Carbon-doped Boron Nitride Nanosheets Research Articles

Singlet oxygen triggered by carbon doped boron nitride nanosheets for enhanced removal of tetracycline by peroxymonosulfate activation

The catalytic performance of non-radical based AOP (advanced oxidation processes) is less susceptible to the inorganic anions and natural organic matters (NOMs), thus non-radical based AOP is widely used in complex aqueous matrices. However, the activity of catalysts mediating the non-radical pathway is limited. Herein, a catalyst based on non-radical pathway with excellent catalytic activity was designed. Pyrolysis in one step was used to prepare carbon doped hexagonal boron (C-BN) catalyst, this catalyst showed excellent degradation performance in activating peroxymonosulfate (PMS) for tetracycline (TC) degradation. After doping C, the removal rate of TC (10 mg/L) could reach over 99% within 25 min, which was three times that of h-BN. Surface area, hydrophilicity, and electron transport rate all contributed to the improvement of catalytic performance. Combined with experimental and DFT (density functional theory) analysis, 1O2 and electron transfer mechanisms played a significant role in the degradation of TC in the 40% C-BN system. Because of that, the catalyst maintained excellent catalytic activity under different pH, different pollutants, different anions, and other environmental factors, showing its good resistance. This study could enrich the degradation mechanism of non-radical based AOP in the C-BN catalysts.

Carbon-doped boron nitride nanosheets as an efficient metal-free catalyst for the selective oxidation of H2S.

We report the first use of carbon-doped boron nitride (BCN) for H2S-selective catalytic oxidation. The obtained carbon-doped BN with an ultrathin layer structure exhibits outstanding H2S elimination and high S yield. In particular, BN doped carbon nanosheets display better catalytic performance than traditional catalysts, such as iron- and carbon-based catalysts. The findings of the present work shed a new light on metal-free catalysts for efficient catalytic removal of toxic H2S.

Carbon-doped boron nitride nanosheets: A high-efficient electrocatalyst for ambient nitrogen reduction

h-BN-based electrocatalysts with low-cost and high efficiency have a great potential for electrochemical nitrogen reduction reaction (NRR). The carbon-doped boron nitride (C-BN) nanosheets are proposed as the excellent metal-free electrocatalysts for converting nitrogen to ammonia (NH3). In 0.1 M Na2SO4 solution, it obtains NH3 yield of 44.59 ± 1.79 μg h−1 mgcat−1 at − 0.9 V vs reversible hydrogen electrode (RHE), with a high faradaic efficiency (FE) of 13.27 ± 0.42 % at − 0.7 V vs RHE, and an outstanding electrochemical durability. Density functional theory (DFT) calculations reveal that carbon-doping dramatically reduces the band gap to 1.40 eV and induces charge accumulation on carbon atom to facilitate N2 adsorption. The synergistic interaction of C and B atoms at the double-active-site of C-BN significantly decreases the energy barrier (from *NH-NH to *NH-NH2) for the potential-determining step. The results confirm that C-BN has the potential as an efficient metal-free NRR electrocatalyst in neutral media.

Carbon-doped boron nitride nanosheets with adjustable band structure for efficient photocatalytic U(VI) reduction under visible light

Effectively separating uranium from aqueous solution is pivotal in the sustainable development of the nuclear industry and environmental protection. In this work, non-metal photocatalysts, carbon-doped BN (BCN) nanosheets were used to extract uranium by the photocatalytic reduction technique, and the doping in the form of carbon rings can regulate the bandgap and electronic structure by manipulating carbon amount. Benefiting from the porous structure and strong visible-light absorption, the U(VI) separation ratio of 97.4% could be achieved after 1.5-hour visible irradiation with an apparent rate value of 2.97 h−1 over BCN-80. Additionally, BCN-80 displayed good reusability and stability with the U(VI) separation ratio > 90% even after five cycles, and the enhanced U(VI) photoreduction was attributed to the synergistic effect of photoinduced electrons and formed ketyl radicals. This work demonstrates the great potential of BCN materials in U(VI) enrichment and will lay the foundation for further developing novel semiconductor photocatalysts.

Molten salt synthesis of carbon-doped boron nitride nanosheets with enhanced adsorption performance

Owing to their large specific areas, high thermal stability and chemical inertness, two-dimensional boron carbon nitride nanosheets (BCNNs) have captured much attention in recent years in the field of adsorption of pollutants. The formation of BCNNs via incorporating carbon into boron nitride (BN) can effectively improve the photoelectric and adsorption properties of the latter. In this work, carbon-doped BN (BCN) nanosheets were prepared at 1100 °C via a molten salt route using boric acid, melamine and glucose as the main starting materials. The effects of molten salt type and carbon doping level on the formation of BCN were investigated, and their isothermal adsorption properties in a methylene blue (MB) aqueous solution were evaluated based on the Langmuir and Freundlich models. The results indicated that using molten LiCl-KCl as a liquid medium was more favorable than NaCl-KCl to the formation of BCNNs. As-prepared BC0.4N sample possessed a sheet-like structure of about 10 nm thick and a specific surface area as high as 484 m2 g−1. Moreover, the adsorption test of MB demonstrated a high adsorption capacity of 249.04 mg g−1, which was about 14 times higher than that in the case of the pristine BN, and the kinetic rate constant value in the case of using BC0.4N is about ten times as high as that of BN following a pseudo-second-order model, suggesting that the as-formed BC0.4N nanosheets could be potentially used as a value-added effective adsorbent for future wastewater remediation.

Carbon-doped boron nitride nanosheets as highly sensitive materials for detection of toxic NO and NO2 gases: A DFT study

Using density functional theory calculations, we investigate sensing mechanism of C-doped hexagonal boron nitride (h-BN) nanosheets toward NO and NO2 molecules. The results indicate that C-doping induces a large spin density and electron density redistribution in h-BN, which leads to improved adsorption energy of NO and NO2. The adsorption of NO and NO2 is able to alter significantly electronic structure of C-doped h-BN nanosheets as evidenced by relatively large variation in the band gap values. Moreover, the application of an external electric field can avoid the strong adsorption of NO and NO2 molecules over C-doped h-BN sheets. Compared to NO and NO2, the adsorption of CO, CO2, H2O or NH3 on C-doped h-BN sheets is remarkably weaker, suggesting that the sensing of NO and NO2 can be performed selectively in the presence of these molecules. Therefore, C-doped h-BN nanosheets can be viewed as promising and sensitive room-temperature sensors for NO and NO2 molecules.

Synthesis of carbon-doped boron nitride nanosheets and enhancement of their room-temperature ferromagnetic properties

Introducing ferromagnetism in light-element materials that contain only s and p electrons has captured much attention for their possible application in spintronic devices. In this study, we explored the ferromagnetic properties of carbon-doped boron nitride (BCN) nanosheets obtained by high-temperature annealing of a stacked mixture of boron nitride nanosheets (BNNSs) and graphene prepared by urea-assisted aqueous exfoliation. Three types of BCN nanosheets, referred to as BCN (1:1), BCN (1:2) and BCN (1:3), were successfully synthesized through multistep processes. Strong ferromagnetic responses were observed in the BCN nanosheets with a saturation magnetization of 0.142 emu/g at room temperature. It was found that the thickness of the precursors plays a critical role in the determination of the ferromagnetic properties of the BCN nanosheets. Our results provide a new possibility for the manipulation of ferromagnetism in light-element systems.

Template-free synthesis of carbon-doped boron nitride nanosheets for enhanced photocatalytic hydrogen evolution

Photocatalytic hydrogen production from water is a promising strategy for the direct conversion of sunlight into chemical energy, which is considered as a long-term and sustainable solution to address worldwide energy and environmental issues. Herein, we develop carbon doped boron nitride (BCN) as metal-free photocatalysts by using solid-gas reaction and molecular design method of boron source. Four kinds of boron carbon nitride (BCN) were synthesized through mixed glucoses with melamine phosphate borate (MPB), melamine borate (MB), boric acid (BA) and boron oxide (BO), respectively. It can be found that the morphology of BCN-MPB (nanosheets) is different from bulk BCN-MB, bulk BCN-BA and bulk BCN-BO. The BCN-MPB nanosheets show much higher specific surface area, the longer lifetime of photoexcited charge carriers, and the stronger electron transport ability compared to those of bulk BCN. Thus, BCN-MPB nanosheets exhibit significantly improved photocatalytic hydrogen activities under visible light illumination compared to those of bulk BCN. Our work represents a facile and template-free synthesis strategy for the rational design of eco-friendly, stable and inexpensive photocatalysts, and paves new pathways for tuning their photoreactivity in sustainable light-to-energy conversion.

Carbon-doped boron nitride nanosheet as a promising metal-free catalyst for NO reduction: DFT mechanistic study

Currently, metal-based catalysts are commonly used to convert highly toxic gases like NO molecules into less toxic gases, such as N2O molecules through the process of reduction reaction that has a low activation energy (Ea) and high efficiency. Due to the high cost, environmental hazards and limited supply of metal-based catalysts, development of metal-free catalysts that are low cost and environmentally friendly has increased. For this research, NO reduction mechanism using the carbon-doped boron nitride nanosheets (CBNs) as a metal-free catalyst was investigated by density functional theory (DFT). For the NO reduction mechanism, the dimer mechanism pathway was investigated using the following equation: 2NO → N2O + Oad. In addition, the catalytic activity of carbon atom substitution onto BNs for NO reduction was studied. The results showed that the trans-(NO)2 structure of CNBNs (D5) is a potentially crucial intermediate with thermodynamically and kinetically favorable, in which the calculated rate-determining step along the most energetically favorable pathway is 0.62 eV. Hence, our results presented here suggest that CNBNs can be a highly active metal-free material in NO removal, which will reduce NO into environmentally friendly gases.