Carbon-based Electrode Materials Research Articles

Combined effect of nitrogen-doped functional groups and porosity of porous carbons on electrochemical performance of supercapacitors

In this work, nitrogen-doped porous carbons obtained from chitosan, gelatine, and green algae were investigated in their role as supercapacitor electrodes. The effects of three factors on electrochemical performance have been studied—of the specific surface area, functional groups, and a porous structure. Varying nitrogen contents (from 5.46 to 10.08 wt.%) and specific surface areas (from 532 to 1095 m2 g−1) were obtained by modifying the carbon precursor and the carbonization temperature. Doping nitrogen into carbon at a level of 5.74–7.09 wt.% appears to be the optimum for obtaining high electrochemical capacitance. The obtained carbons exhibited high capacitance (231 F g−1 at 0.1 A g−1) and cycle durability in a 0.2 mol L−1 K2SO4 electrolyte. Capacitance retention was equal to 91% at 5 A g−1 after 10,000 chronopotentiometry cycles. An analysis of electrochemical behaviour reveals the influence that nitrogen functional groups have on pseudocapacitance. While quaternary-N and pyrrolic-N nitrogen groups have an enhancing effect, due to the presence of a positive charge and thus improved electron transfer at high current loads, the most important functional group affecting energy storage performance is graphite-N/quaternary-N. The study points out that the search for the most favourable organic precursors is as important as the process of converting precursors to carbon-based electrode materials.

Dual-doped carbon hollow nanospheres achieve boosted pseudocapacitive energy storage for aqueous zinc ion hybrid capacitors

Rechargeable aqueous zinc ion hybrid capacitors (ZHCs) have attracted increasing attention for energy storage devices due to low cost, high safety and environmental friendliness. However, it suffers from low energy/power density and poor cycling stability due to the lack of suitable electrode materials, especially the promising cathode candidates with satisfactory capacity and excellent cycling stability. Herein, we developed dual-doped carbon hollow nanospheres (PN-CHoNS) through a dual-functional template induced strategy combined with the subsequent carbonization treatment, which can act as potential cathode materials. Impressively, when employed to assemble the ZHCs, the device can deliver an exceptional energy density of 116.0 Wh kg−1 at a power density of 141 W kg−1 and an extremely high power density of 21660 W kg−1 under a decent energy density of 36.1 Wh kg−1, as well as ultra-long cycling stability up to 12000 cycles. Moreover, the systematic characterization and density functional theory calculation decipher that dual-doping could promote the chemical absorption/desorption kinetics of Zn ions to boost the electrochemical charge storage of carbon. This work can not only provide a rational strategy to construct advanced carbon-based electrode materials, but also deepen the fundamental understanding of the charge storage mechanism of heteroatom-doped carbonaceous materials.

An overview of recent developments of carbon-based sensors for the analysis of drug molecules

This review summarizes some recent developments in the fabrication of modified sensors and biosensors using carbon-based materials. The great potential of carbon-based electrodes as sensing platforms is exciting due to their unique electrical and chemical properties, high accessibility and high biocompatibility. Carbon-based materials are particularly interesting due to almost infinite possibility of their functionalization with a wide variety of organic molecules, biologically important compounds and pharmaceuticals. This review is specifically focused on recent developments in the utilization of various carbon-based electrodes in sensing devices for the electrochemical investigation of drug molecules. Various voltammetric techniques considered in this effort include linear sweep voltammetry (LSV), cyclic voltammetry (CV), differential pulse voltammetry (DPV), square wave voltammetry (SWV), and square wave adsorptive stripping voltammetry (SWAdSV). The carbon-based electrode materials considered in this review comprise carbon paste, carbon nanotubes, graphite, graphene, and glassy carbon. The analytes chosen are some routinely used drugs such as paracetamol (PC), diclofenac sodium (DCF), 5-fluorouracil (5-FU), cetirizine (CTZ) and salbutamol (SAL). All here reported sensing electrodes produced very good results in electrochemical investigations of these drug molecules.

Synthesis of the cathode and anode materials from discarded surgical masks for high-performance asymmetric supercapacitors

Advanced carbon-based electrode materials derived from wastes are essential to high-performance supercapacitors due to their abundance and sustainability. In this work, we fabricate novel cathodes and anodes based on discarded surgicalmask-derived carbon (DSM-C). Discarded surgicalmasks are good candidates for carbon-based electrode materials due to their unique fibrous structure and simple composition compared to conventional biomass sources. Benefiting from the excellent electrical conductivity of DSM-C and abundant redox reactions from nickel oxide (NiO), the electrochemical performances of NiO/DSM-C composites have been greatly improved. Specifically, the DSM-C and NiO/DSM-C electrodes show high specific capacitances of 240 F g−1 and 496 F g−1 at 1 A g−1 respectively, and excellent rate capability. Moreover,asymmetric supercapacitors (ASCs) are assembled using DSM-C and NiO/DSM-C as anodes and cathodes, respectively. They deliver a high energy density of 57 Wh kg−1 at a power density of 702 W kg−1, accompanied by superior cycling stability (98.5% capacitance retention after 10,000 cycles). This work shows prospective applications of DSM-C as an electrode material for energy storage systems.

Designing porous carbon-based multicomponent electrode material for high performance supercapacitor

Hybrid supercapacitors, due to the synergistic effect of each composition, show higher specific capacitance and improved cycle stability compared with most traditional supercapacitors. In this work, multicomponent compound NiCo pyrophosphate/nitrogen doped carbon (NiCoPN/C) is elaborately designed and applied as the electrode for hybrid supercapacitors. The obtained sample possesses a hierarchically porous structure with surface area of up to 341.7 m2 g−1. In the electrochemical test, the sample gives a specific capacitance of 1240 F g−1 at the current density of 1 A g−1. The asymmetric supercapacitor NiCoPN/C-5//AC exhibits a high specific energy of 44.68 W h kg−1 when specific power is 715 W kg−1. After 10000 cycles, the specific capacitance retention of the capacitor remains at 83.7%.

Enhanced dechlorination of 1,2-dichloropropane to propene in a bioelectrochemical system mediated by Dehalogenimonas

Bioelectrochemical systems (BES) are promising technologies to enhance the growth of organohalide-respiring bacteria and to treat chlorinated aliphatic hydrocarbons. In this study, two carbon-based cathodic electrode materials, a graphite brush and a carbon cloth, were used as hydrogen suppliers to couple growth of Dehalogenimonas and dechlorination of 1,2-DCP to nontoxic propene in the cathode vessel. The BES with graphite brush electrode consumed ~4000 µM 1,2-DCP during 110 days and exhibited a degradation rate 5.6-fold higher than the maximum value obtained with the carbon cloth electrode, with a cathode potential set at −0.7 V. Quantitative PCR confirmed that Dehalogenimonas gene copies increased by two orders of magnitude in the graphite brush BES, with an average yield of 1.2·108±5·107 cells per µmol of 1,2-DCP degraded. The use of a pulsed voltage operation (cathode potential set at −0.6 V for 16 h and −1.1 V for 8 h) increased the coulombic efficiency and degradation of 1,2-DCP when compared with a continuous voltage operation of −1.1 V. Bacterial cell aggregates were observed in the surface of the graphite brush electrodes by electron scanning microscopy, suggesting biofilm formation. This study expands the range of chlorinated compounds degradable and organohalide-respiring bacteria capable of growing in BES.

Carbon Nanofiber and Poly[2‐(methacryloyloxy) ethyl] Trimethylammonium Chloride Composite as a New Benchmark Carbon‐based Electrocatalyst for Sulfide Oxidation

There is an overwhelming desire to develop new sulfide oxidation electrocatalysts that perform at low potentials and exhibit high current density for the removal and efficient sensing of sulfide. This article describes a comparative electrochemical analysis of various commercially available carbon materials and polymer/surfactant composite electrocatalysts for direct electrooxidation of sulfide in an aqueous solution. The composites were prepared from five different carbon materials-multiwalled carbon nanotubes, fullerene-C 60 , graphene, glassy carbon, and carbon nanofibers (CNF)-and four different polymers: chitosan, polyvinylidene fluoride, Nafion, and indigenously synthesized poly[2-(methacryloyloxy)ethyl] trimethylammonium chloride (PMTC). The carbon@polymer composites were prepared by a simple ultrasonication technique, and the electrodes were prepared by drop-drying the prepared composite on indium tin oxide (ITO) substrates. The CNF@PMTC showed the highest positive zeta potential that allowed an accumulation of many negatively charged sulfide ions at the CNF@PMTC surface. Cyclic voltammetry was used for the electrooxidation of sulfide in an aqueous solution of tris buffer (0.05 M; pH 8.0) and KNO 3 (0.1 M). The lowest sulfide oxidation peak potential (i.e., -51 mV vs. standard hydrogen electrode) with a high catalytic current response (730 µA/cm 2 ) of the CNF@PMTC-modified ITO electrode among the tested and previously reported carbon-based electrode materials make it ideal for direct sulfide electrooxidation. Taking this and its simple preparation method into account, CNF@PMTC can be considered a benchmark carbon-based electrocatalyst for sulfide oxidation.

Microwave-Assisted Preparation of Hierarchical N and O Co-Doped Corn-Cob-Derived Activated Carbon for a High-Performance Supercapacitor

Microwave (MW) treatment was reported as an efficient method to prepare porous carbon-based electrode material with high capacity for a high-performance supercapacitor. Herein, the superiority of the mechanism of MW treatment was tried to be revealed by preparing a N and O co-doped porous activated carbon (MWAC) based on a heteroatom-rich corn cob and compared to that of the conventional heating method. The resulting MWAC has a large specific surface area of 2508 m²/g with hierarchical micro- and mesoporous structures and abundant heteroatom doping of O and N. In a three-electrode system, the MWAC shows a superior specific capacitance of 560 F/g at a discharge current density of 0.5 A/g in a 6 mol/L KOH aqueous electrolyte. The symmetric supercapacitor fabricated by MWAC electrodes in a 6 mol/L KOH electrolyte shows excellent capacity retention of 96.8%, even after 10 000 galvanostatic charge–discharge cycles at the current density of 1 A/g. The aqueous (6 mol/L KOH) symmetric supercapacitor delivers a high energy density of 9.24 Wh/kg at a power density of 250 W/kg. The results prove that the MW heating shows more superiority in retaining inherent heteroatoms and creating hierarchical micro- and mesoporous structures of activated carbon for supercapacitors with high performance.

Zirconium boride as a novel negative catalyst for vanadium redox flow battery

Poor hydrophilicity and low electrochemical activity of carbon-based electrode materials limit the wide application of vanadium redox flow battery (VRFB). The electrochemical properties of electrodes are generally optimized by acid treatment, heat treatment or the introduction of catalysts. Nowadays, there are mainly three types of catalysts for VRFB, including metal, metal oxide and carbon-based materials. In this work, the idea of metal boride as a catalyst for VRFB is firstly proposed because of high electrical conductivity, good stability, strongcorrosion resistance, and special physical and chemical properties. In this study, nano ZrB2 is used firstly as a new type of catalyst for V3+/V2+ redox pair. The results display that ZrB2 exhibits excellent electrochemical activity and reversibility in V3+/V2+ redox process. This is because nano ZrB2 has certain catalytic activity and excellent electrical conductivity, improving charge transfer dynamics. Furthermore, it has a large specific surface area, providing more active sites. At 40–120 mA cm−2, the discharge capacity and energy efficiency of ZrB2 modified cell are higher than that of pristine cell. Energy efficiency of ZrB2 cell (72.96%) is 5.75% higher than that of pristine cell (67.21%) at 120 mA cm−2. These results indicate that ZrB2, as a new type of negative electrode catalyst, has a good application prospect in VRFB and opens up a new category of VRFB catalysts.

Wide voltage-window biomass carbon-based MnO electrodes for supercapacitors

Biomass carbon-based MnO electrode materials were synthesized using ramie as the biomass precursor of carbon and potassium permanganate as the precursor of MnO. The ramie-activated carbon/manganese monoxide (RAC/MnO) composite electrodes exhibited a specific capacitance of 720 F/g at a current density of 0.5 A/g. A symmetric cell assembled using the composite electrodes showed a specific capacitance of 45 F/g at 0.5 A/g and an energy density of 12.25 Wh/kg at a power density of 350 W/kg. The excellent electrochemical performance was analyzed by characterizing the electrodes’ chemical composition, microstructure, crystal orientation, specific surface area, and pore distribution. Because of the large overpotential of MnO, the composite electrode’s working voltage reached 1.4 V, which is 40% higher than 1.0 V of traditional carbon electrodes. As such, supercapacitors can have higher energy density and power density with the RAC/MnO composite electrodes. The experimental equipment for synthesizing the electrodes is very simple and is promising for large-scale commercialization.

Revealing the electrocatalytic behaviour by a novel rotating ring-disc electrode (RRDE) subtraction method: A case-study on oxygen reduction using anthraquinone sulfonate

The state-of-the-art procedure for investigating homogenous and heterogeneous electrocatalysts is cyclic voltammetry (CV). However, this technique usually requires an inactive electrode material. One common problem arising e. g. in studying the oxygen reduction reaction (ORR) is the significant background contribution to the overall ORR current provided by many carbon-based and metal-based electrode materials. Furthermore, rotating ring-disc electrodes (RRDEs) made of common materials like glassy carbon/platinum (GC/Pt) can be affected by overlapping reduction potentials on the disc. Interference from overlapping reactions on the ring might also occur, particularly in connection with oxygen reduction and hydrogen peroxide oxidation in ORR studies.We present herein a novel subtraction method which allows a semi-quantitative description of homogeneous electrocatalysts and helps to overcome the overlapping problems described above using anthraquinone-2-sulfonate (AQS) as a “case study material” for the ORR.

Dual-doping activated carbon with hierarchical pore structure derived from polymeric porous monolith for high performance EDLC

The fabrication of dual-doped activated carbon with a hierarchical pore structure is an effective way for the preparation of the high performance carbon-based electric double layer capacitor. Herein, nitrogen and sulfur dual-doped activated carbon (NSC) with hierarchical pore structure was obtained by directly carbonizing/activating polymer-based blend monolith. The as-obtained NSC samples exhibit a high specific surface area (1570–2550 cm2 g−1), a developed hierarchically pore structure, and have an appropriate nitrogen and sulfur content. Furthermore, originating from the synergistic effect by pore structure, heteroatom, and proper graphitized crystal structure, the optimized NSC-based electrode exhibits a high specific capacitance of 330.5 F g−1 at a current density of 0.5 A g−1, superior rate capability of 66% at 20 A g−1 and acceptable cycling stability in the three-electrode system. Meanwhile, the assembled carbon-based symmetric capacitor exhibits an acceptable energy density and a remarkable power density of 11 kW kg−1 with 6 mol L−1 KOH as the aqueous electrolyte. These results demonstrate that the as-resulting NSC could be a competitive candidate for carbon-based electrode materials, and this work would be a valuable exploration that as a facile synthetic strategy to prepared dual-doped activated carbon for electric double layer capacitor.

CNTs embedded in layered Zn-doped Co3O4 nano-architectures as an efficient hybrid anode material for SIBs

Advantageous utilization of sodium-ion batteries (SIBs) requires superior performance, enriched with cost-effective anode materials, having excellent storage capability, high conductivity, and structural stability. Hybrid structures based on inorganic metal oxides and organic nano-carbons are evolving as satisfactory electrode materials for the next-generation SIBs owing to their exceptional properties. In this study, Co2.98Zn0.02O4/CNTs hybrid is synthesized using a facile hydrothermal followed by a solvothermal route. As prepared hybrid has been utilized as an anode in a Na half cell and the results are compared with Co2.98Zn0.02O4 and bare Co3O4 anodes. Galvanostatic charge-discharge profiles revealed a high reversible capacity of 721 mAh g−1 for the electrode containing carbon nanotubes (CNTs) i.e. Co2.98Zn0.02O4/CNTs exhibiting remarkable coulombic efficiency of 99% as compared to the other two electrodes. The hybrid anode showed improved capacity retention (289 mAh g−1) after 100 cycles as computed from the cyclic test which is much higher than bare Co3O4. The rate capability test of Co2.98Zn0.02O4/CNTs showed that specific capacity retained as high as 138 mAh g−1@10 C which is an outstanding rate performance, whereas bare Co3O4 couldn’t perform even after 0.5 C. Sodium insertion/extraction is also improved for Co2.98Zn0.02O4/CNTs, as revealed by electrochemical impedance and diffusion coefficient. From these findings, it is inferred that carbon-based Zn-doped Co3O4 hybrid electrode materials can be a superior combination for high-performance and fast charging future SIBs.

Engineered Carbon Electrodes for High Performance Capacitive and Hybrid Energy Storage

ABSTRACT Here we demonstrate, the use of a bio-material coconut sprout (CS) as a single precursor to prepare highly efficient carbon-based electrode materials and a separator with excellent mechanical properties and good chemical stability, for both capacitive and hybrid energy storage systems. A hybrid sodium ion capacitor is fabricated using hard carbon derived from CS (CSDHC) as Na+ intercalating anode and high specific surface area porous carbon (SSA ~2000 m2 g−1) derived through KOH activation of CS (CSDPC) as a cathode material. The full cell device delivered specific energy of 88 Wh kg−1 at a specific power of 273 W kg−1, when cycled in a potential window of 1.5 - 4.0 V, and showed remarkable rate capability along with excellent long-term cycling stability. Further, symmetric supercapacitor cells are assembled using CSDPC in both aqueous and organic-based electrolytes, which delivered maximum specific energy of 24.7 Wh kg−1 at a specific power of 7.3 kW kg−1. Most interestingly, we used the spongy sprout as the separator in all the assembled cells, which showed excellent mechanical properties and good chemical stability even after 10000 cycles of charge and discharge. The present study will pave the way to explore bio-derived engineered carbon materials with unique structure design and tunability for energy-related applications

Porous structural effect of carbon electrode formed through one-pot strategy on performance of ionic liquid-based supercapacitors

Understanding of porous structural effect of carbon electrode on the electrochemical performance of ionic liquids-based supercapacitors is essential for the design of carbon-based electrode materials due to the large ion size and high viscosity induced sluggish ion diffusion rate. Herein, we report the electrochemical performance of supercapacitors using imidazolium-type ionic liquid as electrolyte and nitrogen-doped porous carbon with tunable porous structure as model electrodes synthesized by a one-pot multiscale silica-templated strategy through pH regulation. The results reveal that the porous structure has significant influence on the electrochemical performance of the accordingly assembled supercapacitors. Carbon-based electrode materials with interconnected macro-, meso- and micro-pores can significantly improve the energy density of the thus-assembled symmetric supercapacitor devices, delivering an energy density of 93 Wh·kg−1 at power density of 1.75 kW·kg−1. Benefiting from the interconnected multiscale pores, the assembled device can provide 48 Wh·kg−1 at a power density of 87 kW·kg−1 and lighten 20 white LEDs efficiently. Moreover, the assembled supercapacitor retains 88% of its initial capacitance after 10,000 continuous charge-discharge cycles at 10 A·g−1.

A Review: Electrode and Packaging Materials for Neurophysiology Recording Implants.

To date, a wide variety of neural tissue implants have been developed for neurophysiology recording from living tissues. An ideal neural implant should minimize the damage to the tissue and perform reliably and accurately for long periods of time. Therefore, the materials utilized to fabricate the neural recording implants become a critical factor. The materials of these devices could be classified into two broad categories: electrode materials as well as packaging and substrate materials. In this review, inorganic (metals and semiconductors), organic (conducting polymers), and carbon-based (graphene and carbon nanostructures) electrode materials are reviewed individually in terms of various neural recording devices that are reported in recent years. Properties of these materials, including electrical properties, mechanical properties, stability, biodegradability/bioresorbability, biocompatibility, and optical properties, and their critical importance to neural recording quality and device capabilities, are discussed. For the packaging and substrate materials, different material properties are desired for the chronic implantation of devices in the complex environment of the body, such as biocompatibility and moisture and gas hermeticity. This review summarizes common solid and soft packaging materials used in a variety of neural interface electrode designs, as well as their packaging performances. Besides, several biopolymers typically applied over the electrode package to reinforce the mechanical rigidity of devices during insertion, or to reduce the immune response and inflammation at the device-tissue interfaces are highlighted. Finally, a benchmark analysis of the discussed materials and an outlook of the future research trends are concluded.

Construction of S-doped hierarchical porous carbons by acid-free treatment strategy for supercapacitors

The pollution from acid treatment process in the preparation process of hierarchical porous carbons is a substantial challenge for industrial application of supercapacitors (SCs), which necessitates the development of green alternative technologies. In this work, S-doped hierarchical porous carbons (S-HPCs) are prepared from cheap coal tar pitch by a less harmful in situ KHCO3 activation strategy. The sample obtained at 800°C (S-HPC800) possesses 3D framework structure with hierarchical pores, large specific surface area (1485 m2 g-1) and O, S-containing functional groups. Due to these synergistic characteristics, SHPC800 as supercapacitor electrode exhibits high specific capacitance of 246 F g-1 at 0.1 A g-1 with a capacitance retention of 68.3% at 40 A g-1 and excellent cycle stability with 96.7% capacitance retention after 10, 000 charge-discharge cycles. This work provides an environmentally friendly approach to prepare advanced carbon-based electrode materials from industrial by-products for energy storage devices.

From flax fibers to activated carbon electrodes: The role of fiber refining

Flax-based activated porous carbon materials (APCs) were prepared via KOH and urea synergistic activation in the carbonization process using flax pulp as a biocompatible and eco-friendly biomass precursor. A refining process was used to pretreat the flax pulp fibers, which has been known to improve and optimize the performance of APCs. The morphological and physicochemical structures of APCs were investigated, and the results showed that APCs exhibited high specific surface area and porous microstructure. Furthermore, APCs were rationally designed as a sustainable electrode material. The APC prepared by 60 °SR (Shopper-Riegler beating degree) flax pulp, named APC-60, exhibited the highest specific capacitance of 265.8 F/g at a current density of 0.5 A/g. The specific capacitance retention at 59% remained for the APC-60 electrodes at a high current density of 10 A/g. These results suggested that the flax-based APCs could be a promising carbon-based electrode material for sustainable electrochemical energy storage.

Heteroatom-doped porous carbons derived from lotus pollen for supercapacitors: Comparison of three activators

Facile preparation of carbon-based electrode materials with high specific surface area and controllable pore structure through a green and mild strategy is highly desirable for high-performance supercapacitors. Here, hierarchically porous carbon materials were prepared by three types of metal chlorides, including ZnCl2, FeCl3, and CuCl2. Compared with porous carbons obtained by traditional ZnCl2 or FeCl3 activation, hierarchically porous carbon obtained by a facile CuCl2 activation possessed higher yield, larger specific surface area, more developed hierarchical pore structure, and higher heteroatom contents. Benefiting from the synergy of unique morphology, hierarchical pore architecture with abundant micro-/mesopores and coexistence of numerous redox-active nitrogen and sulfur funtionalities, the as-prepared hierarchically porous carbon activated by CuCl2 exhibited superior electrochemical performance in aqueous electrolyte, including a large specific capacitance of 389.3 F g−1 at a current density of 1 A g−1, excellent rate capability and good cycling stability in a three-electrode system. Moreover, the assembled carbon-based symmetric supercapacitor based on CuCl2-activated carbon electrode delivered a significantly increased energy density of 30.4 Wh kg−1 at a power density of 496.0 W kg−1 in comparison to ZnCl2 or FeCl3-activated carbon electrodes. Therefore, CuCl2 activation is proved to be an effective chemical activation agent for the synthesis of biomass-derived carbon materials for high-performance supercapacitors.

Optimization of specific capacitance and water splitting efficiency of N-enriched carbon by incorporating oxides of transition metals via an ancient chemical technique

Abstract The carbonaceous materials owing to their high natural abundance and operational stability showed significant promise as the replacement of costly noble-metal-based electrode materials in the energy storage and conversion devices. The incorporation of heteroatoms (like N, transition metals etc.) enhances the electrochemical performance of these carbon-based materials. However, significant investigations are still required to develop a facile method for synthesizing heteroatom-incorporated carbon. Herein, an ancient chemical technique was adopted to develop a series of iron and/or nickel oxide incorporated N-enriched carbons within a few seconds. The physicochemical properties of the N-enriched carbon altered when the amount and type of the incorporated metal oxides was regulated. These changes modulated the ion diffusion, double layer formation, substrate adsorption-desorption and charge transfer process in the N-enriched carbons. Incorporation of iron oxide enhanced the charge storage and transfer performance of the N-enriched carbon. The nickel oxide facilitated its substrate adsorption-desorption and charge transfer efficiency in water polarization process. The N-enriched carbon with moderate iron oxide loading showed superior charge storage and OER performance whereas, that with highest loading showed superiority towards the HER. This investigation established the viability of “sugar snake” process as a synthetic technique for developing efficient carbon-based electrode materials.