Porous Carbon Microspheres Research Articles

Soft-templating of biomass derivatives into edge-N doped 3D-interconnected hierarchical porous carbon for multi-scenario supercapacitive energy storage

Rational design of the pore structure for carbon materials is of great significance for solving the low specific capacitance and poor rate capability of supercapacitors. A novel soft-templating strategy is proposed by using biomass-derived sodium lignosulphonate as a carbon precursor and sublimable hexamethylenetetramine as a soft template. The hexamethylenetetramine nanoparticles are formed in the confined spaces of the precursor, and then these templates sublime to leave mesopores after the lignosulfonate transformed from linear structure to bulk structure by thermostabilization treatment. A high nitrogen content of 40 wt% in hexamethylenetetramine is also beneficial for the subsequent in-situ N-doping. The as-obtained nitrogen-doped hierarchical porous carbon microspheres possess a high specific surface area of 1416 m2 g−1 with an N-doping content of 4.32 % (86.26 % edge-N). In a two-electrode system, the soft-templating carbon exhibits a decent specific capacitance of 234 F g−1 at 0.1 A g−1, an excellent rate capability of 62.4 % at 50 A g−1, and a high energy density of 8.1 Wh kg−1 at 15.0 kW kg−1 in 6 M KOH aqueous electrolyte. Moreover, advanced additive manufacturing technology of direct ink writing was applied to construct a quasi-solid-state in-plane interdigital microsupercapacitor by using the soft-templating carbon, and it presents a superior areal/volumetric capacitance, rate performance, mechanical stability, and flexibility with PVA/H2SO4 gel electrolyte. This work broadens the pore structure engineering methodology by novel soft-templating biocarbon for multi-functional and multi-scenario energy storage systems.

Regulating the Electronic Structure of Cu Single-Atom Catalysts toward Enhanced Electro-Fenton Degradation of Organic Contaminants via 1O2 and •OH.

Heterogeneous electro-Fenton degradation with 1O2 and •OH generated from O2 reduction is cost-effective for the removal of refractory organic pollutants from wastewater. As 1O2 is more tolerant to background constituents such as salt ions and a high pH value than •OH, tuning the production of 1O2 and •OH is important for efficient electro-Fenton degradation. However, it remains a great challenge to selectively produce 1O2 and improve the species yield. Herein, the electronic structure of atomically dispersed Cu-N4 sites was regulated by doping electron-deficient B into porous hollow carbon microspheres (CuBN-HCMs), which improved *O2 adsorption and significantly enhanced 1O2 selectivity in electro-Fenton degradation. Its 1O2 yield was 2.3 times higher than that of a Cu single-atom catalyst without B doping. Meanwhile, •OH was simultaneously generated as a minor species. The CuBN-HCMs were efficient for the electro-Fenton degradation of phenol, sulfamethoxazole, and bisphenol A with a high mineralization efficiency. Its kinetic constants showed insignificant changes under various anions and a wide pH range of 1-9. More importantly, it was energy-efficient for treating actual coking wastewater with a low energy consumption of 19.0 kWh kgCOD-1. The superior performance of the CuBN-HCMs was contributed from 1O2 and •OH and its high 1O2 selectivity.

Boosting the potassium storage property of spongia-like copper phosphide anode via nano-in-micro construction

Metal phosphides (MPs) show great promise as anode material in potassium-ion batteries (PIBs) owing to their cost-effectiveness and high theoretical capacity. Despite that, MPs anode usually manifests inferior poor cyclability as a result of dramatic volume fluctuation during discharge–charge cycling. Herein, a scalable salt template-assisted spray-drying method is developed to fabricate the porous carbon microspheres wrapped CuP2 nanoparticles (p-CuP2/C) with a nano-in-micro structure. The combination of the CuP2 nanoparticles, large meso-porous carbon microspheres can simultaneously offer plenty of reactive sites, promote electrolyte penetration, and maintain structural integrity. Additionally, the proposed synthesis strategy is suit for the industrial manufacture. As an anode for PIBs, the p-CuP2/C anode presents a high reversible capacity (494 mAh/g at 0.05 A/g), excellent cycling stability (a capacity degradation rate of 0.04 % per cycle during 2000 cycles at 2 A/g), and superior rate capability (244 mAh/g at 2 A/g). More impressively, pairing with a potassium Prussian blue cathode, the potassium-ion coin cell shows an excellent cycling lifespan with 87.1 % capacity retention after 200 cycles at a current density of 0.1 A/g, the assembled pouch cell also maintains stable cycling at 0.3 A/g over 80 cycles. This research could offer a facile approach to develop other advanced anodes with industrial practicability for alkali ion batteries.

Porous carbon microspheres assembled by defective nitrogen and sulfur co-doped nanosheets as anode materials for lithium-/sodium-ion batteries

Porous carbon microspheres assembled by defective nitrogen and sulfur co-doped nanosheets as anode materials for lithium-/sodium-ion batteries

Multi-layered carbon accommodation of MnO2 enabling fast kinetics for highly stable zinc ion batteries

Large-scale durable aqueous zinc ion batteries for stationary storage are realized by spray-coating conductive PEDOT(Poly(3,4-ethylenedioxythiophene)) wrapping MnO2/carbon microspheres hybrid cathode in this work. The porous carbon microspheres with multiple layers deriving from sucrose provide suitable accommodation for MnO2 active materials, exposing more redox active sites and enhancing the contact surface between electrolyte and active materials. As a result, MnO2/microspheres are adhered to the current collector by a conductive PEDOT coating without any binder. The ternary design retards the structural degradation during cycling and shortens the electron and ion transport path, rendering the full batteries high capacity and long cycle stability. The resulting batteries perform the capacity of 277, 227, 110, 85 and 50 mAh/g at 0.2, 0.5, 1, 2 and 5 A/g, respectively. After 3000 cycles the initial capacity retains 86%, and 80% after 5000 cycles. GITT indicates PEDOT wrapping MnO2/microspheres cathode enables better ion intercalating kinetics than conventional MnO2. The work could represent a novel and significant step forward in the studies on the large-scale application of zinc ion batteries.

Ion-crosslink alginate emulsion droplets toward synthesis of porous carbon microspheres as anodes for lithium-ion batteries

Porous carbon microsphere (PCM) is an important anode material for lithium-ion batteries; however, the preparation of PCM at large scale is still complex, sometimes even needing sophisticated instruments. Herein, we developed a water-in-oil (W/O) phase-separation strategy to prepare PCM in terms of simple and low-cost manner. As-prepared PCM has a large surface area of 182 m2/g, and abundant mesopores, which benefits the penetration of Li+-carrying electrolyte into the electrode. Therefore, the optimized PCM electrode shows a high-rate capability (408 mA h g−1 at 2 A/g). This work broadens a new vision in preparing PCM for energy-storage/-conversion applications.

Hydrothermal preparation of N and O-rich porous carbon microspheres and their capacitance properties

In this paper, N and O-rich porous activated carbon (N-O/AC) microsphere with various pore sizes was prepared by thermal and KOH activation of g-C3N4@graphene oxide (CN@GO) microsphere. CN@GO microsphere was pre-prepared through a hydrothermal method directly from glucose and melamine, which resulted into high content and uniform doping of O and N in the final product. CN@GO microsphere was composed of GO/CN/GO sandwich nanochips, forming a porous structure with various pore sizes. The obtained N-O/AC has high energy density (33.19 Wh/kg) and high power density (499.93 W/kg), in company with excellent cyclic stability (remaining 98.64 % after 1000 cycles). The N-O/AC derived from the hydrothermal method provides a low-cost way of constructing porous carbon matrix composites with pseudo-capacitance.

Effects of binder content on potato starch-derived porous carbon microspheres for high-performance supercapacitors

Potato starch-based carbon microspheres (PCMs) have successfully synthesized from potato starch by a simple strategy based on (NH4)2HPO4 and KOH activation. The PCMs presents a large specific surface area (SSA) of 2048 m2 g−1. The electrochemical behaviors of the PCMs with different binder content in 6 mol L−1 KOH were studied by impedance spectroscopy, cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD). The results show that PCMs-85 (the binder content is 5 wt%) has a small equivalent series resistance (ESR), high specific capacitance, compacted density, and areal density. PCMs-85 exhibited good cycling durability of 100 % after 10,000 cycles at 1 A g−1 and delivered an energy density of 6.35 Wh L−1 and a volume power density of 167.38 W L−1. The corresponding capacitive performances of PCM-85-based symmetrical two-electrode supercapacitors are investigated in 6 mol L−1 KOH, 1 mol L−1 Na2SO4 and 1 mol L−1 TEA.BF4/AN electrolyte. The PCMs supercapacitor with 6 mol L−1 KOH electrolyte exhibits a mass-specific capacitance of 172 F g−1 with volumetric capacitances of 145 F cm−3 at 1 A g−1.

Facile fabrication of sulfonated porous yeast carbon microspheres through a hydrothermal method and their application for the removal of cationic dye

Water pollution containing dyes become increasingly serious environmental problem with the acceleration of urbanization and industrialization process. Renewable adsorbents for cationic dye wastewater treatment are becoming an obstacle because of the difficulty of desorbing the dye from the adsorbent surface after adsorption. To overcome this dilemma, herein, we report a hydrothermal method to fabricate sulfonic acid modified yeast carbon microspheres (SA/YCM). Different characterization techniques like scanning electron microscopy, FTIR spectroscopy, and X-ray diffraction have been used to test the SA/YCM. Decorated with sulfonic acid group, the modified yeast carbon microspheres possess excellent ability of adsorbing positively charged materials. The removal rate of Methyl blue (MB) by renewable adsorbent SA/YCM can reach 85.3% when the concentration is 500 mg/L. The SA/YCM regenerated by HCl showed excellent regeneration adsorption capacity (78.1%) after five cycles of adsorption–desorption regeneration experiment. Adsorption isotherm and kinetic behaviors of SA/YCM for methylene blue dyes removal were studied and fitted to different existing models. Owing to the numerous sulfonic acid groups on the surface, the SA/YCM showed prominent reusability after regeneration under acidic conditions, which could withstand repeated adsorption–desorption cycles as well as multiple practical applications.

Oxygen Vacancy-Rich NiCo2O4 on Carbon Framework with Controlled Pore Architectures as Efficient Bifunctional Electrocatalysts for Zn-Air Batteries

Transition metal oxides are considered alternative electrocatalysts for ZAB owing to their multiple oxidation states. However, they have limitations such as low electrical conductivity and the deficiency of reactive sites. In this study, to overcome these shortcomings and improve electrocatalytic activity, oxygen vacancies and porous architectures were introduced through a partial reduction process and a porous carbon framework. Open porous carbon microspheres with uniformly loaded NiCo2O4 nanosheets and oxygen vacancies (V-NCO/OPC) displayed enhanced electrocatalytic performance with a low Tafel slope (68 mV dec-1) in the oxygen reduction reaction (ORR) and a low overpotential (402 mV) at 10 mA cm–2 in the oxygen evolution reaction (OER). The combined effect of the oxygen vacancies and porous architecture can offer sufficient active sites, modify the electronic structure of the metal oxide surface, and facilitate mass transport, enhancing the electrocatalytic properties of V-NCO/OPC. Furthermore, when applied for ZAB, V-NCO/OPC demonstrated better electrochemical performance including discharge power density (154.9 mW cm-2) at the current density of 175.9 mA cm-2, low voltage gap (0.85 V) at the initial cycle, and long-term (250 h) cycle stability at the current density of 10 mA cm−2 than those of noble-metal electrocatalysts.

MOF-derived porous carbon microspheres Ni@C-acid as solid-phase microextraction coating for extraction of polycyclic aromatic hydrocarbons from tea infusions

The improvement of the stability and adsorption properties of materials on targets in sample pre-treatment has long been an objective. Extensive efforts have been made to achieve this goal. In this work, metal-organic framework Ni-MOF precursors were first synthesized by solvothermal method using polyvinylpyrrolidone (PVP) as an ideal templating agent, stabiliser and nanoparticle dispersant. After carbonization and acid washing, the nanoporous carbon microspheres material (Ni@C-acid) was obtained. Compared with the material without acid treatment (Ni@C), the specific surface area, pore volume, adsorption performance of Ni@C-acid were increased. Thanks to its excellent characteristics (high stability, abundant benzene rings), Ni@C-acid was used as fiber coatings in headspace solid-phase microextraction (HS-SPME) technology for extraction and preconcentration of polycyclic aromatic hydrocarbons (PAHs) prior to gas chromatography-flame ionization detector (GC-FID) analysis. The experimental parameters of extraction temperature, extraction time, agitation speed, desorption temperature, desorption time and sodium chloride (NaCl) concentration were studied. Under optimal experimental conditions, the wide linear range (0.01-30 ng mL−1), the good correlation coefficient (0.9916-0.9984), the low detection limit (0.003-0.011 ng mL−1), and the high enrichment factor (5273-13793) were obtained. The established method was successfully used for the detection of trace PAHs in actual tea infusions samples and satisfied recoveries ranging from 80.94-118.62 % were achieved. The present work provides a simple method for the preparation of highly stable and adsorbable porous carbon microsphere materials with potential applications in the extraction of environmental pollutants.

Fast ionic conductor MnSe supported Micron-Si embedded in three-dimensional N-doped carbon matrix for lithium-ion batteries

Silicon is regarded as the most potential anode for the next generation lithium-ion batteries (LIBs) since its superhigh specific capacity and abundant reserves. Nonetheless, the grievous volume variation and inferior connate conductivity imped its further step on the commercial application. Herein, three-dimensional (3D) porous N-doped carbon microspheres, in which silicon is embedded and supported by MnSe, are fabricated via a simple spray drying method, named as MnSe/Si@NC. Such synergy conduces to the weaker polarization phenomenon and lower reactive barrier. Multi kind of electrochemical tests announce that the 3D network supported by MnSe and synthetical chemical bridge bonds, can remarkably ameliorate electron conductivity and structural stability. Benefit from the reasonably designed materials, the MnSe/Si@NC-10 anode expresses an outstanding cycling stability of 1030.8 mAh·g−1 at 2 A g−1 over 1000 cycles and extremely low-capacity loss rate for each cycle with about 0.27 ‰. In a word, this work can provide reference for the designing and preparation of high-performance anode materials utilized in LIBs.

Co–B supported on waxberry-like hierarchical porous carbon microspheres: An efficient catalyst for hydrogen generation via sodium borohydride hydrolysis

Rapid release of hydrogen at ambient condition is highly favorable and is necessary for fuel cell power generation on-demand. Hydrolysis of hydrides offers such advantage with sodium borohydride (NaBH4) as a representative exemplar. Despite with exceptionally high hydrogen content, the hydrolysis kinetics of NaBH4 is sluggish in the absence of catalyst. Co–B alloy has generally been employed as effective catalyst in the hydrolysis of borohydrides. However, Co–B particles are prone to agglomeration during the reaction, reducing the activity and durability of the catalyst. In this work, waxberry-like hierarchical porous carbon microspheres (HPCMs) were successfully prepared and were used as carriers to support Co–B particles to form the Co–B/HPCMs catalyst. The effects of HPCMs with different nitrogen contents in Co–B/HPCMs on the catalytic dehydrogenation rate of NaBH4 hydrolysis were systematically investigated. The experimental results showed that Co–B/HPCM-2 exhibited excellent catalytic activity in the hydrolysis of NaBH4 at 298 K, with a low activation energy of 43.3 kJ ·mol−1 and a high hydrogen generation rate of 3083.1 mlH2·min−1·g−1. Moreover, after five consecutive cycles, its catalytic activity maintained at 91.7 % of the initial catalytic activity, displaying satisfactory cycling performance. The findings obtained from this study are expected to expand a novel path for the development of efficient Co-based catalysts in heterogeneous catalytic reactions.

Molecular secondary recombination for pitch-derived carbon microsphere toward ultra-high sodium storage

Because the direct carbonization of low-cost pitch will form a highly graphitized soft carbon, and the soft carbon lacks a low-voltage platform to store sodium, so the sodium storage performance is poor. Therefore, in this research, by combining defect and pore engineering, the porous carbon microspheres with primary oxygen crosslinking were reorganized through secondary sulfur crosslinking to achieve the oxygen/sulfur complex crosslinked defect structure. At the same time, small molecular sulfur fragments filled the pores of the porous carbon microspheres to form the ultramicropores structure. It is worth noting that this pitch-derived carbon microsphere exhibits a new sodium storage mechanism of a new 'high-voltage platform'. Therefore, it shows stable cycle performance (220 mAh g−1 at 1 A g−1 after 2000 cycles) and excellent rate performance (101 mAh g−1 at 10 A g−1) in half cells; In addition, the structure of the ultramicropores can improve the initial coulomb efficiency of carbon microspheres. The sodium storage mechanism dominated by surface adsorption was determined by kinetic analysis and in-situ characterization techniques. This study provides a new idea for precise molecular regulation of anode materials for sodium ion batteries.

Stable hydrogen storage of lithium borohydrides via the catalytic effect of Ni2B induced by thermodynamic destabilization reaction

Lithium borohydride (LiBH4) is regarded as a potential hydrogen storage material due to its high gravimetric and volumetric capacity, but its practical application suffers from high operating temperature and poor reversibility. Herein, porous hollow carbon microspheres composed of carbon-coated Ni nanoparticles with high content (denoted as Ni/C) are rationally designed as functional support, which not only induces effective nanoconfinement of LiBH4 but also promotes efficiently homogeneous destabilization reaction between LiBH4 and Ni nanoparticles. The introduction of Ni nanoparticles leads to the decrease of the Gibbs free energy change for H2 desorption of LiBH4 based on the formation of Ni2B down to −0.95 eV while this value reaches 1.19 eV for bulk LiBH4, validating the effective role of Ni in thermodynamically destabilizing H2 desorption. Impressively, the average B–H bond length of LiBH4 on Ni2B reaches 1.291 Å and thus the corresponding dissociation energy of removing one H atom from LiBH4 is lowered to 1.00 eV, much lower than bulk LiBH4 (4.22 eV) and even LiBH4 on Ni (1.27 eV), which verifies superior role of Ni2B than Ni in catalytically enhancing H2 desorption. Therefore, a capacity of 8.86 wt.% is obtained for LiBH4 confined into Ni/C at 320 °C after 10 cycles.

One step synthesis of cerium-based porous carbon microsphere by ultrasonic spray pyrolysis and its adsorption of rhodamine B

Cerium-based porous carbon microsphere (Ce/PCM) was synthesized by one step ultrasonic spray pyrolysis (USP), and the structure was analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and Raman spectrometer. Furthermore, the adsorption performance of Ce/PCM was tested by Rhodamine B. (Rh B). The characteristic’s results showed the structure and specific surface area of Ce/PCM were affected by the pyrolysis temperature, and 800-Ce/PCM had the maximum specific surface area as 472.9 m2·g−1. The adsorption evaluation showed that 800-Ce/PCM had the best removal efficiency, and the maximum adsorption capacity was as high as 508.2 mg·g−1. The results suggested the adsorption kinetics of Ce/PCM for Rh B follows pseudo second-order dynamics and Freundlich model, which indicated that the adsorption process includes chemical adsorption and multilayer adsorption. Kinetic thermodynamic studies proved the absorption was endothermic reaction. The analysis of absorption mechanism indicated that the removal mechanism mainly includes pore filling, hydrogen bonding and surface adsorption.

Confinement and phase engineering boosting 1T phase MoS2/carbon hybrid for high‐performance capacitive deionization

AbstractCapacitive deionization (CDI) has attracted significant attention as a water treatment technology owing to its low cost, high efficiency, and eco‐friendliness. However, the unsatisfactory desalination performance of traditional electrode materials hinders the development of CDI. Herein, 1T‐MoS2/C hybrid microspheres are successfully fabricated through confinement and phase engineering strategies. The confinement effect of porous hollow carbon microspheres reduces the overgrowth and agglomeration of MoS2 nanosheets, which is beneficial for exposing more active sites and enhancing stability. Meanwhile, the 1T phase MoS2 displays high intrinsic conductivity and large interlayer spacing, which is conducive to rapid insertion/extraction of Na+. Consequently, 1T‐MoS2/C hybrid becomes a prospect electrode material for CDI, which showcases outstanding desalination capacity (48.1 mg/g at 1.2 V), eminent desalination rate as well as exceptional stability. Moreover, the desalination mechanisms are clarified through various characterizations and density functional theory calculations. This study provides new perspectives on designing high‐performance MoS2‐based CDI electrode materials.

Hierarchical porous hollow carbon microsphere/carbon nanotube heterostructures for high-performance supercapacitor

Constructing carbon nanotube (CNT)-based electrode materials is an effective strategy for the development of supercapacitors with high-rate capability. In this work, hierarchical porous hollow carbon microsphere (HCM)/CNT heterostructures were prepared by calcination of 3-aminophenol formaldehyde resin microspheres (AFSs) with the assistance of ethanolamine and Ni salts. This approach, which ingeniously combines the template and CVD methods, not only generates both HCMs and CNTs, but also achieves the growth of CNTs on HCMs. The length and dispersion of CNTs as well as the porous structure of HCMs could be easily controlled by adjusting the amount of ethanolamine and the size of AFS. Combining the advantages of the fascinating structure, i.e., abundant micro-, meso-, and macropores, high electrical conductivity, and good wettability induced by the presence of high-level N atoms, the optimal sample exhibited superior electrochemical performance, such as a high specific capacitance of 234.9 F g−1 at 2 A g−1, excellent cycling stability with the capacitance retention of 93.9 % after 10,000 cycles. More importantly, it possessed outstanding rate capability because its capacitance remained almost constant as the current density was increased above 5 A g−1. This research sheds light on an avenue to construct CNT-based carbon heterostructures for efficient energy storage.

Soluble starch-derived porous carbon microspheres with interconnected and hierarchical structure by a low dosage KOH activation for ultrahigh rate supercapacitors

The developed porous structure and high density are essential to enhance the bulk performance of carbon-based supercapacitors. Nevertheless, it remains a significant challenge to optimize the balance between the porous structure and the density of carbon materials to realize superior gravimetric and areal electrochemical performance. The soluble starch-derived interconnected hierarchical porous carbon microspheres were prepared through a simple hydrothermal treatment succeeded by chemical activation with a low dosage of KOH. Due to the formation of interconnected spherical morphology, hierarchical porous structure, reasonable mesopore volume (0.33 cm3 g−1) and specific surface area (1162 m2 g−1), the prepared carbon microsphere has an ultrahigh capacitance of 394 F g−1 @ 1 A g−1 and a high capacitance retention of 62.7 % @ 80 A g−1. The assembled two-electrode device displays good cycle stability after 20,000 cycles and an ultra-high energy density of 11.6 Wh kg−1 @ 250 W kg−1. Moreover, the sample still exhibits a specific capacitance of 165 F g−1 @ 1 A g−1 at a high mass loading of 10 mg cm−2, resulting in a high areal capacitance of 1.65 F cm−2. The strategy proposed in this study, via a low-dose KOH activation process, provides the way for the synthesis of high-performance porous carbon materials.

ZIF-8 Template-Assisted Synthesis of Polyimide-Derived Nitrogen-Oxygen Co-doped Porous Carbon Microspheres for Supercapacitors

ZIF-8 Template-Assisted Synthesis of Polyimide-Derived Nitrogen-Oxygen Co-doped Porous Carbon Microspheres for Supercapacitors