B-doped Graphene Research Articles

Potential of graphene as an adsorbent for HSSS· radical – A DFT investigation

The sulfane sulfur molecules are known to regulate many biological processes for the normal functioning of cells. Herein, the interactions of pristine, B-doped, N-doped, BN-codoped, monovacancy defected, and Stone-Wales (SW) defected graphene with HSSS· radical have been investigated theoretically in the framework of density functional theory (DFT) with an aim to understand if pristine or modified graphene can be used as an adsorbent for HSSS· radical. The analysis based on the structural details, Wiberg bond, ZPE-corrected adsorption energies, reaction enthalpies, reaction free energies and density of states (DOS) reveal that the pristine, BN-codoped, monovacancy defected and SW defected graphene would serve as potential adsorbents for adsorption of HSSS· radicals; the monovacancy defected graphene could be the best choice for this job. It is found that the B-doped graphene would act as a weak adsorbent but the N-doped graphene would not at all be suitable for adsorption of HSSS· radicals.

A novel synthesis route with large-scale sublattice asymmetry in boron doped graphene on Ni(111)

One of the promising ways to functionalize graphene is incorporation of heteroatoms in carbon sp2 lattice, as it is proven to be an efficient and versatile method for controllably tuning chemistry of graphene. We present unique, contamination-free method for selectively doping graphene with B dopants, which are incorporated in layer from a reservoir created in the bulk of Ni(111) single crystal, during standard CVD growth process, leading to clean, versatile and efficient method for creating B-doped graphene. We combine experimental (STM, XPS) and theoretical (DFT, simulated STM) studies to understand structural and chemical properties of substitutional B dopants. Along with previously reported substitutional B in fcc sites, we have observed, for the first time, two more defects, namely substitutional B in top sites and interstitial B in octahedral subsurface sites. Extensive STM investigations confirm presence of low and high concentration regions of B dopants in as-prepared B-doped graphene, indicating non-uniform boron incorporation. Among two substitutional sites, no preference is observed in low-concentration B-doped regions, whereas in high B concentration regions, one of the sublattices is preferred for incorporation, along with alignment of defects. This generates an asymmetric sublattice doping in as-grown B-doped graphene, which is theoretically predicted to result in notable band gap.

Optimizing thermoelectric performance in molecular junction: The role of van der Waals interface coupling with boron-doped electrodes

The key prerequisite for fully rationalizing and optimizing thermoelectric performance of molecular devices is to effectively overcome the inherent mismatch between electrode molecular orbital energy and Fermi level (FL). Two structures were formed by stacking bis-phenylethynyl-anthrancene (BPA-molecule) with B-doped armchair/zigzag graphene nanoribbon (AGNR@B/ZGNR@B) electrodes. Optimal distance between the molecule and these two B-doped graphene nanoribbons was related to interfacial stacking mode (BPA-AGNR@B optimization distance is 3.387\\AA for the case of top-site stacking, and it is 3.472\\AA for malposed stacking of BPA-ZGNR@B). Thermal conductivities of both the two B-doped systems based on mass mismatch mechanism are greatly improved at FL. The role of mass matching effect on total thermal conductance of BPA-AGNR@B system is pivotal to result in significant enhancements, but it is not the case for BPA-ZGNR@B, because large layer spacing weakens mass matching effect. In addition, boron-doped molecular junctions (BPA-AGNR@B and BPA-ZGNR@B) show an excellent thermoelectric quality factor (ZT) of 3.5/3.3 near FL.

An ultrasensitive electrochemical sensor based on boron-doped porous graphene for efficient detection of nitrite in food

Boron (B) doping plays a critical role in adjusting the electronic properties of carbon materials. In this work, B-doped porous graphene (B-PG) was successfully prepared by a simple strategy and used as an advanced electrode material for the detection of nitrite (NO-2) in food. The scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize this B-PG. Due to the ideal doping of boron atoms, the material has good conductivity and exhibits excellent electrochemical catalytic performance. NO-2 was used as the representative analytes to demonstrate the sensing performance of B-PG. It is found that the B-PG modified GCE exhibited a linear response over the concentration range from 3 μM – 3 mM and 3 mM – 15 mM, with a detection limit of 1.1 μM. The designed electrochemical sensor has good analytical performance, such as high sensitivity, good reproducibility and acceptable accuracy, and can be successfully applied to the accurate and precise detection of residual NO-2 in food.

Laser-induced nitrogen and boron co-doped graphene film for dye-sensitized solar cell applications

Heteroatom-doped graphenes play a crucial role in developing metal-free electrocatalysts for dye-sensitized solar cells (DSSCs). This work demonstrates an approach to synthesizing nitrogen and boron dual-doped porous graphene as an efficient DSSC counter electrode (CE) by one-step laser induction technology. The morphologies, crystal structure, and chemical composition of N and/or B-doped laser-induced graphene were characterized and confirmed by SEM, XRD, and XPS measurements. Electrochemical results indicate that the conductivity and electrocalalytic activity of the nitrogen and boron co-doped graphene (BN-LIG) for triiodide reduction were enhanced after B-doping. Hence, the DSSC based on BN-LIG CE achieved a power conversion efficiency of 4.99%, which is 90.9% of a DSSC with Pt CE.

Theoretical study of a Ti4 cluster interacting with B-doped and non-doped multivacancy graphene

A density functional theory study was performed to understand the interactions of a small Ti4 cluster with multi-vacancy graphene. We also consider the effect produced by the B-doping of the vacancy defect. In this sense, we analyze the binding mechanisms of the metal cluster. The focus is set on its stability on the substrate, geometrical structure and the interactions participating between the cluster and graphene substrate. A qualitative study of the principal bonds was carried out employing overlap population and bond order chemical descriptors. Additionally, as an attempt to comprehend better the electronic structure and related properties, we performed total density of states, band structure and magnetic moment calculations to characterize the electrical and magnetic properties of the B-doped and non-doped systems.

A DFT study of the optoelectronic properties of B and Be-doped Graphene

The electronic and optical properties of Boron (B) and Beryllium (Be)-doped graphene were determined using the ab initio approach based on the generalized gradient approximations within the Full potential linearized Augmented Plane wave formalism (FP-LAPW) formalism. Our findings demonstrated that doping at the edges of graphene is notably stable. In both systems, Be-doped graphene proves more efficient in manipulating the band gap of graphene. Both B and Be induce P-type doping in graphene. B-doped graphene exhibits a negligible magnetic moment of 0.000742, suggesting its suitability for catalytic semiconductor devices. Conversely, Be-doped graphene displays a large magnetic moment of 1.045 µB indicating its potential in spintronics. Additionally, this study elucidates the influence of the dielectric matrices on the optical properties of graphene. These findings underscore a stable and controllable method for modelling graphene at its edges with B and Be atoms, opening new avenues for designing of these devices.

Study on ORR reaction of B-doped graphene supported Co atoms with different defects

The performance of single atom catalyst (SAC) is strongly affected by its carrier. Five configurations with single vacancy, double vacancy, and defect site were calculated using density functional theory (DFT), and it was found that the electronic structure and state density were effectively regulated after introducing the B atom. The ORR activity was studied by doping different coordination layers. The results show that when doped with the second coordination layer of Co-DVG-N4 configuration, B can improve the adsorption strength of the central Co atom to the oxygen intermediate and show excellent ORR activity. Co-DVG-N4-B4(12.9 %) and Co-DVG-N4-B5(16.1 %) have relatively low overpotentials of 0.49 V and 0.47 V, providing an effective theoretical basis for rationalizing efficient electrocatalysts based on Co carbon materials.

Laser-Irradiated B-Doped Graphene Showing Enhanced Capacitance in a Fluorine-Free Water-in-Bisalt Electrolyte

Laser-Irradiated B-Doped Graphene Showing Enhanced Capacitance in a Fluorine-Free Water-in-Bisalt Electrolyte

Adhesion properties of the B- and N-doped graphene/Fe(110) interface

Influence of B and N substitutional impurities on the adhesion properties, electronic and magnetic characteristics of the external and internal graphene/Fe(110) semi-coherent interface was investigated by the projector augmented-wave method within the density functional theory. The analysis of interatomic distances, charge densities, charge transfer and magnetic states of atoms was performed. It was shown that B-doped graphene has a higher adhesion energy on the Fe(110) surface and in the iron bulk in comparison with the undoped systems; whereas, N-doped graphene in the Fe bulk demonstrates the opposite trend and on the surface it has no effect. Boron acts as electron donor that increases charges of the nearest C atoms by 0.5–0.6e. Nitrogen due to its high electronegativity is an acceptor and as a result the nearest C atoms lose 0.2–0.3e. Both impurities, depending on the position, influence differently on the magnetic moment of the nearest iron atoms.

Screening for the adsorption-activated H2O2 and peroxymonosulfate for high-performance heteroatom-doped graphene: Molecular dynamics simulation and DFT

As an green and efficient metal-free catalyst, heteroatom-doped graphene has gradually become a research topic in the catalytic field, but the active sites and mechanisms of the catalytic reactions are still not thorough enough. In this paper, the adsorption-activation properties of two activated molecules, H2O2 and peroxymonosulfate (PMS), on graphene (GR) and heteroatom (N, P, B, Si, F) doped graphene were investigated by means of computational methods. Molecular dynamics (MD) simulation results showed that the adsorption activation process of activated molecules on the surface of the six catalysts occurs in their first adsorption layer, in which B-doped graphene (BGR) has better catalytic activation performance for H2O2, while N-doped graphene (NGR) has better catalytic activation performance for PMS. Density function theory (DFT) revealed that the lowest molecular orbital gap of H2O2 at -BCO2 (0.691 eV), PMS at -NC2 has the lowest gap (0.432 eV). It is inferred that -BCO2 and -NC2 functional groups are the main functional regions of H2O2 activation by BGR and PMS activation by NGR, respectively. This work provides useful guidance for the design and optimization of high-performance metal-free catalysts, and the realization of green remediation for wastewater in the electrocatalytic oxidation process.

Density Functional Theory Analysis of the Impact of Boron Concentration and Surface Oxidation in Boron-Doped Graphene for Sodium and Aluminum Storage

Graphene is thought to be a promising material for many applications. However, pristine graphene is not suitable for most electrochemical devices, where defect engineering is crucial for its performance. We demonstrate how the boron doping of graphene can alter its reactivity, electrical conductivity and potential application for sodium and aluminum storage, with an emphasis on novel metal-ion batteries. Using Density Functional Theory calculations, we investigate both the influence of boron concentration and the oxidation of the material on the mentioned properties. It is demonstrated that the presence of boron in graphene increases its reactivity towards atomic hydrogen and oxygen-containing species; in other words, it makes B-doped graphene more prone to oxidation. Additionally, the presence of these surface functional groups significantly alters the type and strength of the interaction of Na and Al with the given materials. Boron-doping and the oxidation of graphene is found to increase the Na storage capacity of graphene by a factor of up to four, and the calculated sodiation potentials indicate the possibility of using these materials as electrode materials in high-voltage Na-ion batteries.

(Invited) Modification of Properties of N- and B-Doped Graphene by Heteroatom Functionalization

Since its discovery in 2004, the graphene has attracted great attention owing to its unique chemical bonding structure, which has excellent chemical, thermal, mechanical, electrical and optical properties. Due to the graphene being a zero band-gap material, it has a limited development in the field of nano electronics. Therefore, to broaden its application scope, it is very important to carry out a study on opening the band gap of graphene. One general strategy for achieving this goal is doping graphene with heteroatoms; in this approach, the properties of graphene are controlled by the nature of the dopant elements and by the percentage of doping being N-doped graphene is of n-type doping, while B-doped graphene is of p-type doping. Compared with that of the intrinsic graphene, the Fermi level of N doped graphene moves up 5 eV; on the contrary, the Fermi level of B doped graphene moves down 3 eV.However, it would be convenient to develop additional tools to achieve further control of the electronic properties of graphene materials. In this context, one of the possibilities would be to functionalize those dopant elements on the graphene sheet in such a way that the electron density and electronegativity of the heteroatom are effectively controlled. This objective could, in principle, be achieved by applying concepts from organic chemistry. Organic synthesis offers proven chemical reactions that are applicable to different types of nitrogen and boron compounds.In the work described here, we´ll present our results on the covalent functionalization of the nitrogen atom or boron atom of N-doped and B-doped graphene. In a simple strategy, electron-donating and -withdrawing groups present on aromatic rings can be used to modulate the electronic properties of the material.

Photocatalytic activity of B-doped nano graphene oxide over hydrogenated NiO-loaded TiO2 nanotubes

A hydrogenated NiO-loaded anatase TiO2 with unique heterostructure nanotube arrays (denoted as H:(NiO/TiO2)) NTs were synthesized, followed by the attachment of boron-doped reduced nanographene oxide nanoparticles (B-nGO NPs) to form a vigorous composite photoelectrode B-nGO/H:(NiO/TiO2) NTs. The p-n junction created between p-type NiO and n-type TiO2 produces sufficient built-in electric field to facilitate the electron–hole pair separation and boost the interfacial electron transfer, subsequently a hydrogenation treatment to adjust the donor density and maximize the electron–hole separation. The microstructure characterization with synchrotron-based X-ray techniques straightened out that the created NiO oxygen vacancies can provide emptier d-orbitals to accept more photoexcited electrons. With the incorporation of B-nGO NPs, the partially replacement of C atoms of nGO by B atoms can form an electron–hole-rich configuration in the heterostructure to decrease the Fermi level, with a more rapid electron transfer toward TiO2 substrate during photocatalysis, which also confirmed by quantum-chemical calculations. The as-synthesized B-nGO/H:(NiO/TiO2) NTs exhibited a high photocurrent density (2.0 mA/cm2) and an effective photoconversion efficiency (2.07%) under simulated sunlight irradiation (AM1.5G, 100 mW/cm2). The eventuated photoconversion efficiency is 6 times enhanced with respect to the pristine TiO2, along with an impressive hydrogen evolution rate of 31 μmol/h/cm2. Moreover, the photocurrent durability test has confirmed the stability of B-nGO/H:(NiO/TiO2) electrode, with only a slight decay of <1% after continuous illumination for more than 4 h. Incident photon conversion efficiency spectra have revealed a boosted photo-response under visible light region (extended to ∼520 nm) with the synergistic attachment of NiO and B-nGO.

On the Challenge of Obtaining an Accurate Solvation Energy Estimate in Simulations of Electrocatalysis

The effect of solvation on the free energy of reaction intermediates adsorbed on electrocatalyst surfaces can significantly change the thermochemical overpotential, but accurate calculations of this are challenging. Here, we present computational estimates of the solvation energy for reaction intermediates in oxygen reduction reaction (ORR) on a B-doped graphene (BG) model system where the overpotential is found to reduce by up to 0.6 V due to solvation. BG is experimentally reported to be an active ORR catalyst but recent computational estimates using state-of-the-art hybrid density functionals in the absence of solvation effects have indicated low activity. To test whether the inclusion of explicit solvation can bring the calculated activity estimates closer to the experimental reports, up to 4 layers of water molecules are included in the simulations reported here. The calculations are based on classical molecular dynamics and local minimization of energy using atomic forces evaluated from electron density functional theory. Data sets are obtained from regular and coarse-grained dynamics, as well as local minimization of structures resampled from dynamics simulations. The results differ greatly depending on the method used and the solvation energy estimates are deemed untrustworthy. It is concluded that a significantly larger number of water molecules is required to obtain converged results for the solvation energy. As the present system includes up to 139 atoms, it already strains the limits of computational feasibility, so this points to the need for a hybrid simulation approach where efficient simulations of much larger number of solvent molecules is carried out using a lower level of theory while retaining the higher level of theory for the reacting molecules as well as their near neighbors and the catalyst. The results reported here provide a word of caution to the computational catalysis community: activity predictions can be inaccurate if too few solvent molecules are included in the calculations.

Graphene for reliable corrosion protection to magnesium alloy in the marine: A first-principles calculation

The detailed mechanisms of graphene to protect magnesium and its alloys are of paramount importance owing to their vulnerable oxidizing corrosion disadvantage. Herein, a density functional theory is used to comprehensively reveal the specific adsorption and penetrating diffusion processes of O adatom on the non–, F-, N-, B-, Si-, P-, S-doped defective graphene, respectively. Theoretical simulations confirm that the graphene is an effective protector for the vulnerable oxidizing corrosion surface of magnesium and its alloy, but the chloride gives rise to the penetrating diffusion of oxygen to be much easier through the defective graphene, which significantly deteriorates its protecting ability to the magnesium surface. Fortunately, we find that the optimal B-doped defective graphene with the highest penetrating diffusion energy barriers can provide a reliable ability to effectively protect vulnerable oxidizing magnesium surface, and thus it can achieve superior oxidative and corrosive resistances in the marine.

Hydrothermally development of boron-integrated graphene nanoparticles for p-n junction diode applications

In this work, boron doped graphene nanoparticles (NPs) were synthesized by the hydrothermal route with different boron tribromide concentrations such as 52, 104, and 156 μL. The structural, morphological and optical properties of the prepared NPs were studied using different characterization techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), atomic force microscopy (AFM), UV–vis spectroscopy and photoluminescence spectroscopy (PL). The XRD pattern reveals the hexagonal crystal structure. The SEM image showed textured sheet-like layers which got agglomerated to form fluffy structures. The TEM images recorded single-crystalline nature and also confirms the particle size was reduced upon increasing boron tribromide solution concentration with recognizable particle shape. The topographic properties of the synthesized B-doped graphene NPs were also studied through AFM images. The UV visible absorbance characteristics peaks 243 and 372 nm were observed correspond to π – π* in C–C bands and n- π* transition. After that as grown NPs were used to fabricate diode junctions on p-Si substrates (p-Si/n-B-doped graphene). The electrical performance of each p-Si/n-B-doped graphene diodes junction was examined using I–V characteristics and electrical parameters of diode junction such as ideality factor, barrier height and reverse saturation current were found 2.9–4.3, 0.75–0.83 eV and 4.88 × 10−6-7.26 × 10−6 A. The calculated ideality factor values of the p-Si/n-B-doped graphene diodes are decreased with increase in boron tribromide solution concentration.

Structure, electronic and optical properties of B single- and double-doped graphene

We investigate the structural, electrical, and optical properties of pure, B single- and double-doped graphene by the first-principles calculation. The results of the formation energy are used to obtain the most stable doped configuration. The energy band of graphene can be opened by B-doped and exhibit a direct bandgap. The Fermi level is mainly contributed by the C 2p orbitals and the B 2p orbitals. Both the complex refractive index and the complex dielectric function satisfy the Kramers-Krönig (K-K) relationship. The peak of the photoconductivity and absorption coefficient of B-doped graphene is weakened. We also found that the electronic transition of B-doped graphene complies with the parity selection rule, and its optical transition is an allowable direct transition. This result is helpful to understand the basic electrical and optical properties of B-doped graphene and has a guiding role in the graphene-based device application.

New insights into enhanced electrochemical advanced oxidation mechanism of B-doped graphene aerogel: Experiments, molecular dynamics simulations and DFT.

B-doped graphene, as an efficient and environmental-friendly metal-free catalyst, has aroused much attention in the electrochemical advanced oxidation process (EAOP), but the bottleneck in this field is to determine the relationship between the surface structure regulation and activity of catalysts. Herein, the B-doped graphene aerogel (BGA) fabricated gas diffusion electrode was prepared and used as a cathode for EAOP to remove tetracycline (TC). Higher free radical yield (169.59μM), faster reaction speed (0.35min-1) and higher TC removal rate (99.93%) were found in the BGA system. Molecular dynamics simulation unveiled the interaction energy of BGA was greater than the raw graphene aerogel (GA). The adsorption-activation process of H2O2 and the degradation process of TC occurred in the first adsorption layer of catalysts. And both processes turned more orderly after B doping, which accelerated the reaction efficiency. Results of density functional theory displayed the contribution of three B-doped structures to improve the binding strength between H2O2 and BGA was: - BCO2 (-0.23eV) >- BC2O (-0.16eV) >- BC3 (-0.09eV). -BCO2 was inferred to be the main functional region of H2O2 in-situ activation to hydroxyl radical (•OH), while -BC2O and -BC3 were responsible for improving H2O2 production.

Adsorption of singlet and triplet oxygen on B-doped graphene: adsorption and electronic characteristics.

The density functional calculations of electronic and structural properties of the adsorption of dioxygen on boron-doped graphene surfaces are conducted using spin-polarized density functional theory methods, including van der Waals correction. The results show significant differences in the adsorption characteristics of singlet and triplet oxygen on boron-doped graphene surfaces. Both triplet and singlet show only weak attraction to intrinsic and singly doped graphene. The singlet oxygen adsorption on doped graphene shows fascinating features involving chemisorption with dioxetane ring formation with appreciable charge transfer. In contrast, the triplet oxygen is only weakly physisorbed on the boron-doped surfaces. Chemisorption of singlet oxygen occurs with noticeable charge transfer and leads to almost featureless band structures, while the triplet oxygen physisorption proceeds with a well-defined band structure. Chemisorption of the singlet oxygen is attributed to the enormous mixing of π* of dioxygen and the p-orbitals of dopant and carbon. Because of the difference in adsorption characteristics, chemically modified graphene can find use in detecting and trapping singlet oxygen, which has potential applications in photodynamic therapy.