N-doped Nanoporous Carbon Research Articles

Impacting the Surface Chemistry of NiAu by Immobilizing on MgO/N-Rich Nanoporous Carbon Heterostructures for Boosting Catalytic Activities.

Tuning the physical and chemical interaction between metal-metal' (M-M') and metal-support is an ideal way to realize enhanced catalytic activity of metal nanoparticles (NPs). As a proof of concept, herein we report the fabrication of nickel-gold (Ni-Au) alloy nanoparticles attached to N-doped nanoporous carbon (NPC) intervened with MgO (Ni73Au27@MgO-NPC), achieved through the impregnation of metal precursors into Schiff-base network polymer (SNP) framework along with Mg(OH)2 and pyrolysis at 800 °C in N2 atmosphere. With high stability and heterogeneity, the nickel rich Ni73Au27@MgO-NPC exhibited higher catalytic activities with turnover frequencies of 29,272 h-1 (hydrogenation of p-nitrophenol), 93,843 h-1 (degradation of methyl orange), and 2,218 h-1 (epoxidation of stilbene), compared to commercial 10 wt % Pd/C. Enhanced catalytic activity is correlated to the synchronized electron density enhancement in Au, by Ni and MgO/N-rich nanoporous carbon heterostructures, as evident from detailed X-ray photoelectron spectroscopic studies.

Molecular simulation using transfer-learned potentials for the disordered nanoscale structure of nitrogen-doped nanoporous carbons

Machine learning (ML)-based molecular dynamics (MD) simulations of the formation of a class of N-doped nanoporous carbons are performed to assess their disordered partially graphitized nanoscale structure. The study is motivated by the effectiveness of so-called nitrogen assembly carbons (NACs) for catalysis applications. Benchmark simulations for pure-C disordered graphitic systems reveal the importance of reliably capturing the vdW component of the potentials in order to accurately describe the tendency for layering of disordered graphene-like sheets. In our modeling, this is achieved by a transfer learning strategy incorporating features of the energetics from the optB88-vdW DFT functional into potentials initially trained with a less expensive functional, thereby providing a superior description of the pure-C systems. Generation from MD simulations of realistic partially graphitized structures is significantly more challenging for N-doped versus for pure C systems. However, such structures are achieved by a tailored MD simulation protocol mimicking the experimental synthesis process and in particular incorporating an annealing and subsequent quenching stages. Simulated PXRD patterns effectively reproduce the features of experimental observations for NACs, including the appearance of a prominent but broad (002) peak at around 25∘, and the development of another weaker feature associated with in-layer ordering of mixed C-N graphene-like sheets.

Auto-reduction of Au(III) on Fe-Doped, Pyrrolic-N-Modified nanoporous carbon derived from ZIF-8 for the electrochemical immunosensing of CA-125

Ovarian cancer (OC) is associated with high late mortality owing to hidden symptoms in the early stages and limited screening measurements. Therefore, it is urgent to develop a highly efficient label-free immunosensor for targeting cancer antigens. In this study, we developed a gold-loaded iron-doped nanoporous carbon (denoted as Au@Fe-NC) as an ideal substrate for cancer antigen detection with high specificity and sensitivity. First, an Fe, N-doped nanoporous carbon (Fe-NC) material was synthesized by carbonizing a Fe-doped metal-organic framework at 900 °C under continuous nitrogen flow. The resultant Fe-NC contains pyrrolic-N, which facilitates the auto-reduction of Au3+ to Au⁰ without requiring an external reducing agent. Thus, the Au@Fe-NC was spontaneously formed by mixing an aqueous HAuCl₄ solution with Fe-NC. The immunosensor developed using Au@Fe-NC exhibits outstanding stability as well as high sensitivity to carbohydrate antigen 125 (CA-125), a tumor marker, presenting a linear dynamic range of 0.1 pg mL−1 to 1 µg mL−1 and a detection limit of 0.1 pg mL−1. The proposed Au@Fe-NC-based immunosensor has the ability to detect CA-125 in human serum samples and is a promising material for OC diagnosis.

Utilizing Carbonaceous Materials Derived from [BMIM][TCM] Ionic Liquid Precursor: Dual Role as Catalysts for Oxygen Reduction Reaction and Adsorbents for Aromatics and CO2.

This work presents the synthesis of N-doped nanoporous carbon materials using the Ionic Liquid (IL) 1-butyl-3-methylimidazolium tricyanomethanide [BMIM][TCM] as a fluidic carbon precursor, employing two carbonization pathways: templated precursor and pyrolysis/activation. Operando monitoring of mass loss during pyrolytic and activation treatments provides insights into chemical processes, including IL decomposition, polycondensation reactions and pore formation. Comparatively low mass reduction rates were observed at all stages. Heat treatments indicated stable pore size and increasing volume/surface area over time. The resulting N-doped carbon structures were evaluated as electrocatalysts for the oxygen reduction reaction (ORR) and adsorbents for gases and organic vapors. Materials from the templated precursor pathway exhibited high electrocatalytic performance in ORR, analyzed using Rotating Ring-Disk electrode (RRDE). Enhanced adsorption of m-xylene was attributed to wide micropores, while satisfactory CO2 adsorption efficiency was linked to specific morphological features and a relatively high content of N-sites within the C-networks. This research contributes valuable insights into the synthesis and applications of N-doped nanoporous carbon materials, highlighting their potential in electrocatalysis and adsorption processes.

Highly exposed active sites of MOFs-derived N-doped nanoporous carbon decorated with platinum for enhanced energy storage application

The depletion of traditional energy sources, such as fossil fuels, has prompted the direct synthesis of materials with high-capacity performance for energy storage applications. Nitrogen-doped porous carbon (NPC) derived from Zeolite imidazole framework ZIF-8 stands out as a prime candidate for the development of electrochemical double-layer capacitors (EDLCs) due to their high stability and versatile morphology. In this study, the surface of NPC supported onto nickel foam (NF) was decorated with platinum nanoparticles (PtNPs) using an efficient and cost-effective electrodeposition method. The electrodeposition conditions were evaluated in the form of deposition potential and time. PtNPs-decorated NPC electrode deposited at −0.4 V for 120 s shows outstanding properties compared to other electrodes. The electrochemical properties of fabricated electrodes were assessed in 6 M KOH using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The PtNPs-NPC at −0.4 V electrode demonstrated a remarkable characteristic specific capacitance (Cs) of 1700 ± 1.12 F g−1 at 0.2 A g−1. This electrode displayed high cyclic stability, with only a 2.0 % reduction in its capacitance retention over 5000 cycles. The Cs of PtNPs-NPC at −0.4 V smoothly declined in the first 1000 cycles from 1164.73 ± 1.02 to 1153.20 ± 1.16 F g−1, with a retention of 99.01 %. Even after 5000 cycles, it becomes 1142.25 ± 1.16 F g−1 with a retention of 98.07 %. PtNPs-decorated NPC at −0.4 V also showcased the highest energy density (E) and power density (P) of 80 ± 1.11 Wh kg−1, and 1038.42 ± 1.32 W kg−1, respectively. In contrast, the pristine NPC exhibited an E, and P of 25.0 ± 1.92 Wh kg−1, and 882.0 ± 1.52 W kg−1, respectively. Our strategy demonstrates a new strategy for decoration of NPC surface, opening up possibilities for further exploration of different NPs to engineer promising electrode materials for supercapacitor (SCs) applications.

Tailoring a N-Doped Nanoporous Carbon Host for a Stable Lithium Metal Anode

Li metal is a promising anode candidate due to its high theoretical capacity and low electrochemical potential. However, dendrite formation and the resulting dead Li cause continuous Li consumption, which hinders its practical application. In this study, we realized N-doped nanoporous carbon for a stable Li metal host composed only of lightweight elements C and N through the simple calcination of a nitrogen-containing metal–organic framework (MOF). During the calcination process, we effectively controlled the amount of lithophilic N and the electrical conductivity of the N-doped porous carbons to optimize their performance as Li metal hosts. As a result, the N-doped porous carbon exhibited excellent electrochemical performances, including 95.8% coulombic efficiency and 91% capacity retention after 150 cycles in a full cell with an LFP cathode. The N-doped nanoporous carbon developed in this study can realize a stable Li metal host without adding lithium ion metals and metal oxides, etc., which is expected to provide an efficient approach for reliable Li metal anodes in secondary battery applications.

Highly dispersed palladium nano-catalyst anchored on N-doped nanoporous carbon microspheres derived from chitosan for efficient and stable hydrogenation of quinoline

Under the background of green chemistry, the synthesis of N-heterocycles using efficient, stable and long-life catalysts has still faced great challenges. Herein, we used biomass resource chitosan to fabricate a nanoporous chitosan carbon microsphere (CCM), and successfully designed a stable and efficient Pd nano-catalyst (CCM/Pd). Various physicochemical characterizations provided convincible evidences that the palladium nanoparticles (NPs) were tightly and evenly dispersed on the CCM with a mean diameter of 2.28 nm based on the nanoporous structure and abundant functional N/O groups in CCM. Importantly, the graphitized constructure, the formed defects and larger surface area in CCM were able to promote the immobilization of Pd NPs and the electron transfer between Pd and CCM, thereby significantly improving the catalytic activity. The CCM/Pd catalyst was applied for hydrogenation of quinoline compounds, which showed excellent catalytic activity and durability, as well as good substrate applicability. The application of renewable biomass-based catalysts contributes to the progression of a green/sustainable society.

Dual Single-Atomic Co-Mn Sites in Metal-Organic-Framework-Derived N-Doped Nanoporous Carbon for Electrochemical Oxygen Reduction.

Synthesizing dual single-atom catalysts (DSACs) with atomically isolated metal pairs is a challenging task but can be an effective way to enhance the performance for electrochemical oxygen reduction reaction (ORR). Herein, well-defined DSACs of Co-Mn, stabilized in N-doped porous carbon polyhedra (named CoMn/NC), are synthesized using high-temperature pyrolysis of a Co/Mn-doped zeolitic imidazolate framework. The atomically isolated Co-Mn site in CoMn/NC is recognized by combining microscopic as well as spectroscopic techniques. CoMn/NC exhibited excellent ORR activities in alkaline (E1/2 = 0.89 V) as well as in acidic (E1/2 = 0.82 V) electrolytes with long-term durability and enhanced methanol tolerance. Density functional theory (DFT) suggests that the Co-Mn site is efficiently activating the O-O bond via bridging adsorption, decisive for the 4e- oxygen reduction process. Though the Co-Mn sites favor O2 activation via the dissociative ORR mechanism, stronger adsorption of the intermediates in the dissociative path degrades the overall ORR activity. Our DFT studies conclude that the ORR on an Co-Mn site mainly occurs via bridging side-on O2 adsorption following thermodynamically and kinetically favorable associative mechanistic pathways with a lower overpotential and activation barrier. CoMn/NC performed excellently as a cathode in a proton exchange membrane (PEM) fuel cell and rechargeable Zn-air battery with high peak power densities of 970 and 176 mW cm-2, respectively. This work provides the guidelines for the rational design and synthesis of nonprecious DSACs for enhancing the ORR activity as well as the robustness of DSACs and suggests a design of multifunctional robust electrocatalysts for energy storage and conversion devices.

Enhanced Adsorption-Photocatalytic Degradation of Organic Pollutants via a ZIF-67-Derived Co-N Codoped Carbon Matrix Catalyst.

Stable and efficient photocatalytic degradation of organic pollutants has been achieved via a ZIF-67-derived Co-embedded N-doped nanoporous carbon material catalyst (Co-N/C). The catalyst features a well-distributed structure, suitable specific surface area, and more active sites according to the various characterization analyses. The photocatalytic activity of Co-N/C was evaluated by the degradation of the target pollutant Rhodamine B (RhB). As a result, RhB could establish an adsorption-desorption equilibrium in the dark within 30 min and was thoroughly degraded into H2O and CO2 by Co-N/C under 500 W visible light irradiation in 40 min. Moreover, radical-quenching experiments and reactive oxygen species monitoring were performed to further probe the plausible photodegradation mechanism of RhB. Co-N/C is also appropriate for other alternative dyes and antibiotics affording ideal removal efficiencies. After the reaction, Co-N/C could be facilely separated by an external magnetic field and reused for eight reaction cycles without obvious deactivation of its photocatalytic properties. This study is expected to provide an instructive guideline for the design of efficient and recyclable composite photocatalysts derived from metal-organic frameworks for a broad range of environmental remediation processes.

Tailored Crafting of CoP/Ni2P Nanoparticles Coupled with N-Doped Nanoporous Carbon to Enable Efficient Hydrogen and Oxygen Evolution

Rationally tailoring a nonprecious metal and highly active bifunctional catalyst with desirable nanoarchitecture and composition for water electrolysis is of key value for sustainable and clean energy production. Herein, we designed nanoporous N-doped carbon (NC) as a support for dispersion and anchoring of bimetallic phosphide nanoparticles (CoP/Ni2P). Thanks to the uniformly anchored nanosized CoP/Ni2P nanoparticles offering rich active sites and the coupling effect between these nanoparticles and a nanoporous NC support to ensure promising conductivity and structural stability, the as-prepared hybrid (CoP(Ni2P)/NC) exhibits prominent electrocatalytic performances toward hydrogen evolution (or oxygen evolution) in alkaline electrolytes, in terms of a small overpotential of 216 mV (or 338 mV) at 10 mA cm–2 and a low Tafel slope of 84 mV dec–1 (or 60 mV dec–1), as well as exceptional long-term stability.

N-Doped Nanoporous Carbon Scaffolds As Catalysts for CO2 Reduction

The need for clean energy solutions in order to significantly lower our carbon footprint is placing increasing attention on renewable energy, such as wind and solar. However, these technologies suffer from intermittency issues, thus making efficient energy storage and conversion a major requirement. One of the solutions to this problem is electrochemical CO2 reduction (CO2RR), using renewable energy to produce green fuels and chemicals. However, the reduction of CO2 is thermodynamically and kinetically unfavorable. To overcome this, the development of highly efficient and selective electrocatalysts is a key goal of CO2RR research.Carbon has been attracting interest as a promising candidate due to its high specific surface area, good conductivity, and low-cost. However, its catalytic performance is limited by the electroneutrality of the carbon atoms in the primarily graphitic lattice. In order to activate the CO2 molecules and enhance the adsorption of intermediates, a range of novel carbon catalysts has been developed, with nitrogen doping being the most common approach. The N atom has a similar size as C and thus the lattice mismatch after doping is minimal [1]. At the same time, the N atom also has a higher electronegativity than C which will break the electroneutrality of the carbon lattice and enhance the conductivity of the material [2-3]. Furthermore, N doping results in a range of N-based surface species, thus potentially allowing the tuning of the CO2RR products [4].In this work, a novel, self-supported, nanoporous carbon scaffold (NCS) was used as the carbon substrate. The NCS is a templated, binder-free mesoporous carbon material with tunable pore sizes, a high surface area, good conductivity, and scalability [5]. Here, N doping of the NCS was achieved by heat treatment in NH3. An in house flow cell that can be switched between flow-through and flow-by modes was developed, allowing the NCS to be used as a model material to understand the impact of fluid flow on mass transfer limitations in the CO2RR and on any local pH effects that may be present.The CO2RR performance was tested in the flow cell using a CO2-saturated KHCO3 solution. The bare NCS was confirmed to generated only H2, while the N-doped NCS gives roughly a 50:50 ratio of H2:CO at all potentials, with the onset potential being ca. -0.55 V vs RHE. The effect of the NCS pore size was also investigated, showing that an NCS membrane with a nominal 85 nm pore diameter produced roughly 45% CO, while the NCS-12 (12 nm pore size) material gave somewhat more CO (ca. 55-60%). At the same time, the NCS-12 gave lower current densities, despite its higher surface area, likely due to poorer pore accessibility. Furthermore, running the cell in the flow-through mode gave higher currents at all of the NCS-based catalysts, most likely due to removal of trapped gases. Current work is focused on determining the effect of the N content and the type of N-based functionalities attached to the NCS surface on the CO2RR performance.

Bimetallic zeolitic imidazole framework derived Co@NC materials as oxygen reduction reaction catalysts application for microbial fuel cells

Microbial fuel cells (MFCs), a promising future energy conversion technology, play a significant role in the area of sustainable and renewable energy. In air-cathode MFCs, the catalytic activity for oxygen reduction reaction (ORR) of cathode electrocatalyst is the key factor to the performance of MFCs. Development of efficient and economical ORR electrocatalysts is an important step for the wide application of MFCs. Herein, Co wrapped carbon nanotubes (CNTs) N-doped nanoporous carbon materials (Co@NC-Co x Zn y ) are constructed via a facile zinc-assisted growth pyrolytic approach of bimetallic zeolitic imidazole frameworks (BMZIFs)-derived strategy. They are directly prepared via carbonization of the precursor Co x Zn y -BMZIFs. During the pyrolysis process, the evaporation of zinc plays critical role in the in-situ growth of CNTs. For instance, the optimal catalyst, Co@NC-Co 1 Zn 3 , exhibits excellent ORR performance activity and stability with on-set potential ( E on-set ) of 0.830 V ( vs. RHE) and diffusion-limited current density ( j L ) of 6.706 mA cm −2 , which is superior to the benchmark catalyst of commercial 20 wt% Pt/C. Additionally, Co@NC-Co 1 Zn 3 displays four-electron pathway, long-term stability and better resistance to methanol tolerance. The MFC with Co@NC-Co 1 Zn 3 cathode shows a maximum power density of 1039 mW m −2 , and outperforms the MFC with commercial 20 wt% Pt/C catalyst (678 mW m −2 ). This work paved the way for exploring cost-effective, superior performance non-precious metal-based catalysts for air-cathode MFCs. • A facile, cost-effective, Co@NC-Co 1 Zn 3 exhibits superior ORR performance and long-term stability. • A zinc-assisted evaporated produces Co@CNTs structure, which is the essential for the superior ORR activity. • The maximum power density of Co@NC-Co 1 Zn 3 -MFC is higher than that of Pt/C-MFC.

Morphologically tunable nanoarchitectonics of mixed kaolin-halloysite derived nitrogen-doped activated nanoporous carbons for supercapacitor and CO2 capture applications

We report an integrated approach by combining in-situ activation, doping and natural nanotemplating to design low-cost and highly efficient N-doped nanoporous carbons for energy storage and carbon capture applications. N-doped nanoporous carbons are prepared by impregnating sucrose, 3-amino 1,2,4-triazole and the ZnCl2 into the nanochannels of the mixed kaolin-halloysite nanotube nanoclay, followed by carbonization and clay template removal. The prepared materials exhibit micro and mesoporosity, high specific surface areas (1360–1695 m2 g−1), and nitrogen content (7.73–12.34 wt%). The optimized material offers the specific capacitance of 299 F g−1 (0.3 A g−1) and 134 F g-1 (10 A g−1) with excellent cycling stability (91% capacity retention after 4000 cycles/5 A g−1). N-doping together with the interconnected micro and mesoporous structure, offers a more ion accessible surface and further provides enhanced charge transfer, hydrophilicity, and the interaction of the electrode-electrolyte ions. The optimized material adsorbs 24.4 mmol g−1 of CO2 at 30 bar pressure and 0 °C. The synthesized materials performed better as supercapacitor and CO2 adsorbent than halloysite clay, kaolin clay, activated carbon, nanoporous carbons, and mesoporous silica. The method presented here will provide a unique platform for synthesizing a series of advanced nanostructures for electrochemical and carbon capture applications.

Co/CoO nanoparticles armored by N-doped nanoporous carbon polyhedrons towards glucose oxidation in high-performance non-enzymatic sensors

The Co/CoO nanoparticles armored by porous N-doped carbon polyhedrons were successfully prepared from ZIF-67 via a pyrolysis-reorganization method, demonstrating excellent sensing performance towards glucose oxidation.

ZIF 67 derived Co–Sn composites with N-doped nanoporous carbon as anode material for Li-ion batteries

Owing to low cost and high theoretical capacity of 994 mAh g −1 , tin has received much attention for its applications relevant to energy storage devices including lithium-ion batteries. However, the structural instability of tin-based compounds becomes prominent during lithium-ion insertion/extraction mechanism and this decreases its cyclic life and rate capacity. Mitigating the structural instability and corresponding improvement in rate capacity require novel strategies, and herein composite of SnO 2 with nanoporous carbon was synthesized using ZIF-67 which creates a framework composed of Co–Sn alloy and Sn–C network that is responsible for enhanced structural stability. The electrochemical behavior of the Co–Sn@NC composite with three different molar ratios of 2-methylimdazole was investigated using cyclic voltammetry (CV), and a multi-channel battery analyzer. The later analysis revealed that after 50 cycles at a current density of 0.1 A g −1 , Co–Sn alloy with carbon matrix having the maximum amount of N -doped organic linker delivered the highest reversible capacity of 601 mAh g −1 . This can be attributed to well-dispersed nano Co–Sn alloy embedded within the porous structure of carbon matrix, thus providing an effective cushion for releasing volumetric strain that develops within the structure. • Composite of SnO 2 with nanoporous carbon was synthesized using ZIF-67. • Creation of framework composed of Co–Sn alloy and Sn–C network, responsible for enhanced structural stability. • Co–Sn@NC-3 with higher loading of organic linker delivered the highest reversible capacity of 601 mAh g −1 .

Sodium storage performance of ultrasmall SnSb nanoparticles

Sodium-ion batteries have been emerging as a potential alternative to lithium-ion batteries, especially for large-scale applications. In this work, a hybrid of ultrasmall SnSb nanoparticles (the diameter <2 nm) encapsulated in three-dimensional N-doped nanoporous carbon frameworks (SnSb/3D-NPC) was synthesized by a facile chemical reduction method. To the best of our knowledge, this is the smallest SnSb nanoparticle ever reported. As a sodium-ion battery anode, SnSb/3D-NPC delivers a high reversible capacity (693.6 mAh g−1 at 0.2 A g−1 after 100 cycles), superior rate performance (359.1 mAh g−1 at 20 A g−1) and cycling stability (266.6 mAh g−1 at 5 A g−1 after 15,000 cycles), which outperform other SnSb-based materials. These remarkable performances originate from: (i) ultrasmall SnSb nanoparticles and their uniform distribution, which increase the specific surface of electrodes and thus guarantee the full utilization of active materials, enhance pseudocapacitive contributions for Na storage, shorten Na+ diffusion distance, and reduce the strain during the sodiation/desodiation process; and (ii) the unique 3D integrated structure of SnSb/3D-NPC, which supplies a conductive network, efficient electrolyte diffusion paths and more active sites for Na+ insertion/extraction, suppresses the aggregation of SnSb nanoparticles, and buffers large volume change of SnSb through carbon nanocages during the cycling process.

Ordered Macroporous Superstructure of Nitrogen-Doped Nanoporous Carbon Implanted with Ultrafine Ru Nanoclusters for Efficient pH-Universal Hydrogen Evolution Reaction.

The electrochemical hydrogen evolution reaction (HER) is an attractive technology for the mass production of hydrogen. Ru-based materials are promising electrocatalysts owing to the similar bonding strength with hydrogen but much lower cost than Pt catalysts. Herein, an ordered macroporous superstructure of N-doped nanoporous carbon anchored with the ultrafine Ru nanoclusters as electrocatalytic micro/nanoreactors is developed via the thermal pyrolysis of ordered macroporous single crystals of ZIF-8 accommodating Ru(III) ions. Benefiting from the highly interconnected reticular macro-nanospaces, this superstrucure affords unparalleled performance for pH-universal HER, with order of magnitude higher mass activity compared to the benchmark Pt/C. Notably, an exceptionally low overpotential of only 13 mV@10mA cm-2 is required for HER in alkaline solution, with a low Tafel slope of 40.41mV dec-1 and an ultrahigh turnover frequency value of 1.6 H2 s-1 at 25mV, greatly outperforming Pt/C. Furthermore, the hydrogen generation rates are almost twice those of Pt/C during practical overall alkaline water splitting. A solar-to-hydrogen system is also demonstrated to further promote the application. This research may open a new avenue for the development of advanced electrocatalytic micro/nanoreactors with controlled morphology and excellent performance for future energy applications.

Cellulose Nanofiber Composite with Bimetallic Zeolite Imidazole Framework for Electrochemical Supercapacitors.

Cellulose nanofiber (CNF) and hybrid zeolite imidazole framework (HZ) are an emerging biomaterial and a porous carbonous material, respectively. The composite of these two materials could have versatile physiochemical characteristics. A cellulose nanofiber and cobalt-containing zeolite framework-based composite was prepared using an in-situ and eco-friendly chemical method followed by pyrolysis. The composite was comprised of cobalt nanoparticles decorated on highly graphitized N-doped nanoporous carbons (NPC) wrapped with carbon nanotubes (CNTs) produced from the direct carbonization of HZ. By varying the ratio of CNF in the composite, we determined the optimal concentration and characterized the derived samples using sophisticated techniques. Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS) confirmed the functionalization of CNF in the metallic cobalt-covered N-doped NPC wrapped with CNTs. The CNF–HZNPC composite electrodes show superior electrochemical performance, which is suitable for supercapacitor applications; its specific capacitance is 146 F/g at 1 A/g. Furthermore, the composite electrodes retain a cycling stability of about 90% over 2000 charge–discharge cycles at 10 A/g. The superior electrochemical properties of the cellulose make it a promising candidate for developing electrodes for energy storage applications.

Two-dimension N-doped nanoporous carbon from KCl thermal exfoliation of Zn-ZIF-L: Efficient adsorption for tetracycline and optimizing of response surface model

N-doped nanoporous carbon (NC) with two-dimensional structure derived from Zn-ZIF-L via KCl exfoliation and carbonization at different temperature were prepared for adsorptive removal of tetracycline (TC). Characterizations revealed the effective dopant of N atoms and low degree of graphitization with more defects related to the enhanced adsorption capacity of the NC materials. Benefiting from the huge surface area (2195.57 m2 g−1), high porosity (1.34 cm3 g−1) and accessible sheeting structure, the NC-800 exhibited its fast and efficient adsorption of TC in 60 min. Meantime, the maximum adsorption of TC could reach 347.06 mg g−1. Effects of pH, humic acid (HA) and ionic strength (Na+, Ca2+) were studied along with the interactions among influencing factors investigated by response surface model (RSM). By optimizing experimental conditions from RSM, the adsorption capacity could increase to 427.41 mg g−1. Additionally, electrostatic interaction and hydrogen bond interaction might play a dominating role in adsorption reaction. The NC-800 could maintain a high adsorption level after four cycles. Therefore, the NC-800 with great adsorptive property and reusability could be considered as an effective adsorbent with promising potential in applications for water treatment.

Solvent-free synthesis of N-doped nanoporous carbon materials as durable high-performance pH-universal ORR catalysts

Metal-free carbons as durable high-performance oxygen reduction electrocatalysts, deemed to be promising alternatives to the platinum-group metals (PGMs), are vital to large-scale commercialization of fuel cells. Herein, a solvent-free synthetic strategy has been proposed to prepare N-doped nanoporous metal-free carbonaceous materials originating from various types of plant residues (papaya skin – fruit, bamboo shoot – forestry, wheat straw – farming and cabbage stem – vegetable). The optimal metal-free carbon, possessing maximized reaction surface area and optimized distributions of nanopore structures and nitrogen species, can function as the durable high-performance pH-universal ORR electrocatalyst, reaching or surpassing the benchmark 20% Pt/C catalyst within the wide scope of pH. This paper substantiates the solvent-free, scalable and bio-universal preparation approach to converting various biomass wastes into durable high-performance pH-universal ORR carbonaceous catalysts, capable of expanding the repertoire of cathode catalysts employed by fuel cells that demand diverse pH environments.