Formation Mechanism and Porosity Development in Porous Boron Nitride

Abstract

In the past decade, porous boron nitride (BN) has proven promising as a novel class of inorganic materials in the field of separations and particularly adsorption. Owing to its high surface area and thermal stability, porous BN has been researched for CO2 capture and water cleaning, for instance. However, most research remains at laboratory scale due to a lack of understanding of the formation mechanism of porous BN, which is still largely a 'black box' and prevents scale-up. Partial reaction pathways have been unveiled, but they omit critical steps in the formation, including the porosity development, which is key to adsorption. To unlock the potential of porous BN at a larger scale, we have investigated its formation from the perspective of both chemical formation and porosity development. We have characterised reaction intermediates obtained at different temperatures with a range of analytical and spectroscopic tools. Using these analyses, we propose a mechanism that highlights the key stages of BN formation and its porosity, including the intermediates and gaseous species formed in the process. We identified that the formation of non-porous carbon nitride is crucial to form porous BN with release of porogens, such as HCN and CO2. This work paves the way for scaled-up processes to use porous BN to its full potential at industrial level for gas and liquid separations.

A Response Surface Model to Predict and Experimentally Tune the Chemical, Magnetic and Optoelectronic Properties of Oxygen‐Doped Boron Nitride**

“…The XRD patterns confirm the turbostratic nature of the materials with only broad peaks at 2θ values of 26° and 44°, corresponding to the (002) and (100) planes, respectively [41] . We note that prior studies from our group provide corroborating details on the structural features of the material [10,36,37] . We characterised the chemical structure and composition in BNO using FT‐IR spectroscopy and XPS (Figure 2 and Supplementary Figures 3–30).…”

“…As such, this necessitates multivariate analysis, which involves the observation and analysis of more than one statistical outcome variable at a time [35] . The selection of the synthesis parameters is based on our experience from previous studies focused on boron nitride [10,36,37] …”

“…[35] The selection of the synthesis parameters is based on our experience from previous studies focused on boron nitride. [10,36,37]…”

“…[41] We note that prior studies from our group provide corroborating details on the structural features of the material. [10,36,37] We characterised the chemical structure and composition in BNO using FT-IR spectroscopy and XPS (Figure 2 and Supplementary Figures 3-30). All the samples exhibit the two characteristic IR bands of BN at ~1380 cm À 1 (in-plane BÀ N transverse stretching) and ~800 cm À 1 (out-of-plane BÀ NÀ B bending).…”

Simultaneous Estimation of Gas Adsorption Equilibria and Kinetics of Individual Shaped Adsorbents

“…We synthesized boron nitride (BN) in its powder form, using a methodology previously reported. 41 Further, we obtained the shaped form of BN, by pelletizing the synthesized powder. To achieve this, we placed 50 mg of BN powder, without any binder, into a 5 mm pellet die, which was then placed in a Specac Manual Hydraulic Press (Specac Limited, U.K.).…”