Effect Of Heteroatom Doping Research Articles

An Ion-Sensitive Field Effect Transistor Using Metal-Coordinated Zeolite-Templated Carbons as a Three-Dimensional Graphene Nanoribbon Network

Zeolite template carbon (ZTC) is a carbon material composed of a three-dimensional network of graphene nanoribbons (GNR), and thus, is expected to exhibit electronic characteristics identical to those of GNR. ZTC is capable of doping heteroatoms in its structure, which offers the advantage of controlling its electronic properties by the presence of the heteroatoms. In this study, we prepared heteroatom-doped ZTCs and applied them to an ion-sensitive field effect transistor (ISFET), for investigating the effect of heteroatom doping on its electronic properties. The ISFET characteristics of un-doped ZTC include bipolarity, whereas oxygen-doped ZTC shows p-type semiconductor characteristics, and nitrogen-doped ZTC shows n-type characteristics. Furthermore, copper and nitrogen co-doped ZTC exhibits high sensor sensitivity (the change of electric conductivity reaches up to 50%) as a carbon-based ISFET. As a result of the analytical evaluation, a copper-nitrogen complex is formed in the co-doped ZTC, and the electronic interaction between copper and nitrogen atoms is able to change electrochemically. Owing to the presence of the copper-nitrogen complex, the co-doped ZTC shows specific ISFET characteristics.

Atomic-Level Understanding of the Effect of Heteroatom Doping of the Cocatalyst on Water-Splitting Activity in AuPd or AuPt Alloy Cluster-Loaded BaLa4Ti4O15

Various studies on functionalization of water-splitting photocatalysts have been performed toward their practical usage. Control of the cocatalyst has been investigated, and recently, in addition to particle-size control, alloying has been extensively used to achieve this goal. It is essential to investigate photocatalysts with precisely controlled cocatalysts to obtain a detailed understanding of the effect of heteroatom doping of the cocatalyst on the photocatalytic activity and thereby establish clear design guidelines for functionalization. However, previous studies have investigated photocatalysts with a variety of particle sizes and doping ratios (chemical compositions). In this study, we succeeded in loading precisely controlled Au24Pd and Au24Pt clusters on BaLa4Ti4O15, which is one of the most advanced photocatalysts, using precisely synthesized alloy clusters as the precursor. Experiments with the photocatalysts loaded with precisely controlled cocatalysts revealed the following three features o...

Conversion of peanut biomass into electrocatalysts with vitamin B12 for oxygen reduction reaction in Zn-air battery

The conversion of biomass into functional carbon materials as electrocatalysts for oxygen reduction reaction (ORR) is a new bridge to use agricultural residues for renewable energy industries. Herein, hierarchical porous carbon material doped with nitrogen and cobalt (Co)-based nanoparticles (N/CoPSAC) has been prepared from biomass (i.e. peanut shells and vitamin B12). The resulting catalyst of N/CoPSAC demonstrates excellent electrocatalytic activities in alkaline media, such as more positive on-set potential and half-wave potential, 4-electron oxygen reduction (n = 3.81) and outstanding stability. The observed ORR activities of N/CoPSAC can be attributed to the synergistic effect of interconnected 3D porous structure and heteroatom doping. Furthermore, the performance evaluation of N/CoPSAC in a more practical setup of Zn-air batteries shows superior durability to that of the benchmark Pt-based electrocatalysts. Hence, the N/CoPSAC electrocatalyst derived from peanut biomass holds a good potential to be used as an alternative for commercial Pt/C in Zn-air batteries.

Robust noble metal-based electrocatalysts for oxygen evolution reaction.

The oxygen evolution reaction (OER) is a kinetically sluggish anodic reaction and requires a large overpotential to deliver appreciable current. Despite the fact that non-precious metal-based alkaline water electrocatalysts are receiving increased attention, noble metal-based electrocatalysts (NMEs) applied in proton exchange membrane water electrolyzers still have advantageous features of larger current and power densities with lower stack cost. Engineering NMEs for OER catalysis with high efficiency, durability and utilization rate is of vital importance in promoting the development of cost-effective renewable energy production and conversion devices. In this tutorial review, we covered the recent progress in the composition and structure optimization of NMEs for OER including Ir- and Ru-based oxides and alloys, and noble-metals beyond Ir and Ru with a variety of morphologies. To shed light on the fundamental science and mechanisms behind composition/structure-performance relationships and activity-stability relationships, integrated experimental and theoretical studies were pursued for illuminating the metal-support interaction, size effect, heteroatom doping effect, phase transformation, degradation processes and single-atom catalysis. Finally, the challenges and outlook are provided for guiding the rational engineering of OER electrocatalysts for applications in renewable energy-related devices.

Porous nitrogen and oxygen co-doped carbon microtubes derived from plane tree fruit fluff for high-performance supercapacitors

Porous nitrogen and oxygen co-doped carbon microtubes (PCMTs) were prepared via carbonization followed by activation of plane tree fruit fluffs (PTFFs) and employed as high-performance supercapacitor electrode materials. The pore structures, surface chemistry and degree of graphitization of the final products can be facilely tailored by adjusting the activation temperature, which changed remarkably as the activation temperature increased from 650 to 900 °C. The PCMT-850 obtained by activating at 850 °C possessed despite the second largest specific surface area (1533 m2/g), but the highest mesopore ratio (9.13%), the maximal nitrogen content (2.20 at.%) and highest degree of graphitization as well as excellent electrical conductivity. The PCMT-850-based carbon electrode exhibited the highest charge storage capacity with a specific capacitance of 257.6 F/g at a current of 1 A/g and the lowest internal resistance in 6 M KOH. The high supercapacitor performance can be attributed to the combined effects of its pore structure, heteroatom doping effects and degree of crystallinity. The favorable capacitive performance render the waste biomass PTFFs serve as novel resources of nitrogen and oxygen co-doped carbon materials for high-performance supercapacitors.

Tuning the Reactivity of Small Metal Clusters by Heteroatom Doping.

The reactivity of small metallic clusters, nanoparticles composed of a countable number of atoms (typically up to ∼100 atoms), has attracted much attention due to the fascinating properties these objects possess toward a variety of molecules. Cluster reactivity often is significantly different from the homologous bulk, with gold as prototypical example. Bulk gold is the noblest of all metals, whereas small gold clusters react with carbon monoxide, molecular oxygen, and hydrocarbons, among others. Furthermore, cluster reactivity is strongly size and composition dependent, allowing a wide range of tuning possibilities. The study of cluster reactivity usually follows two routes of investigation. In the first, research aims for fundamental understanding of mechanisms, mainly driven by curiosity. One consequence of the inherent small size of a cluster is that atoms can arrange themselves very differently from the crystallographic structure of the homologous bulk. In addition, quantum confinement effects dominate the electronic structure of a cluster with atom-like electronic shells instead of the electronic bands in bulk. These features result in a very rich and size-dependent interaction of a cluster with small molecules, governed by a fine interplay between the geometry and the electronic structure of the system. An alternative research approach uses the investigation of chemical reactions of isolated small clusters in the gas phase as model systems for the reactions taking place in more complex systems. This offers several advantages compared to more conventional methods and techniques used to study such complex systems. First, clusters can be produced under well-defined conditions, with control over size, composition, and charge state. Second, clusters in the gas phase solely interact with the molecule(s) chosen by the researcher, since contaminations are limited by the high vacuum conditions of the experiments. Third, due to the small number of atoms involved, detailed quantum chemical calculations can be performed on the systems under investigation. Thus, even though gas phase clusters differ significantly in size and in environmental conditions from those encountered, for example, in industrial catalysis, they can be used to unravel the complicated nature of a metal-molecule chemical bonding process. In this Account, both routes of investigation are discussed. The nature of the interaction between small gas phase clusters with diverse molecules is described, stressing the broader relevance of these studies. Particular emphasis is given to the effect of heteroatom doping. By adding a different element to a cluster, its geometric and electronic structure is modified, thereby altering its reactivity. Specifically, the effect of varying size and composition of doped gold, platinum, and aluminum clusters on their reactivity toward diverse molecules, relevant for catalytic applications, is discussed. Most studies presented here combine experiments based on mass spectrometric techniques with density functional theory calculations, allowing a deep understanding of the reaction mechanisms at a molecular level.

Biomass-derived porous carbon materials for advanced lithium sulfur batteries

Abstract Biomass, as the most widely used carbon sources, is the main ingredient in the formation of fossil fuels. Biomass-derived novel carbons (BDNCs) have attracted much attention because of its adjustable physical/chemical properties, environmentally friendliness, and considerable economic value. Nature contributes to the biomass with bizarre microstructures with micropores, mesopores or hierarchical pores. Currently, it has been confirmed that biomass has great potential applications in energy storage devices, especially in lithium-sulfur (Li–S) batteries. In this article, the synthesis and function of BDNCs for Li–S batteries are presented, and the electrochemical effects of structural diversity, porosity and surface heteroatom doping of the carbons in Li-S batteries are discussed. In addition, the economic benefits, new trends and challenges are also proposed for further design excellent BDNCs for Li–S batteries.

Effects of heteroatom doping on the performance of graphene in sodium-ion batteries: A density functional theory investigation

Heteroatom doped-graphene is a potential candidate as an anode material in sodium-ion batteries (SIBs). However, one of the major issues holding back its development is that a complete understanding of the doping effects accounting for the Na-ion storage of heteroatom-doped graphene has remained elusive. In this work, first principles calculations have been conducted to systematically investigate the electronic and geometric effects in various heteroatom-doped graphene. Graphene doping with pyridinic-N, pyrrolic-N, F and B improves the electrochemical Na storage due to the electronic effect which originates from electron deficient sites (i.e. defects or electron deficient atoms). On the other hand, P doping improves the Na storage ability of graphene due to the geometric effect caused by bond length mismatch. In contrast, the introduction of graphitic-N and S into graphene is inefficient for Na storage because of their inability to accept electrons from Na. Interestingly, the diffusion energy barriers obtained for Na on doped graphene are lower than that for the pristine graphene. Furthermore, co-doping strategy is predicted to achieve even better Na storage capacity due to the synergistic effect.

Role of Doped Nitrogen in Graphene for Flow‐Induced Power Generation

Flow‐induced power generation using nanomaterials, for example, graphene–water interface, has become an attractive energy harvesting mechanism. The effect of heteroatom doping of graphene on flow‐induced electricity is investigated by the authors. Nitrogen‐doped graphene is shown to generate 1.5 times higher power compared with pristine graphene due to surface charges and increase in effective interfacial area. Thus, doping‐induced surface tuning of graphene enhances output performance. The flow‐induced power generation using doped‐graphene allows relaxing the material selection constraints in the triboelectric series.

Three-Dimensional Heteroatom-Doped Nanocarbon for Metal-Free Oxygen Reduction Electrocatalysis: A Review

The oxygen reduction reaction (ORR) at the cathode is a fundamental process and functions a pivotal role in fuel cells and metal–air batteries. However, the electrochemical performance of these technologies has been still challenged by the high cost, scarcity, and insufficient durability of the traditional Pt-based ORR electrocatalysts. Heteroatom-doped nanocarbon electrocatalysts with competitive activity, enhanced durability, and acceptable cost, have recently attracted increasing interest and hold great promise as substitute for precious-metal catalysts (e.g., Pt and Pt-based materials). More importantly, three-dimensional (3D) porous architecture appears to be necessary for achieving high catalytic ORR activity by providing high specific surface areas with more exposed active sites and large pore volumes for efficient mass transport of reactants to the electrocatalysts. In this review, recent progress on the design, fabrication, and performance of 3D heteroatom-doped nanocarbon catalysts is summarized, aiming to elucidate the effects of heteroatom doping and 3D structure on the ORR performance of nanocarbon catalysts, thus promoting the design of highly active nanocarbon-based ORR electrocatalysts.

Carbon aerogel-based supercapacitors modified by hummers oxidation method

Carbon aerogels of an inter-connected three-dimensional (3D) structure are a potential carbon material for supercapacitors. We report a new oxidation modification method to prepare a series of modified carbon aerogels (OM-CA) by Hummers oxidation method. Oxidation-modified carbon aerogels (OM-CA) are obtained from carbon aerogel powders oxidized by Hummers method. Sulfuric acid stoichiometry is studied in order to investigate the effect of the surface oxygen group on surface area and electrochemical performance. Additionally, heteroatoms are doped into carbon aerogels in the oxidation process. The effect of heteroatom doping on electrochemical performance as a supercapacitor electrode material is investigated. When the amount of sulfuric acid is 40 wt%, the dopping manganese content is 0.9 mol%, the specific surface area of OM-CA is 450 m2/g, and its specific capacitance is 151 F g−1 at 0.5 A g−1, which is achieved by heteroatom doping and texture properties. In addition, OM-CA composite supercapacitors exhibit a stable cycle life at a current density of 0.5 A g−1 and retain 98.0% of initial capacitance over 500 cycles, and OM-CA-40% still presents a higher capacity, up to 148 F g−1 at 0.5 A g−1. The high specific surface area and specific capacitance suggest the porous carbon material has potential applications in supercapacitors.

Facile Synthesis of Nitrogen and Halogen Dual‐Doped Porous Graphene as an Advanced Performance Anode for Lithium‐Ion Batteries

AbstractNonmetal‐dual doped graphene has attracted considerable attention as high‐performance anode material for lithium‐ion batteries (LIBs) due to the synergistic effects of heteroatom dopants. Herein, nitrogen and halogen (including Cl, Br, and I) dual‐doped graphene is successfully synthesized by a general wet chemical method and lithium storage performance of N, Cl codoped graphene as anode material for LIBs is investigated in detail. The dual‐doped heteroatoms introduce abundant defects and expand the interlayer spacing of graphene to benefit lithium insertion and extraction. When used as a typical anode material, the N and Cl dual‐doped porous graphene reveals a high specific capacity of 1200 mA h g−1 at 0.1 A g−1 and 1010 mA h g−1 at 1.0 A g−1. The as‐prepared sample exhibits superior cycling performance, whose specific capacity remains 95% at 5.0 A g−1 after 1800 cycles. The excellent performance mainly stems from the synergistic effect of structure modification and heteroatom doping, and the capacitive effects are dictated by kinetical analysis. The synthesized nitrogen and halogen dual‐doped porous graphene is a promising anode material for LIBs.

Biomass-derived carbon materials with structural diversities and their applications in energy storage

Currently, carbon materials, such as graphene, carbon nanotubes, activated carbon, porous carbon, have been successfully applied in energy storage area by taking advantage of their structural and functional diversity. However, the development of advanced science and technology has spurred demands for green and sustainable energy storage materials. Biomass-derived carbon, as a type of electrode materials, has attracted much attention because of its structural diversities, adjustable physical/chemical properties, environmental friendliness and considerable economic value. Because the nature contributes the biomass with bizarre microstructures, the biomass-derived carbon materials also show naturally structural diversities, such as 0D spherical, 1D fibrous, 2D lamellar and 3D spatial structures. In this review, the structure design of biomass-derived carbon materials for energy storage is presented. The effects of structural diversity, porosity and surface heteroatom doping of biomass-derived carbon materials in supercapacitors, lithium-ion batteries and sodium-ion batteries are discussed in detail. In addition, the new trends and challenges in biomass-derived carbon materials have also been proposed for further rational design of biomass-derived carbon materials for energy storage.

Superior potassium storage in chitin-derived natural nitrogen-doped carbon nanofibers

Potassium ion batteries (KIBs) are drawing intensive attention as the next-generation energy storage technology, owning to their similar electrochemical properties to lithium system and rich abundance of potassium resources. The carbonaceous materials with low cost, nontoxicity and high safety have been considered as promising candidates for KIBs anodes. However, they still suffer from several problems, such as poor cycling and rate capability, complex activation process steps and multiple procedures to import heteroatoms doping. Herein, the N-doped carbon nanofibers (NCFs) are fabricated by direct pyrolysis of bio-waste chitin, which is the second most abundant biopolymer throughout nature. The as-prepared NCFs used as KIBs anodes, without any additional activation steps, are systematically investigated for the first time. They deliver high capacity, excellent rate capability and long-term cycling stability, which benefit from the multiple synergistic effects of suitable interlayer spacing, heteroatom doping and unique one dimensional mesoporous structure. With the spotlight of environmental friendliness, low cost and high energy density in energy storage field, the chitin-based NCFs demonstrate great potential for future low-cost energy storage applications.

Tailoring the thermostability and hydrogen storage capacity of Li decorated carbon materials by heteroatom doping

Li decorated graphene is supposed to be a promising material for the hydrogen storage, which can be further improved by heteroatom doping. But a unified promoting mechanism for various doping types and species are still lacking, which hinders the rational design of advanced materials. The potential of N/B doped Li decorated graphene for hydrogen storage is investigated with DFT calculations. A covalent interaction between Li and the graphene substrates is identified to control the thermostability and hydrogen storage capacity (HSC) of the Li decorated substrate, which is in turn subject to the electronegativity of doping species and the doping types. Additionally, a conceptual descriptor is proposed to predict the HSC of Li decorated graphene. These results provide a unified explanation and prediction of the effects of heteroatom doping on Li decorated carbon materials for hydrogen storage.

Metallic Transition Metal Selenide Holey Nanosheets for Efficient Oxygen Evolution Electrocatalysis.

Catalysts for oxygen evolution reaction (OER) are pivotal to the scalable storage of sustainable energy by means of converting water to oxygen and hydrogen fuel. Designing efficient electrocatalysis combining the features of excellent electrical conductivity, abundant active surface, and structural stability remains a critical challenge. Here, we report the rational design and controlled synthesis of metallic transition metal selenide NiCo2Se4-based holey nanosheets as a highly efficient and robust OER electrocatalyst. Benefiting from synergistic effects of metallic nature, heteroatom doping, and holey nanoarchitecture, NiCo2Se4 holey nanosheets exhibit greatly enhanced kinetics and improved cycling stability for OER. When further employed as an alkaline electrolyzer, the NiCo2Se4 holey nanosheet electrocatalyst enables a high-performing overall water splitting with a low applied external potential of 1.68 V at 10 mA cm-2. This work not only represents a promising strategy to design the efficient and robust OER catalysts but also provides fundamental insights into the structure-property-performance relationship of transition metal selenide-based electrocatalytic materials.

Doping and controllable pore size enhanced electrochemical performance of free-standing 3D graphene films

Abstract High quality free-standing 3D nanoporous graphene (3DNG) films were fabricated using nanoporous nickel as template and catalyst. The effect of heteroatom doping and pore size on the electrochemical performance of the 3D graphene films as supercapacitor electrodes are systematically studied. Compared with macroporous graphene films, nanoporous graphene films exhibit an extraordinarily large operational window in neutral, acidic and alkaline aqueous electrolytes, as well as high packing density. Nitrogen and oxygen doping play different roles in different aqueous electrolytes on the electrical conductivity and pseudocapacitance of 3DNG. The realization of both high packing density, 3.65 mg/cm 2 , and the maximum working window, as well as the synergistic effect between N and O doping, gives rise to a high areal capacitance of 435 mF/cm 2 in neutral electrolyte and excellent cycle stability up to 5000 cycles. The results provide a potential strategy to further increase the volumetric or areal energy density of carbon-based aqueous supercapacitor.

Nickel cobaltite nanosheets strongly anchored on boron and nitrogen co-doped graphene for high-performance asymmetric supercapacitors

Strongly coupled boron and nitrogen co-doped graphene (BN-G) hybrids with nickel cobaltite (NiCo2O4) nanosheets (NCO/BN-G) were fabricated by a facile soft-chemical method for asymmetric supercapacitors with high-performance. The strong interaction between BN-G and NiCo2O4 nanosheets are explored by various techniques. The effect of heteroatom doping on electrochemical properties of the hybrids is systematically investigated. The strong synergistic effect between NiCo2O4 and BN-G leads to a specific capacitance of 106.5 mA h g−1 at the current density of 0.5 A g−1 and capacitance retention of 96.8% after 10 000 cycles at 5 A g−1, much better than those of the pure NiCo2O4 and its hybrid with N-doped graphene. Moreover, an asymmetric supercapacitor device, assembled with NCO/BN-G and activated carbon (NCO/BN-G//AC), exhibits a maximum energy density of 45.6 Wh kg−1 and an excellent cycling stability. The improved electrochemical performance of the NCO/BN-G hybrid is attributed to the good conductivity of BN-G and the synergistic effect between NiCo2O4 nanosheets and BN-G combined together through a plane-to-plane contact mode.

Cost-Effective Alkaline Water Electrolysis Based on Nitrogen- and Phosphorus-Doped Self-Supportive Electrocatalysts.

Water splitting into hydrogen and oxygen in order to store light or electric energy requires efficient electrocatalysts for practical application. Cost-effectiveness, abundance, and efficiency are the major challenges of the electrocatalysts. Herein, this paper reports the use of low-cost 304-type stainless steel mesh as suitable electrocatalysts for splitting of water. The commercial and self-support stainless steel mesh is subjected to exfoliation and heteroatom doping processes. The modified stainless steel electrocatalyst displays higher oxygen evolution reaction property than the commercial IrO2 , and comparable hydrogen evolution reaction property with that of Pt. More importantly, an all-stainless-steel-based alkaline electrolyzer (denoted as NESSP//NESS) is designed for the first time, which possesses outstanding stability along with lower overall voltage than the conventional Pt//IrO2 electrolyzer at increasing current densities. The remarkable electrocatalytic properties of the stainless steel electrode can be attributed to the unique exfoliated-surface morphology, heteroatom doping, and synergistic effect from the uniform distribution of the interconnected elemental compositions. This work creates prospects to the utilization of low-cost, highly active, and ultradurable electrocatalysts for electrochemical energy conversion.

Enhanced sodium-ion storage of nitrogen-rich hard carbon by NaCl intercalation

The sodium-ion battery (SIB) has been considered as one of the most important and promising candidates for large-scale storage of electrical energy. Developing cost-effective but high-performance anode materials is crucial for SIBs. Herein a hard carbon-based anode material is synthesized from polyurethane foam. In order to boost its performance, NaCl, one of the most abundant and low-cost salts in the ocean, is used to intercalate hard carbon. To the best of our knowledge, reports on NaCl intercalation in sodium ion battery anode materials are very scarce so far. After Na+ intercalation, the as-obtained sample delivers a capacity of over 210 mAh g−1 at 20 mA g−1. Moreover, a 90 mAh g−1 specific capacity with over 78% retention can be achieved after 1000 cycles at 1 A g−1 current density, which is 100% higher than that of untreated samples. The much enhanced performance can be attributed to a synergetic effect of both heteroatom doping and Na+ intercalation which can improve the electronic/ionic conductivity and enlarge the lattice spacing of the hard carbon as well. This work demonstrates that NaCl-intercalated nitrogen-rich hard carbons are very promising in their ability to serve as a kind of low-cost but efficient anode material for SIBs.