Electric Double Layer Capacitance Research Articles

Capacitive deionization exploiting La-based LDH composite electrode toward energy efficient and selective removal of phosphate

Capacitive deionization (CDI) is a promising technology for removing phosphate from wastewater. Its practical implementation is however hindered by the constraints on the electrode materials. To boost the adsorption capacity, phosphate selectivity, and cost-effectiveness of the electrode, this study proposed a composite electrode blending Lanthanum-based layered double hydroxide (CaLa LDH) and activated carbon (AC). It capitalizes on the synergistic effects of electric double layer capacitance (EDLC) of AC and the diffusion-controlled charge storage (pseudocapacitive behavior) of CaLa LDH. By optimizing the mass ratios of the constituents and the electrode material loading capacities, the composite electrode AC/Ca-La LDH-5020 was developed, which contains 20 mg of 50 wt% CaLa LDH. This composition achieved a remarkable phosphate adsorption capacity of 34.8 mg P /g and a low energy consumption of 0.0051 kWh/g P in constant voltage (CV) mode. It represented a 241 % increase in adsorption capacity (mg P/g) and 71 % decrease in specific energy consumption (kWh/g P) compared to the electrode made solely of AC. Particularly the moderate inclusion of Lanthanum contributes to its cost-effectiveness. Moreover, further studies extensively examined the impacts of electrical driving force, including applied voltage in constant current (CC) mode and applied current in constant voltage (CV) mode, on the phosphate removal efficiency. The composite electrode remained stable performance with the presence of the high content of coexisting anions (e.g.，Cl−，SO42−, HCO3−, NO3−), obtaining high selectivity coefficient of phosphate over other anions. This study highlighted the practical potential of AC/Ca-La LDH composite electrode for advancing CDI technology for phosphate removal in an efficient, energy-saving and cost-effective manner.

High-performance supercapacitor of ZnO-incorporated structurally modified g-C3N4 with circular mesoporous channels attained via a template-free approach

Abstract Here, the superior structural features of graphitic carbon nitride (g-C3N4) in combination with integrated mesoporous channels have been explored for its use as a supercapacitor electrode material. A facile template-free strategy is adopted for the preparation of ZnO-incorporated modified g-C3N4 nanocomposite, where material characterization via x-ray difraction, Fourier transfrom infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy and x-ray photoelectron spectroscopy analysis revealed the presence of structurally modified g-C3N4 having uniform circular mesoporous channels with well-dispersed ZnO with strong Zn–C and Zn–N interactions. The electrical double-layer capacitance together with the pseudocapacitance of the ZnO/g-C3N4 electrode material resulted in improved performance, leading to a specific capacitance of 146.3 F g−1 at a current density of 0.5 A g−1; an increased capacitance is observed in 5000 repeated charge–discharge cycles. A symmetric coin cell supercapacitor fabricated from the material displayed an energy density of 38.8 mWh kg−1 at a power density of 4259 mW kg−1. Additionally, the long life of 6000 cycles (retaining 100% specific capacitance) exhibited by the coin cell supercapacitor further indicates the promising energy storage nature of the ZnO-incorporated modified g-C3N4 mesoporous nanoarchitecture. Real life application of the ZnO/g-C3N4-derived supercapacitor is illustrated by lighting up a green LED with a series connection of four coin cells.

A deep autoencoder for electric double layer capacitance prediction in electrochemical sensors

This study explores the application of a deep autoencoder neural network to accurately predict the electric double layer capacitance from real-world parameters in binary, asymmetric electrolytes under low concentration conditions. By utilizing a modest simulation-based dataset of just 250 samples, the deep autoencoder neural network model developed in this study effectively predicted the capacitance by learning the critical features and relationships of the electric double layer model and encoding this learned representation into a low-dimensional latent space. From the latent variables, the decoder block of the neural network learned to effectively recreate the high-dimensional input. To enhance the model's robustness, prevent overfitting, and better simulate real-world conditions, noise was incorporated into the training and test data. The model demonstrated strong performance across various conditions, such as ionic size, ionic charge, and surface potential, yielding satisfactory results on both clean and noisy test datasets. A key feature of this approach was the mapping of real-world electric double layer parameters to the latent variables of the model, allowing for direct input of physical parameters to predict the electric double layer capacitance. This research highlights the potential of machine learning techniques to expedite the design and analysis of complex multi-physics systems such as electrochemical sensors by reducing the dependence on extensive domain expertise throughout the design process.

An electrical double-layer supercapacitor based on a biomass-activated charcoal electrode and ionic liquid with excellent charge-discharge cycle stability 

Supercapacitors that exhibit high power density and safety are emerging as alternative energy storage devices. The construction and performance of a supercapacitor using the ionic liquid, triethylammonium thiocyanate, as the electrolyte and biomass-activated charcoal films as the electrode are described. Enhancements in both energy and power density were observed even for 10,000 charge-discharge cycles. The fabricated supercapacitor with ionic liquid and activated charcoal-based electrodes showed an impressive specific capacitance retention of 142% even after 10,000 cycles at a scan rate of 500 mv s-1, which is attributed to the clearing of ion conducting pathways and enhanced charge transport with increasing temperature. Impedance analysis confirmed the reduction of resistive losses with increasing cycle numbers. The initial energy and power densities of the Electrical double-layer capacitance (EDLC) were 0.926 W h kg-1 and 5681 W kg-1, and they showed 42.2 % and 60.6 % increments after supercapacitors cycles. The study reveals low-cost biomass-based activated carbon electrodes and trimethylamine thiocyanate can be used to prepare supercapacitors with remarkable cycling performances.

Enhanced construction of 3D carbon skeleton through molten salt coupling activation effect for high efficiency capacitive deionization of lead (II) ions removal in wastewater

Efficiently eliminating of highly toxic ultra-dilute lead ions (Pb2+) from wastewater is a challenging task. Capacitive deionization (CDI) technology, based on the electrochemical capacitance mechanism, has emerged as a pivotal approach to address this challenge. In this work, a KNO3-mediated molten salt-coupled activation strategy was proposed to prepare nitrogen-doped hierarchical porous biomass carbon electrode material (3DCF-650-0.2) with a three-dimensional carbon skeleton, which was integrated into a symmetrical CDI device for Pb2+ removal. The 3DCF-650-0.2 electrode exhibited a high specific capacitance of 330.3 F g-1 at a current density of 1 A g-1, with a capacity retention rate of 98.45% after 10,000 cycles at 10 A g-1. Furthermore, the electrochemical adsorption capacity of the CDI device for Pb2+ reached 72.86 mg g-1 (1.2 V, 50 mg L-1), and the CDI device retained a high adsorption capacity of 91.14% after twenty adsorption/desorption cycles. These excellent adsorption properties are attributed to the in-situ activation and gas foaming of KNO3, which favors the production of reasonable pore structure (electric double-layer capacitance) and an appropriate pyrrolic nitrogen doping amount (selective adsorption) in the carbon materials. This work provides insight into the mechanism of the molten salt-coupled activation strategy, offering new ideas for the targeted design of high-performance CDI biomass carbon materials.

Unraveling the Ionic Storage Mechanism of Flexible Nitrogen-Doped MXene Films for High-Performance Aqueous Hybrid Supercapacitors.

2D MXene nanomaterials have excellent potential for application in novel electrochemical energy storage technologies such as supercapacitors and batteries, but the existing pure MXene is difficult to meet the practical needs. Although the electrochemical properties of modified MXene have been improved, the unclear ion storage mechanism still hinders the development of MXene-based electrode materials. Herein, the study develops flexible self-supported nitrogen-doped Ti3C2 (Py-Ti3C2) films by the highly mobile, high nitrogen content, oxygen-free pyridine-assisted solvothermal method, and then deeply investigates the energy storage mechanism of hybrid supercapacitors in four aqueous electrolytes (H2SO4, Li2SO4, Na2SO4, and MgSO4). The experimental results suggest that the Py-Ti3C2 film electrode exhibits a pseudocapacitance-dominated energy storage mechanism. Particularly, the specific capacity of the Py-Ti3C2 in 1M H2SO4 (506 F g-1 at 0.1 A g-1) is 4-5 times higher than other electrolytes (≈110 F g-1), which could be attributed to the substantially higher ionic diffusion coefficient of H+ than those of Li+, Na+, Mg2+ with small ionic size, high ionic conductivity, and fast pseudocapacitance response. Theoretical analysis further confirms that Py-Ti3C2 has strengthened conductivity and electrical double-layer capacitance performance. Meanwhile, it has lower free energy for protonation and deprotonation of functional groups, which gives excellent pseudocapacitance performance.

Fluorinated reduced graphene oxide nanosheets for symmetric supercapacitor device performance

This study explores the potential of using spent lithium-ion battery anodes (graphite) for fabricating symmetric energy devices through a simple regeneration process. Specifically, the use of fluorine-doped reduced graphene oxide (RGO) nanosheets derived from waste batteries as the basis for a symmetric supercapacitor (SC) device is investigated. To enhance the electrochemical energy storage capabilities, a facile hydrothermal technique is employed to synthesize fluorinated graphene. Fluorination of the graphene sheets is successfully realized, as confirmed by the presence of boron with a 2.94 at.% fluorine-doped level, according to the Energy dispersive spectroscopy (EDS) spectrum analysis. Electrochemical analysis of the F-RGO electrode performance consistent with electric double-layer capacitance. Moreover, with a three-electrode system, the F-RGO electrode achieves a maximum specific capacitance of 207F/g under a current density of 1 A/g. A two-electrode symmetric device employing F-RGO exhibits a specific capacitance of 54F/g at 1 A/g. Furthermore, electrochemical impedance measurements demonstrate low charge transfer resistance (Rct) values, specifically 8.63 Ω for F-RGO, signifying improved electrochemical performance. Thus, fluorine atomic doping in RGO nanosheets contributes to the improvements of the specific capacitance and overall superior electrochemical performance of F-RGO, and F-RGO is a highly electrochemical active material for high-performance energy storage electrodes for SCs.

Effect of Heterojunction Dynamics on Electrochemical Properties of ZnS/MoS2 Type-II Nanocomposite for Photovoltaic Application

In the present work, ZnS/MoS2 nanocomposite has been synthesized by hydrothermal route. X-ray diffraction analysis revealed ZnS and MoS2 phases, showing the crystallite size of 19.5 and 9.25 nm from W-H and S-S plots, respectively. The lattice parameters of MoS2 and ZnS were found to be a = b = 3.79 Å, c = 12.4 Å and a = b = 3.2 Å, and c = 9.5 Å, respectively. The dislocation density, stacking fault and strain from W-H and S-S plots were found to be 4.1 × 10−4, 2.4 × 10−3, −1.2 × 10-3 and −2.4 × 10−2, respectively. The absorbance peaks of the nanocomposite were observed at 209, 246 and 320 nm revealing a band gap of 3.3 eV with refractive index of 2.32. Scanning electron microscopy and transmission electron microscopy imaging demonstrated ZnS nanoparticles over MoS2 sheets with an average particle size of 45.9 and 23.8 nm, respectively. In cyclic voltammetry analysis, pure ZnS and nanocomposite showed maximum oxidation current of 0.25 and 0.51 mA, respectively. Electrochemical impedance spectroscopy analysis revealed the presence of Warburg diffusion with a high exchange current density of 2.5 mA along with electrolyte’s and working electrode’s resistance to be 1000 Ω and 100 Ω, respectively. Charge transfer resistance, Warburg impedance, electrical double layer capacitance and film’s capacitance was found to be 10 Ω, 1000 Ω·s−1/2, 100 μF and 1 μF, respectively.

An environmentally sustainable ultrasonic-assisted exfoliation approach to graphene and its nanocompositing with polyaniline for supercapacitor applications

In the present work, a green high-yielding method for the preparation of graphene is introduced via ultrasonic-assisted liquid phase exfoliation (LPE) of graphite in a green solvent medium, since the common preparation method of graphene via graphite oxide is hazardous. A high concentration of 3.2 mg/ml graphene is achieved here in a comparatively short duration of 3 h ultrasonication. By using a mixed solvents strategy (acetophenone and isopropyl alcohol, 1:19 V/V), surface energy requirements needed for the exfoliation of graphite are satisfied here with acetophenone, where isopropyl alcohol further facilitated the exfoliation via non-conventional CH-π and OH-π interactions. Turbostratic graphene in high-yield (16 %) in a simple means of ultrasonic assisted LPE is the added attraction of the present procedure. The less-defective structure of graphene, its few-layered turbostratic nature, and edge functionalization of the sheets are evident from the material characterization via Raman spectroscopy, XRD, TEM-SAED, and XPS analyses. Here, we report a combination of the attractive conducting polymer polyaniline (PANI) with the as-prepared graphene for supercapacitor applications, where the PANI/graphene nanocomposites with different aniline concentrations (PANI1.125/G, PANI4.5/G, and PANI9/G) have been prepared via in-situ polymerization of aniline in the graphene dispersion. The structure and morphology of the nanocomposites are investigated using different characterization techniques which revealed that the molecular structure of the PANI is retained in the nanocomposites even with a strong interaction with graphene. FESEM and TEM images revealed the good coverage of graphene sheets with PANI that limit the volume change of PANI during the repeated charge-discharge processes. Electrochemical studies showed that PANI4.5/G has the highest specific capacitance of 126.16 mF/cm2 at a current density of 1 mA/cm2, resulting from the perfect combination of the pseudocapacitance behavior of the PANI along with the electrical double layer capacitance of graphene. A symmetric supercapacitor device is also fabricated with PANI4.5/G, which showed the highest areal capacitance of 116.38 mF/cm2 similar to that with three-electrode studies and also good cycling stability with 87 % capacitance retention in the specific capacitance after 6000 cycles. It also exhibited an energy density of 16 µWh/cm2 (0.29 Wh/kg) and a power density of 3.99 mW/cm2 (72.72 W/kg).

Electronic Response and Charge Inversion at Polarized Gold Electrode

We have studied polarized Au(100) and Au(111) electrodes immersed in electrolyte solution by implementing finite‐field methods in density functional theory‐based molecular dynamics simulations. This allows us to directly compute the Helmholtz capacitance of electric double layer by including both electronic and ionic degrees of freedom, and the results turn out to be in excellent agreement with experiments. It is found that the electronic response of Au electrode makes a crucial contribution to the high Helmholtz capacitance and the instantaneous adsorption of Cl can lead to a charge inversion on the anodic polarized Au(100) surface. These findings point out ways to improve popular semi‐classical models for simulating electrified solid‐liquid interfaces and to identify the nature of surface charges therein which are difficult to access in experiments.

Radial gradient characteristics formed by the interstitial space of MWCNT yarn owing to twisting

The interstitial space of a multiwalled carbon nanotube (MWCNT) yarn is key to creating electric double-layer capacitance for harvesting energy. Despite various fabrication methods for MWCNT yarns, the formation mechanism of the interstitial space inside the yarns is poorly understood. Herein, the twisting process of a cylindrical MWCNT bundle into a yarn was simulated using the mesoscale coarse-grained particle dynamics model. A larger fraction of interstitial space was observed in the sheath region of the yarn, where large-diameter MWCNTs were mainly distributed. Small-diameter MWCNTs first swirled toward the inner core during the twisting process, causing the large-diameter MWCNTs to be sparsely distributed throughout the sheath region. The proposed methodology and its results can be applied to the geometric design of twisted MWCNT bundles to maximize the fraction of the interstitial space therein.

Selective electro-capacitive deionization of Yb(III) by nanospherical N-doped carbon supported nickel‑iron bimetallic oxide, nitride and phosphide

The separation of rare earth elements from the mining waste water is highly important but still facing challenge. In this study, three different porous composite electrode materials were well-designed by decorating the nickel‑iron bimetallic oxide, nitride or phosphide onto nitrogen-doped carbon nanosphere, respectively (termed as NiFeO@NC, NiFeN@NC and NiFeP@NC), and utilized in capacitive deionization device for electrosorption of Yb(III) from water under the low-voltage electric field. The characterization and electrochemical results indicated that the incorporation of N or P atom lead to the reduced specific surface area and the enhanced electrochemical properties (i.e., larger specific capacitance, lower charge transfer resistance). In addition, NiFeN@NC and NiFeP@NC exhibited the excellent electrosorption capacities of Yb(III) with 105.24 mg·g−1 and 90.31 mg·g−1, respectively, under conditions of a flow rate of 20 mL·min−1, a voltage of 1.2 V, and pH of 5.0, which was extremely higher than NiFeO@NC (i.e., 50.7 mg·g−1). Moreover, all these three materials also demonstrated the remarkable electrosorption selectivity of Yb(III) from the mixed solution, and the robust durability with over 90 % of initial capacities after ten consecutive electrosorption-desorption cycles. Furthermore, the XPS characterizations and electrosorption results revealed that the electrosorption mechanism mainly depended on the synergistic effects of intrinsic Faraday redox reaction, electric double layer capacitance and active binding sites. Therefore, this work provided a feasible strategy for the separation of rare earth elements from aqueous solution, and the prospective applications related to the recovery of rare earth elements from mining wastes or spent permanent magnets in future life.

Multi-metal-doped transition metal compounds for high-performance asymmetric capacitive deionization

To address the limited ion adsorption capacity of carbon-based capacitive deionization (CDI) which primarily relies on double-layer mechanism, recent efforts have focused on the rational design and development of efficient Faradaic materials for CDI applications. In this study, we synthesized and applied Co- and Mn-doped transition metal compounds (Cu₂O@MCF) as the electrodes for asymmetric CDI using a simple hydrothermal method. The synthesized electrodes were analyzed using various characterization techniques, to confirm the successful doping and structural integrity. Electrochemical performance assessments revealed significant improvements in ion-capture capacity and overall desalination efficiency. Specifically, the optimized asymmetric CDI cell configuration, consisting of Cu₂O@MCF(Cl) as an anode and Cu₂O@MCF(Na) as a cathode, led to a significant increase in salt adsorption capacity (27.42 mg/g) over conventional symmetric carbon electrode (11.22 mg/g), an increase of over 2.4 times. Furthermore, the synthesized electrodes demonstrated effective phosphate ion removal, highlighting their potential applicability in wastewater treatment. The findings suggest that multi-metal doping significantly enhances electrode performance by synergistically combining electric double-layer capacitance and pseudocapacitance effects, due to their unique morphological and electrochemical properties. These results contribute to sustainable water treatment and resource recovery efforts, showcasing the effectiveness of the materials in improving CDI performance and opening new avenues for their application in environmental cleanup and resource management.

Boron-doping tunes nitrogen species to abundant edge-N and B-N matrix for efficient phosphate removal in capacitive deionization: Additional accessible sites and defective centers

The elimination of eutrophication necessitates the implement of a clean and efficient phosphate removal strategy. Capacitive deionization (CDI) is recently regarded a promising approach for removing pollutants from aqueous environment with high-efficiency, facile operation, and low-energy consumption. Development of electrode materials with good properties is crucial for CDI. In this study, novel edge-N-modified boron-doped hierarchical carbon composites (MBCNs) were prepared via a hard template strategy for phosphate electrosorption. According to the pseudo-second-order kinetic, the MBCN2 electrode exhibited a dynamic capacity of 196.02 mg PO43− g−1 in 150 min with an initial concentration of 100 mg PO43− L−1 at 1.2 V. And it also demonstrated an exceptional saturation capacity of 399.70 mg PO43− g−1 under the Langmuir model. Based on theoretical analysis and experimental results, the incorporation of boron atoms in the carbon framework indicated a dual reinforcement. This included an enhanced proportion of edge-N modifications for defective centers and sufficient high-polarity B-N matrix for additional available active sites. The joint contribution of edge-N and B-N matrix revealed favorable electrical double layer capacitance, which resulted in good phosphate removal performance. This work disclosed the synergistic impact of dual nonmetallic atom doping, providing insights into the efficient phosphate removal anode for CDI.

Electrochemical membrane systems for remediating ammonium-containing wastewater via coupling capacitance adsorption and oxygen reduction

As the main nitrogen-containing pollutant of industrial and agricultural wastewater, ammonium (NH4+) is obtainable from the natural nitrogen cycle and industrial emission. Electrochemical recovering nitrogen (N) from nitrate-polluted wastewater to produce ammonia (NH3) is a promising route to mitigate pollution risks and create economic values. Since side reactions at the electrodes are inevitable, and the competition mechanism between electric double layer capacitance (EDLC) behavior and side reactions is still unclear. Herein, electrochemical selective NH4+ recovery from wastewater was achieved by coupling NH4+ adsorption and side oxygen reduction reaction (ORR) in a novel electrochemical membrane extraction system using Ti3C2TX-based gas-diffusion cathodes. Batch experiments showcase simultaneous NH4+ removal and recovery, with TiOX/TiC-C exhibiting the highest removal capability of 408 mgN g−1. In situ Raman spectroscopy revealed the critical role of the four-electron transfer ORR reaction in the conversion of NH4+ to NH3. Density functional theory (DFT) showed that excellent electron-donating ability for NH4+ of TiOX/TiC-C electrode (1.97 eV) facilitated NH4+ diffusion onto electrode interface. The study sheds light on the intricate interplay between NH4+ adsorption and ORR, highlighting the significance of tailored support and vacancy engineering in advancing wastewater treatment and resource recovery.

Cobalt-catalyzed carbonization from polyacrylonitrile for preparing nitrogen-containing ordered mesoporous carbon CMK-1 electrode with high electric double-layer capacitance

Ordered mesoporous carbon CMK-1 was prepared via carbonization at a relatively low temperature (the first step) followed by partial graphitization (the second step of carbonization at higher temperature) inside the ordered mesopores of cobalt-loaded mesoporous silica MCM-48 using polyacrylonitrile (PAN) as a carbon/nitrogen source. This first step of the carbonization is called “infusibilization”, and the resultant material is denoted as PANinf. In an advanced temperature-programmed desorption analysis of the PANinf/MCM-48 composite, the temperature of the observed HCN signal indicated that carbonization was reduced from 550 to 450 °C by a Co catalyst. The amount of typical N2 formation associated with the selective removal of pyridinic N species, resulting in the graphitic surface formation, also increased at a relatively high temperature (approximately 1000 °C) with the aid of the Co catalyst. The CMK-1 prepared through cobalt-catalyzed carbonization exhibited a higher electric double-layer capacitance with an Et4N+BF4–/propylene carbonate electrolyte, and higher electrical conductivity than CMK-1 prepared without a catalyst. This also implied the progress of graphitization within the carbonaceous wall. These results suggest that the edge planes of the graphitic domains in CMK-1 are predominantly exposed on the surfaces of the carbonaceous walls, resulting in an increase in the number of adsorptive sites for the electrolyte during capacitance measurements.

The Faradaic-Induced hybrid capacitive engine enables high-performance selective defluorination via capacitive deionization

Fluoride (F-) contamination has become a pressing environmental concern owing to its extensive origins and severe toxicity. Capacitive deionization (CDI) emerges as a promising technique for efficient defluorination, with the development of electrode materials being pivotal to its efficiency. Herein, we present a novel design of Sb-decorated N-rich carbon composites (SNTPCs) for the formation of a hybrid capacitive engine that integrates Faradaic-induced pseudocapacitance and electrical double layer capacitance, enabling efficient F- electrosorption. This approach features a distinctive N-rich carbonaceous laminar framework that not only guarantees rapid ion diffusion and electron transfer but also provides a dense electrical double layer for F- storage. The Sb sites are electrically stimulated to release the intrinsic affinity with F-, forming the Faradaic Sb-F bonds. The SNTPC2 electrode exhibits the exceptional saturation removal capability and dynamic electrosorption capacity for defluorination, reaching 178.58 and 34.77 mg F/g at 1.2 V respectively, which exceeds most reported F- capture electrodes. It also demonstrates excellent selectivity towards F- in complex conditions and exhibits effectiveness across a wide range of pH values. Additionally, the utilized electrode performs outstanding regeneration performance after 20 consecutive cycles. This study provides innovative perspectives for the effective elimination of fluoride pollution in aquatic environments.

Molten salt-mediated hierarchical porous carbon derived from biomass waste for high-performance capacitive storage

Biomass-derived carbon (BDC) materials are the suitable precursors for the fabrication of carbon electrodes of supercapacitors because of the sustainability, environmental friendliness, power capability, and structural diversity. The fabrication of BDC with low cost and excellent electrochemical properties is important for the practical applications of BDC in energy storage fields. Herein, ambrosia melon peels are used as carbon precursors for the fabrication of sustainable BDC electrodes through the molten salt-mediated pyrolysis procedure. The ambrosia melon peels-derived porous carbon (AMPPC) possesses high specific surface area of 529.9 m2 g−1. The AMPPC electrode shows the charge storage behavior of electrical double-layer capacitance with high ionic conductivity, high specific capacitance (218.3 F g−1 at 0.5 A g−1) and outstanding rate performance. In addition, the symmetric supercapacitor based on the AMPPC electrodes presents high specific energy density and specific power density (8 kW kg−1). It can be used as energy source to power helicopter model, clock, and calculator. Thus, the work gives an inspiration of design of BDC from the low-cost biomass waste and provides a simple way for the fabrication of BDC for the carbon electrodes of supercapacitors, lithium-ion batteries and so on.

Electrochemical and surface investigations of N, S codoped carbon dots as effective corrosion inhibitor for mild steel in acidic solution

Mild steel is a versatile, inexpensive, highly flexible, and easily weldable material widely used in construction, pipelines, transportation, shipping, and other industries. However, it is also extremely susceptible to corrosion processes under the influence of weather phenomena, posing a significant threat to society and human health. In this work, we investigated the corrosion inhibition capacity of a new type of N, S codoped carbon dots (N, S-CDs) on Q235 carbon steel in the acidic medium. The goal product was synthesized by hydrothermal method using o-phenylenediamine and amidinothiourea as precursors. Combined with electrochemistry, Fourier transform infrared (FTIR) spectroscopy, scanning electrochemical microscopy (SECM), and theoretical calculations, the inhibition properties of N, S-CDs on Q235 carbon steel in HCl solution were evaluated. The potentiodynamic polarization (PDP) curves and electrochemical impedance spectroscopy (EIS) results indicated that the corrosion inhibition efficiency reached 90.3 % and 92.4 % at 100 mg/L concentration, respectively. Indeed, the presence of N, S-CDs reduced the electric double-layer capacitance, increased the thickness of the adsorption film on the carbon steel surface, and reduced the corrosion current density, resulting in a delay of corrosion. X-ray photoelectron spectroscopy (XPS) analysis and surface characterization confirmed the successful doping of N, S and the formation of adsorption films, the Langmuir adsorption isotherm also confirmed the superior inhibition of N, S-CDs on the surface of Q235 carbon steel through physical and chemical adsorption mechanisms. At the same time, quantum chemical calculations and molecular dynamics (MD) simulations revealed its inhibition mechanism at the molecular/atomic level.

(Nanocarbons Division Poster Award, 1st Place) Nd2O3 Templated Carbon Nanostructures for Energy Storage

Increased energy consumption has triggered the development of various energy storage devices. Supercapacitors have gained attention as energy storage devices due to their high-power density and long cycle life. The energy density of supercapacitor can be increased by combining electric double layer capacitance (EDLC) and pseudocapacitance (PC). A hybrid material based on rare-earth metal oxide templated carbon will be presented that combines both EDLC and PC within the same material. Specifically, neodymium hydroxide (Nd(OH)3) reacted with acetylene and steam to form carbon coated Nd2O3. Both Nd(OH)3 nanorods and nanospheres were used to prepared templated carbon followed by partial or complete washing of metal oxide. The resulting carbon exhibit the surface area of 1245 m2/g. Asymmetric coin cell was constructed with capacitance of 180.5 F/g and energy density of 76.8 Wh/kg This work paves the door to develop novel hybrid supercapacitors.