Effect Of Heteroatom Doping Research Articles

Peri‐Acenoacene for Solution Processed Distributed Feedback Laser: The Effect of 1,2‐Oxaborine Doping

AbstractZigzag edged nanographenes such as peri‐acenoacenes are promising materials for organic lasers, but the effects of heteroatom doping on the electronic properties and gain medium performance remain unclear. Herein, the facile synthesis of a new 1,2‐oxaborine (BO) doped peri‐tetracenotetracene derivative, the bis(1,2‐oxaborine)peri‐tetracenotetracene (BOTT‐Mes), is reported. X‐ray crystallographic analysis confirms the BO‐doped planar structure and the nonexistence of intermolecular π–π stacking in solid state. Compared with the all‐carbon peri‐tetracenotetracene derivative (TT‐Ar), the BO‐doped BOTT‐Mes exhibits more disrupted π‐conjugation at the BO sites, a lower‐lying highest occupied molecular orbital, and a larger energy gap. Due to its rigid skeleton and nonaggregative feature, it displays well‐resolved absorption and emission spectra with a small Stokes shift (8 nm) and high photoluminescence quantum yield (80%) when it is dispersed in a polystyrene (PS) thin film. Notably, 1,2‐oxaborine doping improves the film amplified spontaneous emission (ASE) performance, with a lower ASE threshold (Eth‐ASE = 66 µJ cm–2) as compared to the TT‐Ar doped PS film (Eth‐ASE = 100 µJ cm–2). Furthermore, a low threshold (22 µJ cm–2) solution‐processed distributed feedback laser is fabricated, indicating the feasibility of using BOTT‐Mes as gain medium for practical laser applications.

Nitrogen-Doped Carbon Nanodots Produced by Femtosecond Laser Synthesis for Effective Fluorophores.

Understanding the effect of heteroatom doping is crucial for the design of carbon nanodots (CNDs) with enhanced luminescent properties for fluorescence imaging and light-emitting devices. Here, we study the effect and mechanisms of luminescence enhancement through nitrogen doping in nanodots synthesized by the bottom-up route in an intense femtosecond laser field using the comparative analysis of CNDs obtained from benzene and pyridine. We demonstrate that laser irradiation of aromatic compounds produces hybrid nanoparticles consisting of a nanocrystalline core with a shell of surface-bonded aromatic rings. These nanoparticles exhibit excitation-dependent visible photoluminescence typical for CNDs. Incorporation of nitrogen into pyridine-derived CNDs enhances their luminescence characteristics through the formation of small pyridine-based fluorophores peripherally bonded to the nanoparticles. We identify oxidation of surface pyridine rings as a mechanism of formation of several distinct blue- and green-emitting fluorophores in nanodots, containing pyridine moieties. These findings shed additional light on the nature and formation mechanism of effective fluorophores in nitrogen-doped carbon nanodots produced by the bottom-up route.

Modulating electronic structure of ternary NiMoV LDH nanosheet array induced by doping engineering to promote urea oxidation reaction

The NiMoV LDH/NF electrode realizes high-efficiency catalysis for UOR in view of the rapid kinetics, high intrinsic activity and robust durability in variable urea concentration and pH values conditions. • Mo and V dopants in NiMoV LDH optimizes the electronic structure to facilitate the in-situ conversion of Ni 3+ species. • Co-doping of Mo and V atoms in NiMoV LDH enhances the adsorption energy of Ni site to urea molecule during UOR process. • 1.40 V is required to achieve 100 mA cm −2 in urea oxidation for NiMoV LDH in alkaline. • The NiMoV LDH electrode is suitable for a wide range of urea concentrations and pH changes. Fabrication of advance electrocatalysts for urea oxidation reaction (UOR) is of great significance for purifying urea-enriched wastewater and producing hydrogen. Here, a doping engineering strategy is adopted to obtain a ternary NiMoV layered double hydroxide (LDH) nanosheet array supported on the three-dimensional (3D) nickel foam substrate. The synergistic effect brought by the unique 2D/3D hierarchical structure could expose more active sites and accelerate charge and mass transfer. In addition, experimental and theoretical results confirm that Mo and V dopants are capable of modifying the local electronic structure of Ni sites to optimize the adsorption energy for urea molecules. Therefore, the as-prepared NiMoV LDH/NF electrode realizes high-efficiency catalysis for UOR in view of the rapid kinetics, high intrinsic activity and robust durability. Specifically, NiMoV LDH/NF electrode presents a low potential of 1.40 V to deliver 100 mA cm −2 for UOR, which is about 260 mV less for its urea-free counterpart in alkaline electrolyte. When anodic NiMoV LDH/NF electrode and cathodic Pt/C electrode are integrated into a two-electrode system for water electrolysis in variable urea concentration and pH values conditions, urea-assisted electrolysis water system exhibit the lower potential (≤1.63 V) than that of conventional water electrolysis at 100 mA cm −2 . This work shows that the local electronic structure adjustment of the active site caused by the heteroatom doping effect could improve the electrocatalytic oxidation performance of some small molecules.

The effect of heteroatom doping on the active metal site of CoS2 for hydrogen evolution reaction.

The exploration of cost-effective hydrogen evolution reaction (HER) electrocatalysts through water splitting is important for developing clean energy technology and devices. The application of CoS2 in HER has been drawing more and more attention due to its low cost and relatively satisfactory HER catalytic performance. And CoS2 was found to exhibit excellent HER catalytic performance after appropriate doping according to other experimental investigations. However, the theoretical simulation and the intrinsic catalytic mechanism of CoS2 remains insufficiently investigated. Therefore, in this study, density functional theory is used to investigate the HER catalytic activity of CoS2 doped with a heteroatom. The results show that Pt-, N- and O-doped CoS2 demonstrates smaller Gibbs free energies close to that of Pt, compared with the original CoS2 and CoS2 doped with other atoms. Furthermore, HER catalytic performance of CoS2 can be improved by tuning d-band centers of H adsorption sites. This study provides an effective method to achieve modified CoS2 for high-performance HER and to investigate other transition metal sulfides as HER electrode.

Investigation of the Heteroatom Doping Effect on Gasification Fine Slag Residue Carbon Oxygen Reduction Reaction Catalysts

Investigation of the Heteroatom Doping Effect on Gasification Fine Slag Residue Carbon Oxygen Reduction Reaction Catalysts

Recent Advancements in the Synthesis and Application of Carbon-Based Catalysts in the ORR

Fuel cells are a promising alternative to non-renewable energy production industries such as petroleum and natural gas. The cathodic oxygen reduction reaction (ORR), which makes fuel cell technology possible, is sluggish under normal conditions. Thus, catalysts must be used to allow fuel cells to operate efficiently. Traditionally, platinum (Pt) catalysts are often utilized as they exhibit a highly efficient ORR with low overpotential values. However, Pt is an expensive and precious metal, posing economic problems for commercialization. Herein, advances in carbon-based catalysts are reviewed for their application in ORRs due to their abundance and low-cost syntheses. Various synthetic methods from different renewable sources are presented, and their catalytic properties are compared. Likewise, the effects of heteroatom and non-precious metal doping, surface area, and porosity on their performance are investigated. Carbon-based support materials are discussed in relation to their physical properties and the subsequent effect on Pt ORR performance. Lastly, advances in fuel cell electrolytes for various fuel cell types are presented. This review aims to provide valuable insight into current challenges in fuel cell performance and how they can be overcome using carbon-based materials and next generation electrolytes.

Functional sulfur-doped zinc-nickel-cobalt oxide nanorods materials with high energy density for asymmetric supercapacitors

Transition metal oxides as the most promising electrode materials for supercapacitors has attracted widespread attention. However, their applications are limited by their sluggish charge transfer kinetics and insufficient active sites. Herein, we report the preparation of sulfur-doped zinc-nickel-cobalt oxides (S-ZNCO) using the synergistic effect of heteroatom doping and defect engineering by hydrothermal treatment and sulfurization method. The morphology and microstructure are characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction (SAED), energy dispersive spectrometry (EDS) mapping, X-ray photoelectron spectroscopy (XPS) and Raman spectra. The results demonstrate the successful doping of sulfur atoms and introduction of oxygen vacancies, which increases the redox reaction active sites and further improves the electrochemical kinetics of the electrode material, giving rise to a high specific capacitance (2919.60 F g−1 at 1 A g−1) and better electrical conductivity of the S-ZNCO electrode. Furthermore, the assembled S-ZNCO-NF//AC device achieves a high energy density of 72.97 W h kg−1 at a power density of 825 W kg−1. This work opens up new opportunities to design of advanced transition metal compounds for supercapacitors.

Study of the Secondary Heteroatoms Doping on Nitrogen‐Doped Carbon and Their Oxygen Reduction Reaction Performance Evaluation

AbstractThe dual heteroatom doped mesoporous carbon (MC) is an excellent substitute for platinum‐based catalyst in cathodic oxygen reduction reaction (ORR) of fuel cells. In this work, nitrogen (N) as the primary heteroatom doping, phosphorus (P), boron (B), and sulfur (S) as the secondary heteroatom doping are introduced in the MC framework. Santa barbara amorphous (SBA‐15) employed as the supporting material to investigate the secondary heteroatom doping effect on MC towards ORR performance. Compared with B and S doping, the P doping modifies the charge delocalization in the MC structure. In addition, it enhances the surface area (971 m2/g), defect sites (1.18), high pyridinic (28.72 %) and high graphitic content (44.42 %) thereby facilitated the remarkable ORR activity. Moreover, electrochemical studies proved that N and P dual doped mesoporous carbon (NPMC) has a better carrier concentration (5.58×1015 cm−3) and higher flat band potential (0.548 V vs RHE) which is confirmed by the Mott‐Schottky analysis. Further, ORR studies demonstrated that NPMC material exhibited more positive onset potential (0.86 V), two‐electron pathway, lower Tafel slope (63 mV/dec) as well as Rct (11 Ω/cm2). In addition, the resultant material is found to be highly active towards ORR with excellent methanol tolerance and stability.

Photoreduction of Carbon Dioxide to Formic Acid with Fe-Based MOFs: The Promotional Effects of Heteroatom Doping and Alloy Nanoparticle Confinement

Photoreduction of Carbon Dioxide to Formic Acid with Fe-Based MOFs: The Promotional Effects of Heteroatom Doping and Alloy Nanoparticle Confinement

High‐performance activated carbons for supercapacitor: Effects of porous structures, heteroatom doping, and morphology

In this work, we prepare a series of activated carbons (ACs) of different morphologies, porous structures, and oxygen contents from glucose with hydrothermal synthesis (HTS) followed by a one-step (H2O-steam or KOH) or two-step (H2O-steam-KOH or KOH-H2O-steam) activation. The largest surface area of the prepared ACs is more than 3400 m2/g, and the corresponding mesopore volume is 1.21 cm3/g. The fraction of oxygen in the ACs varies in a range of 3.94 to 9.9 at%. The electrochemical performance of the symmetric supercapacitor cells (SCs) made from the as-prepared ACs is characterized in different aqueous electrolytes. The optimum capacitance of the SCs is 421 F/g at 0.5 A/g and 304 F/g at 10 A/g. The oxygen-enriched functional groups have limited contribution to the energy storage for the SCs with neutral electrolyte and profound effects on the increase of the energy storage for the SCs with strong acidic and alkaline electrolytes. The processing routes developed in this work likely open an avenue to tailor the structures and oxygen-enriched functional groups of ACs.

Carbon nanotube fibers with high specific electrical conductivity: Synergistic effect of heteroatom doping and densification

Low contact resistance of carbon nanotube (CNT) fibers are fundamental component to improve the electrical transport properties of CNT fibers. To reduce the contact resistance of CNT fibers, we have demonstrated synergistic effect of macroscopic densification in combination with heteroatom doping. Boron and nitrogen atoms were introduced into the hexagonal carbon lattice of the CNTs through judicious combination of high temperature thermal doping and plasma treatment. Chlorosulfonic acid (CSA) was chosen to provide selectively quaternary nitrogen on the sidewall of the CNTs. During this process, densification of the CNT fibers also proceeded, and consequently reduced the hopping or tunneling distance for inter-CNT electron transfer. As a result, we achieved remarkable electrical conductivity of the CNT fibers as high as 5,896 Sm2/kg. The mechanism study by which heterogeneous conduction model proved the decrease of the electrical barrier height of the CNT fibers. These results provide a substantial step towards the use of CNT fibers as conductive materials.

Single Step, Direct Pyrolysis Assisted Synthesis of Nitrogen-Doped Porous Carbon Nanosheets Derived from Bamboo wood for High Energy Density Asymmetric Supercapacitor

Herein, we report a scalable, large-area synthesis of nitrogen-doped carbon nanosheets (N-AC) from bamboo biomass using KOH and urea as the activating and doping agent, respectively, for high performance asymmetric supercapacitor applications. The carbonization of the biomass bamboo at 300 °C for 2 h yields N-AC0 (char) while activation at 900°C for 2 h under inert atmosphere yields N-AC. The detailed characterization of N-AC revealed the significance of heteroatom doping for the supercapacitor application. The N-AC electrode delivered the half-cell specific capacitance of 475 Fg−1 at 1 Ag−1. The assembled asymmetric N-AC||N-AC0 supercapacitor device delivered the highest specific capacitance of 296 Fg−1 at 1 Ag−1 with specific energy of 42 Whkg−1 at specific power of 4500 Wkg−1, which are very high compared to other reported nitrogen-doped carbon materials. This enhanced performance can be attributed to the synergistic effect of larger specific surface area (of 769.714 m2g−1) and hetero-atom (N) doping, which helped in rapid charge-transfer, improved electrical conductivity and efficient electrode-electrolyte interactions. Furthermore, the N-AC asymmetric supercapacitor device works until 1.2 V with 6 M KOH as with 150% capacitance retention over 10,000 charge-discharge cycles. Thus, the strategy presented here provides new directions to synthesize low cost, green, sustainable electrodes for high energy supercapacitor applications.

Effect of heteroatom doping on the charge storage and operating voltage window of nickel-based sulfide composite electrodes in alkaline electrolytes

Broadening the voltage window of nickel-based sulfide composite electrodes in alkaline electrolytes is enormously challenging. In prior work, the voltage window of nickel-based sulfide composite electrodes was broadened to 1.8 V (−0.5–1.3 V. vs SCE). Herein, the voltage window widening mechanism of nickel-based sulfide composite electrodes in alkaline electrolytes is discussed in detail. Our results show that co-doped boron and nitrogen atoms and sulfur vacancies increase the number of electrochemical energy storage sites and accelerate the electrochemical reaction, thereby enhancing charge storage. Additionally, heteroatom doping and the presence of sulfur vacancies can effectively inhibit the water decomposition reaction, broadening the voltage window of nickel-based sulfide composite electrodes in alkaline electrolytes and even exceeding the thermodynamic limit of water. Introducing a mesoporous structure increases the electrolyte storage space, accelerating the OH− transfer and charge transfer dynamics. Aqueous and all-solid-state asymmetric supercapacitor devices are assembled, and at a power density of 1800 W kg−1, the aqueous asymmetric device can obtain a high energy density of 56 Wh kg−1. The all-solid-state asymmetric device shows a high energy density of 49.72 Wh kg−1 at a power density of 1000 W kg−1. A theoretical basis is provided for preparing high-energy nickel-based sulfide supercapacitors with a wide voltage window.

The Synergistic Effect of Heteroatom Doping and Vacancy on The Reduction of CO2 by Photocatalysts

AbstractAgainst the backdrop of rapid world economic growth and energy shortages, we are facing a big challenge about carbon‐containing resources converting. To solve the problems of energy and environmental, developing the catalysts to converse the carbon‐containing resources with high‐efficiency is very important. It has been proved that the vacancy and heteroatom doping can promote the activity of photocatalyst to reduce CO2. Herein, we provide a concise overview on the synergistic effects of defect and heteroatom doping about how to improve the activity of photocatalysts to reduce CO2, and to make a future perspective in the synergistic effects of vacancy and heteroatom doping for photocatalytic CO2 reduction.

Integrated Three-Dimensional Carbon Nanopolyhedron/Metal Sulfides: An Efficient Electrocatalyst Toward Oxygen Reduction Reaction

Carbon-based materials hybridized with metal sulfides have gained growing attention as catalytic materials for oxygen reduction reaction (ORR) due to their synergistic effects in terms of richer structural features and higher electrochemical activities. Here, a series of Zn/Co/Fe-based metal-organic frameworks (MOFs) as the precursors, which can be adopted as efficient ORR catalysts, were synthesized through a sulfuration–calcination treatment. The effects of precursor composition, heteroatom doping, and pyrolysis temperature on the structure and electrochemical performance of the catalysts were discussed in detail. It is found that well-grown carbon nanotubes (CNTs) on the surface of graphitic carbon matrix are formed under the synergy effect of trimetallic-based species during pyrolysis. Benefiting from the three-dimensional unique structure with appropriate dopants and high porosity, the catalyst derived from the optimized Zn/Co/Fe-MOFs achieves a half-wave potential of 0.87 V in an alkaline medium for ORR, which is comparable with commercial electrocatalysts. In addition, an outstanding ORR durability of the proposed catalyst in alkaline media was also demonstrated. This work highlights the potential to rationally design and fabricate high-performance ORR catalysts for commercialization.

Heteroatom-doped porous carbon-supported single-atom catalysts for electrocatalytic energy conversion

Electrocatalysts play a crucial role in the development of renewable energy conversion and storage nanotechnologies. The unique advantages of heteroatom-doped porous carbon-supported single-atom electrocatalysts (SAC-HDPCs) are clear. These SAC-HDPCs exhibit outstanding activity, selectivity and stability due to their distinct electronic structure, satisfactory conductivity, controllable porosity and heteroatom-doping effect. Rapid and significant developments involving the synthesis, characterization, and structure-property-function relationship of SAC-HDPCs have been made in recent years. In this review, we describe recent research efforts involving advanced (in situ) characterization techniques, innovative synthetic strategies, and electrochemical energy conversion examples of SAC-HDPCs. The electrocatalytic performance of SAC-HDPCs is further considered at an atomic level, and the mechanisms underlying this performance are also discussed in detail. We expect that these analyses and deductions will be useful for the design of new materials and may help to establish a foundation for the design of future SAC-HDPCs.

Effects of Heteroatom Doping of Carbon Dots from Sugar on Optical Properties, Phenolic Content, Antioxidant Activity, Photostability, and Cytotoxicity

AbstractCarbon dots (CDs) are fascinating nanomaterials with technologically relevant properties; however, the effects of heteroatom doping on several properties of CDs have not been studied. In this work, a facile method for the synthesis and heteroatom doping of carbon dots from table sugar was developed using nitric acid, phosphoric acid, and sulfuric acid as simultaneous catalysts and dopants. The optical properties, phenolic content, antioxidant activity, photostability, and cytotoxicity of the CDs were measured and compared. L‐ascorbic acid, a well‐known antioxidant, and avobenzone and oxybenzone, common UV absorbers in sunscreens, were used for comparison. Interestingly, heteroatom doping has adverse effects on several properties of the CDs as the undoped CDs yielded the highest UV‐vis absorption, phenolic content, antioxidant activity, photostability, and biocompatibility. Only fluorescence quantum yields were improved by heteroatom doping. These findings will be crucial for choosing precursors for the synthesis of CDs because heteroatoms inherently present in precursors can have negative effects on the properties of the resulting CDs.

Effect of heteroatom doping and morphology tuning of CNT-derived material for potassium-ion hybrid capacitors

Carbon-based materials are all-around anodes for potassium-ion (K+) storage systems. To further boost the electrochemical performance, heteroatom doping (“HD”) and morphology tuning (“MT”) are two prominent ways. However, the detailed influence of “HD” and “MT” is still confused with each other, leading to a derived question that does the preparation sequence between “HD” and “MT” affect the ultimate performance? To reveal these questions, multi-wall carbon nanotube (CNT) is selected as a precursor, and further modulated to N/S dual-doped carbon with hierarchical morphology and corresponding counterparts, respectively. By comprehensive comparisons, “MT” shows an advantage in introducing structural imperfection, making full use of surface absorption and capacitive contribution, while “HD” is good at expanding interlayer, facilitating the diffusion/intercalation of K+. The revealed individual effects of “HD” and “MT” give a convenience to elucidate the role of preparation sequence played in the ultimate performance, subsequently guiding to synthesize N/S dual-doped carbon with hierarchical morphology derived from CNT. Such subtle structure design balances the capacity and capacitive contribution, and shows excellent performance in K-ion hybrid capacitor (a high power density of 21428.6 W kg−1 and remarkable long cycle life of 14,000 times). This unique construction of superior universal anode with great performance provides a new avenue for next storage development and commercial application.

Citric acid-based carbon dots: From revealing new insights into their biological properties to demonstrating their enhanced wound healing potential by in vitro and in vivo experiments

Citric acid, as a carbon precursor, has extensively been considered by researchers to synthesize fluorescent carbon nanodots (CNDs), which emit strongly in the blue spectral range. In an endeavor to repurpose CNDs for applications other than those until now reported, non-doped, nitrogen-doped, and nitrogen/sulfur co-doped CNDs, were synthesized using citric acid as one of the most exploited carbon sources. This study explored the effect of heteroatom doping on the biological properties of CNDs placing more emphasis on wound healing. The three CND species were examined with respect to cell proliferation/toxicity, cell migration, bactericidal, anti-inflammatory, and antioxidant properties. From the results, it became apparent that the N,S-doped CNDs exhibit remarkable bactericidal properties, while the N-doped CNDs exhibit the best anti-inflammatory and antioxidant properties. Based on it, in-vitro antioxidant experiments were carried out for the N-doped CNDs, which validated our findings. Next, the N-doped CNDs were evaluated for their wound healing potency by carrying out relevant in-vivo experiments. The results showed that wounds treated with the CNDs were healed four days faster than control wounds. This study provides valuable insights into inspiring new advancements of CNDs and draws a roadmap towards their broader range of biomedical applications underlining the potency in wound healing.

Regulating the heteroatom doping in metallogel-derived Co@dual self-doped carbon onions to maximize electrocatalytic water splitting

The effect of systematic heteroatom doping on carbon-coated metal nanoparticles in enhancing electrocatalytic OER activity was explored using a series of homogeneously dispersed cobalt nanoparticles encased in N,O-dual self-doped carbon onions.