Co-doped Porous Carbon Research Articles

Microwave Regenerable Nickel, Zinc Co-doped Nitrogen-Coordinated Porous Carbon Catalyst for Nitrogen Fixation.

More than 90% of the global NH3 synthesis is dominated by the Haber-Bosch process, which consumes 2% of the worldwide energy and generates 1.44% of the global carbon emission. The electrochemical N2 reduction reaction (NRR) is regarded as an attractive alternative route to produce NH3 under mild reaction conditions, but the electrocatalysts suffer from the difficulty of N≡N cleavage. In this work, we report a leaf-like MOF-derived Ni/Zn bimetallic co-doped nitrogen-coordinated porous carbon (Ni/Zn-NPC) as a cost-effective NH3 synthesis electrocatalyst. The resultant electrocatalyst achieved a high NH3 production rate of 22.68 μg h-1 mgcat-1 at -1.0 V vs a reversible hydrogen electrode (RHE) in a 0.1 M Na2SO4 electrolyte. The Ni/Zn-NPC material can be called a microwave regenerable catalyst because microwave treatment has proven to be a crucial part of the multi-field coupling to detoxify and make the catalyst reactive, further improving its stability. Density functional theory (DFT) was chosen to explore the mechanism of Ni/Zn-NPC for NRR, providing a profound prediction of the structure of the active site and related reaction pathways and revealing that trace Ni doping optimizes the local coordination environment and N2 adsorption of Zn atoms.

In Situ N, O Co-Doped Nanoporous Carbon Derived from Mixed Egg and Rice Waste as Green Supercapacitor.

The conversion of nitrogen-oxygen-rich biomass wastes into heteroatomic co-doped nanostructured carbons used as energy storage materials has received widespread attention. In this study, an in situ nitrogen-oxygen co-doped porous carbon was prepared for supercapacitor applications via a two-step method of pre-carbonization and pyrolytic activation using mixed egg yolk/white and rice waste. The optimal sample (YPAC-1) was found to have a 3D honeycomb structure composed of abundant micropores and mesopores with a high specific surface area of 1572.1 m2 g-1, which provided abundant storage space and a wide transport path for electrolyte ions. Notably, the specific capacitance of the constructed three-electrode system was as high as 446.22 F g-1 at a current density of 1 A g-1 and remained above 50% at 10 A g-1. The capacitance retention was 82.26% after up to 10,000 cycles. The symmetrical capacitor based on YPAC-1 with a two-electrode structure exhibited an energy density of 8.3 Wh kg-1 when the power density was 136 W kg-1. These results indicate that porous carbon materials prepared from mixed protein and carbohydrate waste have promising applications in the field of supercapacitors.

Unraveling the Ion Uptake Capacitive Deionization of Sea- and Highly Saline-Water by Sulfur and Nitrogen Co-Doped Porous Carbon Modified with Molybdenum Sulfide.

In parallel to the depletion of potable water reservoirs, novel technologies have been developed for seawater softening, as it is the most abundant source for generating deionized water. Although salt removal at subosmotic pressures and ambient temperatures by applying low-operating potentials with high energy efficiency made capacitive deionization (CDI) an advantageous water-softening process, its practical application is limited by insufficient ion removal capacity and low concentration influent. The performance of a CDI system is in progress with engineering the electrode active materials, also facilitating the advance design in highly saline- and seawater study. Herein, an innovative strategy was developed to provide high-performance CDI systems based on efficient and electrochemical ion-uptake active materials with a simple initial preparation. Nitrogen-doped porous carbons (N-pCs) received benefits from a high specific surface area and good surface wettability. The N-pCs were modified with molybdenum oxide/sulfide intercalative array and developed as CDI electrode active materials for desalination of both low/medium saline- and seawater. The MoS2/S,N-pC electrode materials exhibited perfect optimized salt adsorption capacity (SACs) of 47.9 mg g-1 when compared to N-pC (37.9 mg g-1) and MoO3/N-pC (39.6 mg g-1) counterparts at 1.4 V in a 750 ppm NaCl solution. In addition, the assembled CDI cells exhibited reasonable cycle stability and retained 96.7% of their initial SAC in continuous CDI cycles for 128,000 s. The fabricated CDI cell rendered an excellent salt removal efficiency (SRE, %) of 13.34% from the real seawater sample at 1.2 V. In detail, the SRE % of the NaCl, KCl, MgCl2, and CaCl2 soluble salts with respect to seawater sample exhibited a remarkable SRE % of 30.8%, 36%, 32.6%, and 19.3%, respectively. These SRE % values (>13.34%) provide convincing evidence on the reasonable ion uptake capability of the fabricated CDI cells for removing Na+, K+, Mg2+, and Ca2+ ions compared to other soluble component. The advanced cell design parallel to the promising outcomes provided herein makes these CDI systems immensely propitious for efficient water softening.

Nitrogen-phosphorous co-doped porous carbon from cross-linked polymers for supercapacitor applications

Herein, we report co-doped porous carbon with nitrogen-phosphorous derived from cross-linked polyvinyl alcohol and polyvinylpyrrolidone (AC-PA/PP/AP-x) polymers synthesized using a simple single activation process. Diammonium hydrogen phosphate (AP) acting as nitrogen and phosphorous source was used to dope the cross-linked polymer precursors. The properties of the as synthesized carbon materials were analysed using the following techniques: scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS) mapping, Raman spectroscopy and nitrogen sorption isotherm. The optimized AC-PA/PP/AP-0.5 sample possess the highest porous surface properties i.e., specific surface area (2656 m2g−1), pore volume (1.08 cm3g−1) and micropore volume (0.99 cm3g−1). The sample also achieved a remarkable specific capacitance (252Fg−1) corresponding to a specific current of 1Ag−1measured within the presence of 2.5 M KNO3 aqueous electrolyte, in three electrode set-up. The constructed symmetric AC-PA/PP/AP-0.5//AC-PA/PP/AP-0.5 SC with a good electrical series resistance (ESR = 0.6 Ω), delivers a great specific energy (27.3 W h kg-1) and specific power (400 W kg-1) when monitoring at 0.5Ag−1using same electrolyte. Good capacitance retention of 90 % was obtained while charge-discharging (CD) the device for about 10,000 cycles at 5Ag−1. The CD cycling also yielded a coulombic efficiency of 99.8 %. Thus, this porous carbon produced via cross-linking and heteroatom doping, has a well-connected hierarchical porous structure that includes both micropores and mesopores. This structure is important for charge storage and transport. Therefore, the fabricated symmetric cell is a promising supercapacitor energy storage device, where a high power is requisite.

Multifunctional MOF-Derived Au, Co-Doped Porous Carbon Electrode for a Wearable Sweat Energy Harvesting-Storage Hybrid System.

As an efficient alternative for harnessing the energy from human's biofluid, a wearable energy harvesting-storage hybrid supercapacitor-biofuel cell (SC-BFC) microfluidic system is established with one multifunctional electrode. The electrode integrates metal-organic framework (MOF) derived carbon nanoarrays with embedded Au, Co nanoparticles on a flexible substrate, and is used for the symmetric supercapacitor as well as the enzyme nanocarriers of the biofuel cell. The electrochemical performance of the proposed electrode is evaluated, and the corresponding working mechanism is studied in depth according to the cyclic voltammetry and density functional theory calculation. The multiplexed microfluidic system is designed to pump and store natural sweat to maintain the continuous biofuel supply in the hybrid SC-BFC system. The biofuel cell module harvests electricity from lactate in sweat, and the symmetric supercapacitor module accommodates the bioelectricity for subsequent utilization. A numerical model is developed to validate the normal operation in poor and rich sweat under variable situations for the microfluidic system. One single SC-BFC unit can be self-charged to ≈0.8V with superior mechanical durability in on-body testing, as well as energy and power values of 7.2 mJ and 80.3 µW, respectively. It illustrates the promising scenery of energy harvesting-storage hybrid microfluidic system.

ZnO quantum dots @ nitrogen and sulfur Co-doped porous carbon nanosheets for the detection of lung cancer biomarkers in exhaled breath

The development of non-selective sensors as an e-nose system for breath analysis application generates unique breath prints delineating the fundamental body metabolism aiding early diagnosis of lung cancer. In this work, size dependent ZnO quantum dots (QDs) were controlled by pH and finely dispersed on nitrogen and sulfur co-doped porous carbon nanosheet (CNS) for exploration of their chemi-resistive gas sensing property. Application of these nanocomposites to different lung cancer biomarkers (toluene, isoprene acetone and benzene) depicts unique responses to each at different operating temperatures. Particularly, the composite with lower ZnO QDs size on sulfur rich porous carbon nanosheet (SC-SQD) exhibited 2.5 times of the response to toluene compared to the composite with higher QDs size and sulfur poor porous carbon nanosheet (NC-LQD) in the concentration range between 1 ppm and 5 ppm. It was demonstrated that for 5 ppm of toluene, a response of 31.4 was observed with a response and recovery time of 18 s and 58 s, respectively. The sensor exhibited an estimated lower limit of detection of 800 ppb. Besides, the sensor exhibited a gradual decrease (∼9.55%) in response to 5 ppm toluene at 90% humidity. This superior performance can be explained by the density of defect states, reactive oxygen species (ROS) and oxidation states of functionalization.

Effect of Heteroatoms on Pseudocapacitance for N/O Co-doped Porous Carbon in an Alkaline Aqueous Electrolyte

Effect of Heteroatoms on Pseudocapacitance for N/O Co-doped Porous Carbon in an Alkaline Aqueous Electrolyte

Synergistic coupling of NiFe-layered double hydroxide nanosheets with Co-doped porous interconnecting carbon frameworks for efficient bifunctional electrocatalysis

The design of low-cost and durable electrocatalysts with high catalytic performance of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is crucial for the development of sustainable energy technologies. NiFe-layered double hydroxide (NiFe-LDH) is a promising electrocatalyst for OER, but the poor ORR activity limits its large-scale application as a bifunctional electrocatalyst in energy storage and conversion devices. The rational design of hierarchical nanohybrids is an effective strategy to construct bifunctional OER/ORR electrocatalysts. Herein, a high-performance OER/ORR bifunctional non-noble metal electrocatalyst (NiFe-LDH/CoNC-PIN) was projected. The Co-doped carbon frameworks with porous interconnecting networks (CoNC-PIN) is prepared by pyrolysis of ZIF-8/67 via a salt template strategy, followed by the uniform in situ growth of ultrathin NiFe-LDH nanosheets on CoNC-PIN to construct the hierarchical NiFe-LDH/CoNC-PIN hybrid. The molten NaCl template in pyrolysis activates the surface of ZIF-8/67 and connects them into porous carbon networks to improve the surface area, porosity and electronic conductivity of catalysts. Due to the efficient electron transfer and strong coupling between CoNC-PIN and NiFe-LDH, the NiFe-LDH/CoNC-PIN exhibits a small OER overpotential of 249 mV at 10 mA/cm2, a low Tafel slope of 27.7 mV/dec, an ORR half-wave potential of 0.80 V, and excellent durability and structural stability. This strategy provides a novel insight to fabricate advanced OER/ORR bifunctional non-noble metal electrocatalysts.

Phosphorus-Mediated Local Charge Distribution of N-Configuration Adsorption Sites with Enhanced Zincophilicity and Hydrophilicity for High-Energy-Density Zn-Ion Hybrid Supercapacitors.

Tailor-made carbonaceous-based cathodes with zincophilicity and hydrophilicity are highly desirable for Zn-ion storage applications, but it remains a great challenge to achieve both advantages in the synthesis. In this work, a template electrospinning strategy is developed to synthesize nitrogen and phosphorous co-doped hollow porous carbon nanofibers (N, P-HPCNFs), which deliver a high capacity of 230.7 mAh g-1 at 0.2 A g-1 , superior rate capability of 131.0 mAh g-1 at 20 A g-1 , and a maximum energy density of 196.10Wh kg-1 at the power density of 155.53W kg-1 . Density functional theory calculations (DFT)reveal that the introduced P dopants regulate the distribution of local charge density of carbon materials and therefore facilitate the adsorption of Zn ions due to the increased electronegativity of pyridinic-N. Ab initio molecular dynamics (AIMD)simulations indicate that the doped P species induce a series of polar sites and create a hydrophilic microenvironment, which decreases the impedance between the electrode and the electrolyte and therefore accelerates the reaction kinetics. The marriage of ex situ/in situ experimental analyses and theoretical simulations uncovers the origin of the enhanced zincophilicity and hydrophilicity of N, P-HPCNFs for energy storage, which accounts for the faster ion migration and electrochemical processes.

Co Single Atoms Anchored in N and P Co-doped Porous Carbon Fibers for Efficient Water Splitting.

Single atom catalysts (SACs) show potential application for highly efficient water splitting. Herein, we designed Co single atoms (SAs) dispersed on N and P co-doped porous carbon nanofibers as electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The configuration of Co SAs is proved to coordinate with 4 N/O atoms. The long-range interactions between doped P atoms and Co-N4 (O) sites could modulate the electronic structures of M-N4 (O) sites, which greatly reduce the adsorption energies of HER and OER intermediates at metal sites. Density Functional Theory calculations reveal that CoSA /CNFs exhibits optimized HER and OER kinetics when P coordinates with two N atoms. The atomically dispersed Co electrocatalyst exhibits the low overpotentials of 61, 89 and 390 mV for acidic HER, alkaline HER and OER at 10 mA cm-2 current density, along with the Tafel slope of 54, 143 and 74 mV dec-1 , respectively. This work demonstrates the prospect of utilizing di-heteroatom-doping transition metal SACs, and provides a novel and general strategy for the preparation of SACs.

N, S co-doped porous graphene-like carbon synthesized by a facile coal tar pitch-blowing strategy for high-performance supercapacitors

Herein, coal tar pitch (CTP) derived nitrogen and sulfur co-doped porous graphene-like carbon (NSPC) is performed by an ammonium sulfate-assisted chemical blowing strategy. Afterward, NSPC was activated by KOH to form a-NSPC features a bubble-like structure with a thin porous shell and a well-balanced porous ratio. Serving as electrode materials for supercapacitors, the capacitance of a-NSPC was 368 F g−1 at 0.5 A g−1. Meanwhile, the prepared materials exhibit excellent cycling stability after 10,000 cycles. This work may not only prepare superior electrode materials but also provide a feasible strategy for large-scale production of high-performance and low-cost electrode materials.

Unveiling Superior Capacitive Behaviors of One-Pot Molten Salt-Engineered B, N Co-Doped Porous Carbon Sheets.

Heteroatom-doped porous carbon materials with distinctive surface properties and capacitive behavior have been accepted as promising candidates for supercapacitor electrodes. Currently, the researches mainly focus on developing facile synthetic method and unveiling the structure-activity relationship to further elevate their capacitive performance. Here, the B, N co-doped porous carbon sheet (BN-PCS) is constructed by one-pot pyrolysis of agar in KCl/KHCO3 molten salt system. In this process, the urea acts as directing agent to guide the formation of 2D sheet morphology, and the decomposition of KHCO3 and boric acid creates rich micro- and mesopores in the carbon framework. The specific capacitance of optimized BN-PCS reaches 361.1 F g-1 at a current density of 0.5 A g-1 in an aqueous KOH electrolyte. Impressively, the fabricated symmetrical supercapacitor affords a maximum energy density of 43.5Wh kg-1 at the power density of 375.0W kg-1 in 1.0mol L-1 TEABF4 /AN electrolyte. It also achieves excellent long-term stability with capacitance retention of 91.1% and Columbic efficiency of 100% over 10000 cycles. This study indicates one-pot molten salt method is effective in engineering advanced carbon materials for high-performance energy storage devices.

Facile Synthesis of Functionalized Porous Carbon by Direct Pyrolysis of Anacardium occidentale Nut-Skin Waste and Its Utilization towards Supercapacitors.

Preparing electrode materials plays an essential role in the fabrication of high-performance supercapacitors. In general, heteroatom doping in carbon-based electrode materials enhances the electrochemical properties. Herein, nitrogen, oxygen, and sulfur co-doped porous carbon (PC) materials were prepared by direct pyrolysis of Anacardium occidentale (AO) nut-skin waste for high-performance supercapacitor applications. The as-prepared AO-PC material possessed interconnected micropore/mesopore structures and exhibited a high specific surface area of 615 m2 g-1. The Raman spectrum revealed a moderate degree of graphitization of AO-PC materials. These superior properties of the as-prepared AO-PC material help to deliver high specific capacitance. After fabricating the working electrode, the electrochemical performances including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy measurements were conducted in 1 M H2SO4 aqueous solution using a three-electrode configuration for supercapacitor applications. The AO-PC material delivered a high specific capacitance of 193 F g-1 at a current density of 0.5 A g-1. The AO-PC material demonstrated <97% capacitance retention even after 10,000 cycles of charge-discharge at the current density of 5 A g-1. All the above outcomes confirmed that the as-prepared AO-PC from AO nut-skin waste via simple pyrolysis is an ideal electrode material for fabricating high-performance supercapacitors. Moreover, this work provides a cost-effective and environmentally friendly strategy for adding value to biomass waste by a simple pyrolysis route.

One-step synthesis of nitrogen and sulfur co-doped hierarchical porous carbon derived from acesulfame potassium as a dual-function agent for supercapacitors and lithium‑sulfur batteries

Acesulfame potassium (AK) is an artificial sweetener that contains N and S functional groups in its organic moiety and is suitable as porous carbon precursor. In this study, AK derived carbon (AKC) was obtained via direct carbonization and in situ doping without additives under the dual conditions of inert gas protection and high temperatures. The obtained AKCs exhibited high porosity structure with a specific surface area of 2043 m2 g−1 and 3.22 wt% N and 8.61 wt% S dual heteroatom doping. When applied to the supercapacitor electrode, the AKC ensured a high capacitance of 264 F g−1 at 0.5 A g−1, which maintained 86.1 % of the initial capacitance after 5000 cycles at 5 A g−1, and an ultra-high energy density of 16.3 Wh kg−1 in a full cell device. By analyzing its application in the lithium‑sulfur battery cathode, the S-loaded AKC exhibited a high capacity of 1075 mAh g−1 at 0.1C, and 490.5 mAh g−1 after 150 cycles with 66.5 % of capacity retention. The excellent performance of AKC can be attributed to its high specific surface area, pore structure, and sulfur and nitrogen co-doping combine effect. Overall, AKCs exhibited excellent electrochemical performances, thereby proposing a new synthetic strategy of preparing dual heteroatom doped porous carbon for high-performance electrode materials through a single precursor and low-cost perspective.

Nitrogen and sulfur co-doped porous carbon derived from polypyrrole-polythiophene for efficient peroxydisulfate activation towards degradation of aniline

To enhance the catalytic activity of carbon materials and streamline their synthesis process, it is necessary to optimize the doping of heteroatoms and reduce the dependence on organic solvents. This can be achieved by utilizing carbonized Polypyrrole-Polythiophene (C(Ppy-Pth)), which is obtained through simultaneous and in-situ co-doping of N and S. This material can serve as an effective activator of peroxydisulfate (PDS) for the degradation of aniline (AN). The results showed that Ppy-Pth could be efficiently synthesized by using cetyltrimethyl ammonium bromide, pyrrole, thiophene, FeCl3, and H2O2 in water. Based on the price, self-decomposition and oxidation efficiency, the performance of PDS activated by C(Ppy-Pth) was superior to that of peroxymonosulfate (PMS) in degrading AN. The optimum conditions for catalyzing PDS and degrading 30 mg/L AN by C(Ppy-Pth) were 0.10 g/L C(Ppy-Pth)-1000-1/1, 2.10 mM PDS, and pH0 = 3.00, which resulted in 86.69% AN removal in 30 min. Carbonation temperature, N/S ratio and pyridine N content are the key factors affecting the catalytic activity of C(Ppy-Pth). Quenching, probe, and electrochemical experiment revealed that in the catalytic PDS system with C(Ppy-Pth)-1000-1/1 (pH0 = 3.00), the oxidation of AN mainly occurred through the generation of hydroxyl radical (·OH), superoxide anion (O2·-), and electron transfer on the C(Ppy-Pth)-1000-1/1 surface. The steady-state concentration of ·OH and O2·- were 2.65 × 10−14 M and 1.97 × 10−13 M, respectively, and the contribution rate of ·OH oxidation was 31.28%. The oxidation of AN by sulfate radical (SO4·-) and singlet oxygen (1O2) could be neglected. This study provides a promising strategy for the construction of PDS catalyst and wastewater treatment.

Promotion of the Efficient Electrocatalytic Production of H2O2 by N,O- Co-Doped Porous Carbon

H2O2 generation via an electrochemical two-electron oxygen reduction (2e- ORR) is a potential candidate to replace the industrial anthraquinone process. In this study, porous carbon catalysts co-doped by nitrogen and oxygen are successfully synthesized by the pyrolysis and oxidation of a ZIF-67 precursor. The catalyst exhibits a selectivity of ~83.1% for 2e- ORR, with the electron-transferring number approaching 2.33, and generation rate of 2909.79 mmol g-1 h-1 at 0.36 V (vs. RHE) in KOH solution (0.1 M). The results prove that graphitic N and -COOH functional groups act as the catalytic centers for this reaction, and the two functional groups work together to greatly enhance the performance of 2e- ORR. In addition, the introduction of the -COOH functional group increases the hydrophilicity and the zeta potential of the carbon materials, which also promotes the 2e- ORR. The study provides a new understanding of the production of H2O2 by electrocatalytic oxygen reduction with MOF-derived carbon catalysts.

N, S co-doped porous carbon nanosheet foam as MALDI matrix for efficient and direct profiling of biomolecules and environmental contaminants

It is still urgent to develop a powerful method for high-throughput and sensitive analysis of various small biomolecules and environmental contaminants. Herein, a three-dimensional foam consisting of nitrogen and sulfur co-doped porous carbon (N, S-C) nanosheet synthesized was served as an excellent matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) efficiently and directly detecting various small biomolecules and pollutant compounds. This N, S-C nanosheet possessed the advantages of carbon foam for resonant chamber, high-contents of N/S heteroatoms co-doping, large surface area, hierarchical pore and good UV absorption. The use of N, S-C matrix could exhibit higher MS intensities, lower background noise, better salt tolerance and higher sensitivity for probing the various analytes, much superior to the traditional CHCA (α-cyano-4-hydroxycinnamic acid) matrix and control materials (C and N-C). The limit of detection (LOD)s of 1-hydroxy-pyrene, 4-nitrocatechol and nitroguaiacol were calculated to be 0.1 μg/mL, 1 μg/mL and 8 μg/mL at a signal-to-noise ratio (S/N) of 3. Moreover, the rapid and precise detections of 4-nitrocatechol, nitroguaiacol, and 1-hydroxy-pyrene in PM2.5 real sample have also been achieved. Through density functional theory (DFT) simulations, we reveal the sensing mechanism of small molecular deprotonation with the N and S co-doping into carbon matrix. This work may be promising to provide an excellent carbon matrix for the analysis of MALDI-TOF MS method in the biological and environmental field.

A green strategy to prepare nitrogen-oxygen co-doped porous carbons from macadamia nut shells for post-combustion CO2 capture and supercapacitors

In the process of preparing heteroatom-doped carbon materials by activating biomass with conventional activators (e.g. KOH or NaOH), not only the activators are highly corrosive to the equipment, but also the heteroatom content of the prepared carbon materials is low, which limits their large-scale production. In this study, a green method was proposed to synthesize nitrogen-oxygen co-doped porous carbons in one step under air atmosphere. In the preparation process, macadamia nut shells, potassium chloride(KCl) and melamine were used as precursors, templating agents and nitrogen sources, respectively. KCl can be used as a flame retardant to allow pyrolysis in the gas stream. This process promotes pore formation and the introduction of oxygen species. The presence of KCl also reduced the loss of nitrogen during pyrolysis. The prepared porous carbon had a high nitrogen and oxygen content of 20.2 wt% and 23.3 wt%, respectively. The highest CO2 uptake of the samples was 1.39 mmol/g at 0.15 bar and 25 °C, with a selectivity of 39.33. In addition, the material exhibited an impressive specific capacitance of 254.5 F g−1 at 1 A g−1. The unique green preparation method is expected to provide new ideas for post-combustion CO2 capture and energy storage.

N/S Codoped Three-Dimensional Porous Carbons for High-Performance Supercapacitors with Remarkable Rate Performance

N/S Codoped Three-Dimensional Porous Carbons for High-Performance Supercapacitors with Remarkable Rate Performance

An environment-friendly strategy to prepare oxygen-nitrogen-sulfur doped mesopore-dominant porous carbons for symmetric supercapacitors

We report an environment-friendly method of particular mesopore-dominant oxygen-nitrogen-sulfur co-doped porous carbons from biomass-derived carbon materials (BCMs) using methylene blue (MB) as self-doping media for high performance supercapacitors. The as-prepared BCMs possess a high specific surface area of 1734.58 m2/g, large pore volume of 1.80 cm3/g, high oxygen (8.08 %), nitrogen (3.13 %) contents, and ultra-strong MB adsorption capacity (1337.83 mg/g). This unique architecture provides ion shuttle back and forth pore size to enhance double layer capacitance, and rapid diffusion of electrolyte ions. Besides, after adsorption with methylene blue, N/S elements (4.22/1.17 wt%) co-doped into BSMs led to multiple synergistic effects, improve surface wettability and supply additional pseudo-capacitance. The as-obtained co-doped BCMs exhibited the highest specific capacitance of 208 F/g at 1 A/g in a three-electrode system, and the symmetric supercapacitor showed superior cycling stability with high retention of 100 % at 5 A/g over 20,000 cycles. The symmetric supercapacitor showed a high energy density of 6.89 Wh/kg at a power density of 5272.23 W/kg in a 1 M Et4NBF4/PC electrolyte. The high energy density and high power density of as-obtained carbon materials can approach commercial porous carbon YP-50, demonstrating the good potential for practical application. Overall, this study is valuable for the multifunctional applications of BCMs in dye wastewater treatment and capacitive energy storage, and builds a bridge to the future between environment and capacitive energy storage.