithium used as metallic anode and all the consequences on fire risks. The paper is not about the risk of fire due to the battery technology, but is related to the consequences on stability of small vessels if, for security reason a large amount of water is used to cool down the battery packs. The paper will consider the case study of a small passenger ship, examining the general arrangement adopted and the position of the batteries, and the consequences caused by the installation on board of the battery packs. The results will show how the fire safety is important and requires special attention, also in consideration of the various possibilities to contain the fire or prevent the risk of explosion. The aim is to give a suggestion for set new standards for firefighting in presence of large batteries and also to focus on possible problems arising in case of fire on hybrid vessels.

An Ultrasensitive Programmable 2D Photoelectric Synaptic Transistor

AbstractThe burgeoning advancement of information technology has engendered a discernible surge in the examination of neuromorphic devices, notably drawing broader attention to artificial vision systems endowed with sensory recognition capabilities. Current photoelectric synapse devices employed in artificial vision systems are generally well‐suited for well‐illuminated conditions, yet exhibit diminished sensitivity in weak‐light scenarios, resulting in a pronounced deterioration of recognition accuracy. Here, an ultrasensitive photoelectric synaptic transistor based on negative quantum capacitance effect resulted from the 2D semi‐metallic graphene layer that partially enclosed within the gate dielectric layer, which manifests a noteworthy reduction in device control voltage and exhibits perception and storage capabilities for weak light of 39.4 nW cm−2 with detectivity above 1016 cm Hz1/2 W−1 is demonstrated. The voltage amplification effect and the concomitant formation of an equivalent local electrostatic field induced by the negative quantum capacitance effect engenders a robust programmable synaptic plasticity for extremely weak light by modifying the control gate. These results represent the inaugural integration of the negative quantum capacitance effect into optoelectronic devices and furnish a robust hardware foundation for developing vision systems in weak‐light environments.

High-performance porous activated carbon derived from Acacia catechu bark as nanoarchitectonics material for supercapacitor applications

BackgroundThe increasing energy demands stemming from the extensive utilization of portable electronic devices are creating a huge energy deficit between demand and supply. In this scenario, it is not only sufficient to pursue and innovate the new renewable energy sources but also requires an ideal device for energy storage and conversion. MethodsIn this work, activated carbon (AC) was prepared from matured bark of Acacia catechu through a series of steps; pre-carbonization, carbonization, and activation. The AC was synthesized at different temperatures (400–800 °C) under inert atmosphere, using orthophosphoric acid as an activator. As-prepared sample (ACBH) was characterized by well-known characterization techniques. Energy storage capability was assessed in terms of Cyclic voltammetry, Galvanostatic charge-discharge, Electrochemical impedance, and Cyclic stability by three-electrode setup. Significant findingsThe ACBH-8 sample demonstrated superior electrochemical performance compared to other samples. The sample ACBH-8, as Negatrode, exhibited a specific capacitance of 282.4 F g−1 at 0.5 A g−1 and retained 95.4 % cyclic stability under 10,000 cycles. The excellent energy storage performance by green-class negatrode materials from the bio-waste substance empowers commercial applications.

Titanium nitride@nitrogen-doped carbon nanocage composites as high-performance cathodes for aqueous Zn-ion hybrid supercapacitors

Aqueous Zn-ion hybrid supercapacitors (AZHSCs) pertain to a new type of electrochemical energy storage device that has received considerable attention. They integrate the advantages of high-energy Zn-ion batteries and high-power supercapacitors to meet the demand for low-cost, long-term durability, and high safety. Nevertheless, the challenge caused by the finite ion adsorption/desorption capacity of carbon electrodes gravely limits their energy densities. This work describes titanium nitride@nitrogen-doped carbon nanocage (TiN@NCNC) composite cathodes for AZHSCs to achieve a greatly improved energy density, and the composites can be facilely synthesized based on the calcination of a mixture of tetrabutyl titanate and zeolitic imidazolate framework-8 in argon atmosphere. The resulting composites are featured by the ultra-fine TiN particles dispersed uniformly on the NCNC surfaces, enhancing the Zn2+ storage capabilities. Using TiN@NCNC cathodes, the AZHSCs can operate stably with a high energy density of 154 Wh kg−1 at a specific power of 270 W kg−1 and achieve a remarkable capacity retention of 88.9 % after 104 cycles at 5 A g−1. At an extreme specific power of 8.7 kW kg−1, the AZHSCs can retain an energy density of 97.2 Wh kg−1. With these results, we stress that the TiN@NCNC cathodes render high-performance AZHSCs and the facile one-pot method can easily be scaled up, which enables AZHSCs a new energy-storage component for managing intermitted renewable energy sources.