A Two-step Approach for Improved Exfoliation and Cutting of Boron Nitride into Boron Nitride Nanodisks with Covalent Functionalizations.

Synthesis of boron nitride nanodisks (BNNDs) with reducing the size and a fewer number of disk layers, and low optical band gap (Eg) is essential for practical applications in electronics and optoelectronic devices. So far, the large-scale preparation of hydroxyl (-OH) and hydroperoxyl (-OOH) functionalized boron nitride nanosheets (BNNSs) and BNNDs with reduced Eg is still a challenge. This research demonstrates the scalable and solution process synthesis of hydroxyl (-OH) and hydroperoxyl (-OOH) functionalization of BNNDs at the edges and basal planes from pristine hexagonal boron nitride (h-BN) by the combination of modified Hummer's method and Fenton's chemistry. Modified Hummer's method induces to exfoliate and cutting the h-BN into BNNDs with a low percentage of -OH functionalization (6.90%), which is further exfoliating and cutting by Fenton's reagent with improved -OH and -OOH functionalization (ca. 17.25%). The combination of these two methods allowing to reduce the size of the OH/OOH-BNNDs to ca. 200 nm with the number of disk layers in the range from ca. 6-11. Concurrently, the Eg of h-BN was decreased from ca. 5.10 eV to ca. 3.58 eV for OH/OOH- BNNDs, which enables the possibility of the application of OH/OOH-BNNDs in semiconductor electronics. The high percentage of -OH and -OOH functionalization's in the OH/OOH- BNNDs enabling to disperse in various solvents with high long-term stability.