Heteroatom-doped Carbon Research Articles

Palladium nanoparticles anchored on Schiff base metal complex derived heteroatom-doped carbon materials for boosting ethanol electrooxidation

Designing appropriate support for noble metal-based catalyst has consistently been an effective strategy to improve the catalytic activity of ethanol electrooxidation reaction (EOR). Here, a novel heteroatom-doped carbon (HDC) material has been prepared by calcination of Schiff base metal complex precursor. The HDC-750 prepared at the optimum temperature (750 °C) has a three-dimensional structure with large specific surface area and unique pores. When the HDC-750 is used as a support for palladium nanoparticles, it can improve the conductivity of catalysts, the permeability of electrolyte and intermediates, and increase the number of anchoring points of palladium nanoparticles. Due to its unique three-dimensional structure and the synergistic enhancement effect of strong metal support interaction between Pd and HDC-750, the Pd/HDC-750 catalyst exhibits high electrochemical active surface area (23.94 m2 gPd−1) and excellent EOR activity (146.3 mA cm−2), which is as high as 2.1 and 3.0 times of that for the Pd/C. After 3600 s durability test, the Pd/HDC-750 shows a high current density of 9.9 mA cm−2, while Pd/C shows only 1.3 mA cm−2.

Phosphorous-doped bimetallic sulfides embedded in heteroatom-doped carbon nanoarrays for flexible all-solid-state supercapacitors

Flexible supercapacitors (SCs) have become a popular research topic due to their extra-long service life, foldability, and wearability. Nevertheless, their low energy density restricts their applications. Here, we synthesized phosphorus-doped bimetallic sulfides embedded in heteroatom-doped (N, S, and P) carbon shells (P-ZCS/HC) using a simple approach to create high-performance flexible electrodes. The three-dimensional architecture made by interlaced nanosheets was preserved, and raised nanoparticles appeared on the rough surface during the annealing operation, increasing the specific surface area and potential exposure to the electrolyte. It is noteworthy that the optimal P-ZCS/HC electrode possessed a remarkable capacity of 1080 C g−1 at 1 A g−1 along with superb cycling stability. These extraordinary properties were primarily caused by plentiful redox reactions, enhanced conductivity, and synergic effects of the P-doped metal sulfides and heteroatom-doped carbon shells. Density functional theory simulations confirmed the good function of the P-doped electrodes and their ability to boost conductivity, improve reactive dynamics, and promote OH− adsorption. Notably, the assembled all-solid-state hybrid SC exhibited a maximum energy density of 62.9 W h kg−1 and a power density of 16 kW kg−1, while being able to maintain 92.0% of its initial capacity after 10,000 cycles. This systematic report provides new insight into the design and synthesis of electrodes with complex components and outstanding structures for the flexible energy field.

Research progress of carbon anode materials for sodium-ion batteries

<p indent=0mm>Due to the merits of abundant resources and low cost, sodium-ion batteries (SIBs) have attracted extensive attention in the field of large-scale energy storage. The deployment of SIBs is limited by electrode materials with high specific capacity and long cycling stability. Carbon materials are promising anode candidates for SIBs due to the advantages of high controllability and excellent stability. Up to now, the researches on carbon materials mainly involve graphite, amorphous carbon, heteroatom-doped carbon and biomass-derived carbon. However, the problems with carbon materials, including thermodynamic instability of sodium-graphite compounds, large volume expansion and low initial Coulombic efficiency, remain and restrict the development of SIBs. Modification on the carbon structure and interfacial optimization of carbon anodes and electrolytes has been demonstrated as effective strategies to promote the electrochemical performances. Herein, we summarize the structural characteristics, electrochemical performances, storage mechanisms, problems, and improvement methods of carbon materials, and provide insights into the researches of carbon anode materials for SIBs.

Biomass-derived bifunctional electrocatalysts for oxygen reduction and evolution reaction: A review

Oxygen electrode catalysts are important as inter-conversion of O2 and H2O is crucial for energy technologies. However, the sluggish kinetics of oxygen reduction and evolution reactions (ORR and OER) are a hindrance to their scalable production, whereas scarce and costly Pt and Ir/Ru-based catalysts with the highest electrocatalytic activity are commercially unviable. Since good ORR catalysts are not always efficient for OER and vice versa, so bifunctional catalysts on which OER and ORR occurs on the same electrode are very desirable. Alternative catalysts based on heteroatom-doped carbon nanomaterials, though showed good electrocatalytic activity yet their high cost and complex synthesis is not viable for scalable production. To overcome these drawbacks, biomass-derived heteroatom-doped porous carbons have recently emerged as low-cost, earth-abundant, renewable and sustainable environment-friendly materials for bifunctional oxygen catalysts. The tunable morphology, mesoporous structure and high concentration of catalytic active sites of these materials due to heteroatom (N)-doping could further enhance their ORR and OER activity, along with tolerance to methanol crossover and good durability. Thus, biomass-derived heteroatom-doped porous carbons with large surface area, rich edge defects, numerous micropores and thin 2D nanoarchitecture could be suitable as efficient bifunctional oxygen catalysts. In the present article, synthesis, N-doping, ORR/OER mechanism and electrocatalytic performance of biomass-derived bifunctional catalysts has been discussed. The selected biomass (chitin, eggs, euonymus japonicas, tobacco, lysine and plant residue) except wood, act as both C and N precursor, resulting in N self-doping of porous carbons that avoids the use of toxic chemicals, thus making the synthesis a facile and environment-friendly green process. The synthetic strategy could be further optimized to develop future biomass-based N self-doped porous carbons as metal-free high performance bifunctional oxygen catalysts for commercial energy applications. Recent advances and the importance of biomass-based bifunctional oxygen catalysts in metal-air batteries and fuel cells has been highlighted. The material design, perspectives and future directions in this field are also provided.

A General Self-Sacrifice Template Strategy to 3D Heteroatom-Doped Macroporous Carbon for High-Performance Potassium-Ion Hybrid Capacitors

HighlightsA newly versatile self-sacrifice method to fabricate selenium and nitrogen co-doped 3D macroporous carbon was developed.The K+ storage mechanism of Se and N active sites was deeply studied by systematic electrochemical characterization combined with theoretical calculations.The assembled K-ion hybrid capacitor possesses high energy/power densities and excellent cycling stability for practical applications.

In-Situ Synthesis of N, O, P-Doped Hierarchical Porous Carbon from Poly-bis(phenoxy)phosphazene for Polysulfide-Trapping Interlayer in Lithium-Sulfur Batteries.

The shuttling of polysulfides is the most detrimental contribution to degrading the capacity and cycle stability of lithium-sulfur (Li-S) batteries. Adding a carbon interlayer to prevent the polysulfides from migrating is feasible, and a rational design of the structures and surface properties of the carbon layer is essential to increasing its effectiveness. Herein, we report a hierarchical porous carbon (HPC) created by carbonization of bis(phenoxy)phosphazene and in-situ doping of triple heteroatoms into the carbon lattice to fabricate an effective polysulfide-trapping interlayer. The generated carbon integrates the advantages of a hierarchical porous structure, a high specific area and rich dopants (N, O and P), to yield chemisorption and physical confinement for polysulfides and fast ion-transport synergistically. The HPC interlayer significantly improves the electrochemical performance of Li-S batteries, including an exceptional discharge capacity of 1509 mA h/g at 0.06 C and a high capacity retention of 83.7 % after 250 cycles at 0.3 C. This work thus proposes a facile in-situ synthesis of heteroatom-doped carbon with rational porous structures for suppressing the shuttle effect.

In situ formation of Co3O4 nanoparticles embedded N-doped porous carbon nanocomposite: a robust material for electrocatalytic detection of anticancer drug flutamide and supercapacitor application.

Theone-step synthesis of heteroatom-doped porous carbons is reportedwith the in situ formation of cobalt oxide nanoparticles for dual electrochemical applications (i.e., electrochemical sensor and supercapacitor). A single molecular template of zeolitic imidazole framework-67 (ZIF-67) was utilized for the solid-state synthesis of cobalt oxide nanoparticle-decorated nitrogen-doped porous carbon (Co3O4@NPC) nanocomposite through a facile calcination treatment. For the first time, Co3O4@NPC nanocomposite derived from ZIF-67 has been applied as an electrode material for the efficient electrochemical detection of anticancer drug flutamide (FLU). The cyclic voltammetry studies were performed in the operating potential from 0.15 to - 0.65V (vs. Ag/AgCl). Interestingly, the fabricated drug sensor exhibited a very low reduction potential (- 0.42V) compared to other reported sensors. The fabricated sensor exhibited good analytical performance in terms of low detection limit (12nM), wide linear range (0.5 to 400μM), and appreciable recovery results (~ 98%, RSD 1.7% (n= 3)) in a human urine sample. Hereafter, we also examined the supercapacitor performance of the Co3O4@NPC-modified Ni foam in a 1M KOH electrolyte, and noticeable a specific capacitance of 525Fg-1 at 1.5 A g-1 was attained, with long-term cycling stability. TheCo3O4@NPC nanocomposite supercapacitor experiments outperform the associated MOF-derived carbons and the Co3O4-based nanostructure-modified electrodes.

Facile, general and environmental-friendly fabrication of O/N-codoped porous carbon as a universal matrix for efficient hydrogen evolution electrocatalysts

Heteroatom-doped porous carbons are widely exploited as efficient matrices to stabilize metal nanoparticles (NPs) for electrocatalysis, whereas their syntheses without additional activation and functional agents and inert gases still remains a grand challenge. Herein, we report the simple yet efficient inert gas-free direct fabrication of hierarchically porous interconnected O/N-codoped carbon nanosheets (designated as AC) and their application as excellent matrices for preparing selected Pt group metal (Ru, Rh, Ir) electrocatalysts toward alkaline hydrogen evolution reaction (HER). The self-templating, self-activation and in-situ O/N-functionalization synthesis of AC is achieved via the one-pot pyrolysis of ethylenediaminetetraacetic acid tetra-sodium without additional inert gas. Compared with NC prepared via annealing the same precursor in N2 atmosphere, the as-formed AC with more mesoporous structure and oxygenated functional groups enables the fabrication of smaller and electron-rich Ru NPs, which deliver an optimal HER activity in terms of an extremely low overpotential of 7 mV at 10 mA cm−2 for HER, superior to that of Rh/AC, Ir/AC, Ru/NC, commercial Pt/C and plenty of previously fabricated Ru-based electrocatalysts. This “three-in-one” synthetic method demonstrates superior generality for other porous carbon materials by using potassium gluconate and potassium sodium tartrate as precursors.

A rational design of cellulose-based heteroatom-doped porous carbons: Promising contenders for CO2 adsorption and separation

The present work demonstrates a facile synthesis of cellulose-based novel microporous carbons (Cell-X) for environmental remediation by virtue of their application as CO2 adsorbents. The presence of heteroatoms (N, S) in highly porous carbon frameworks (1032 m2/g) endowed Cell-X with efficient CO2 adsorption and separation characteristics. The optimized sample, Cell-UK, exhibit significantly large micropore volume (0.7135 cm3/g), abundance of narrow micropores (<0.94 nm) and optimum pyrrolic nitrogen content (58%) which leads to efficient CO2 adsorption (297.1 mg/g at 273 K and 193.7 mg/g at 298 K/1 bar) and moderately high heat of adsorption (36.70 kJ/mol). Additionally, ideal adsorbed solution theory (IAST) determines a CO2/N2 selectivity ~ 110 at 298 K, surpassing the gas separation performance of most reported microporous carbons. Herein, the remarkable CO2 adsorption and separation performance of prepared materials is attributed to the synergistic role of narrow micropores (<0.94 nm) and surface heterogeneity (N/N, S-doped surfaces). These heteroatoms enriched basic sites induced stronger affinity for acidic CO2 molecules by generating Lewis acid-base interactions between gas molecules and adsorbent surfaces. Conclusively, present work demonstrates an effort devoted to the rational designing of tunable porous cellulose-based CO2 adsorbents as promising contenders to mitigate global warming.

Co2P embedded in nitrogen-doped carbon nanoframework derived from Co-based metal-organic framework as efficient oxygen reduction reaction electrocatalyst for enhanced performance of activated carbon air-cathode microbial fuel cell

• The MPD of optimized MFC was 2001 ± 48 mW m −2 , 123% higher than that of control. • The electronic interaction between embedded Co 2 P and N -C improved ORR activity. • Co 2 PNC-NF electrocatalyst exhibited a desired four-electron pathway for ORR. • The double Co site of 001 face of Co 2 P could boost the cracking of OOH* group. A kind of Co 2 P embedded in nitrogen-doped carbon nanoframework (Co 2 PNC-NF) synthesized from directly carbonized Co-based metal-organic framework (ZIF-67) combined with phosphorus was utilized in the microbial fuel cell (MFC) to modify the active carbon air-cathode for the first time. Various techniques involving XRD, FESEM, TEM/EDS, BET and XPS were used to characterize the microstructure, morphology and surface chemical composition belonging to as-synthesized Co 2 PNC-NF. The electrochemical measurements revealed that the active carbon cathode modified by Co 2 PNC-NF got reduced resistance and optimized catalytic behavior in oxygen reduction reaction (ORR) process. The optimized MFC had a high maximum power density reaching 2001 mW m −2 , increasing by 123% compared with the bare active carbon cathode MFC. This result showed that combination between transition-metals phosphide and heteroatom-doped carbon matrices was beneficial to the improvement of MFC performance. Moreover, density functional theory calculations indicated that the special structure of double Co site of 001 face of Co 2 P can accelerate the ORR by boosting the cracking of OOH* group. Therefore, the Co 2 PNC-NF could be applied as an economical and efficient electrocatalyst in MFC to replace noble metal catalyst.

Metal–organic frameworks-derived heteroatom-doped carbon electrocatalysts for oxygen reduction reaction

The development of stable, adequate, and cost-effective catalysts to meet current fuel cell requirements is urgent in the face of ever-intensifying energy demands. Heteroatom-doped carbons are promising non-noble metal-based catalysts expected to replace or reduce platinum consumption required for the electrocatalytic oxygen reduction reaction (ORR). Metal–organic frameworks (MOFs) are rapidly evolving as porous functional materials owing to their high surface area, permanent porosity, and diverse structure, thus rendering their derivatives suitable potential catalysts for electrocatalysis. Herein, we systematically reviewed the latest advances in the design and synthesis of MOF-derived heteroatom-doped carbons, which were further divided into metal-free and metal-containing materials to identify the effects of component manipulation, morphological control, and structural engineering on their ORR performance. Additionally, future challenges and research directions for MOF-derived heteroatom-doped carbon electrocatalysts are proposed. • Recent advances in MOF-derived heteroatom-doped carbons for ORR are discussed. • Rarely involved halogen-doped carbons in earlier studies are summarized. • Challenges and perspectives on MOF-based materials for catalysis are outlined.

Mohr's salt assisted KOH activation strategy to customize S-doped hierarchical carbon frameworks enabling satisfactory rate performance of supercapacitors

The construction of heteroatom-doped hierarchical carbon frameworks has attracted significant research attention as high-performance electrode materials for supercapacitors. Herein, a facile one-step Mohr’s salt-assisted KOH activation strategy has been developed for the production of S-doped hierarchical carbon frameworks with large specific surface area from sustainable spruce bark. We found Mohr’s salt plays multiple roles during the synthesizing process by simultaneously acting as an S source, the template to generate mesopores, and the co-activator beyond KOH. As the electrode for supercapacitors, the high specific capacitance of 281 and 156 F g−1 can be achieved in aqueous electrolyte and ionic liquid electrolyte at 1 A g−1, respectively. More importantly, the electrode also displays excellent rate capability where a high capacitance can be maintained at large charge-discharge operation. Moreover, the supercapacitor device also demonstrated an energy density is high up to 66.26 Wh kg−1 at the power density of 875 W kg−1 in ionic liquid electrolyte. These results acquired could offer a versatile way to convert renewable biomass into value-add porous carbon for electrochemical energy-storage applications.

Oxidative and adsorptive removal of chlorophenols over Fe-, N- and S-multi-doped carbon xerogels

A range of heteroatom-doped carbon gels was studied to identify factors determining the efficiency of oxidative and adsorptive degradation/removal of phenolic compounds from aqueous solutions. Carbon xerogels were obtained via pyrolysis of resorcinol-heterocyclic aldehyde thermosetting resins. By utilizing either nitrogen-, sulfur- or oxygen-bearing heterocycles and impregnating the resins with FeCl3, carbons doped with the selected heteroatoms (N, S, O) and Fe could be obtained. This synthetic approach allows precise control of the doped element(s) amount and type. The efficiency of the chlorophenol removal process was correlated with the texture of the obtained carbon gels (for adsorptive removal), the pH of an aqueous solution and the H2O2 concentration (for oxidative degradation). The coexistence of iron and nitrogen within porous carbons enhances their catalytic properties towards oxidative decomposition of organic compounds via H2O2 activation, while the adsorption capacity for chlorophenols is directly correlated with microporosity and specific surface area values. The extensive mesoporosity and graphitic structure of the Fe and Ncodoped carbons result in efficient oxidative decomposition of the model organic pollutants. Sulfur doping prevented Fe-assisted graphitization during pyrolysis yielding disordered and highly microporous S and Fe codoped materials. The extent of oxidative degradation of chlorophenols decreased with an increasing number of Cl atoms in the phenolic ring. This report shows that Fe and Ncodoped carbons (the so-called FeNC pyrolyzed materials) are more active heterogeneous catalysts for oxidative (chloro)phenol degradation than their nitrogen- and/or iron-free counterparts, showing the importance of simultaneous coexistence of both elements (Fe and N) in the carbon scaffold.

Sulfur-Induced Growth of Coordination Polymer Derived-Straight Carbon Nanotubes on Carbon Nanofiber Network for Zn-Air Batteries.

Low-cost heteroatom-doped carbon nanomaterials have been widely studied for efficient oxygen reduction reaction and energy storage and conversion in metal-air batteries. A Masson pine twigs-like 3-dimensional network construction of carbon nanofibers (CNFs) with abundant straight long Co, N, and S-doped carbon nanotubes (CNTs) is developed by thermal treatment of Co-based polymer coated onto polyacrylonitrile nanofiber network together with thiourea at 900 °C, denoted as CNFT-Co9 S8 -900. It is interesting to note that the introduction of a high concentration of sulfur does not lead to the complete toxicity of catalysts, but promotes the axial growth to selectively form straight CNTs instead of curly bamboo-like CNTs. The highly graphitized in-situ grown Co, N, S-doped CNTs and the 3-dimensional N-doped CNF network provide both active catalytic sites and highly conductive paths, which are beneficial for oxygen reduction reaction (ORR). Thus, the optimal CNFT-Co9 S8 -900 performs the excellent ORR catalytic activity with a half-wave potential of 0.84 V and a diffusion-limited current density of 5.49 mA cm-2 . Furthermore, the CNFT-Co9 S8 -900-based Zn-air devices also possess a high power density of 136.9 mW cm-2 better than commercial Pt/C.

Very efficient dehydrogenation of methanolysis reaction with nitrogen doped Chlorella Vulgaris microalgae carbon as metal-free catalysts

In this study, nitrogen (N) doped metal-free catalysts were obtained as a result of nitric acid (HNO3) activation of carbon sample (C–KOH–N), which was obtained based on Chlorella Vulgaris microalgae by KOH activation (C–KOH). These catalysts have been effectively used to produce hydrogen (H2) from the sodium borohydride (NaBH4) methanolysis reaction. Compared to the C–KOH catalyst, the catalytic activity for C–KOH–N showed a seven-fold improvement. Hydrogen generation rate (HGR) values obtained for the NaBH4 methanolysis reaction for C–KOH and C–KOH–N metal-free catalysts were 3250 and 20,100 mL min−1 g−1. The catalysts were characterized using various analytical techniques such as XPS, XRD, SEM, FTIR, BET, and elemental analysis. This work can provide a new alternative strategy to produce specific heteroatom-doped metal-free carbon catalysts for environmentally friendly conversion to produce H2 efficiently.

Facile Approach To Prepare Multiple Heteroatom-Doped Carbon Material from Bagasse and Its Applications toward Lithium-Ion and Lithium–Sulfur Batteries

The constant search for cost-effective and high-performance materials for Li-ion batteries (LIBs) has increased with time. Here, we synthesized low-cost multi-heteroatom co-doped carbon from biowas...

Soybean root-derived N, O co-doped hierarchical porous carbon for supercapacitors

3D hierarchical porous soybean root-derived carbon (SRC) is successfully developed from N, O-contained natural soybean root through a convenient one-step carbonization activation route. SRC own abundant hierarchical pores, great specific surface area and considerable N and O elements. As-prepared carbon-based electrode exhibits specific capacitance of 269.4 F g−1 at 1 A g−1 and capacitance retention (97% after 20,000 charge and discharge cycles), while assembled symmetric supercapacitor (SSC) has an operating voltage window of 2.0 V and energy density of 23.0 Wh kg−1 at the power density of 500 W kg−1. This work makes natural soybean root be utilized as 3D heteroatom-doped carbon and provide another alternative strategy for high-performance electrode materials.

One-step integration of Co[sbnd]Ni phosphides in N, P co-doped carbons towards highly efficient oxygen electrocatalysis for rechargeable Zn-air battery

The development of highly efficient and robust bifunctional oxygen electrocatalysts is of great importance for optimizing the performance of rechargeable Zn-air batteries. In this study, CoNi phosphides encapsulated in N, P co-doped carbon (CoNiP/PNC) were prepared by a simple one-step pyrolysis method. The obtained catalyst exhibited outstanding oxygen reduction and oxygen evolution reaction (ORR and OER) activities in alkaline media. It exhibited a positive half-wave potential of 0.84 V versus the reversible hydrogen electrode for ORR, as well as a low overpotential of 470 mV to achieve 10 mA cm−2 for OER, comparable with the benchmark Pt/C and IrO2 catalysts. Furthermore, the rechargeable Zn-air battery was fabricated, which showed a high specific capacity of 729.3 mAh gZn-1, a high peak power density of 171.0 mW cm−2, and good stability. It reveals that the interplay between heteroatom-doped carbon layers and CoNi phase leads to the high ORR activity, and the in-situ formed bimetallic hydroxides/oxides contribute to the great OER performance. This work would inspire the future development of bifunctional electrocatalysts towards electrocatalysis in energy conversion and storage fields.

Biowaste-originated heteroatom-doped porous carbonaceous material for electrochemical energy storage application

Here, a unique heteroatom-doped spongy carbonaceous material from dwarf banana peel has been synthesized successfully using the one-step hydrothermal method. The discarded banana peel was reused as a carbon source for the formation of heteroatom-doped porous carbon. This biowaste-derived heteroatom-doped porous carbonaceous material (BH-PCM) has plenty of interconnected pores with an acceptable surface area of 213m2g−1. Thoroughly characterized BH-PCM has been used as electrode material for supercapacitor using a three-electrode system with an aqueous 1M H2SO4 solution. The as-synthesized BH-PCM holds an excellent specific capacitance of 137Fg−1 at 0.5Ag−1 and an impressive rate performance with a capacitance enduring 51Fg−1 at 5.0Ag−1. After 10,000 galvanostatic charge–discharge cycles, an initial capacitance of 94% was maintained. To show the practical applicability of the BH-PCM, the symmetrical two-electrode cell was fabricated and delivered the gravimetric specific capacitances of 87Fg−1 at 1Ag−1. The excellent electrochemical performance of BH-PCM towards supercapacitor was due to their high surface area, reasonable heteroatom doping rate, and a suitable degree of graphitization. This study offers a green approach for the development of environmental-friendly potential carbon-based electrode, by converting biowaste to clean/green energy.

Biowaste-derived heteroatoms-doped carbon for sustainable sodium-ion storage

Heteroatoms doped porous carbon as anode for sodium ion batteries have been successfully prepared from the bio-waste through a three-step process involving carbonization, activation and doping. The as-prepared nitrogen and sulfur-doped tangerine peel-derived porous carbon delivers a discharge capacity of 377 mAh g1 after 100 cycles at a current density of 50 mA g1 and long-term cycling stability at a current density of 500 mA g1 for 2000 cycles. The interconnected porous structure together with heteroatoms doping enhances the electrochemical storage properties of nitrogen and sulfur-doped tangerine peel-derived porous carbon. Furthermore, a full-cell SIB configuration employing nitrogen and sulfur-doped tangerine peel-derived porous carbon in combination with the Na3V2(PO4)3-C cathode successfully retained 95% of the discharge capacity after 50 cycles. These findings suggest the capability of similar types of biowaste-derived carbonaceous materials with heteroatoms-doping for future large-scale energy storage applications.