Boron-doped Graphene Nanosheets Research Articles

Boron-doped graphene anode coupled with microporous activated carbon cathode for lithium-ion ultracapacitors

Lithium-ion hybrid capacitors combine the advantages of both high energy of lithium-ion batteries and high-power of ultracapacitors by using one highly reversible battery-type electrode (e.g., graphite, carbon matrix, metal oxides, etc.) and another high surface area supercapacitor-type electrode (e.g., activated carbon) in one unit cell. This work reports the fabrication of a lithium-ion capacitor using boron-doped graphene nanosheets as anode and microporous carbon from activated rice husk as a cathode. The lithium-ion storage characteristics of boron-doped graphene nanomaterials and adsorption properties of microporous carbon leads to the realization of their usage in a lithium-ion capacitor electrode materials. The lithium-ion capacitor full cell with lithiated boron-doped graphene nanomaterial anode and activated rice husk cathode demonstrates energy densities of 162 and 83 W h kg−1 at power densities of 590, 14750 W kg−1, respectively. The mechanistic performance of the LIC full cell below and above the open circuit voltage (OCV) was analysed to understand the diffusion and adsorption control in the achievable energy. The cell cycles till 25,000 cycles with 65 % capacitance retention at 1 A g−1 current density. This study demonstrates a striking balance between the high energy and high power capabilities in a single unit lithium-ion capacitor cell through the utilization of adsorptive as well diffusive ion storage mechanism of the electrode active materials. The full cell is analysed for self discharge and leakage current to realise the practical feasibility of the electrode active materials. Also, the electrochemical impedance spectra reveal the probable reason behind the degradation of cycling performance.

Boron-doped graphene-supported manganese oxide nanotubes as an efficient non-metal catalyst for the oxygen reduction reaction

An efficient, low cost and non-precious hybrid metal catalyst compound consisting of boron-doped graphene nanosheets (BGNSs) and manganese oxide (MnO2) nanotubes is used as a catalyst for the oxygen reduction reaction (ORR).

Gold-nanoparticle-decorated boron-doped graphene/BDD electrode for tumor marker sensor

A boron-doped graphene (BG)/boron-doped diamond (BDD) composite film was obtained by continuously growing BDD and BG by chemical vapor deposition. In this process, the sp3 CC bonds in the diamond phase structure are directly converted into sp2 CC bonds in graphene to combine the two carbon materials, while BG nanosheets are vertically grown on the exposed planes of BDD crystals. These process features impart the vertical BG (VBG)/BDD film a large specific surface area and high electrocatalytic activity, resulting in an electroactive surface area of 2.35 cm2. Electrodeposition can be used to load a large number of Au nanoparticles (NPs) on the VBG/BDD electrode. The Au-VBG/BDD electrode was used to construct an immunosensor capable of simultaneously quantifying carcinoembryonic antigen (CEA) and carcinoma antigen 125 (CA 125) at concentrations of 0.5–100 pg mL–1 and 0.5–100 mU mL–1, respectively, with corresponding detection limits of 0.15 pg mL–1 and 0.09 mU mL–1. This method is suitable for the practical detection of CEA, CA125, and other tumor markers in human body fluids, allowing early cancer diagnostics and timely treatment.

Boron doped graphene nanosheets as negative electrode additive for high-performance lead-acid batteries and ultracapacitors

Sulfation at the negative electrode is one of the major failure modes of lead-acid batteries. To overcome the issues of sulfation, in this work we synthesize Boron doped graphene nanosheets as an efficient negative electrode additive for lead-acid batteries. 0.25 wt % Boron doped graphene nanosheets additive in negative electrode which contains around 3% of Boron doping shows impressive electrochemical performance in first discharge capacity, ∼60% increase the capacity in relation to the conventional lead-acid cell. Noticeably, 15–20% enhancement in the discharge capacity at lower C rates and almost double increase in capacity at higher C rates show Boron doped graphene nanosheets as a potential additive for lead-acid battery operating under high rate partial state of charge applications. The superior electrochemical performance is due to the p-type or hole conductivity of the Boron doped graphene lattice, which reduces lead sulfate formation and thereby enhances active material utilization, charge acceptance, and reduces hydrogen evolution. Besides, the high C-rate performance of Boron doped graphene nanosheets additive cell is due to the capacitive property of Boron-doped graphene nanosheets which delivers specific capacitance of 90 F g−1 at 2 A g−1 with >75% capacity retention at the end of 2000 cycles.

Copper nanoparticles anchored onto boron-doped graphene nanosheets for use as a high performance asymmetric solid-state supercapacitor.

There is a high demand for high energy and power density in the field of energy storage devices. To rectify these limitations, a novel asymmetric solid-state supercapacitor (ASSC) was designed and fabricated using a copper anchored boron doped graphene nanosheet (CuBG) as a negative electrode and reduced graphene nanoplatelets as a positive electrode with H2SO4/PVA as the quasi-solid electrolyte. The CuBG was prepared using a two step hydrothermal process followed by pyrolysis at different temperatures using chemical vapour deposition (CVD), using copper sulphate (CuSO4) and boron-trioxide (B2O3) as precursors, for doping in graphene oxide. Owing to the remarkable structure and morphology of Cu nanoparticles on nanosheets of boron intercalated with graphene oxide, the nanosheets exhibit a high specific capacitance of 483 Fg−1 at 1 Ag−1 with a capacitance retention of 96% after 5000 cycles, respectively, in a two-electrode system. In addition, the designed and fabricated solid state ASSC device of rGO//CuBG exhibited a high energy and power density of 132.5 W h kg−1 and 1000 W kg−1, respectively, in a wide potential window of 2.0 V, with an excellent stability, retaining 91% of its initial specific capacitance after 5000 cycles. The electrochemical capacitance of CuBG was also evaluated in a three and two electrode system using a KOH and KOH/PVA solid electrolyte respectively. A specific capacitance of 87.5 Fg−1 was achieved at 1 Ag−1 using the fabricated asymmetric device with a 31.1 W h kg−1 energy density at a corresponding power density of 800 W kg−1 and an 85% capacitance was retained after 5000 cycles. The kinetics of the interfacial charge transport phenomena were analysed using a Nyquist plot of the electrochemical impedance analysis.

Conductive Boron-Doped Graphene as an Ideal Material for Electrocatalytically Switchable and High-Capacity Hydrogen Storage.

Electrocatalytic, switchable hydrogen storage promises both tunable kinetics and facile reversibility without the need for specific catalysts. The feasibility of this approach relies on having materials that are easy to synthesize, possessing good electrical conductivities. Graphitic carbon nitride (g-C4N3) has been predicted to display charge-responsive binding with molecular hydrogen-the only such conductive sorbent material that has been discovered to date. As yet, however, this conductive variant of graphitic carbon nitride is not readily synthesized by scalable methods. Here, we examine the possibility of conductive and easily synthesized boron-doped graphene nanosheets (B-doped graphene) as sorbent materials for practical applications of electrocatalytically switchable hydrogen storage. Using first-principle calculations, we find that the adsorption energy of H2 molecules on B-doped graphene can be dramatically enhanced by removing electrons from and thereby positively charging the adsorbent. Thus, by controlling charge injected or depleted from the adsorbent, one can effectively tune the storage/release processes which occur spontaneously without any energy barriers. At full hydrogen coverage, the positively charged BC5 achieves high storage capacities up to 5.3 wt %. Importantly, B-doped graphene, such as BC49, BC7, and BC5, have good electrical conductivity and can be easily synthesized by scalable methods, which positions this class of material as a very good candidate for charge injection/release. These predictions pave the route for practical implementation of electrocatalytic systems with switchable storage/release capacities that offer high capacity for hydrogen storage.

Synthesis and characterization of boron doped graphene nanosheets for supercapacitor applications

Heteroatom doping in carbon nanostructured materials is one of the effective approaches to enhance the energy storage in supercapacitors. Graphene oxide (GO) was synthesized by thermal reduction under argon atmosphere at 500°C and boron doped graphene nanosheets were prepared through hydrothermal (HB-GNS) using boric acid (H3BO3). The atomic doping level of boron was calculated (2.56%) from X-ray photoelectron spectroscopic (XPS) studies. Electrochemical analysis of thermally reduced graphene nanosheets (T-GNS) and HB-GNS shows the electric double layer capacitance behavior in Cyclic Voltammetry (CV) study. The HB-GNS electrode exhibited a maximum specific capacitance of 113F/g (1A/g), where as T-GNS showed the specific capacitance of 53F/g (1A/g). The electrochemical impedance measurement shows low Rct values for HB-GNS as compared to the T-GNS materials. The boron doping (HB-GNS) increases twice the specific capacitance of T-GNS. These results indicate the superior electrochemical performance of HB-GNS due to boron doping in graphene nanosheets as high energy storage electrode materials for supercapacitors.

Facile Synthesis of Boron-doped Graphene Nanosheets with Hierarchical Microstructure at Atmosphere Pressure for Metal-free Electrochemical Detection of Hydrogen Peroxide

Hydrogen peroxide (H2O2) is an essential mediator for most of the oxidative biological reactions in enzyme-based biosensor systems, such as glucose oxidase, cholesterol oxidase, and alcohol oxidase. Synthesis of new catalysts to detect the concentration of H2O2 more precisely is indispensable for enzyme-based electrochemical biosensors. In this study, boron-doped graphene nanosheets (BGNs) with 2.2 atomic percentage (at%) boron doping level and a hierarchical microstructure were synthesized by an atmospheric-pressure carbothermal reaction as a noble-metal free catalyst for sensing H2O2. The isolated boron atoms on the BGNs surface act as the electrocatalytic sites by transferring charges to neighbor carbon atoms, and the hierarchical microstructure provides multidimensional electron transport pathways for charge transfer and therefore enhances the electrocatalytic ability. BGNs possess a higher reduction current in the cyclic voltammetry (CV) measurement than that of pristine graphene nanosheets (GNs) over the detection range of 0.0 to 10.0mM at −0.4V (vs. Ag/AgCl). The BGNs modified electrochemical sensor shows a linear range from 1.0 to 20.0mM of H2O2 with a sensitivity of 266.7±3.8μAmM−1cm−2 and limit of detection (LOD) of 3.8μM at a signal-to-noise (S/N) ratio of 3. The beneficial hierarchical microstructure and the synergetic effects arising from doping boron in GNs accomplish the better performance of the BGNs modified electrochemical sensor.

Highly-dispersed boron-doped graphene nanosheets loaded with TiO2 nanoparticles for enhancing CO2 photoreduction.

Boron doped graphene nanosheets (B-GR) as a p-type semiconductor, provides much more edges to facilitate the loading of TiO2 nanoparticles (P25). Highly-dispersed P25/B-GR nanosheets with the size of 20-50 nm, are successfully synthesized by the vacuum activation and ultraphonic method. The nanosized morphology can decrease the local density of defects which are induced by the boron substitutional doping, and make the B-GR keeping excellent conductivity and p-type transport property. Ti-O-C bonds are formed during the mixing process, which could efficiently transfer the electrons from TiO2 to B-GR and the holes from B-GR to TiO2. The tunable bandgap of B-GR determines the large potential application of P25/B-GR in the photoreduction of CO2 and other gaseous organic pollutants.

Covalent functionalization based heteroatom doped graphene nanosheet as a metal-free electrocatalyst for oxygen reduction reaction

Oxygen reduction reaction (ORR) is an important reaction in energy conversion systems such as fuel cells and metal-air batteries. Carbon nanomaterials doped with heteroatoms are highly attractive materials for use as electrocatalysts by virtue of their excellent electrocatalytic activity, high conductivity, and large surface area. This study reports the synthesis of highly efficient electrocatalysts based on heteroatom-doped graphene nanosheets prepared through covalent functionalization using various small organic molecules and a subsequent thermal treatment. A series of nitrogen-doped reduced graphene oxide (NRGOn) nanosheets exhibited varying degrees and configurations of nitrogen atoms within the graphitic framework depending on the type of precursors used. On the basis of the rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) experiments, NRGO3, with a high degree of pyridinic-N content, displayed the desired one-step, quasi-four-electron transfer pathway during ORR, similar to commercial Pt/C. We also demonstrated the potential of covalent functionalization of sulfur and boron-doped graphene nanosheets.