Boron Doping Research Articles

Superhydrophilicity boron-doped cobalt phosphide nanosheets decorated carbon nanotube arrays self-supported electrode for overall water splitting

Transition metal borides (TMBs) or phosphides (TMPs) have attracted great attention to the design of bifunctional electrocatalysts for energy storage. The superaerophobicity and superhydrophilicity of the catalytic electrode surface are crucial factors to determine the reaction process of the gas electrode. Herein, we report a self-supported electrode of carbon nanotube (CNTs) array grown on carbon cloth (CC) modulated together by boron-doped cobalt phosphide (CoP-B/CNTs/CC). The electrode requires the overpotential of 73.8 mV and 189.5 mV at the current density of ±10 mA cm−2 for hydrogen and oxygen evolution reactions in an alkaline electrolyte (1.0 M KOH), respectively, meanwhile maintaining outstanding long-term durability for more than 300 h. The excellent activity of CoP-B/CNTs/CC is attributed to boron doping regulating its electronic structure and further enriching active sites. The attractive stability of CoP-B/CNTs/CC is due to the unique geometric structure of the self-supported electrode. Furthermore, the superaerophobicity and superhydrophilicity of the electrode surface also accelerate the reaction process of the gas electrode. Expectedly, water splitting cells assembled using CoP-B/CNTs/CC electrodes as cathode and anode, respectively, require a cell voltage of 1.54 V at 10 mA cm−2, which is lower than that of the Pt/C/CC||RuO2/CC couple (1.69 V at 10 mA cm−2). Importantly, CoP-B/CNTs/CC||CoP-B/CNTs/CC achieve stable cell voltage under the step current changes (10 mA cm−2, 50 mA cm−2, and 100 mA cm−2) over 300 h. This work highlights a new path to understanding the effects of the static and dynamic behavior of bubbles on the surface of self-supporting electrodes on catalytic performance.

Study on Optical Energy Gap and the Thickness of Boron Doped Graphenic Carbon (B-GC) Film Prepared by Nanospray Method

Graphenic carbon (GC) provides a potential ability as photovoltaic material due to its tunable properties. Here, we investigate the optical energy gap and the thickness of B-GC material as a p-type in solar cell application. The GC was prepared from old charcoal powders of coconut shells by heating process at 400°C and B-GC powders were prepared by wet mixing method using boric acid as B atom source. B-GC films were then prepared by employing nebulizer as a nanospraying method. All samples were examined through various characterization techniques such as X-Ray Diffarction (XRD), SEM cross section, and UV-Vis spectroscopy. The amorphous characteristic of B-GC is confirmed by broad peaks in XRD patterns, similar to that of reduced graphene oxide (rGO). The present of B along with O and dominant C elements is determined by SEM-EDX result. The B dopants affect the optical bandgap energy (Eg) of GC as an intrinsic material. The thickness of B-GC films was found to be thinner than in a previous study that used a similar method but different equipment. The average thickness of B-GC films is in the range of 127 to 420 nm, followed by an increase in the deposition time for 5 to 20 s. Estimation of the Eg value indicated that B-GC has an energy gap around 2 eV, which is most suitable as a window layer in solar cell applications.

Boron doped diamond electrode for efficient persulfate generation: The modulation of boron doping level on interfacial electron transfer

The inefficient Faradaic efficiency of electro-synthesis of sodium persulfate (Na2S2O8) hinders its industrial application. In this work, modulated high-performance boron-doped-diamond (BDD) electrodes were used to Na2S2O8 electro-synthesis. The effect of boron doping level of BDD electrode on Na2S2O8 generation was studied for the first time. Based on electro-synthesis results, BDD (0.05% B) electrode produced more Na2S2O8 (41.85 mM at 120 min) with the Faradaic efficiency of 90% that is the highest value reported in the literatures. Na2S2O8 was generated by ·OH mediated indirect oxidation, and the BDD (0.05% B) electrode produced more ·OH. Furthermore, the less C-O functional groups on the BDD (0.05% B) electrode surface inhibited the interfacial electron transfer of H2O to O2, and therefore promoted ·OH formation. These findings highlight the relationship between boron doping level, surface functional groups, interfacial electron transfer process and Na2S2O8 generation, providing a theoretical guidance for efficient Na2S2O8 electro-synthesis.

Enhanced removal efficiency of bensulfuron-methyl by a novel boron doping biochar-based Acinetobacter YH0317 at a lower temperature

Biochar-based bacteria are regarded as an efficient strategy for remediating organic pollutants in aquatic environments. Herein, a strain named Acinetobacter YH0317 that could degrade bensulfuron-methyl (BSM) at a lower temperature (15 °C) was isolated from a paddy rice field with long-term BSM application. Then Acinetobacter YH0317 was loaded on unmodified biochar (BC) and boron doping biochar (BBC). Results showed that BBC-based YH0317 significantly enhanced the removal efficiency of BSM (71.8–99.1%) compared with BC-based YH0317 (41.9–44.0%) and YH0317 alone (18.1–20.7%) in 24 h. BBC promoted the growth of YH0317 and secretion of extracellular secretions by providing a carrier and shelter for YH0317. The electrochemical analysis suggested BBC improved the electron transfer rate, which ultimately facilitated the removal of BSM. Hydroponic experiments indicated that BBC-based YH0317 effectively improved the growth of soybean. This work reports a novel BBC-based Acinetobacter YH0317 that could effectively remediate BSM contamination in the water environment.

Boron Dopant Modulated Electron Localization of Tin Oxide for Efficient Electrochemical CO2 Reduction to Formate.

Sn-based electrocatalysts have great economic potential in the reduction of CO2 to HCOOH, while they still suffer from low current density, dissatisfactory selectivity, and poor stability. Inspired by electronic modification engineering, boron-doped SnO2 nanospheres (B-SnO2 ) are successfully synthesized to achieve high-efficiency CO2 reduction reaction (CO2 RR). It is found that the introduction of boron dopants can increase the number of active sites and facilitate the formation of the electron-rich Sn sites in its structure, thus enhancing the activation of CO2 molecules and reducing the energy barrier of *OCHO intermediates on the SnO2 surface. Thus, the B-doped SnO2 electrocatalyst exhibits a remarkable FEHCOOH above 90% within a broad potential window of -0.7 to -1.3V versus reversible hydrogen electrode (RHE) (600mV) and obtains the maximum value of 95.1% (the partial current density of HCOOH is 42.35mA cm-2 ) at -1V versus RHE. In conclusion, this work provides a novel strategy for optimizing the intrinsic properties of electrocatalysts for CO2 RR by the method of tuning the electronic structure.

Mechanism of high PEC performance of B-doped TiO2 nanotube arrays: Highly reactive surface defects and lattice stress

The role of the boron (B) doping induced defect state in the PEC process is still unclear though B doped TiO2 nanotube arrays (TNAs) via anodic oxidation has commonly used to improve the photocatalytic decomposition of water by TNAs. Therefore, this work aims to establish the underlying reasons for the high PEC reactivity and stability maintained by the B doping induced defective states. Special attention is paid to the differences in carrier behavior and surface reactivity in the PEC process between the B doped induced and NaBH4 treatment induced defective states. DFT calculations show that B doping can effectively reduce the generation energy of Ti3+/Vo (oxygen vacancies) pairs and enhance the adsorption energy of defects on the surface of TiO2 (101) for H2O and ·OH. Moreover, due to the presence of B atoms, the surface defects of TiO2 can maintain high adsorption of H2O and ·OH, without being deactivated by the healing of oxygen vacancies, which ensures the stability and activity of the catalyst. Meanwhile, the lattice stress induced by B doping forms the internal electric field, which ensures the efficient separation of carriers in the bulk phase and avoids the negative effect of bulk phase defects on carrier separation.

Boron substitution induced FCC Fe/Cr23C6 interfacial strengthening: An ab initio study

Boron is added to stainless steels and polycrystalline superalloys to promote ductility, corrosion resistance, and retard creep at high temperatures (above 700 °C). However, the role of local atomic environment(s) and how boron may impact the interfacial properties between the Cr23C6 precipitate, and the matrix are not fully understood. In the present work, we consider the face-centered cubic (FCC) Fe (001)/Cr23C6 (001) interface as a model system to study how the interfacial local atomic structure and energy are affected by boron doping using first-principles density functional theory (DFT) calculations. The atomic structure(s) and energetics of a coherent interface were calculated by including the elastic contribution using linear elasticity theory combined with DFT. Boron has a significant effect on the interfacial energy and the atomic arrangement near the interface region through the increased covalent bonding, thereby ordering the interface and making any diffusion processes less favorable energetically. In turn, this may contribute to the retardation of the Cr23C6 precipitate growth and coarsening. Because of the concurrent precipitation of the NbC, Cr23C6, and Sigma phases, it affects the whole cascade of microstructural evolution processes contributing to creep. More specifically, the ancillary additions of boron to the A-terminated Cr23C6 significantly reduce the interfacial energy (∼0.09 J/m2) between the iron matrix and the Cr23C6: from ∼ 0.38 J/m2 without doping to 0.29 J/m2 with doping. This interfacial energy decrease due to boron additions is an important factor in interface strengthening and retarding creep in austenitic stainless steels. Such B-induced short-range order interface strengthening is facilitated via promoting interface covalence bonding and considerable local lattice distortion due to the atomic size misfit. These results were obtained using the new interface model described in the paper. This new interface model allows to quantitatively distinguish the highly complex asymmetric interface structures and corresponding interfacial energies and surface energies.

A unique sustainable chemical method for the recovery of pure silicon from waste crystalline silicon solar panels

The present work suggests a unique approach for recovering pure silicon from end-of-life silicon solar panels by a direct treatment which does not involve the use of Hydrofluoric Acid (HF). Firstly, the better alkaline treatment between NaOH and KOH was determined. Then, effects of HF etching time and concentration were studied by comparing different etching treatments. Metal impurities such as Ag, Sn, and heavy metal Pb decreased considerably during the acid leaching studies with suitable concentrations. The major impurity Aluminium was reduced significantly by a two-step chemical treatment which ensures minimal silicon loss. Although it is possible to recover 4 N pure silicon by both (with and without HF etching) methods, direct treatment is preferred since the process eliminates potential human health and environmental concerns associated with HF. The recovered silicon samples were analysed by ICP-OES to detect impurity concentration, by XRD for phase identification and SEM analysis for surface morphology. The critical doping impurities, boron and phosphorous dropped considerably to 18.7 ppm and ND in direct treatment. Thus, the study not only provides an alternative way for recovering pure silicon without the use of harmful chemicals such as HF, but it also recommends a 6 M nitric acid leaching treatment before the etching procedure to lower the concentration of metallic impurities. The results are based on treatments with commercial grade chemicals which ensures the scalability of the process at commercial batch. The profit analysis of the recoverable metals was carried out and estimated to be nearly $19 for an 18 kg c-Si module.

BiVO4/boron-doped diamond heterojunction photoanode with boron doping engineering and enhanced photoelectrocatalytic activity

Photoelectrocatalysis is one of the most promising strategies to address ever-growing wastewater problems. A novel heterojunction photoanode formed by depositing a photocatalyst on a boron-doped diamond (BDD) layer has been considered an ideal material for the practical application of photoelectrocatalytic (PEC) degradation due to its advantages of light responsiveness, excellent charge transport, and robustness. In this study, various BiVO4/BDD heterojunction photoanodes with different diamond crystalline qualities and electrical conductivities were successfully fabricated by tuning the boron (B) doping concentration of the BDD layer. It was proposed that the charge transport efficiency of the photoanodes is promoted by optimizing the crystalline qualities and electrical conductivities of BDD films, thereby enhancing the PEC activity of the BiVO4/BDD heterojunction photoanode. Our results suggested that the electrical conductivity of BDD increased and the crystalline quality of BDD deteriorated with increasing B doping concentration. As a result, the PEC activity of the BiVO4/BDD heterojunction photoanode first increased and then decreased. The optimal PEC activity of the BiVO4/BDD heterojunction photoanode was achieved corresponding to the [B]/[C] gas ratio at 500 ppm, producing a current density of 3.3 mA/cm2 at 1.6 VRHE (the potential versus a reversible hydrogen electrode) in 0.1 M Na2SO4 under AM 1.5 irradiation, which was 1.7 times (1.9 mA/cm2) that of the photoanode with a [B]/[C] gas ratio of 3000 ppm. Meanwhile, the optimized tetracycline hydrochloride (TCH) degradation efficiency was 63.5 % within 9 min (500 ppm gas phase), which was 2.5 times (25.1 %) that of the highly doped photoanode with a [B]/[C] gas ratio of 3000 ppm. This study revealed that the excellent PEC performance benefited from the high crystalline quality and high electrical conductivity of BDD, which depended on the optimized B doping concentration. The idea of enhancing the PEC activity of the photoanode by optimizing the properties of the conductive electrode material proposed in this study provides a conceptual reference for fabricating potential high-performance photoanodes in the future.

Lewis acid sites incorporation promotes CO2 electroreduction to multicarbon oxygenates over B-CuO nanotubes

Herein, we designed a C2+-producing catalyst by incorporating Lewis acid boron dopant into porous copper oxides nanotubes (B-CuO NTs) via a convenient electrospinning−calcination method. The B-CuO NTs catalyst achieved a 60.5% C2+ Faraday efficiency (FE) including 47% of ethanol, a 4-fold increase over CuO in a flow cell at − 0.6 V vs reversible hydrogen electrode (RHE). In situ characterizations demonstrate that the strong ability for *CO adsorption on B-CuO NTs facilitates the hydrogenation to the *CHO intermediate and promotes the C-C coupling further to *OCCHO intermediate via the proton-coupled electron transfer reactions. Theoretically calculations demonstrate that B doping induced polarized charge redistribution could suppress the *CHO transfer to C1 products by reducing the energy barrier for further OC-CHO coupling. This work provides a comprehensive understanding of Lewis acid B doping effect on regulating the C-C coupling pathway and improving the C2 selectivity.

Enhanced capacitive performance by synergistic effect of interfacial functional groups and doping defects in honeycomb-like multi-chamber carbon

As a typical double-layer capacitive electrode material, carbon nanomaterials show desirable application potential in the field of capacitive deionization (CDI) and supercapacitors (SCs). In this work, interfacial functional groups and B\\O co-doping defects are simultaneously introduced into multi-chamber carbon with confinement effect, and their practical applications in CDI and flexible capacitors are also studied. Specifically, the oxygen-rich carbon source and boron source, dissolved and mixed completely via co-crystallization method, released amount of gas during the pyrolysis process to produce multi-chamber honeycomb-like carbon with ultrathin walls, which were further introduced into abundant interfacial functional groups by dopamine to optimize the carbon surface. At the same time, part of boron atoms entered the carbon lattice to form boron doping at high temperature, followed by the integration with the oxygen heteroatoms in carbon source to generate abundant boron and oxygen codoping defects. The as-prepared diatomic defects by the synergistic effect promote the wettability and pseudocapacitance of the material. In addition, the derived carbon materials are endowed with good hydrophilic ability and surface activity under the modification of dopamine functional groups. The ideal hydrophilic ability ensures that the porous structure of material can be infiltrated by electrolyte to provide large effective specific surface area, which enhances the electrical double-layered capacity. The interfacial functional groups also offer additional pseudocapacitance, so as to improve the ion adsorption capacity of PDA-BOC.

Boron-10 stimulated helium production and accelerated radiation displacements for rapid development of fusion structural materials

Boron doping, combined with neutron capture in fission reactors, has been used to simulate the helium effect on fusion structural materials. However, inhomogeneous helium bubble formation was often observed due to boron segregation to grain boundaries. The excess radiation displacements due to 10B(n, α)7Li reaction, the high-energy lithium and helium ions, also were not accounted for, which can significantly accelerate the displacements-per-atom (dpa) accumulation alongside helium production (appm). Hereby an isotopically pure 10B doping approach is proposed to simulate the extreme environment inside fusion reactors with a high He appm-to-dpa ratio of about 10, which is about 102 × larger than in fission reactors. Computational modeling showed that ∼13% of total radiation displacement was induced by 10B(n, α)7 Li in the case of 1 000 appm 10B doped Fe samples, which becomes even greater with increasing 10B loading. Spatially homogenous radiation damage and helium generation are predicted for grain sizes less than 1 μm, even if the boron partially formed precipitates or segregates on grain boundaries. Feasibility studies with various 10B doping (and 235U-codoping) levels in research reactors showed the estimated helium generation and radiation damage would significantly mimic fusion conditions and greatly expedite fusion materials testing, from many years down to months.

Synthesis and Evaluation of Boron, Cerium, and Silver Ternary Doped Titanium Dioxide Photocatalysts for Degradation of Ciprofloxacin (CIP) Antibiotic under UV - A Irradiation

Synthesis and Evaluation of Boron, Cerium, and Silver Ternary Doped Titanium Dioxide Photocatalysts for Degradation of Ciprofloxacin (CIP) Antibiotic under UV - A Irradiation

A Theoretical Study on Photocatalytic Water Splitting of Boron Doped Defective Zirconium Dioxide

At present, environmental crisis and energy problems are becoming more and more serious. Finding a sustainable green energy source is urgent. Solar energy has attracted widespread attention. Here, we have meticulously investigated the application of boron atom-doped defective zirconia catalysts for photocatalytic water splitting through theoretical calculations. We know that doping boron atom greatly promotes the generation of oxygen vacancy defects in the zirconia catalyst, and the boron atom-doped defective zirconia catalyst has better photocatalytic water splitting performance than the pristine zirconia catalyst. In addition, boron atom-doped defective zirconia catalysts have higher stability. Through electronic structure analysis, the photo-response in the photocatalytic water splitting system and the fundamental reasons for the improvement of catalyst stability were explored. The introduction of boron atom promoted the generation of defect impurity electronic states, which made the antibonding state of the catalyst more stable cling to the Fermi level. Finally, the great photocatalytic water splitting performance of the boron-doped defective zirconia catalyst was confirmed with the difference in Gibbs free energy in photocatalytic water splitting process.

Transition metal-functionalized porphyrin-like C70 fullerenes as sensors and adsorbents of formaldehyde- DFT, NBO, and QTAIM study

C70 fullerenes are effective formaldehyde sensors and adsorbents, with nitrogen or boron doping significantly increasing their sensitivity in detecting formaldehyde gas. C70 fullerenes doped with nitrogen atoms are effective in removing formaldehyde from the air. In this work, the potential of transition metal- (Ti, Cr, Fe, Ni, and Zn) functionalized porphyrin C70 fullerenes (MF-PC70Fs) for sensing and removing formaldehyde were investigated using DFT, QTAIM, and NBO. The HOMO-LUMO gaps for Ti, Cr, Fe, Ni, and Zn-functionalized materials were computed, resulting in values of 1.27, 0.07, 1.84, 1.84, and 1.80 eV, respectively. The absorption energies of formaldehyde onto MF-PC70Fs were computed, revealing that the PC70Fs functionalized with Ti had the highest adsorption strength, while those functionalized with Ni had the lowest. The HOMO-LUMO gap of Cr- and Fe-functionalized PC70Fs was significantly changed after adsorbing formaldehyde. Accordingly, they may be used as conductivity-type sensors for detecting formaldehyde. Also, Cr-, Fe-, and Zn-functionalized PC70Fs can be used as formaldehyde work function type sensors. According to the calculated time recovery of MF-PC70Fs, Fe- and Zn-functionalized PC70Fs are more favourite materials than Cr-functionalized in formaldehyde sensors.

A DFT study to investigate the physical, electrical, optical properties and thermodynamic functions of boron nanoclusters (MxB2n0; x=1,2, n=3,4,5)

First Principle DFT calculations employing the B3LYP/LanL2DZ/SDD level of theory were used to analyze the various characteristics of boron nanoclusters (B6, B8, and B10). These pure structures were further doped with four transition metals (Ta, Ti, Tc, and V) to examine the enhancement of the pure structures' structural, electrical, and optical features. To study structural stability, we have estimated cohesion energy and imaginary frequencies. Cohesion energies were entirely negative, with a range of −3.37 eV to −8.07 eV, and most constructions had no imaginary frequencies, indicating their structural occurrences. The calculated adsorption energy suggests that the order of stability of the pristine boron nanoclusters is B10>B8>B6, and TcB10 and Tc2B10 are the more stable structures. Mulliken charge, DOS, HOMO-LUMO, and the HOMO-LUMO gap have all been examined in-depth to provide insight into electrical characteristics. UV–Vis and CD measurements show the doped boron nanoclusters have excellent optical properties. Aside from calculating thermodynamic functions, we have also calculated the global DFT parameters, which give us a deep quantum mechanical understanding of the optimized structure for further research and applications in the field of science and technology.

SЕNSORS BASED ON POLYCRYSTALLINE 3C-SiC: IMPACT OF BORON DOPING

As a chemically inert wide bandgap semiconductor material with high hardness and thermal conductivity, stable electrical characteristics, silicon carbide SiC is attractive for harsh environment electronics and sensors applications. The concept of harsh environment includes extremes of temperature, pressure, shock loads, radiation and chemical attacks those arise in aircraft and automotive engines, industrial gas turbines, during oil and gas exploration, etc.
 Lower growing temperatures of polycrystalline cubic silicon carbide, pc-3C-SiC, compared to monocrystalline allow to significantly reduce its cost and expand the possibilities of application. It follows from previous works that the thermal sensitivity of pc -3C-SiC can be significantly increased by doping with an acceptor impurity of boron during the growth of the material. The purpose of this work is to determine the properties of pc-3C-SiC doped with boron for the creation of photosensors and thermosensors, as well as thermal anemometers for extreme operating conditions.
 It is shown that pс-3C-SiC doping with a boron impurity in the growth process causes the formation of acceptor-type centers in the band gap and the appearance of features in the photosensitivity spectrum, which may be of practical interest for photovoltaics. For temperatures T > 150K, the conductivity of the doped sample increases almost exponentially with an activation energy of 0.28 eV, which is close to the activation energy of the photoconductivity of the same sample. This indicates that the ionization process of equilibrium and non-equilibrium charge carriers occurs from the same impurity centers. Boron doping causes the appearance of a broad photoconductivity band with a maximum at 1.7 eV in the impurity absorption region of pc-3C-SiC, similar to the situation in single crystal 3C-SiC.
 It was determined that the temperature coefficient of resistance for boron-doped pc-3C-SiC is 3.0´10-2 K-1 at T=300K and 1.1´10-2 K-1 at T=700K, which is almost an order of magnitude higher than for thermocouples, as well as for metals from which anemometer threads are made. The discussion of the obtained results allows to associate the value of the activation energy E=0.28 eV with the level of shallow boron in pc-3C-SiC and to assume this center is a point defect containing a boron atom that replaces a silicon atom in the 3C-SiC lattice, i.e. BSi.
 Photosensors that can be used as solar cells in the near-IR range of 0.6 - 1.8 μm, and as photocells in the visible range of 0.4 - 0.6 μm are proposed. The ability of pc-3C-SiC to work in extreme operating conditions, as well as the low cost of device manufacturing technology based on it, compared to other SiC polytypes, allow it to be considered a suitable material for creating temperature sensors, thermo-anemometers and photosensors, as well as detectors for monitoring nuclear facilities.

Hydrothermal Synthesis of Boron-Doped Graphene for High-Performance Zinc-Ion Hybrid Capacitor Using Aloe Vera Gel Electrolyte

The great interest in developing emerging zinc-ion capacitors (ZIC) for energy storage applications is due to their inexpensiveness and the future necessity for hybrid electrical energy storage devices. The Zn-ion hybrid capacitor device was assembled using boron (B)-doped reduced graphene oxide (B-RGO) material, which acts as the cathode, and pure zinc metal as an anode. This research work aims to study the influence of B-doped reduced graphene oxide (B-RGO) with Aloe vera gel as an electrolyte. The reduced graphene oxide (RGO) and B-RGO electrode active materials were confirmed through X-ray diffraction (XRD), RAMAN, Fourier transformation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and field emission-transmission electron microscopy (FE-TEM) analysis. The surface morphological images reveal that a few-layered nanostructure B-RGO was used in the Zn-ion hybrid capacitor device. The electrochemical performance of the Zn-ion hybrid capacitor was evaluated through cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) measurements, with a wide active potential range of 0–2 V versus Zn/Zn+. The mixture composition of Aloe vera extract and 1M ZnSO4 electrolyte generated a stable voltage and exhibited good capacitive behavior. The fabricated ZIC coin cell device with the Aloe vera gel semi-gel electrolyte containing ZnSO4 demonstrated improved Zn+ ionic exchange and storage efficiency. Moreover, the B-RGO electrode active material exhibited excellent cycle stability. The simple one-step electrochemical technique is the most suitable process for boron doping into graphene nanosheets for future energy storage applications.

Arc discharge synthesis of graphene with enhanced boron doping concentration for electrochemical applications

The physicochemical properties of graphene, such as the bandgap and electrical conductivity, can be tuned when the carbon atoms are replaced with other heteroatoms. In addition to nitrogen, boron is a dopant that can compensate for the properties lacking in graphene; however, boron-doped graphene has not received significant attention owing to its low doping rate. In this study, we report an improvement in the doping efficiency of arc graphene by utilizing a boron precursor and graphene oxide as anode carbon fillers. X-ray photoelectron spectroscopy revealed that the doping level of the synthesized graphene flakes (5.7at.%) was significantly higher than that of boron-doped arc graphene reported in the literature (3at.%). Cyclic voltammetry, electrochemical impedance spectroscopy, and constant-current charge/discharge experiments were performed to investigate the electrochemical properties of boron-doped graphene. The synthesized boron-doped graphene exhibited an areal capacitance of 66 μF cm−2, which is superior to that of other doped carbon materials. The electrochemical activity of boron-doped graphene is affected more by functionalized doping than by substitutional doping, because of the improved wettability displayed by the former. Boron-doped graphene flakes required for various applications can be easily obtained by arc discharge synthesis.

B-TiO2/CuInS2 photocatalyst based on the synergistic effect of oxygen vacancy and Z-scheme heterojunction for improving photocatalyst CO2 reduction

Photocatalytic reduction CO2 into valuable solar fuels is a promising strategy to alleviate the greenhouse effect and the energy crisis on Earth. In this work, a B-TiO2/CuInS2 photocatalyst has been synthesized through a simple hydrothermal-calcination method for efficient reducing CO2 into CO and CH4. Boron doping and sensitization of CuInS2 ensure the excellent visible light response capacity of the composite catalyst. The synergistic effect between oxygen vacancies and Z-scheme heterojunction also endow the photocatalyst with strong carrier separation capability. Consequently, the optimized B-TO/CIS-2.5 sample exhibited the best CO (21.39 μmol g−1 h−1) and CH4 (4.83 μmol g−1 h−1) production, approximately 9 and 14 times higher than that of TO and B-TO, respectively. This study provides a reliable approach for developing photocatalysts with boosted CO2 reduction activity and high stability.