Boron Co-doping Research Articles

Influence of Kubas-type interaction of B–Ni codoped graphdiyne with hydrogen molecules on desorption temperature and storage efficiency

We have investigated functionalized 2D carbon allotrope, graphdiyne (GDY), as a promising hydrogen storage media. Density functional theory with a range of vdW corrections was employed to study Ni decoration of pristine and boron-doped GDY and the interaction of resulting structures with molecular hydrogen. We showed that boron-doped GDY is thermally stable at 300 K, though, its synthesis requires an endothermic reaction. Also, boron doping enhances Ni binding with the graphdiyne by increasing the charge transfer from Ni to GDY. Ni doping drastically influenced hydrogen adsorption energies: they rise from ~70 meV per H2 molecule on pristine GDY to a maximum of 1.29 eV per H2 becoming too high in value for room temperature reversible applications. Boron doping improves the situations: in this case, after Ni decoration desorption temperature estimation is ~300–500 K. Overall, each Ni adatom on B-doped GDY can bind only one H2 molecule within the needed energy range, which gives low hydrogen uptake (~1.2 wt%). However, doping with boron led to the decrease in the value of hydrogen adsorption energy and good desorption temperature estimations, therefore, codoping of metal atoms and boron could be an effective strategy for other transition metals.

(Invited) Boron and Nitrogen Co-Doped Porous Carbon Nanofibers As Metal-Free Electrocatalysts for Highly Efficient Ammonia Electrosynthesis

NH3 synthesis via the electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions has been regarded as a sustainable strategy for fertilizer production, hydrogen fuel storage, and mitigating greenhouse gas emissions. Electrochemical reduction reaction of nitrogen to ammonia has been widely investigated as a potential technology to overcome thermodynamic barrier of high-temperature and high-pressure needed for industrial Haber-Bosch process. The design of construction of heteroatoms (e.g., B, N, P, S) doped carbon materials have become a research focus as metal-free electrocatalysts owing to their good electrochemical stability and high electronic conductivity. N-doping carbon materials could induce the protonated pyridinic N and adjacent atomic vacancy site, which are favor of N2 adsorption. Besides, on account of charge density difference, B-doping carbon materials could induce inhomogeneity for carbon to adsorb N2 molecules. Compared with single heteroatom dopant, heteroatom co-doping could bring in charge redistribution of carbon, which can facilitate the chemisorption of N2 molecules and following electron transfer.Herein, we present a metal-free B and N co-doped porous carbon nanofibers (B/N-CNF) fabricated by an electrospinning and calcination strategy. The FESEM image of B/N-CNF showed the typical morphology of the cross-linked carbon networks composed of nanofibers with a diameter of ~100 nm. The contents of B and N dopant for B/N-CNF were 29.9% and 27.6%, respectively. The N2 adsorption-desorption isotherms curve of B/N-CNF exhibited a high BET specific surface area of 748 m2 g-1 and a mesopores structure with pore diameter of around 4 nm and volume of ~0.39 cm3 g-1. Benefitting from a high surface area and synergistic effect between B and N dopants, the B/N-CNF exhibited a high electrocatalytic activity for NRR in a basic electrolyte, achieving the highest FE of 13.2% at -0.5 V and the NH3 yield rate of 32.5 μg h-1 mg-1 cat. at -0.7 V. Such a high NRR activity was superior to most of the previously reported B- or N- doped carbon materials. It was found that B atoms facilitated the cleavage of N≡N bonds, and the N atoms enhanced the electronic conductivity of CNF nanofibers.The B/N-CNF delivered superior catalytic activity for electrochemical NRR, featured by the highest FE of 13.2% at -0.5 V and NH3 yield of 32.5 μg h-1 mg-1 cat. at -0.7 V in basic electrolytes. The high NRR performance could be attributed to the synergistic effect between B and N co-dopants. The FE value of B/N-CNF was almost the highest among all previously reported carbon-based materials with single N- or B-doping. Moreover, an electrolyzer with B/N-CNF as the cathode and commercial Ir/C as the anode was successfully fabricated to confirm the NRR activity of B/N-CNF driven by alkaline batteries and solar panels. The developed B/N-CNF presented in this work paves a promising pathway for rational design of highly efficient dual heteroatoms doped carbon materials for not only NRR, but other electrochemical energy conversion reactions.

Advancing the mechanical properties of Si/B co-doped boron carbide through TiB2 reinforcement

Boron carbide experiences glass-like brittle behavior when subjected to high shear stresses due to stress-induced amorphization. Strategies to mitigate amorphization have primarily focused on Si/B co-doping. However, the overall mechanical properties of Si/B co-doped boron carbide are unknown. Here, we delivered a comprehensive report on the mechanical properties of Si/B co-doped boron carbide; and proposed an effective strategy to improve the mechanical properties through TiB2 reinforcement. Vickers hardness of 25.0 GPa, indentation toughness of 2.1 MPa·m0.5, Young’s modulus of 430 GPa, and flexural strength of 338 MPa were measured for Si/B co-doped boron carbide. The reinforcement with TiB2 increased the overall mechanical properties to 26.6 GPa for hardness, 2.3 MPa·m0.5 for indentation toughness, and 410 MPa for flexural strength. The improvements were attributed to the combined effects of grain size refinement and crack propagation alteration due to TiB2 addition.

Edge-enriched graphene with boron and nitrogen co-doping for enhanced oxygen reduction reaction

Carbon-based electrocatalysts for oxygen reduction reaction (ORR), especially in anion exchange membrane fuel cells (AEMFCs), have received a lot of attention because they exhibit excellent stability and are comparable to commercial Pt/C catalysts. Currently, to maximize the catalytic activity of carbon-based electrocatalysts, there are two major strategies: heteroatom doping or exposing active edge sites. However, the approach of increasing heteroatomic dopants of active edge sites has been rarely addressed. In this study, we present a simple strategy to prepare edge-enriched graphene catalysts with an increased ratio of heteroatomic dopants suitable for ORR of AEMFCs. The catalysts were prepared under harsh oxidation conditions, followed by a simple co-doping process with boron and nitrogen. The ORR activity of the catalysts was observed to be related to an increase of edge sites with heteroatomic dopants. We believe that the edge-enriched structure leads to accelerated electron transfer with enhanced oxygen adsorption.

Defect and Threading Dislocations in Single Crystal Diamond: A Focus on Boron and Nitrogen Codoping

For the fabrication of vertical power electronic components, the use of a freestanding highly boron‐doped single crystal diamond substrate is mandatory, on top of which a thin low‐doped active layer is overgrown. The crystalline quality of this substrate is of prime importance as the high doping level required is also likely to lead to the generation of extended defects in the active layer. Herein, the improvement of the quality of thick highly boron‐doped diamond films grown by chemical vapor deposition (CVD) is investigated. Codoping with a low amount of nitrogen is explored as a way to limit the formation and propagation of extended defects. It is shown that the growth rate and boron concentration are not impacted by the addition of nitrogen with the parameters used in this study. Surface morphology and defect density estimated for each amount of nitrogen are presented; and Raman spectroscopy confirms that nitrogen addition compensates the strain induced by boron incorporation in single crystal diamond. Codoping with nitrogen is thus demonstrated as a useful strategy to obtain high quality boron‐doped diamond substrates potentially suitable for the development of power devices.

Boron and Nitrogen Co-Doped Porous Carbons Synthesized from Polybenzoxazines for High-Performance Supercapacitors

Boron and nitrogen co-doped porous carbons (BNPC-X) were synthesized from boron-containing polybenzoxazines through carbonization and chemical activation, where X represents the weight ratio of boric acid to benzoxazine resin. The as-prepared BNPC-X were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, element analysis and electrochemical measurements. The results show that the BNPC-0.15 possesses relatively high weight fractions of boron (2.97 wt %) and nitrogen (2.43 wt %), a homogeneous pore distribution, and remarkable electrochemical capacitive performance. It exhibits high specific capacitance (286 F·g−1 at 0.05 A·g−1), excellent rate capability (at A·g−1), and good charge–discharge stability (>92% capacitance retention after 1,000 cycles at 1.0 A·g−1) in 6 M KOH aqueous solution.

Fabrication and characterization of arc melted Si/B co-doped boron carbide

Boron carbide undergoes stress-induced amorphization when subjected to large non-hydrostatic stresses that exceed its elastic limit. This has been proposed as the source for the abrupt loss of shear strength in boron carbide which limits its engineering applications. Si/B co-doping was suggested as one of the means to suppress stress-induced amorphization but this has not been experimentally verified. Here, by utilizing arc melting, we prepared Si/B co-doped boron carbide with increased Si content as compared to conventional methods. Through Raman analysis in conjunction with indention and elemental analyses based on SEM and STEM (ζ-factor microanalysis), it is suggested that Si/B co-doping is a promising avenue for suppressing stress-induced amorphization. A comprehensive characterization of microstructure, chemistry, and structural change of boron carbide as a result of Si/B co-doping was elucidated.

Facile Preparation of Boron and Nitrogen Codoped Green Emission Carbon Quantum Dots for Detection of Permanganate and Captopril.

A hydrothermal strategy for preparing boron and nitrogen codoped carbon quantum dots was studied using the precursors of p-amino salicylic acid, boric acid and ethylene glycol dimethacrylate. The boron and nitrogen codoped carbon quantum dots have high fluorescence intensity, good monodispersity, high stability, superior water solubility, and a fluorescence quantum yield of 19.6%. Their average size is 5 nm. Their maximum excitation and emission wavelengths are 380 and 520 nm, respectively. Permanganate (MnO4-) quenched boron and nitrogen codoped carbon quantum dots fluorescence through inner filter effect and static quenching effects. The linear relation between quenching efficiency and MnO4- concentration ranged from 0.05 to 60 μmol/L with a detection limit of 13 nmol/L. In the presence of captopril, MnO4- was reduced to Mn2+ and the fluorescence of boron and nitrogen codoped carbon quantum dots was recovered. The linear range between recovery and captopril concentration was from 0.1 to 60 μmol/L. The limit of detection was 0.03 μmol/L. The developed method can be employed as a sensitive fluorescence sensing platform for MnO4-. It has been successfully used for captopril detection in mouse plasma.

One-step nitrogen, boron codoping of porous carbons derived from pomelo peels for supercapacitor electrode materials

In this work, porous KOH-activated biomass carbon (KBC) was obtained from pomelo peel, a simple and effective strategy of one-step incorporating N and B into the porous carbon was introduced. Ammonium borate trihydrate was successfully used to fabricate N, B-codoped KOH-activated biomass carbon (NBKBC) in one-step. NBKBC shows a slight reduction in specific surface area but a distinct higher specific capacitance than KBC. Furthermore, the as prepared NBKBC electrode exhibits an excellent cycling performance. These excellent electrochemical properties of NBKBC were on account of high specific surface area and abundant hierarchically honeycomb-like pores, in particular, N, B codoping. Results shows that it is promising to use such one-step N, B codoping of porous carbons for the synthesis of high performance supercapacitor electrode materials with cheap and easy-available biomass carbons as precursors.

In-built fabrication of MOF assimilated B/N co-doped 3D porous carbon nanofiber network as a binder-free electrode for supercapacitors

Polyacrylonitrile (PAN) based carbon nanofibers (CNFs) show enormous potential as a high performance and cost-effective supercapacitor electrode material. However, there are two intrinsic limitations that prevent their deployment in this field, namely their low surface area and limited transporting channels for ion diffusion. Here, we design an approach that concurrently addresses both problems. We employ electrospinning of PAN and zeolitic imidazolate framework (ZIF-8) nanoparticles to fabricate highly porous CNFs, followed by a sodium borohydride treatment and freeze-drying to maintain the three-dimensionalities of carbon nanofibers networks. Nitrogen and boron co-doping could be achieved together by controlling the conditions for stabilization and carbonization after the ammonium borate tri-hydrate treatment. The novel ZIF-8 incorporated 3D nitrogen and boron co-doped carbon nanofiber electrode was tested as a binder-free supercapacitor electrode and delivered a high specific capacitance of 295 F g−1 at a 0.5 A g−1 current density, exceeding that of PAN-based carbon nanofiber supercapacitor electrodes. Indeed, the novel electrode also maintained a high rate capability and remarkable cyclic stability of 94.5% capacitance retention even after 10 000 charge-discharge cycles. This superior electrochemical performance is attributed to the large surface area, mesoporous nature and high wettability of the B and N doped carbon nanofiber electrode. This study will inspire the development of new 3D PAN and metal organic framework based porous electrode materials for high performance energy storage devices.

Ultrasound-Assisted Nitrogen and Boron Codoping of Graphene Oxide for Efficient Oxygen Reduction Reaction

Development of naturally abundant, low cost, and energy-efficient electrocatalysts for the oxygen reduction reaction (ORR) is essential for commercialization of fuel cells. In this work, we report simple ultrasonication assisted synthesis of nitrogen and boron dual-doped graphene oxide (NB/GO) and demonstrate its application as an effective ORR catalyst realizing predominantly 4e– reduction of O2 to OH– in 0.1 M KOH. Enhanced ORR electrocatalysis of the dual B and N codoped GO as opposed to GO singly doped with B or N arises from the synergistic interaction of the boron and nitrogen species. The content and configuration of both N and B dopants can be readily tailored by controlling the ultrasonic conditions, thereby permitting tuning of the ORR activity. Furthermore, the developed NB/GO metal-free catalyst exhibited very promising long-term durability and resistance to methanol poisoning compared to the state-of the art Pt/C catalyst.

Boron and Nitrogen Co-Doping of Graphynes without Inducing Empty or Doubly Filled States in π-Conjugated Systems

Substitutional B and N doping is a powerful way to modulate the electronic properties of carbon π-conjugated materials. However, the B and N dopants in all the previously reported hybrid materials ...

Self-Assembled Nanofiber Networks of Well-Separated B and N Codoped Carbon as Pt Supports for Highly Efficient and Stable Oxygen Reduction Electrocatalysis

We report a facile synthesis strategy that achieves two goals of carbon support design for oxygen reduction catalysis: (1) self-assembly of hierarchical porous structure, with (2) well-separated nitrogen and boron codoping. The B and N codoped carbon nanofibers (BNCNF) grow directly on a cobalt foil catalyst via a “dissolution–diffusion–precipitation” mechanism using tert-butylamine borane as the source of boron, nitrogen, and carbon. The process releases gaseous boron and nitrogen at different temperatures and times, which greatly inhibits the formation of disadvantageous B–N bonds in the support. BNCNF has hierarchical porosity, large surface area, good structural stability, abundant reaction active sites, and facilitates highly dispersed distribution of platinum nanoparticles. Owing to strong interactions and multiple synergistic effects, Pt/BNCNF has increased oxygen reduction activity and durability in HClO4 solution over that of commercial Pt/C. Pt/BNCNF facilitates a Pt mass activity of 355.4 mA mg–1 (approximate 3.5 times larger than Pt/C) at 0.9 V vs RHE. Furthermore, Pt/BNCNF has better stability and maintains 90.4% of its initial mass activity after 5000 potential cycling tests, which is remarkably higher than that of Pt/C at 50.6%.

Boron and Nitrogen Co-doped Graphene Used As Counter Electrode for Iodine Reduction in Dye-Sensitized Solar Cells

A counter electrode (CE), which acts as an efficient catalyst, plays a pivotal role in dye-sensitized solar cells (DSSCs). Graphene doped by heteroatoms has been regarded as a material having a high reduction catalytic activity to develop efficient Pt-free alternative CE. However, the doping effects accounting for such a catalytic activity remain unknown. In this study, by means of density functional theory calculations, we determined the band gaps, formation energies, and regions of charge-induced impurities to examine the possibilities of B-doped, N-doped, and B–N co-doped graphene (BNG) sheets to replace platinum as CE. Our results demonstrated that the B–N co-doped graphene (BNG) is suitable to be used for CE owing to its small band gap, small formation energy, and having appropriate region of charge-induced impurities. In addition, we considered the iodide reduction reaction on the negatively charged BNG sheet. After injecting two extra electrons, the I2 molecule can strongly adsorb on the BNG surfac...

Synergistic Effects of Boron and Sulfur Co-doping into Graphitic Carbon Nitride Framework for Enhanced Photocatalytic Activity in Visible Light Driven Hydrogen Generation

During in situ thermal co-polymerization of melamine using boric acid and thiourea as the dopant, graphitic carbon nitride (g-C3N4) co-doped with boron and sulfur has been successfully synthesized....

A novel boron and nitrogen co-doped three-dimensional porous graphene sheet framework as high performance Li-ion battery anode material

A boron and nitrogen co-doped 3D porous graphene sheet framework (BN-3DG) is prepared by simple heat treatment of borane tert-butylamine with cobalt ion-exchanged cationic resin. The material has a high specific surface area of 1347 m2 g−1 and is rich in macro, meso and microporous tertiary pore structures. XPS analysis shows that boron and nitrogen are successfully doped within the carbon structure. As a Li-ion battery anode, BN-3DG950 delivers high specific capacities of 1050 and 307 mA h g−1 after 200 cycles at 0.01 and 4 A g−1 respectively. Defects caused by boron and nitrogen co-doping increases the number of available Li-ion storage sites, and the unique interconnected pore structure of the 3D graphene sheet framework enables high cycling stability with rapid electron and Li-ion transport for high rate capability.

Synthesis of Boron and Nitrogen Codoped Porous Carbon Foam for High Performance Supercapacitors

A facile and efficient method to prepare boron and nitrogen codoped porous carbon foam (BNPC) derived from starch with urea as nitrogen source and boric acid as both boron source and templet is pre...

Boosting graphene reactivity with co-doping of boron and nitrogen atoms: CO oxidation by O2 molecule

The aim of this study is to compare the catalytic activity of BCmNn-doped graphene sheets (Gr-BCmNn; m, n = 0, 1, 2, 3 and m + n = 3) towards the oxidation of CO molecule. By performing periodic density functional theory calculations, we show how BN co-doping can boost the surface reactivity of graphene and improve its catalytic performance in the CO + O2 reaction. Our results indicate that the positively charged B atom in Gr-BCN2 and Gr-BN3 sheets is beneficial to the capture of O2 molecule and serve as the catalytic active sites for the CO oxidation reaction. Both Langmuir–Hinshelwood (LH) and Eley–Rideal (ER) mechanisms are considered for the CO oxidation reaction over Gr-BCN2 and Gr-BN3. It is found that the CO oxidation proceeds first via the LH mechanism CO + O2 → OCOO → CO2 + O∗ and then via the ER mechanism CO + O∗ → CO2. The origin of high catalytic activity of these surfaces is attributed to the large electronegative difference between the B and N atoms.

Effect of boron and phosphorus codoping on the electronic and optical properties of graphitic carbon nitride monolayers: First-principle simulations

We study the effect of boron (B) and Phosphorous (P) co-doping on electronic and optical properties of graphitic carbon nitride (g-C$_3$N$_4$ or GCN) monolayer using density functional simulations. The energy band structure indicates that the incorporation of B and P into a hexagonal lattice of GCN reduces the energy band gap from $3.1$ for pristine GCN to $1.9$ eV, thus extending light absorption toward the visible region. Moreover, on the basis of calculating absorption spectra and dielectric function, the co-doped system exhibits an improved absorption intensity in the visible region and more electronic transitions, which named $\pi^*$ electronic transitions that occurred and were prohibited in the pristine GCN. These transitions can be attributed to charge redistribution upon doping, caused by distorted configurable B/P co-doped GCN confirmed by both electron density and Mulliken charge population. Therefore, B/P co-doped GCN is expected to be an auspicious candidate to be used as a promising photoelectrode in Photoelectrochemical water splitting reactions leading to efficient solar H$_2$ production.

The role of compensation defects in Eu3+ stabilization under reductive atmosphere in Sr2SiO4 matrix

Luminescent materials based on strontium orthosilicate doped with a fixed concentration of europium and co-doped with various concentrations of sodium, lithium and boron were synthesized in order to study the role of co-dopants in luminescent properties of europium ions. The obtained materials were characterized using powder X-ray diffraction (XRD) technique. The results of the optical measurements indicate that the incorporation of sodium or lithium increases emission intensity of Eu3+, but does not stabilize Eu3+ under reductive (5% H2/N2) atmosphere, which was observed for the boron co-doping. Moreover, it is shown that the sodium or lithium co-doping facilitates the reduction process of Eu3+ → Eu2+. The obtained results suggest that diffusion limited processes are crucial for the stabilization of Eu3+ during the reduction step of synthesis.