Functionalization of hexagonal boron nitride (hBN) by the hydroxyl group imparts enhanced dispersion properties and offers a wide range of applications. Thermal exfoliation and functionalization of hBN is an easy and efficient technique, where the pristine hBN is oxidized at 1000 degrees in an oxygen environment followed by hydrolyzation resulting in functionalized hBN (BNOH). Most of the studies reported assume that the oxidation of the hBN is uniform across the bulk material and lacks information about the crystalline and surface property at each step of the process. However, the oxidation does not take place uniformly on the surface due to possible sintering of the material at elevated temperature, which restricts the supply of oxygen to the inner layer of the bulk resulting in non-uniform oxidation of the bulk material. No work is reported, so far, to elaborate the separation of the BNOH based on the degree of oxidation. This research highlights the impact of dispersion and settling time on the phase separation/identification of the BNOH as a function of the degree of oxidation. This concept can be utilized for the large-scale production and targeted application of the material depending on the dispersion and BET surface area. The oxidized hBN showed a very low BET surface area ascribed to agglomeration or sintering. However, the hydrolyzation opens up the pores leading to a higher BET surface area of BNOH. BNOH-top, middle, and bottom are products collected based on decreasing oxygen content (Fig. 1a). Interestingly, the highly functionalized BN surface exhibits high dispersity and low BET area, and vice-versa. The functionalization has changed the surface morphology of the material as shown by SEM images (Fig.1b and c).

Phase identification of functionalized hexagonal boron nitride

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