The effect of the boron source composition ratio on the adsorption performance of hexagonal boron nitride without a template

• Spherical h-BN was synthesized by controlling the boron source composition ratio.
• Without extra spherical template, solid Na2O was equal to a spherical template.
• At boron source composition ratio of 1:1, h-BN had best adsorption performance.

An inexpensive boric acid (H3BO3) and borax (Na2B4O7·10H2O) mix was used as a source of boron with different composition ratios, and urea was used as a nitrogen source, in flowing ammonia atmosphere, for the preparation of hexagonal boron nitride (h-BN) with different micro-morphologies. Under a certain synthesis process, the effects of the molar ratio of borax and boric acid (or simply the boron source composition ratio for short) on the phase composition of the sample were studied; the work also explored the effect of boron source composition ratio on the micro-morphology, adsorption desorption isotherm and specific surface area of the h-BN powder. The main purpose of this work was to determine the optimum composition ratio of preparing spherical mesoporous h-BN and ensure that the micro-mechanism underpinning the formation of spherical mesoporous h-BN was understood. The results showed that at the optimum boron source composition ratio of 1:1, globular mesoporous spheres with a diameter of approximately 600–800 nm could be obtained with the highest pore volume and specific surface area (230.2 m2/g).

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