Nitrogen-doped Carbon Structure Research Articles

Controlled chemical transformation of lignin by nitric acid treatment and carbonization

This study focuses on understanding the chemical reactions and results of Kraft lignin transformation through nitric acid treatment and subsequent carbonization. With its rich carbon content, lignin stands out as a promising candidate for the manufacturing of high-value carbon materials. The lignin underwent effective nitration, depolymerization, and oxidation under ambient conditions and at 40 °C, while a slight increase in reaction temperature significantly reduced the reaction time. The molecular weight Mw was effectively reduced from 4371 g/mol to 767 g/mol. The acid-treated lignin samples with incorporated nitro groups were further carbonized to create nitrogen-doped carbon structures. The resulting materials show stable nitrogen content (about at 5 wt%) even after carbonization due to the transformation of nitro groups into thermally stable pyridinic moieties, thereby exhibiting enhanced electrocatalytic properties compared to nitrogen-free carbon materials derived from Kraft lignin. The nitric acid-assisted treatment of lignin obviates the need for catalysts, and additional extraction or purification steps for preparing bio-derived carbon precursors, rendering it facile, fast, and cost-efficient.

Domain-Limited Sub-Nanometer Co Nanoclusters in Defective Nitrogen Doped Carbon Structures for Non-Invasive Drug Monitoring.

In this work, sub-nanometer Co clusters anchored on porous nitrogen-doped carbon (C─N─Co NCs) are successfully prepared by high-temperature annealing and pre-fabricated template strategies for non-invasive sensing of clozapine (CLZ) as an efficient substrate adsorption and electrocatalyst. The introduction of Co sub-nanoclusters (Co NCs) provides enhanced electrochemical performance and better substrate adsorption potential compared to porous and nitrogen-doped carbon structures. Combined with ab initio calculations, it is found that the favorable CLZ catalytic performance with C─N─Co NCs is mainly attributed to possessing a more stable CLZ adsorption structure and lower conversion barriers of CLZ to oxidized state CLZ. An electrochemical sensor for CLZ detection is conceptualized with a wide operating range and high sensitivity, with monitoring capabilities validated in a variety of body fluid environments. Based on the developed CLZ sensing system, the CLZ correlation between blood and saliva and the accuracy of the sensor are investigated by the gold standard method and the rat model of drug administration, paving the way for non-invasive drug monitoring. This work provides new insights into the development of efficient electrocatalysts to enable drug therapy and administration monitoring in personalized healthcare systems.

Rational design of p-ZnS@CN with 3D interconnected hierarchical pore structure through pyrolysis of an organic hybrid zinc thiocyanide for electrochemical lithium storage

3D interconnected porous carbon-coupled metal-sulfide composites have been demonstrated as promising lithium storage materials owing to their large surface areas as well as the acceleration effect to electrochemical kinetics. However, constructing these materials with ordered hierarchical pore structure is still a challenge. To address this issue, we found that the crystals of an organic hybrid zinc thiocyanide [Zn(NCS)2(phen)2] (phen = 1,10-phenanthroline) could become a fluid at 400 °C, and during the melting process, the phen ligand was simulatneously carbonized to form nitrogen-doped carbon materials, while the Zn(NCS)2 species were converted into ZnS quantum dots. This property could allow us to employ a hard template strategy for preparation of a porous p-ZnS@CN composite featuring 3D interconnected hierarchical structure, namely employing SiO2 nanospheres as sacrificial template and [Zn(NCS)2(phen)2] as precursor and thermal treatment this mixture at 400 °C. The as-obtained p-ZnS@CN (p = porous structure, CN = nitrogen-doped carbon) composite possesses ordered macro- and mesoporous nitrogen-doped carbon structures, where the ZnS quantum dots are embedded in. Due to their structural features, p-ZnS@CN showed a superior lithium storage performance in comparison with ZnS nanoparticles. The well-defined 3D interconnected hierarchical pore structure not only enhances the efficiency of lithium-ion diffusion, but also offers ample void space to buffer the volume expansion during lithiation. Given the diversity of crystalline organic hybrid metal thiocyanates, this work opens a new avenue of preparing 3D interconnected porous carbons-coupled metal-sulfide composites.

Job-synergistic engineering from Fe3N/Fe sites and sharp-edge effect of hollow star-shaped nitrogen-doped carbon structure for high-performance zinc-air batteries

Due to the limited sources, high cost, and poor long-term stability of noble metal catalysts, the large-scale commercial application of zinc-air batteries has been restricted. Therefore, designing non-noble metal catalysts with excellent activity and stability for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) blossoms in the ascendant. Herein, we report a hollow star-shaped dual-functional electrocatalyst with uniform and dispersed Fe3N/Fe nanoparticles derived from zeolitic imidazolate framework (ZIFs) by a simple sacrificial template strategy. This hollow structure has the characteristics of low density, thin shell, and high permeability, and its internal cavity not only provides additional three-phase interfaces to accelerate O2 reduction and evolution but also promotes the diffusion of reactants onto the catalyst. By controlling the input amount of iron metal salt, the dispersion degree of FeNP can be effectively adjusted, and the generated Fe3N introduces abundant Fe-NX active sites. Density functional theory calculations show that the strong affinity between Fe3N and FeNP is favorable for promoting the oxygen intermediate reaction, achieving a job-synergistic catalytic effect and high reaction kinetics. The synthesized Fe3N/FeNP-N-C-3.3% exhibits excellent dual-functional activity for OER and ORR, with a high half-wave potential of 0.867 V for ORR (better than the commercial Pt/C of 0.82 V) and an overpotential of only 294 mV for OER at 10 mA cm−2. The rechargeable Zn-air battery prepared with Fe3N/FeNP-N-C-3.3% as an air cathode shows a long-term cycling performance of over 750 h and a maximum power density of 205 mW cm−2. The flexible Zn-air battery has a high open-circuit voltage of 1.48 V and a maximum power density of 52.6 mW cm−2, showing glamorous commercial prospects.

Tailoring the hierarchical porous nitrogen-doped carbon structures loaded single-atomic Ni catalyst for promoting CO2 electrochemical reduction at low CO2 concentration

Although direct reduction of exhaust gases into CO can enable significant economic benefits, the poor activity of CO2 reduction reaction (CO2RR) at low CO2 concentration seriously impedes its application. Herein, a series of Ni single atom sites/nitrogen doped porous carbon materials with different pore sizes were prepared to explore the effect of porosity on the local CO2 concentration in the electrocatalytic process of CO2RR. The results of characterization and experiments demonstrate that surface micropores generated by KOH activation are the key to creating the high local concentration of CO2 around active sites, helping facilitate the reaction kinetics at low CO2 concentration. Therefore, when the reaction is conducted under 20% diluted CO2 condition, the optimal activated macroporous sample exhibits up to nearly 1.3-fold higher faradaic efficiency of CO (FE(CO)) and a 1.7-fold higher of partial current density of CO (jCO) than similar samples without activation. These results offer new insight for designing efficient electrocatalysts for low-concentration CO2 reduction by constructing advanced porous structures.

Atomically dispersed Ni activates adjacent Ce sites for enhanced electrocatalytic oxygen evolution activity.

Manipulating the intrinsic activity of heterogeneous catalysts at the atomic level is an effective strategy to improve the electrocatalytic performances but remains challenging. Here, atomically dispersed Ni anchored on CeO2 particles entrenched on peanut-shaped hollow nitrogen-doped carbon structures (a-Ni/CeO2@NC) is rationally designed and synthesized. The as-prepared a-Ni/CeO2@NC catalyst exhibits substantially boosted intrinsic activity and greatly reduced overpotential for the electrocatalytic oxygen evolution reaction. Experimental and theoretical results demonstrate that the decoration of isolated Ni species over the CeO2 induces electronic coupling and redistribution, thus resulting in the activation of the adjacent Ce sites around Ni atoms and greatly accelerated oxygen evolution kinetics. This work provides a promising strategy to explore the electronic regulation and intrinsic activity improvement at the atomic level, thereby improving the electrocatalytic activity.

Synergism of NiFe layered double hydroxides/phosphides and Co-NC nanorods array for efficient electrocatalytic water splitting

The green hydrogen route provides a reliable way to reduce dependence on fossil fuels. Hydrogen production by water electrolysis is an efficient way to convert unstable renewable energy sources into hydrogen energy. Herein, a rod-like N-doped carbon nanorods array cooperated with layered double hydroxide (Ni2Fe@Co-NC/CC) and a tri-metal phosphides composite (P-Ni2Fe@Co-NC/CC) is fabricated, which is believed can facilitate the electron and mass transfer efficiency. The Co element in Ni2Fe@Co-NC/CC can promote the formation of high-valence Ni and activate lattice oxygen to form abundant dual OER active sites. While the P-Ni2Fe@Co-NC/CC can obtain optimized hydrogen adsorption free energy due to synergistic effect of trimetallic phosphides and nitrogen-doped carbon structure to promotes the HER progress. Therefore, due to the synergistic effect between metal hydroxide/phosphide and Co-decorated NC nanorods array, low overpotentials of 240 and 137 mV at 100 mA cm−2 can be achieved for OER and HER with excellent electrocatalytic stability. Besides, the Ni2Fe@Co-NC/CC//P-Ni2Fe@Co-NC/CC device can afford cell voltage of 1.579 V at 50 mA cm−2 in water splitting, which demonstrate a new idea for rational designed electrocatalytic water splitting composites towards high activity and stability.

Nitrogen-doped porous carbon encapsulates multivalent cobalt-nickel as oxygen reduction reaction catalyst for zinc-air battery

In this study, we present a bimetallic ion coexistence encapsulation strategy employing hexadecyl trimethyl ammonium bromide (CTAB) as a mediator to anchor cobalt–nickel (CoNi) bimetals in nitrogen-doped porous carbon cubic nanoboxes (CoNi@NC). The fully encapsulated and uniformly dispersed CoNi nanoparticles with the improved density of active sites help to accelerate the oxygen reduction reaction (ORR) kinetics and provide an efficient charge/mass transport environment. Zinc-air battery (ZAB) equipped CoNi@NC as cathode exhibits an open-circuit voltage of 1.45 V, a specific capacity of 870.0 mAh g−1, and a power density of 168.8 mW cm−2. Moreover, the two CoNi@NC-based ZABs in series display a stable discharge specific capacity of 783.0 mAh g−1, as well as a large peak power density of 387.9 mW cm−2. This work provides an effective way to tune the dispersion of nanoparticles to boost active sites in nitrogen-doped carbon structure, and enhance the ORR activity of bimetallic catalysts.

Chitin-Derived Nitrogen-Doped Carbon Nanopaper with Subwavelength Nanoporous Structures for Solar Thermal Heating.

Sustainable biomass-derived carbons have attracted research interest because of their ability to effectively absorb and convert solar light to thermal energy, a phenomenon known as solar thermal heating. Although their carbon-based molecular and nanoporous structures should be customized to achieve enhanced solar thermal heating performance, such customization has insufficiently progressed. In this study, we transformed a chitin nanofiber/water dispersion into paper, referred to as chitin nanopaper, with subwavelength nanoporous structures by spatially controlled drying, followed by temperature-controlled carbonization without any pretreatment to customize the carbon-based molecular structures. The optimal carbonization temperature for enhancing the solar absorption and solar thermal heating performance of the chitin nanopaper was determined to be 400 °C. Furthermore, we observed that the nitrogen component, which afforded nitrogen-doped carbon structures, and the high morphological stability of chitin nanofibers against carbonization, which maintained subwavelength nanoporous structures even after carbonization, contributed to the improved solar absorption of the carbonized chitin nanopaper. The carbonized chitin nanopaper exhibited a higher solar thermal heating performance than the carbonized cellulose nanopaper and commercial nanocarbon materials, thus demonstrating significant potential as an excellent solar thermal material.

The origin of selective nitrate-to-ammonia electroreduction on metal-free nitrogen-doped carbon aerogel catalysts

Electrocatalytic nitrate reduction reaction (NitRR) to NH3 provides an appealing route to reform the energy-consuming ammonia industry. Considerable studies have demonstrated transition-metal-based catalysts for the NitRR, while most of them suffer from high cost, poor stability, and unsatisfactory selectivity. In this work, a group of carbon-based aerogel catalysts with regulated N species have been developed for highly efficient nitrate-to-ammonia reduction. The results show that the electrocatalytic performance is dependent on the graphitic-N moiety, where the catalyst with the highest content of graphitic-N moiety exhibits a maximum NH3 yield rate of 1.33 mgNH3 h−1 cm−2 with the faradaic efficiency of ca. 95%. The theoretical investigation further reveals the strong adsorption of nitrate on graphitic-N moiety as the reason for the enhanced NO3ˉ-to-NH3 activity. This study, thus, provides a fundamental understanding of the intrinsic mechanism of the NitRR on nitrogen-doped carbon structures, facilitating the rational design of metal-free catalysts for advanced electrosynthesis.

Exploiting Asymmetric Co States in a Co-N-C Catalyst for an Efficient Oxygen Reduction Reaction

Co-NC catalysts have attracted extensive concerns derived from their high oxygen reduction reaction (ORR) activity, but the catalytic mechanism of Co species with different forms remains controversial. Herein, we prepare Co-NC catalysts with a cobalt nanoparticle-supported and nitrogen-doped carbon structure using the ZIF-67 precursor, in which the Co states in the catalyst present an asymmetric state of an exposed carbon coating (Asy-Co) and a symmetric state of buried carbon (Sy-Co). The acid etching process removed the exposed asymmetric cobalt nanoparticles on the surface. The specific role of cobalt nanoparticles with different forms in the Co-NC catalysts was comprehensively clarified through analyzing the chemical coordination environment by XPS and XAFS. The half-wave potential (E1/2 = 0.83 V) and onset potential (Eon = 1.04 V) of the Co-NC catalysts obtained after acid etching decreased significantly. Thus, the cobalt species removed by the acid etching process offered confirmed contributions to the catalytic activity. This work puts forward an important reference for the design and exploitation of non-noble metal catalysts using symmetry-derived motifs.

Graphitic-nitrogen-enriched carbon skeleton with embedment of Fe3C for superior performance air cathode in zinc-air battery

Combining catalytic active materials with nitrogen-doped carbon structure has been an effective strategy for designing high-performance electrocatalysts, where N species plays a vital role in modulating the electronic structure of composite material. The N dopant in the carbon structure exists in different states, but it has been ambiguous which type of N structure contributes the most to the overall catalytic activity. Here, Fe3C nanoparticles embedded in graphitic nitrogen-dominated carbon framework (Fe3C@NC) has been successfully fabricated from Fe@ZIF-8 and exhibits excellent oxygen reduction reaction (ORR) activity and stability. Experiments and theoretical calculations confirm the interaction between Fe3C and N-doped carbon. Moreover, graphitic nitrogen is proved to exhibit the highest promotion contribution among different N states, which can effectively reduce the energy barrier of the potential determining step (from O2 to ∗OOH) for ORR. The Fe3C@NC composite is applied as the air cathode in a Zn-air battery, which shows a high EOCV (open-circuit voltage) of 1.48 V, a power density of 155.6 mW/cm2, and a specific capacity of 798 mAh/gZn. This work suggests the synergy of Fe3C, N species, and carbon layer in promoting the performance of ORR catalysts.

Regulated electronic structure and improved electrocatalytic performances of S-doped FeWO4 for rechargeable zinc-air batteries

The exploration of active and long-lived oxygen reduction reaction (ORR) catalysts for the commercialization of zinc-air batteries are of immense significance but challenging. Herein, the sulfur doped FeWO4 embedded in the multi-dimensional nitrogen-doped carbon structure (S-FeWO4/NC) was successfully synthesized. The doped S atoms optimized the charge distribution in FeWO4 and enhanced the intrinsic activity. At the same time, S doping accelerated the formation of reaction intermediates during the adsorption reduction of O2 on the surface of S-FeWO4/NC. Accordingly, the S-FeWO4/NC catalyst showed more positive half-wave potential (0.85 V) and better stability than that of the FeWO4/NC catalyst. Furthermore, the S-FeWO4/NC-based zinc-air battery exhibited considerable power density of 150.3 mW cm−2, high specific capacity of 912.7 mA h g−1, and prominent cycle stability up to 220 h. This work provides an assistance to the development of cheap and efficient tungsten-based oxygen reduction catalysts and the promotion of its application in the zinc-air battery.

Pyrolysis-free and universal synthesis of metal-NC single-atom nanozymes with dual catalytic sites for cytoprotection

Metal-nitrogen-doped carbon single-atom nanozymes (M − NC SAzymes) have tremendous prospects to replace natural enzymes for the treatment of reactive oxygen species (ROS)-related diseases. However, developing a pyrolysis-free and universal synthesis of M − NC SAzymes with robust enzyme-mimicking activity still remains a challenge. Herein, a promising cytoprotective agent (Fe-NC SAzymes) with multiple enzyme-mimicking activities was fabricated based on the reaction of Schiff bases with Fe ions via one-pot solvothermal method. In Fe-NC SAzymes, Fe-Nx moieties served as the main catalytic sites to mimick oxidase, peroxidase, and catalase; meanwhile, the co-catalytic sites of the π-conjugated nitrogen-doped carbon structure mimicked superoxide dismutase to achieve the multiple enzyme-mimicking catalysis. Owing to the dual catalytic sites and pyrolysis-free synthesis strategy, Fe-NC SAzymes showed enhanced catalytic performance and excellent biocompatibility, which could scavenge excessive intracellular ROS to alleviate oxidative stress. The viability of cells subjected to oxidative stress recovered from 1.4% to 80.3% after Fe-NC SAzymes treatment, demonstrating an outstanding cytoprotective performance. Remarkably, this synthetic strategy can be expanded to other metal-NC SAzymes (Cu, Mn, Co, Zn, and Ni), which provides a feasible route to design specific functional SAzymes for ROS-related diseases therapy.

Understanding the Catalytic Sites of Metal-Nitrogen-Carbon Oxygen Reduction Electrocatalysts.

The development of low-cost catalysts containing earth-abundant elements as alternatives to Pt-based catalysts for the oxygen reduction reaction (ORR) is crucial for the large-scale commercial application of proton exchange membrane fuel cells (PEMFCs). Nonprecious metal-nitrogen-carbon (M-N-C) materials represent the most promising candidates to replace Pt-based catalysts for PEMFCs applications. However, the high-temperature pyrolysis process for the preparation of M-N-C catalysts frequently leads to high structural heterogeneity, that is, the coexistence of various metal-containing sites and N-doped carbon structures. Unfortunately, this impedes the identification of the predominant catalytic active structure, and thus, the further development of highly efficient M-N-C catalysts for the ORR. This Minireview, after a brief introduction to the development of M-N-C ORR catalysts, focuses on the commonly accepted views of predominant catalytic active structures in M-N-C catalysts, including atomically dispersed metal-Nx sites, metal nanoparticles encapsulated with nitrogen-doped carbon structures, synergistic action between metal-Nx sites and encapsulated metal nanoparticles, and metal-free nitrogen-doped carbon structures.

Novel g-C3N4 assisted metal organic frameworks derived high efficiency oxygen reduction catalyst in microbial fuel cells

The usage of efficient electrocatalyst in an appropriate way can significantly improve the oxygen reduction performance of microbial fuel cells (MFCs) cathode, which may accelerate its commercial application. In this work, isoreticular metal organic framework-3 (IRMOF-3) that modified with g-C3N4 and pyrolyzed at 850 °C (IR/CN-x%), exhibits a superior catalytic activity in alkaline electrolytes for oxygen reduction reaction (ORR). At high temperatures, after zinc evaporation, IRMOF-3 converts to a metal-free carbon skeleton that has large specific surface area. As a nitrogen source and supporting template, g-C3N4 introduces more activated nitrogen, and forms a new metal-free hierarchically porous nitrogen-doped carbon structure. As-synthesized IR/CN-50% as cathode catalyst displays a half-wave potential of 0.89 V (vs. RHE) and limit current density of 6.35 mA cm−2 in 0.1 M KOH, which is superior to commercial Pt/C (0.86 V@5.51 mA cm−2). Furthermore, IR/CN-50% shows approximately four-electron pathway and a yield of less than 4% hydrogen peroxide. Results from electrochemical tests further confirm IR/CN-50% possesses better durability and higher methanol tolerance than Pt/C. Besides, MFCs modified with IR/CN-50% present maximum power density (1402.8 mW m−3) better than the MFCs equipping with Pt/C catalyst (1292.8 mW m−3), which is a promising alternative electrocatalyst for MFCs.

Improving Polysulfides Adsorption and Redox Kinetics by the Co4 N Nanoparticle/N-Doped Carbon Composites for Lithium-Sulfur Batteries.

Improved conductivity and suppressed dissolution of lithium polysulfides is highly desirable for high-performance lithium-sulfur (Li-S) batteries. Herein, by a facile solvent method followed by nitridation with NH3 , a 2D nitrogen-doped carbon structure is designed with homogeneously embedded Co4 N nanoparticles derived from metal organic framework (MOF), grown on the carbon cloth (MOF-Co4 N). Experimental results and theoretical simulations reveal that Co4 N nanoparticles act as strong chemical adsorption hosts and catalysts that not only improve the cycling performance of Li-S batteries via chemical bonding to trap polysulfides but also improve the rate performance through accelerating the conversion reactions by decreasing the polarization of the electrode. In addition, the high conductive nitrogen-doped carbon matrix ensures fast charge transfer, while the 2D structure offers increased pathways to facilitate ion diffusion. Under the current density of 0.1C, 0.5C, and 3C, MOF-Co4 N delivers reversible specific capacities of 1425, 1049, and 729 mAh g-1 , respectively, and retains 82.5% capacity after 400 cycles at 1C, as compared to the sample without Co4 N (MOF-C) values of 61.3% (200 cycles). The improved cell performance corroborates the validity of the multifunctional design of MOF-Co4 N, which is expected to be a potentially promising cathode host for Li-S batteries.

Noble-Metal-Free Iron Nitride/Nitrogen-Doped Graphene Composite for the Oxygen Reduction Reaction.

Considerable effort has been devoted recently to replace platinum-based catalysts with their non-noble-metal counterparts in the oxygen reduction reaction (ORR) in fuel cells. Nitrogen-doped carbon structures emerged as possible candidates for this role, and their earth-abundant metal-decorated composites showed great promise. Here, we report on the simultaneous formation of nitrogen-doped graphene and iron nitride from the lyophilized mixture of graphene oxide and iron salt by high-temperature annealing in ammonia atmosphere. A mixture of FeN and Fe2N particles was formed with average particle size increasing from 23.4 to 127.0 nm and iron content ranging from 5 to 50 wt %. The electrocatalytic oxygen reduction activity was investigated via the rotating disk electrode method in alkaline media. The highest current density of 3.65 mA cm–2 at 1500 rpm rotation rate was achieved in the 20 wt % catalyst via the four-electrode reduction pathway, exceeding the activity of both the pristine iron nitride and the undecorated nitrogen-doped graphene. Since our catalysts showed improved methanol tolerance compared to the platinum-based ones, the formed non-noble-metal system offers a viable alternative to the platinum-decorated carbon black (Pt/CB) ORR catalysts in direct methanol fuel cells.

Co@Co3O4 nanoparticle embedded nitrogen-doped carbon architectures as efficient bicatalysts for oxygen reduction and evolution reactions

Abstract The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play crucial roles in efficient energy conversion and storage solutions. Here, Co@Co 3 O 4 nanoparticle embedded nitrogen-doped carbon architectures (denoted as Co@Co 3 O 4 /NCs) are prepared via a simple two-step and in situ approach by carbonization and subsequent oxidation of Co-MOF containing high contents of carbon and nitrogen. When evaluated as electrocatalyst towards both ORR and OER in a KOH electrolyte solution, the as-fabricated Co@Co 3 O 4 /NC-2 exhibits similar ORR catalytic activity to the commercial Pt/C catalyst, but superior stability and good methanol tolerance. Furthermore, the as-fabricated catalysts also show promising catalytic activity for OER. The effective catalytic activities originate from the synergistic effects between well wrapped Co@Co 3 O 4 nanoparticles and nitrogen doped carbon structures.

Nitrogen-rich hard carbon as a highly durable anode for high-power potassium-ion batteries

Carbonaceous electrode materials for potassium-ion batteries (KIBs) are attractive due to the abundant resource of potassium and their rational capability. However, their rate capability and cycle life are mainly hindered by the intercalation chemistry involving repeated potassium insertion/extraction that are difficult to maintain within a short time or long-term cycling. Here, for the first time, a seafood waste (chitin)-derived hierarchically porous nitrogen-doped carbon microsphere (NCS) electrode with a surface-driven potassium storage mechanism is developed. The NCS electrode demonstrates a record high rate capability of 154mAhg−1 at 72C and ultralong cycle life of 4000 cycles without obvious capacity decay (180mAhg−1 at 1.8C), representing the best rate capability and longest cycle life among all electrodes in KIBs and even supassing most electrodes in sodium-ion batteries (NIBs). Further kinetic analysis and first-principle calculations reveal the dominated capacitive surface-driven mechanism of potassium storage in NCS, which is attributed to the hierarchically porous microstructure and nitrogen-doped carbon structure with enhanced potassium adsorption capability and electronic/ionic conductivities.