Boron-doped Graphitic Carbon Nitride Research Articles

Boron-doped sulfonated graphitic carbon nitride as a highly efficient catalyst for the production of 5-hydroxymethylfurfural from carbohydrates

The presence of humins during the conversion of concentrated fructose presents a major obstacle in the large-scale production of 5-hydroxymethylfurfural (HMF) from fructose. Herein, we reported a boron-doped graphitic carbon nitride sulfonated (BGCN-SO3H) as an excellent catalyst for the synthesis of HMF from fructose. The BGCN-SO3H catalyst structures were analyzed using various characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), elemental mapping analysis, and Fourier-transform infrared spectroscopy (FT-IR). The BGCN-SO3H catalyst was evaluated for the synthesis of HMF from fructose. We investigated the influence of catalyst performance, including solvent reactions, catalyst loading, substrates, and volume of solvent to optimize reaction conditions. As a result, the yield of HMF was obtained at 88 % within 5 h when using 30 mg of catalyst. The study of catalyst activity involved examining reactions that allowed recovery and reuse. The research findings offer a method for producing HMF with exceptional efficiency using solid catalysts.

Identification of Active Sites on Boron-Doped Graphitic Carbon Nitride as a Metal-Free Single-Atom Photoelectrocatalyst for the Nitrogen Reduction Reaction

Identification of Active Sites on Boron-Doped Graphitic Carbon Nitride as a Metal-Free Single-Atom Photoelectrocatalyst for the Nitrogen Reduction Reaction

On mechanism of the synthesis of boron-doped graphitic carbon nitride

B-doped graphitic carbon nitrides (B-CNs) represent a promising class of materials that are potentially useful in a variety of applications. Their properties depend on the nature of the B-doping, which in turn is highly dependent on the particular chemical mechanism of B-doping formation. With this in mind, we present here the study of B-doping achieved by the co-calcination of CN-precursor (cyanoguanidine) and B-dopant (boric acid).In this study, the structural theory of the B–CN materials produced from different ratios of CN precursor and B-dopant was derived. Our proposed structure is supported by elemental analysis, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and nuclear magnetic resonance. Based on our results, heptazine carbon replacing tetravalent B− species near the =N+=CN- structural unit is the dominant pattern of B doping in our co-calcined materials. The identification of the nature of the B-doping allowed us to infer the mechanism of its formation in the chemical reactions taking place during calcination.

Metal-free solid base catalysis: Boron-doped graphitic carbon nitride for the efficient synthesis of ethyl coumarin-3-carboxylate

In this work, boron doped graphitic carbon nitride materials (BgCN-x) were successfully prepared by thermal copolymerization of melamine and boric acid. The comprehensive characterization using various techniques, including powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), UV-Visible spectroscopy (UV-Vis), Field emission scanning electron microscopy (FESEM), Energy-Dispersive X-ray spectroscopy (EDS), Field emission transmission electron microscopy (FETEM), and X-ray photoelectron spectroscopy (XPS) revealed the uniform doping of boron in the tri-s-triazine rings of g-C3N4 by substituting the carbon or nitrogen atoms. Furthermore, the basic site concentrations of the catalysts were evaluated using CO2-TPD technique. The BgCN catalysts exhibited significantly enhanced catalytic activity in the base-catalyzed Knoevenagel condensation between salicylaldehyde and diethyl malonate for coumarin synthesis. This work underscores the potential of boron-doped or two-dimensional boron-dominant materials as promising candidates for metal-free heterogeneous base catalysis, paving the way for further advancements in the field.

Template-Free Synthesis of Boron-Doped Graphitic Carbon Nitride Porous Nanotubes for Enhanced Photocatalytic Hydrogen Evolution.

The photocatalytic activity of g-C3N4 can be enhanced by improving photoinduced carrier separation and exposing sufficient reactive sites. In this study, we synthesized B-doped porous tubular g-C3N4 (BCNT) using a H3BO3-assisted supramolecular self-template method, wherein H3BO3 helped in B-doping, building a porous structure, and maintaining one-dimensional nanotubes. The tubular structure had an ultrathin tube wall and large aspect ratio, which are conducive to the directional transmission and separation of photogenerated carriers; moreover, the abundant pore structure of the tube wall could fully expose the reactive sites. The introduction of B and the cyano group modulated the bandgap of g-C3N4 and elevated the position of the conduction band, thus enhancing the photoreduction ability and effectively improving the hydrogen evolution performance. Consequently, the hydrogen evolution of BCNT-2 (220.8, 53.2 μmol·h-1) was 1.82 and 1.54 times that of ultrathin g-C3N4 nanosheets (CNN, 121.3, 34.6 μmol·h-1) under simulated sunlight and LED lamp irradiation, respectively. Thus, this work provides in-depth insights into the rational design of one-dimensional g-C3N4 nanotubes with high hydrogen evolution activity under visible irradiation.

Cobalt Oxide on Boron-Doped Graphitic Carbon Nitride as Bifunctional Photocatalysts for CO2 Reduction and Hydrogen Evolution.

In this work, the prepared cobalt oxide decorated boron-doped g-C3N4 (CoOx/g-C3N4) heterojunction exhibits remarkable activity in CO2 reduction (CO2RR), resulting in high yields of CH3COOH (∼383 μmol·gcatalyst-1) and CH3OH (∼371 μmol·gcatalyst-1) with 58% selectivity to C2+ under visible light. However, the same system leads to high H2 evolution (HER) by increasing the cobalt oxide content, suggesting that the selectivity and preference for the CO2RR or HER depend on oxide decoration. By comparing HER and CO2RR evolution in the same system, this work provides critical insights into the catalytic mechanism, indicating that the CoOx/g-C3N4 heterojunction formation is necessary to foster high visible light photoactivity.

In-situ development of boron doped g-C3N4 supported SBA-15 nanocomposites for photocatalytic degradation of tetracycline

In this study, versatile boron-doped graphitic carbon nitride (gCN) incorporated mesoporous SBA-15 (BGS) composite materials were prepared by thermal polycondensation method using boric acid & melamine as a B-gCN source material and SBA-15 as mesoporous support. The prepared BGS composites are utilized sustainably using solar light as the energy source for the continuous flow of photodegradation of tetracycline (TC) antibiotics. This work highlights that the photocatalysts preparation was carried out with an eco-friendly strategy, solvent-free and without additional reagents. To alter the amount of boron quantity (0.124 g, 0.248 g, and 0.49 g) have to prepare three different composites using a similar procedure, the obtained composites viz., BGS-1, BGS-2 and BGS-3, respectively. The physicochemical property of the prepared composites was investigated by X-ray diffractometry, Fourier-transform infrared spectroscopy, Raman, Diffraction reflectance spectra, Photoluminescence, Brunauer-Emmett-Teller and transmission electron microscopy (TEM). The results shows that 0.24 g boron- loaded BGS composites degrade TC up to 93.74%, which is much higher than the rest of the catalyst. The addition of mesoporous SBA-15 incresed the specific surface area of the g-CN, and heteroatom of boron increased the interplanar stracking distance of g-CN, enlarged the optical absorption range, reducing the energy bandgap and enhanced the photocatalytic activity of TC. Additionally, the stability and recycling efficiency of the representative photocatalysts viz., BGS-2 was observed to be good even at the fifth cycle. The photocatalytic process using the BGS composites demonstrated to be capable candidate for the removal of tetracycline biowaste from aquesous media.

Double charge transfer mechanistic insights into the tailoring of BiOI nanoplates and boron-doped graphitic carbon nitride: a 2D/2D anchored p–n heterojunction nanocatalyst for improved photodegradation

The article highlights the synthesis of a nanocomposite BiOI/BCN-xthat aims to degrade toxic organic pollutants from wastewater bodies. Mechanistic insights incorporating dual charge transfer have been envisioned for boosted photoactivity.

Constructing boron-doped graphitic carbon nitride with 2D/1D porous hierarchical architecture and efficient N2 photofixation

Rational design of cheap and easily available semiconductor photocatalysts for photocatalytic nitrogen fixation has attracted widespread attention. However, the enhancing efficiency of fixation nitrogen into ammonia (NH3) under mild conditions is still a challenge. Based on the energy band engineering theory, the band gap of graphitic carbon nitride (g-C3N4) can be adjusted by boron element doping. In this study, boron-doped graphitic carbon nitride with a porous rod-like 2D/1D hierarchical architecture was prepared (BCN) via a convenient hydrothermal and thermal polymerization method. Due to its special structure, the as-prepared BCN photocatalysts had a high specific surface area, enhanced visible light absorption and good photogenerated carrier separation efficiency. The optimal ammonia yield of BCN can reach 434.74 μmol·g−1·h−1 without the presence of a sacrificial agent, which was 57.35 times higher than that of bulk g-C3N4. According to the analysis of the experimental results, the excellent photocatalytic nitrogen fixation performance was due to the synergistic effect between the doping of nonmetallic boron element and the 2D/1D porous structure, which exposed more active sites, thus boosting the photocatalytic nitrogen fixation efficiency. This study provides a guiding significance for the construction of high-efficiency photocatalysts with a special 2D/1D porous hierarchical architecture in photocatalytic nitrogen fixation.

Rational design of hexagonal zinc oxide/boron-doped g-C3N4 nanosheets as efficient electrocatalyst for enhanced sensing of rutin in fruit samples

The semiconducting metal oxides coupled with carbon materials show a broad interest in developing low-cost and accurate electrochemical sensors. Herein, we designed a sensitive and selective electrode material of hexagonal zinc oxide nanodiscs decorated (ZnO NDs) boron-doped graphitic carbon nitride (B-CN) sheets fabricated over glassy carbon electrode (GCE) for efficient detection of rutin (RT). The prepared electrocatalyst and fabricated sensors were analyzed using different physicochemical and electrochemical characteristics. The prepared electrocatalyst and fabricated sensor confirmed physicochemical and electrochemical characteristics. Notably, the developed sensor shows good sensitive recognition of RT detection (1.0225 μA·μM-1·cm-2), a low limit of detection (LOD= 0.0027 µM), and a wide linear range (0.005–589.685 µM) in phosphate buffer (PB, pH 3.0). The newly developed sensor was also applied to detect potential interfering species and real-sample analysis. The proposed sensor show excellence in selectivity, reproducibility, stability (89.55%), and practicability during electrochemical RT detection. The present report demonstrates to development of a cheap and sensitive platform for RT determination in fruit samples.

Atmospheric pressure conversion of carbon dioxide to cyclic carbonates using a metal-free Lewis acid-base bifunctional heterogeneous catalyst

Conversion of carbon dioxide (CO2) to value-added products is imperative to combat global warming. In this regard, herein we report a metal-free heterogeneous catalyst, boron-doped graphitic carbon nitride for effective conversion of CO2 to cyclic carbonates at atmospheric pressure under solvent-free conditions. The developed catalyst possesses acid-base dual functionality as active sites, which activate both epoxides as well as CO2 simultaneously to carry out the cycloaddition reaction. The catalyst showed a maximum yield up to 99 % with a turnover number of 173. Detailed optimization studies have been performed to find out the best doping content of boron and best conditions by varying the reaction time, temperature and catalysts amount. Furthermore, the ease of catalyst recovery and excellent recyclability demonstrate the sustainability and versatility of the catalyst for selective and efficient conversion of CO2 to cyclic carbonates at mild conditions.

Ionic liquid-assisted synthesis of porous boron-doped graphitic carbon nitride for photocatalytic hydrogen production

This work presents a simple way to prepare boron-doped graphitic carbon nitride (B/g-C3N4), exhibiting an enhanced photocatalytic performance to split water for hydrogen production. B/g-C3N4 was synthesized via the pyrolysis of urea and 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF4), which was adopted as the boron source. The aggregate of B/g-C3N4 nanosheets shows a porous structure since some bubbles are generated under the heat decomposition of ionic liquids. The porous structure is conducive to the exposure of more active sites. Moreover, B-doping will form some localized electronic energy levels in the band gap of g-C3N4, thereby extending its visible light response. As impacted by the porous structure of B/g-C3N4 aggregate and the narrow the band gap, the photocatalytic hydrogen generation rate (901 μmol h−1 g−1) is increased, almost 3 times faster than g-C3N4 (309 μmol h−1 g−1). This work proposed a simple method to prepare the aggregate of B/g-C3N4 nanosheets exhibiting pores under ionic liquid assistance. It can be a novel method to design porous polymer photocatalysts.

Boron dopant simultaneously achieving nanostructure control and electronic structure tuning of graphitic carbon nitride with enhanced photocatalytic activity

The boron-doped graphitic carbon nitride synthesized by two-step heat treatment has a one-dimensional tubular structure and its hydrogen evolution is 2 times higher than that of undoped g-C3N4.

Cobalt molybdate nanorods decorated on boron-doped graphitic carbon nitride sheets for electrochemical sensing of furazolidone.

Ananorod-like structured CoMoO4 embedded on boron doped-graphitic carbon nitride composite (CoMoO4/BCN) has been developedby asimple sonochemical method for electrochemical detection of furazolidone (FUZ). Interestingly, the impedance of CoMoO4/BCN fabricated screen-printed carbon electrode (SPCE) possesses a lower resistance charge transfer (Rct), which favors superior electrochemical detection of FUZ. Such CoMoO4/BCN/SPCE exhibits an ultralow detection limit of 1.6nM with aconcentration range of 0.04-408.9μM, and high sensitivity of11.6μAμM-1cm-2 by DPV method. In addition, biological and water samples were used for demonstration of practical application of CoMoO4/BCN/SPCE towards electrochemical detection of FUZ, and the result exhibits a satisfactory recovery.Graphical abstract.

Spin Polarization-Induced Facile Dioxygen Activation in Boron-Doped Graphitic Carbon Nitride.

Dioxygen (O2) activation is a vital step in many oxidation reactions, and a graphitic carbon nitride (g-C3N4) sheet is known as a famous semiconductor catalytic material. Here, we report that the atomic boron (B)-doped g-C3N4 (B/g-C3N4) can be used as a highly efficient catalyst for O2 activation. Our first-principles results show that O2 can be easily chemisorbed at the B site and thus can be highly activated, featured by an elongated O-O bond (∼1.52 Å). Interestingly, the O-O cleavage is almost barrier free at room temperatures, independent of the doping concentration. It is revealed that the B atom can induce considerable spin polarization on B/g-C3N4, which accounts for O2 activation. The doping concentration determines the coupling configuration of net-spin and thus the magnitude of the magnetism. However, the distribution of net-spin at the active site is independent of the doping concentration, giving rise to the doping concentration-independent catalytic capacity. The unique monolayer geometry and the existing multiple active sites may facilitate the adsorption and activation of O2 from two sides, and the newly generated surface oxygen-containing groups can catalyze the oxidation coupling of methane to ethane. The present findings pave a new way to design g-C3N4-based metal-free catalysts for oxidation reactions.

In situ growth of boron doped g-C3N4 on carbon fiber cloth as a recycled flexible film-photocatalyst

The development of feasible, highly stable and easily recycled metal-free photocatalysts has drawn great attention for wastewater purification. Herein, dip-coating followed with thermal polymerization is developed for in situ growth of boron doped graphitic carbon nitride (BCN) on carbon fiber cloth (CFc) as flexible film photocatalysts. HNO3 treatment on CFc is used to improve the surface hydrophilicity of CF, which is beneficial for the adsorption and nucleation of BCN precursor on CFc in aqueous solution. Boric acid not only works as the boron source but also causes a porous morphology of BCN due to the gasification of water generated from boric acid decomposition during heating process. Because of the close contact between CFc and BCN, CFc induces BCN to better crystalize. Furthermore, the film-photocatalyst exhibits high mechanical stability and recyclability. The porous sheet-like structures, together with the boron doping and CFc support, can improve light capture, charge separation and transport, and dye adsorption. Our work provides a thinking for component and morphology regulation of film-based flexible catalysts towards reusable photocatalysis under outdoor sunlight.

Visible-light photocatalytic diclofenac removal by tunable vanadium pentoxide/boron-doped graphitic carbon nitride composite

The growing consumption of pharmaceutical products is taking a heavy toll on conventional wastewater treatment plants, the incomplete or no-removal of pharmaceutical species. Photocatalysis can be implemented as a refining step in treatment trains to mineralize these pharmaceuticals. In this study, vanadium pentoxide (V2O5) was integrated into boron-doped graphitic-carbon nitride (BCN) to produce visible-light-active vanadium oxide/boron co-doped graphitic-carbon nitride (V2O5-BCN) photocatalysts wherein graphitic carbon nitride (g-C3N4) was produced by thermal poly-condensation of urea. The photocatalysts were characterized and their performance under visible light irradiation was evaluated using diclofenac (DCF) as a representative pharmaceutical active compound. The effects of dopant amount, photocatalyst dosage, initial DCF concentration, solution pH and presence of anions on DCF removal were examined. Results showed that DCF adsorption on V2O5-BCN photocatalysts conformed to the pseudo-second order kinetic model while DCF photodegradation followed the pseudo-first order reaction kinetics. The photocatalysts were found to be stable and reusable. DCF removals reached 100% in < 105 min under visible light irradiation. Overall, the as-synthesized V2O5-BCN heterojunction proved to be a promising photocatalyst for sustainable and low-cost treatment of pharmaceutical-contaminated wastewaters.

Synergistically Boron-Doped and Nitrogen-Deficient Graphitic Carbon Nitride for Efficient Photocatalytic Oxygen Evolution

Synergistically Boron-Doped and Nitrogen-Deficient Graphitic Carbon Nitride for Efficient Photocatalytic Oxygen Evolution

Rapid photo-degradation of various organic dyes with thin-layer boron-doped graphitic carbon nitride nano-sheets under visible light irradiation

We herein prepared the boron-doped graphitic carbon nitride (B-g-C3N4) nano-sheets with 1–5 monolayers and 50−200 nm size via heating the mixture of melamine and boron oxide. We demonstrated that the prepared thin-layer B-g-C3N4 nano-sheets have a high and stable photo-catalytic activity for degrading various organic dyes with a high speed and efficiency under visible light irradiation. In the presence of 2 mg/mL of B-g-C3N4 nano-sheets, Eosin Y (EY, heterocyclic dye), Rhodamine B (RhB, triarylmethane dye), Methylene blue (MB, thiazide dyes) and Methyl orange (MO, Azo dyes) can be completely degraded within 5, 10, 20 and 60 min respectively under visible light irradiation follow the first-order kinetics. The possible route and intermediate products of various dyes during photo-degradation over B-g-C3N4 nano-sheets were also investigated. In comparison with other g-C3N4 or g-C3N4-based materials, the prepared thin-layer B-g-C3N4 nano-sheets have much higher photo-catalytic activity and can be used for visible light-driven degrading various organic dyes. The success of this study provides a promising method for economical, rapid and environmental-friendly treatment of dye-contaminated water.

Boron-doped graphitic carbon nitride as a novel fluorescent probe for mercury(ii) and iron(iii): a circuit logic gate mimic

Boron-g-C3N4 was applied as a novel practical fluorescent probe to detect mercury and ferric ions in real samples.