Co-doped Porous Carbon Research Articles

The preparation of porous carbon from bio-based phthalonitrile resins by a non-template method: Curing, carbonization and its basic properties

Resin-based porous carbon materials are considered to be an important direction for CO2 adsorption and supercapacitors due to their controllable chemical structure, large specific surface area, and stable physicochemical properties. But at present, the main source of resin-based porous carbon materials is petroleum-based polymer materials, which is incongruous with the tenets of green chemistry. Here, a bio-based phthalonitrile precursor containing s-triazine ring structure (TDPH) was synthesized from vanillin, then a nitrogen/oxygen co-doped hierarchical porous carbon with excellent properties, was prepared using TDPH via a two-step process, with urea/zinc chloride as hardener and potassium hydroxide as activator, respectively. The carbon material prepared under optimal conditions can achieve a maximum CO2 adsorption capacity of 6.81 mmol g−1 at 273 K due to its high specific surface area (1607 m2 g−1) and high N/O content (7.06 wt%/14.74 wt%). It is worth noting that the CO2 adsorption capacity at 298 K can still reach 96.3 % of the initial adsorption after 7 cycles. In addition, the electrochemical properties of the resultant porous carbon were tested under a 1 M H2SO4 three-electrode system, and the highest specific capacitance at a current density of 0.1 A g−1 was 473 F g−1 and the specific capacitance retention can still reach 87 % after 65,000 cycles. This work broadens the source of resin-based porous carbon materials and paves a new way for the functionalization of bio-based resins.

Research on the Chloramphenicol Removal Performance of Co-Doped Porous Carbon Materials Derived from Co-Zn Bimetallic ZIFs

Chloramphenicol antibiotics (CAPs) are broad-spectrum antibiotics, and excessive consumption has led to increasingly dangerous residues in the environment. The accumulation of these highly toxic and difficult-to-biodegrade CAPs and their long-term exposure in ecological environments can pose insidious and long-term hazards to human health and aquatic organisms. In this study, co-carbon composite nanocatalysts (CoxZn10−x-NC) with many carbon nanotubes on the surface were prepared via the one-step pyrolysis of bimetallic CoxZn10−x-ZIF with different Co/Zn ratios and used for the degradation of trace amounts of CAPs in a water column. The microstructure and chemical composition of the prepared catalysts were fully characterized using SEM, TEM, and XPS. The CAP degradation experiments demonstrated that Co6Zn4-NC in CoxZn10−x-NC possessed the highest catalytic activity level, removing 100% of the CAPs in 60 min. The CAPs had a corresponding reaction rate constant of 0.22 min−1, and Co6Zn4-NC was able to completely mineralize 44.57% of them. Doping moderate amounts of Zn can effectively improve the carbon nanotube structure on the catalyst surface and promote the generation of monoatomic Co, thus improving catalytic activity. The results of the free-radical burst experiments and electron paramagnetic resonance (EPR) showed that the free-radical pathway mainly dominated within the Co6Zn4-NC+PMS system, in which SO4•− was the main ROS for CAP degradation.

Facile preparation of nitrogen, oxygen and sulfur co-doped porous carbon for zinc-ion hybrid capacitor

Facile preparation of nitrogen, oxygen and sulfur co-doped porous carbon for zinc-ion hybrid capacitor

Self-Assembly Synthesis of Oxygen and Sulfur Co-Doped Porous Graphitic Carbon Nitride Nanosheets for Boosting CO2 Photoreduction.

Graphitic carbon nitride (CN) has garnered considerable attention in the field of visible-light CO2 photoreduction, but its efficiency remains limited by the intrinsic π-conjugated skeleton. Here, O and S were co-doped CN (O, S/CN) by a facile "hydrolysis + calcination" approach to modulate the physicochemical and electronic structure. Distinctive from S doped CN (SCN), O, S/CN owned porous layer structure with several nanosheets and less SO4 2- groups on the surface. The amount of heteroatom-doping was achieved by changing the hydrothermal temperature. The optimum O, S/CN-80 achieved moderate CO production rate of 1.29 μmol g-1 h-1, which was 3.79 times as much as SCN (0.34 μmol g-1 h-1). The O and most S atoms were substitutionally doped and the effect of S doped state on the improved efficiency of CO generation in O, S/CN was also explored based on the theoretical calculations. This work provides an inspiration to develop efficient dual-doped CN photocatalysts for photocatalytic CO2 reduction.

Deep Eutectic Solvent and Molten Salt-Assisted Construction of Wheat Straw-Derived N/O Co-Doped Porous Carbon for Flexible Zinc-Air Batteries.

As a common biomass resource, wheat straw is gradually being derived as carbon materials for oxygen reduction reaction (ORR) in zinc-air batteries (ZABs). Herein, the wheat straw-derived carbon was prepared by ball milling and pyrolysis using deep eutectic solvent (DES) as the medium, which avoided the cumbersome procedures. The hydrogen bond of DES was utilized to reconstructed into a hydrogen bond network structure between DES and lignin/cellulose/hemicellulose of wheat straw. The hydrogen bond network structure was converted into N/O co-doped porous carbon (N/O-WSPC) with abundant N/O co-doped sites after high-temperature pyrolysis. Meanwhile, KHCO3 was employed to further generate hierarchical pore structures and increase the specific surface area of the N/O-WSPC. The N/O co-doped sites provided intrinsic ORR activity, while the porous structure facilitates the mass transfer effect. Therefore, the N/O-WSPC exhibited a half-wave potential of 0.87 V (vs. RHE) and a limiting current density of 5.98 mA cm-2 for ORR. The N/O-WSPC-based flexible ZAB displayed an energy density of 652.23 Wh kg-1 and a charging-discharging cycle duration for over 19 h. The DES-assisted strategy facilitates the sustainable and efficient application of wheat straw-derived carbon materials in energy storage and conversion devices.

Nitrogen and sulfur co-doped porous carbon obtained from direct carbonization of a renewable biomass for counter electrode of efficient dye-sensitized solar cells

It is highly necessary to fabricate cost-effective counter electrode for promoting the development and practical deployment of dye-sensitized solar cells (DSSCs). Herein, nitrogen and sulfur co-doped porous carbon (NSPC) is prepared through directly carbonizing a renewable biomass, Eupatorium fortunei Turcz., and used as an alternative to expensive Pt to fabricate low-cost counter electrode for high-performance DSSCs. Scanning electron microscopy and N2 adsorption analyses demonstrate that the obtained carbon sample displays a hierarchical pore structure containing macropore channels and well-developed mesopores formed on the wall of macropore channels. X-ray photoelectron spectroscopy measurements suggest that nitrogen and sulfur atoms are doped in the framework of as-prepared carbon sample. These favorable characteristics endow the obtained NSPC counter electrode with a superior electrocatalytic performance. Consequently, the assembled DSSC with NSPC counter electrode shows an efficiency of 8.25%, nearly matching the efficiency of the cell with conventional Pt counter electrode.

S-N co-doped porous carbon as metal-free ORR electrocatalysts in zinc-air batteries

The implementation of zinc-air batteries (ZABs) requires the creation of economically feasible electrocatalysts for the oxygen reduction reaction (ORR) process. In this work, sulfur-nitrogen co-doped porous carbon materials (S-N-PC) were synthesized using a straightforward approach including ball milling followed by calcination without solvent. The optimized S-N-PC 1000 demonstrates exceptional ORR performance in 0.1 M KOH, with a half-wave potential of 0.870 V that outperforms commercial Pt/C. Furthermore, it exhibits remarkable durability and exceptional methanol resistance. The S-N-PC 1000 performs excellent performance as an air cathode in ZABs, exhibiting a peak power density of 159.26 mW cm−2 and outstanding stability for up to 720 h. Additionally, the energy efficiency decreases by only 2.52 % after undergoing more than 2000 cycles of charging and discharging at 5 mA cm−2. This study offers a novel concept for the development of eco-friendly porous carbon catalysts for ZABs.

N/S Codoped Porous Carbon Spheres by Extended Stöber Method for Highly Efficient Oxygen Reduction Reaction and Loaded with Pt for Methanol Oxidation Reaction

N/S Codoped Porous Carbon Spheres by Extended Stöber Method for Highly Efficient Oxygen Reduction Reaction and Loaded with Pt for Methanol Oxidation Reaction

N, O and P co-doped hierarchically porous carbon fiber for high performance Zinc-ion hybrid capacitors

Multi-heteroatoms co-doped hierarchically porous carbon-based electrode is an effective strategy to solve the low energy density and poor cycle stability of Zn-ion hybrid capacitors (ZHCs). Herein, N/O/P co-doped porous carbon nanofiber (N-P-PCF) was prepared, which displays fibrous network hierarchically porous structure to fast electron/ Zn2+ transport and enhance Zn2+ adsorption sites. Meanwhile, rich N (9.47 at.%), O (11.29 at.%) and P (1.29 at.%) co-doping can be beneficial for the infiltration of electrode–electrolyte interface and provide an additional pseudocapacitance. The N-P-PCF based ZHCs can yield a large specific capacitance (205 mAh g−1 at 1 A g−1), high energy density (173 Wh kg−1 at 823 W kg−1) and excenllent cycle stability for 10,000 cycles (98.6 % capacity retention), which provides a reliable multi-heteroatoms co-doped porous carbon fiber for high-performance ZHCs.

Defect-rich N, S Co-doped porous carbon with hierarchical channel network for ultrafast capacitive deionization

Developing an eco-friendly and effective approach for preparing N, S co-doped hierarchical porous carbons (NSHPC) for capacitive deionization (CDI) is a huge task for desalination. Herein, NSHPCSKK with interconnected hierarchical pore structures, manufactured via self-activation/co-activation of sodium lignosulfonate (SLS) encapsulation using KNO3-KHCO3 activators, inducing N, S co-doping. Different from NSHPCS and NSHPCSK, NSHPCSKK exhibits the highest specific surface area (SBET, 2264.67 m2/g) and a unique hierarchical pore structure (mesoporous volume/pore volume (Vmeso/ Vpore), 0.65). Small-angle X-ray scattering (SAXS) and scanning electron microscopy (SEM) both reveal the complex interconnected pore structure of NSHPCSKK. Regional Raman imaging conjugated with XPS reveals the presence of extensively distributed N, S co-doped defect structures, providing NSHPCSKK with excellent wettability and electrochemical performance. DFT calculations indicate that the N, S co-doping at the defect sites depicts excellent adsorption capability. Eventually, NSHPCSKK acquired an impressive salt adsorption capacity (SAC) of 20.5 mg/g and the highest average salt adsorption rate (ASAR) of 12.1 mg/g/min, indicating its superior desalting performance. In-situ Raman spectroscopy confirms NSHPCSKK’s rapid ion regeneration mechanism. The research introduces a span-new NSHPC synthesis strategy for fabricating advanced NSHPC with rapid desalination response for upgrading CDI desalination.

Facile Fabrication of Co-Doped Porous Carbon from Coal Hydrogasification Semi-Coke for Efficient Microwave Absorption.

A Co-doped porous carbon was successfully fabricated by a facile carbonizing procedure using coal hydrogasification semi-coke (SC) as the carbon and cobalt nitrate as the magnetic precursors, respectively. The mass ratio of the precursors was changed to regulate the microwave absorption (MA) capabilities. The favorable MA capabilities are a result of a synergistic interaction be-tween the dielectric loss from the carbon framework, the magnetic loss from nano-sized Co particles, and multiple scattering from the residual pores. At a thickness of 4.0 mm, the Co/C composite showed the lowest reflection loss of -33.45 dB when the initial mass ratio of cobalt nitrate and SC was 1:1. The effective absorbing bandwidth (EAB) could achieve 3.5 GHz at 2 mm thickness. This work not only opens up a new avenue for the facile fabrication of dielectric and magnetic loss combinations and their structural design, but it also creates a new route for the high value-added exploitation of SC.

N/O Co-doped Porous Carbon with Controllable Porosity Synthesized via an All-in-One Step Method for a High-Rate-Performance Supercapacitor.

A green and economical methodology to fabricate carbon-based materials with suitable pore size distributions is needed to achieve rapid electrolyte diffusion and improve the performance of supercapacitors. Here, a method combining in situ templates with self-activation and self-doping is proposed. By variation of the molar ratio of magnesium folate and potassium folate, the pore size distribution was effectively adjusted. The optimal carbon materials (Kx) have a high specific surface area (1021-1676 m2 g-1) and hierarchical pore structure, which significantly promotes its excellent capacitive properties. Notably, K2 shows an excellent mass specific capacitance of 233 F g-1 at 0.1 A g-1. It still retained 113 F g-1 at 55 A g-1. The assembled symmetric supercapacitor exhibited an outstanding cyclic stability. It maintains 100% capacitance after 100 000 cycles at 10 A g-1. The symmetric supercapacitor demonstrated a maximum power density of 99.8 kW kg-1. This study focuses on the preparation of layered pore structures to provide insights into the sustainable design of carbon materials.

Extremely Durable K-Ion Batteries Enabled by Heteroatom Co-Doped Highly-Ordered Porous Carbon Spheres with Nearly 100% Capacity Retention up to 11,000 Cycles.

Currently, one major target for exploring K-ion batteries (KIBs) is enhancing their cycle stability due to the intrinsically sluggish kinetics of large-radius K+ ions. Herein, we report a rationally designed electrode, the S/O co-doped hard carbon spheres with highly ordered porous characteristics (SPC), for extremely durable KIBs. Experimental results and theory calculations confirm that this structure offers exceptional advantages for high-performance KIBs, facilitating rapid K+ diffusion and (de)-intercalation, efficient electrolyte penetration and transport, improved K+ storage sites, and enhanced redox reaction kinetics, thus ensuring the long-term cycle stability. As a result, the as-constructed SPC anode delivers a high reversible capacity of ca. 200 mAh g-1 at a high current density of 2.0 A g-1 and robust stability with ∼100% capacity retention up to 11,000 cycles, outperforming most carbon-based KIB anodes. This work offers insight into developing advanced KIBs with durable stability toward practical applications.

In-situ doped and activated N, S co-doped porous carbon derived from organic salt for application in high-performance potassium-ion batteries

Owing to its abundance in nature and low cost, potassium has attracted considerable attention as a substitute for lithium in the manufacture of secondary-ion batteries. However, developing amorphous carbon materials that show fast K+ ion kinetics for application in high-performance potassium-ion battery (PIB) anodes remains challenging. In this study, we designed and synthesized a 3-D hierarchical nitrogen and sulfur co-doped porous carbon electrode via in-situ doping and activation using acesulfame potassium. Owing to its prominent structural advantages, the as-prepared N, S co-doped electrode showed a high reversible capacity (459.8 mAh g−1 at 0.05 A g−1) and long-term cycle stability (205 mAh g−1 after 1000 cycles at 0.5 A g−1). Further, the results of ex-situ Raman spectroscopy and X-ray photoelectron spectroscopy verified the advantages of N and S co-doping with respect to K+ ion intercalation and adsorption/desorption properties within the carbon matrix. Therefore, our findings enhance understanding regarding the advantages of the dual-doped system with respect to K+ ion storage and highlight an efficient strategy for developing high-performance and durable carbon anode materials for PIBs.

ZIF-8-Based Nitrogen and Monoatomic Metal Co-Doped Pyrolytic Porous Carbon for High-Performance Supercapacitor Applications.

Metal-organic frameworks (MOFs) receive wide attention owing to their high specific surface area, porosity, and structural designability. In this paper, ZC-Ru and ZC-Cu electrodes loaded with monatomic Ru and Cu doped with nitrogen were prepared by pyrolysis, ion impregnation, and carbonization process using ZIF-8 synthesized by static precipitation as a precursor. ZC-Cu has a high specific surface area of 859.78 m2 g-1 and abundant heteroatoms O (10.04%) and N (13.9%), showing the specific capacitance of 222.21 F g-1 at 0.1 A g-1 in three-electrode system, and low equivalent series resistance (Rct: 0.13 Ω), indicating excellent energy storage capacity and electrical conductivity. After 10,000 cycles at 1 A g-1 in 6 M KOH electrolyte, it still has an outstanding capacitance retention of 99.42%. Notably, symmetric supercapacitors ZC-Cu//ZC-Cu achieved the maximum power density and energy density of 485.12 W·kg-1 and 1.61 Wh·kg-1, respectively, positioning ZC-Cu among the forefront of previously known MOF-based electrode materials. This work demonstrates the enormous potential of ZC-Cu in the supercapacitor industry and provides a facile approach to the treatment of transition metal.

The MOFs derived Co, Zn co-doping porous carbon framework as the collector for stable Li metal anodes

The Li metal anode is regarded as the most potential electrode material in the next-generation energy storage system, because of the high energy density and specific capacity. However, the advancement of Li metal anode is restricted by the volume changing and dendrite growth. In this paper, the Co and Zn co-doped porous carbon framework (CF-CZ) derived from MOF structure was designed and produced to realize the dendrite-free Li metal anode. The porous structure could accommodate the deposited Li metal, which relaxes the pressure of electrode structure and relieves the volume changes. Meanwhile, the Co, Zn co-doping effectively improves the lithiophilicity of framework, which attracts Li+ and decreases the nucleation barrier. Besides, numerous micropores of MOF structure could divide the Li+ flux to reduce the local current density for dense sedimentation. With the synergies of co-doping and porous structure, the symmetric cell of CF-CZ shows better electrochemical performance (the overvoltage can be stable at 14 mV after 1200 cycles) than pure Cu foil, and the LFP cells deliver 116.4 mAh g−1 at 1 C after 200 cycles. As a consequence, the CF-CZ possesses the potential to be applied in Li metal anodes.

Impact of Exposed Crystal Facets on Oxygen Reduction Reaction Activity in Zeolitic Imidazole Frameworks

Oxygen reduction reactions (ORR) are critical reactions for efficient sustainable and renewable energy storage. However, the limitation of ORR is a slow kinetic reaction due to the multi-step transfer mechanism of electrons. Therefore, electrocatalysts with high ORR activity and stability are needed to overcome the reaction limitations. Zeolitic imidazole framework-67 (ZIF-67) has attracted attention in electrochemical applications due to its multiple redox-active sites and high stability in alkali conditions. The Co-doped porous carbon catalysts derived from ZIF-67 have the potential to be used as ORR catalysts with high performance, while pure phase ZIF-67 electrocatalyst for ORR is rarely studied. The work studies the importance of crystal facets on ORR reactivity. The results show that ZIF-67 nanocube exhibits excellent ORR activity with lower half wave-potential and faster kinetics process compared to its bulk structure. It is proposed that ZIF-67 nanocube provides improvement of selectivity for the four-electron pathway, which is a favorable process with higher reaction efficiency. The density functional theory (DFT) calculations suggest unsaturated Co2+ active sites with enriched (100) facets in the cubic crystal. Therefore, the fast diffusion of oxygen molecules to active sites and strong interaction with intermediate are observed in a cubic structure. The correspondence between experiment and calculation offers enhancement of ORR activity and selectivity from control-specific growth of (100) facet with cubic shape. The work introduces a new strategy for designing highly efficient ORR electrocatalysts with facet-controlled, allowing further study in other electrochemical reactions.

Alkaline hydrogen evolution reaction catalyzed by atomically dispersed ruthenium on phosphorus-nitrogen co-doped porous carbon

Exploring high-efficiency catalyst toward hydrogen evolution reaction (HER) for sustainable hydrogen production is critical for building a forthcoming hydrogen economy. Atomically dispersed catalysts have shown great promises for catalyzing HER yet further fine-tuning the coordination chemical environment to boost the performance is still challenging. Herein, we report the synthesis and electrocatalytic HER application of Ru single atoms dispersed in P, N co-doped porous carbon (Ru SAs@PNC). Spherical aberration corrected scanning transmission electron microscope (AC-STEM) analysis revealed the formation of atomically dispersed Ru single atoms. The as-prepared Ru SAs@PNC catalyst showed excellent HER activity in 1 M KOH, evidenced by a small overpotential of 21 mV @ 10 mA cm−2 and a low Tafel slope of 31 mV dec−1, both of which are comparable to the Pt/C benchmark catalyst. It also exhibited great durability for long-time operation, as demonstrated by negligible overpotential increase in the 50 h E-t test, and outperformed stability in the accelerated durability test. Such excellent HER performance is mainly attributed to the N, P co-doped chemical coordination environment that differs from most widely reported solely nitrogen-coordinated Ru single atoms.

Fe-S Co-doped Porous Carbon Catalyzed Oxidation and Degradation of Dye Wastewater

Fe-S Co-doped Porous Carbon Catalyzed Oxidation and Degradation of Dye Wastewater

Nitrogen and Sulfur Co-doped Biomass-Derived Porous Carbon Electrodes for Ultra-High-Performance All-Aqueous Thermally Regenerative Flow Batteries.

Developing high-performance electrodes for the all-aqueous thermally regenerative ammonia battery (ATRB) system, serving as superior substitutes for commercial carbon cloth electrodes, is anticipated to enhance performance, yet it lacks effective guidance and research. In this work, theoretical analysis is initially used to evaluate the effective conversion and adsorption capacity of nitrogen and sulfur co-doped carbon with respect to copper ion by density functional theory calculation. On the basis of this concept, the nitrogen and sulfur co-doped biomass-derived porous carbon electrode (DGC) is prepared using natural porous carbon materials and thiourea. Compared with commercial carbon cloth electrodes, ATRB with DGC achieves a significant improvement in maximum power density of 49.2%. Via optimization of the doping conditions, the active sites can be effectively regulated to boost charge transfer at the reaction interface. Furthermore, the rapid charge transfer can match the excellent mass transfer performance, generating an impressive net power density of 847.5 W/m2.