Heteroatom-doped Carbon Research Articles

MoP-Mo2C quantum dot heterostructures uniformly hosted on a heteroatom-doped 3D porous carbon sheet network as an efficient bifunctional electrocatalyst for overall water splitting

• MoP-Mo 2 C quantum dot heterostructures uniformly distribute on carbon sheet network. • MoP-Mo 2 C/NPC possesses abundant heterogeneous interfaces and pore structure. • MoP-Mo 2 C/NPC exhibits low overpotentials and ultrahigh stability for HER and OER. In this work, we constructed MoP-Mo 2 C quantum dot heterostructures uniformly hosted on a three-dimensional (3D) hierarchically porous thin N,P-doped carbon sheet network (MoP-Mo 2 C/NPC) by a novel one-pot simultaneous phosphating-carbonization-activation of molybdenum-chelated resin and KOH. Chelate confinement not only prevents the aggregation of MoP/Mo 2 C quantum dots, but also synchronously produces a carbon sheet network doped with N and P without the requirement for post-atom doping. The prepared MoP-Mo 2 C/NPC exhibited a large specific surface area, a high electron conductivity, and abundant active sites for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). As a result, MoP-Mo 2 C/NPC with a low calculated Gibbs free energy for H adsorption exhibited an excellent electrocatalytic activity and an ultrahigh stability for both the HER and OER processes in an alkaline medium. In addition, the assembled MoP-Mo 2 C/NPC || MoP-Mo 2 C/NPC alkaline electrolyzer delivered a current density of 10 mA cm −2 at an overpotential of only 1.55 V, and maintained > 95% of the initial current density after 168 h (1 week) of activity, which is superior to that of the state-of-the-art Pt/C || RuO 2 /C system in the overall water splitting process.

Enhancement of selectivity towards the synthesis of hydrogen peroxide by dimensional effect in mesoporous carbon

Efficient and selective electrocatalysts materials are currently needed for renewable energy conversion. This work studies the influence of internal channel modifications and the type of mesoporous silica that changes the electrocatalytic activities from the synthesized mesoporous carbon. Thus, MCM-41 and SBA-15 functionalized with amine (A) or diamine (D) groups and polyaniline (PANI) after pyrolysis produces derived mesoporous heteroatom-doped carbon that were evaluated as electrocatalyst in oxygen reduction reaction (ORR) for fuel cell systems. ORR can produce two types of products, allowing us to differentiate the main electrocatalytic activities of the synthesized mesoporous carbons. Therefore, the electrocatalytic results correlated the number of electrons transferred with the kind of ORR product generated. CS41/D/PANI, mesoporous carbon obtained from MCM-41 modified with diamine groups, was selective towards the production of H2O2 with 2.6 electrons transferred during the reaction while the CS41/A/PANI, mesoporous carbon obtained from MCM-41 modified with amine groups, presented high catalytic activity compared to Pt/C, leading to complete reduction of O2 to H2O. However, SBA-15 does not generate mesoporous carbons with selectivity for ORR. Then, this result is directly correlated with the influence that the mesoporous carbon suffered by the silica pore size and initial modification with amine or diamine groups. Finally, the chronoamperometry analysis demonstrated carbon materials with stability over a long period and high methanol tolerance compared with noble metals like Pt/C catalysts.

Pyrolyzing soft template-containing poly(ionic liquid) into hierarchical N-doped porous carbon for electroreduction of carbon dioxide

• Soft template-containing poly(ionic liquid) was pyrolyzed to N-doped carbon. • Porosity and N species were modulated by controlling pyrolysis temperatures. • The resultant carbon featured hierarchically small-/ultra-microporous structure. • High-proportioned surface Grap-N species served as the major active sites. • Hierarchical small-/ultra-micropores accounted for the electrocatalysis activity. Heteroatom-doped carbon materials have demonstrated great potential in the electrochemical reduction reaction of CO 2 (CO 2 RR) due to their versatile structure and function. However, rational structure control remains one challenge. In this work, we reported a unique carbon precursor of soft template-containing porous poly(ionic liquid) (PIL) that was directly synthesized via free-radical self-polymerization of ionic liquid monomer in a soft template route. Variation of the carbonization temperature in a direct pyrolysis process without any additive yielded a series of carbon materials with facile adjustable textural properties and N species. Significantly, the integration of soft-template in the PIL precursor led to the formation of hierarchical porous carbon material with a higher surface area and larger pore size than that from the template-free precursor. In CO 2 RR to CO, the champion catalyst gave a Faraday efficiency of 83.0% and a current density of 1.79 mA∙cm −2 at −0.9 V vs. reversible hydrogen electrode ( vs. RHE). The abundant graphite N species and hierarchical pore structure, especially the unique hierarchical small-/ultra-micropores were revealed to enable better CO 2 RR performance.

One-pot synthesis of Mo2C&MoS2 loaded on N/S co-doped carbon materials as the electrocatalyts for hydrogen evolution reaction

Biomass is a potential precursor for preparing functional carbon materials, as the organic component containing nitrogen (N), sulfur (S) would create the atomic dopants to adjust electronic properties of the carbon material. The heteroatom-doped carbon materials loaded with non-precious metal compound is considered to be a promising alternative for hydrogen evolution reaction (HER). Herein, Mo2C and MoS2 nanoparticles with a size of 5 ∼ 20 nm uniformly loaded on the N/S-co-doped carbon sheets (NSC) are prepared via direct pyrolysis of ginkgo leaves with ammonium molybdate tetrahydrate (AMT). Carbon black (CB) is used to replace ginkgo leaves to obtain Mo2C@NC3 to further study the influence of N/S-containing organic components in ginkgo leaves. By comparing with Mo2C@NC3, the XPS reflect the characteristic peak of Mo is positively shifted while the characteristic peak of N 1 s is obviously negatively shifted, indicating a stronger electron interactions of Mo2C&MoS2@NSC3. Benefited from the intense electronics transfer, the efficiency electrochemical active areas of Mo2C&MoS2@NSC3 is larger than Mo2C@NC3 (10.72 vs. 4.97 mF/cm−2), thus the Mo2C&MoS2@NSC3 gives a smaller overpotential of 209 mV to obtain the current density of 10 mA cm−2, together with a low Tafel slope value of 85.5 mV dec-1.

Manipulating oxygenate adsorption on N-doped carbon by coupling with CoSn alloy for bifunctional oxygen electrocatalyst

Highly active bifunctional oxygen electrocatalysts accelerate the development of high-performance Zn-air battery, but suffer from the mismatched activities of oxygen evolution reaction (OER) and oxygen reduced reaction (ORR). Herein, highly integrated bifunctional oxygen electrocatalysts, cobalt-tin alloys coated by nitrogen doped carbon (CoSn@NC) are prepared by MOFs-derived method. In this hybrid catalyst, the binary CoSn nanoalloys mainly contribute to highly active OER process while the Co (or Sn)−N−C serves as ORR active sites. Rational interaction between CoSn and NC donates more rapid reaction kinetics than Pt/C (ORR) and IrO2 (OER). Such CoSn@NC holds a promise as air-cathode electrocatalyst in Zn-air battery, superior to Pt/C + IrO2 catalyst. First-principles calculations predict that CoSn alloys can upgrade charge redistribution on NC and promote the transfer to reactants, thus optimizing the adsorption strength of oxygen-containing intermediates to boost the overall reactivity. The tuning of oxygenate adsorption by interactions between alloy and heteroatom-doped carbon can guide the design of bifunctional oxygen electrocatalysts.

Dissolution of the Heteroatom Dopants and Formation of Ortho-Quinone Moieties in the Doped Carbon Materials during Water Electrooxidation.

Heteroatom-doped carbon materials are widely used as metal-free electrocatalysts and supporting substrates for many metal-based composites. However, almost all the current researches are based on the assumption of the self-stability of the heteroatom-doped carbon materials, neglecting their possible structural evolution during electrocatalysis, especially under harsh oxygen evolution reaction (OER) conditions. Besides, previous researches always focused on the dropcast carbon-based materials with only a few participated dopants, leading to unobservable structural evolution during the electrolysis. Here, heteroatom-doped graphite flakes (GP) with a large quantity of participated dopants are chosen as the research model to multiply the transformation during the electrolysis. Through the combination of theoretical calculations and experiments, we present the nearly complete dissolution of the heteroatoms in N-, P-, and Se-doped carbon materials in the form of the high-valence oxoanions during OER. The oxygen-abundant residues are proven to be responsible for the OER activity. Among the oxygen-containing functional groups in the residues, the ortho-quinone moieties, whose structures change with the doping elements, are finally identified as the active sites. Heteroatom-doped carbon materials as the supporting substrates for the metal-based composite experience a similar transformation, leading to unexpectedly different activity origins. Our work not only reveals the real active sites of the heteroatom-doped carbon materials for OER but also provides new insight into understanding the heteroatom-doped carbon materials as the supporting substrates for other anodic reactions.

Heteroatom-doped hierarchical porous carbon for high performance flexible all-solid-state symmetric supercapacitors

Hierarchical porous carbon shows enormous potential in the field of energy storage due to the open three-dimensional (3D) interconnected porous structure, high porosity, high surface area and excellent conductivity. Herein, we develop a facile strategy to prepare heteroatom-doped hierarchical porous carbon derived from electrostatic self-assembly of chitosan and graphene oxide using potassium citrate as activator. The optimized hierarchical porous carbon exhibits well-developed 3D hierarchical porous framework, large specific surface area and massive nitrogen (4.17 at.%) and oxygen (18.33 at.%) functional groups. Due to their synergistic effect, the NGCA-600 electrode delivers a high specific capacitance of 406 F g –1 at 0.5 A g –1, good rate characteristic and superior cycle stability. Interestingly, the assembled NGCA-600//NGCA-600 all-solid-state symmetrical supercapacitor delivers a large energy density of 14.7 W h kg−1 and superior cycle stability in PVA/KOH gel electrolyte. The above results fully illustrate that the obtained hierarchical porous carbon have broad application prospects in supercapacitors.

Recent progress on porous carbon and its derivatives from plants as advanced electrode materials for supercapacitors

Porous carbon (PC) materials have been extensively employed as electrodes in the energy storage field owing to their large specific surface area (SSA), high durability and unique inner structure. Ulteriorly, the development of new energy-storage systems definitely demands sustainable, low-priced and environmentally nonharmful electrode materials. Many researchers have shifted attention to plant materials and made many efforts, considering that the precursors are rich in carbon elements, easy to scale up, and possess unique channel structures. This review makes retrospect about the recent researches on plant-derived carbon for supercapacitor application, particularly focusing on the influence of structure and components of materials on electrochemical performance. Firstly, the synthesis methods, including physical and chemical activation are discussed in detail. Secondly, multi-component carbon materials, especially heteroatom doping and composite carbon for improving electrochemical performance are also revealed systematically, which contribute to design electrode materials with adjustable pore-size distribution and eligible structure for rapid transport of electrolyte ions and electrons, and hopefully can provide valuable guidance for making full use of the characteristics of plant materials for energy storage. Finally, we put forward current challenges and development trends based on plant-derived carbon materials for supercapacitor application.

Hierarchical mesoporous heteroatom-doped carbon accelerating the adsorption and conversion of polysulfide for high performance Lithium–Sulfur batteries

The critical problem of lithium-sulfur (Li–S) batteries is polysulfide shuttle effect and sluggish kinetics of lithium polysulfide conversion. Herein, a hierarchical mesoporous heteroatom-doped carbon (HMHC) including N, O, S has been fabricated using industrial waste bitumen as carbon source. This HMHC possesses high pore volume, excellent electronic conductivity, strong adsorption of lithium polysulfides and remarkable electrocatalytic effects. This HMHC as sulfur host efficiently suppresses polysulfide shuttle and improves the kinetics of electrochemical reaction. The resultant Li–S batteries with low electrolyte/sulfur (E/S) ratio of 8 μL mg−1 show outstanding electrochemical performance with high initial discharge specific capacity of 1100.6 mAh g−1 at 0.2 C and excellent capacity retention of 91% after 200 cycles. This study provides a facile method to fabricate hierarchical mesoporous heteroatom-doped carbon materials to tackle the problem of polysulfide shuttle in Li–S batteries.

Heteroatom-Doped Metal-Free Carbon Nanomaterials as Potential Electrocatalysts.

In recent years, heteroatom-incorporated specially structured metal-free carbon nanomaterials have drawn huge attention among researchers. In comparison to the undoped carbon nanomaterials, heteroatoms such as nitrogen-, sulphur-, boron-, phosphorous-, etc., incorporated nanomaterials have become well-accepted as potential electrocatalysts in water splitting, supercapacitors and dye-sensitized solar cells. This review puts special emphasis on the most popular synthetic strategies of heteroatom-doped and co-doped metal-free carbon nanomaterials, viz., chemical vapor deposition, pyrolysis, solvothermal process, etc., utilized in last two decades. These specially structured nanomaterials’ extensive applications as potential electrocatalysts are taken into consideration in this article. Their comparative enhancement of electrocatalytic performance with incorporation of heteroatoms has also been discussed.

Heteroatom-doped porous carbon microspheres derived from ionic liquid-lignin solution for high performance supercapacitors

In this work, nitrogen and phosphorus dual-doped alkali lignin-based carbon microspheres (MLCM) were prepared by pre-oxidation and carbonization of ionic liquid ([Mmim]DMP) -lignin solution and used as green-based supercapacitor electrode materials. Compared with the directly carbonized alkali lignin carbon (LC), MLCM had a spherical structure with higher specific surface area (938.1 m2/g) and pore volume (0.64 cm3/g). Moreover, MLCM materials showed superior electrochemical performance. In the 1 mol/L H2SO4 electrolyte system, MLCM presented the highest specific capacitance of 338.2F/g at a current density of 0.8 A/g. Furthermore, MLCM was used as a positive and negative electrode material to assemble a symmetrical supercapacitor. The resultant device maintained excellent cycle stability after 5000 times of charging and discharging process at 2 A/g. Overall, the facile, green and sustainable synthesis strategy of heteroatom-doped porous carbon microspheres developed in this work opens a new avenue for the fabrication of high-performance carbon electrode materials, especially based on abundant and renewable lignin.

Heteroatom-doped porous carbon nanoparticle-decorated carbon cloth (HPCN/CC) as efficient anode electrode for microbial fuel cells (MFCs)

Developing high-performance anode materials is critical for improving microbial fuel cells (MFCs) performance. Carbon nanoparticles derived from plant polyphenols (tannic acid) have attracted our attention due to excellent biocompatibility, great conductivity, easy functionalization, and low cost. In this work, we prepared heteroatom-doped (N, P, S, Co) porous carbon nanoparticles (HPCNs). The HPCNs decorated carbon cloth-based MFCs exhibited areal power density of 1.72 W m−2 and the areal current density of 4.52 A m−2, which was 1.82 times and 1.44 times higher than the carbon cloth (CC) anode. Moreover, the extracellular electron transfer (EET) and cell viability of the electroactive biofilms were substantially enhanced by the proposed anode. Microbial community structure analysis demonstrated that more electrochemically active microorganism types were enriched on the studied anode, and their synergistic effect promoted the EET process. Nanoscale and porous structure of HPCNs can promote biofilm formation. The doping of heteroatoms makes the materials have high conductivity, good biocompatibility and abundant electrochemically active sites, which promote the EET process. This work provides a method for the preparation of anode materials with adjustable structure and excellent properties, and provides a strategy for application of high performance anode in MFCs.

Activity origin of boron doped carbon cluster for thermal catalytic oxidation: Coupling effects of dopants and edges

Catalytic oxidation plays important roles in energy conversion and environment protection. Boron-doped crystalline carbocatalyst has been demonstrated effective; however, the application potential of boron-doped amorphous carbocatalyst remains to be explored. For amorphous carbon material, finite-sized carbon clusters are the basic structural units, which exhibit unique activity due to edge and size effect. Herein, using sulfur dioxide (SO2) and carbon monoxide (CO) oxidation as probe thermal-catalysis reactions, we found the distribution and reactivity of active sites in boron-doped carbon clusters are simultaneously determined by dopants and edges. According to comparisons of oxygen (O2) chemisorption energy at different sites of symmetric and non-symmetric carbon cluster, the most active site is found to be the edge carbon atom with high electron donation ability, which can be accurately identified by electrophilic Fukui function. More importantly, the reactivity of boron-doped cluster is simultaneously influenced by doping configuration and the type of edge, based on which -O-B-O- configuration embedded into K-region edge (isolated carbon–carbon double bonds that do not belong to Clar sextet) is predicted to exhibit the highest reactivity among various boron doping configurations. This work clarifies unique activity origin of heteroatom-doped amorphous carbon materials, providing new insights into designing high-performance carbocatalysts.

Salt Template-Derived Fe-N Co-Doped Ultrathin Carbon for Boosted Performance of Supercapacitors

Heteroatoms-doped ultrathin carbon materials hold great promise for electrochemical energy application. Herein, we develop a salt-templating method to prepare three-dimensional Fe-N co-doped carbon (FeNPC) with ultrathin (~ 5-nm-thick) structural feature. The synthetic procedure involves the following steps: First, fabrication of nanoNaCl templates with uniform particle sizes (~500 nm) via one-pot solution synthesis. Second, fabrication of the precursor by encapsulating of NaCl nanoparticles via the in-situ polymerization of pyrrole monomers under vapor atmosphere. Last, FeNPC formation by subsequent pyrolysis and pickling. The optimized sample displays excellent performance as supercapacitors exhibiting 393.5 F g-1 at 1A g-1 in 6 M KOH. Furthermore, the symmetric supercapacitors assembled with the optimized sample show an energy density of 10.45 Wh kg-1 at a power density of 300 W kg-1 and outstanding cycling stability retaining 93% capacitance at 5A g-1 after 10000 cycles.

Self-Assembly of Caragana-Based into Multiple Heteroatom-Doped 3d-Interconnected Porous Carbon for Advanced Supercapacitors

Self-Assembly of Caragana-Based into Multiple Heteroatom-Doped 3d-Interconnected Porous Carbon for Advanced Supercapacitors

Phytic acid-induced self-assembled chitosan gel-derived N, P–co-doped porous carbon for high-performance CO2 capture and supercapacitor

Heteroatom-doped porous carbon materials (HPCMs) have attracted great attention due to their excellent physical and chemical properties and the enhanced performance of multiple heteroatom co-doping. Herein, N, P-co-doped porous carbon materials (NPPCs) are developed via a novel synthesis of the phytic acid-induced self-assembled chitosan aerogel followed by pyrolysis and activation. Phytic acid serves as a P source, acid regulator and structure-directing agent for improved activation efficiency to create more pores. A little of NaNO 3 is used both as a template and activator simultaneously. The porosity and N content of such NPPCs are controlled by rationally tuning the pyrolysis temperature and the mount of NaNO 3 . The NPPC-0.75-600 delivers a good CO 2 adsorption capability of 3.02 and 5.31 mmol g −1 at 100 and 500 kPa, respectively, and has an excellent stability with almost no adsorption capacity decay even after successive 20 cycles. For supercapacitors (SCs), the NPPC-0.75-700 also displays a high capacitance of 231.2 F g −1 at 1 A g −1 and an outstanding stability at circa 96.7% initial capacity after 10000 cycles. These results highlight the great potential of such NPPCs in CO 2 capture and SCs, and the novel synthetical route offers new insights for the readily scalable production of HPCMs. • Phytic acid induced chitosan gel and served as a P source and activation agent. • N,P-co-doped porous carbon delivered a CO 2 capture ability of 5.31 mmol g −1 at 298 K. • N,P-co-doped porous carbon exhibited specific capacitance at 231.2 F g −1 at 1 A g −1 . • CO 2 capture and supercapacitor performances were substantially improved by P doping.

Self-templating synthesis of heteroatom-doped large-scalable carbon anodes for high-performance lithium-ion batteries

We design a simple and cost-effective strategy to construct a large–scalable nitrogen-rich sulfur-doped porous carbon material as a high-performance anode material for lithium-ion batteries.

Multiple heteroatom-doped photoluminescent carbon dots for ratiometric detection of Hg2+ ions in cell imaging and environmental applications.

Photoluminescence detection and imaging of Hg2+ ions in the biochemical living system are of great importance. In this study, a new photoluminescent probe based on nitrogen (N), sulfur (S), and boron (B) multiple heteroatom co-doped carbon dots (NSB-CDs) is synthesized for the ratiometric detection of Hg2+ ions. The prepared NSB-CDs possess good aqueous solubility, excellent pH and ionic stability, excitation dependency, and high quantum yield (QY = 17.6%). The ratiometric photoluminescent sensor NSB-CDs exhibit high selectivity, sensitivity, and interference towards Hg2+ ions over other metal ions. After adding Hg2+ ions, the emission intensity of the NSB-CDs exhibits a large redshift from 452 to 496 nm (up to 44 nm), corresponding to a notable change from blue to green emission in aqueous solutions. The association constant (Ka), the limit of detection (LOD), and the limit of quantification (LOQ) for NSB-CDs/Hg2+ complex are calculated to be 3.6 × 104 M-1, 3.1 × 10-9 M, and 10.4 × 10-9 M, respectively, in the range of 0-30 × 10-6 M. The live cell bioimaging of HCT-116 cells with NSB-CDs validates the application of multicolor imaging for the detection of Hg2+ ions in aqueous media and biological systems. Moreover, the potential use of the NSB-CDs/Hg2+ complex for real sample analysis is demonstrated.

Heteroatoms Doped Carbon Decorated with Tiny Amount Pt Nanoparticles as a Bifunctional Catalyst for Hydrogen and Chlorine Generation from Seawater

Heteroatoms Doped Carbon Decorated with Tiny Amount Pt Nanoparticles as a Bifunctional Catalyst for Hydrogen and Chlorine Generation from Seawater

Promotion Effects of P and S for Catalytic Oxidation of Methacrolein to Methacrylic Acid Over Heteroatoms Doped Carbon Catalysts

Promotion Effects of P and S for Catalytic Oxidation of Methacrolein to Methacrylic Acid Over Heteroatoms Doped Carbon Catalysts