Controlled Gas Exfoliation of Boron Nitride into Few‐Layered Nanosheets

Abstract

The controlled exfoliation of hexagonal boron nitride (h-BN) into single- or few-layered nanosheets remains a grand challenge and becomes the bottleneck to essential studies and applications of h-BN. Here, we present an efficient strategy for the scalable synthesis of few-layered h-BN nanosheets (BNNS) using a novel gas exfoliation of bulk h-BN in liquid N2 (L-N2 ). The essence of this strategy lies in the combination of a high temperature triggered expansion of bulk h-BN and the cryogenic L-N2 gasification to exfoliate the h-BN. The produced BNNS after ten cycles (BNNS-10) consisted primarily of fewer than five atomic layers with a high mass yield of 16-20 %. N2 sorption and desorption isotherms show that the BNNS-10 exhibited a much higher specific surface area of 278 m(2) g(-1) than that of bulk BN (10 m(2) g(-1) ). Through the investigation of the exfoliated intermediates combined with a theoretical calculation, we found that the huge temperature variation initiates the expansion and curling of the bulk h-BN. Subseqently, the L-N2 penetrates into the interlayers of h-BN along the curling edge, followed by an immediate drastic gasification of L-N2 , further peeling off h-BN. This novel gas exfoliation of high surface area BNNS not only opens up potential opportunities for wide applications, but also can be extended to produce other layered materials in high yields.

2D Crystal–Based Fibers: Status and Challenges

“…The liquid nitrogen infiltrated into the interlayer of h‐BN and gasified, and then peeled h‐BN. Through repeated repetition, few‐layers h‐BN 2D crystals were obtained . This method has the advantages of short cycle, high yield, low energy consumption, without using organic solvents, so it is environmentally friendly and no worries for post‐treatment of products.…”

Construction of a Nanoporous Highly Crystalline Hexagonal Boron Nitride from an Amorphous Precursor for Catalytic Dehydrogenation

“…[11,12] Although both bulk h-BN and BNNT exhibited analogous product distributions,B NNT showed ar ate of propane consumption more than one order of magnitude higher than that of h-BN,p artially because of the higher surface area of BNNT (97 m 2 g À1 )relative to bulk h-BN (16 m 2 g À1 ), and thus as uperior mass transfer effect during the catalytic process. [16] However, the final few-layered h-BNNS obtained through these approaches often suffer from low surface areas or amorphous/low crystalline structures. [14,15] Our group previously presented an efficient strategy for the scalable synthesis of few-layered h-BNNS using agas exfoliation of bulk h-BN in liquid N 2 .…”

“…[14,15] Our group previously presented an efficient strategy for the scalable synthesis of few-layered h-BNNS using agas exfoliation of bulk h-BN in liquid N 2 . [16] However, the final few-layered h-BNNS obtained through these approaches often suffer from low surface areas or amorphous/low crystalline structures. [15,17] Compared with amorphous materials,t heir highly crystalline counterparts have ordered structures and fewer defects,t hus leading to enhanced performance in optoelectronics and catalysis, [18] as shown by the significant development of crystalline metalorganic framework (MOF) nanosheets, [19] and 2D covalent organic frameworks (COFs).…”

Boron and Nitride Dual vacancies on Metal‐Free Oxygen Doping Boron Nitride as Initiating Sites for Deep Aerobic Oxidative Desulfurization

“…Three diffraction peaks appeared at 2θ = 25.7°, 42.5°a nd 76.5°, being attributed to the (002), (100) and (110) crystalline planes diffraction of h-BN, respectively. [21] Moreover, the (100) crystalline planes of V-BNO displayed sharper diffraction peaks compared with that of BNO. With the increase of calcination treatment time, the diffraction peaks of the V-BNO were intensified gradually, and the full-width-half-max-Scheme 1.…”