Controllable preparation of fluorinated boron nitride nanosheets for excellent tribological behaviors

Although fluorinated boron nitride nanosheets (F-BNNSs) have been proved possessing superior lubricating properties via density-functional theory, the effect of fluorine (F) content on the tribological behaviors has not been studied in experiment so far. Because it is still a challenge to obtain F-BNNSs with different F content through the controllable preparation method. Here, F-BNNSs were successfully prepared via solvothermal method, using a nontoxic and noncorrosive solid acid as F source for fluorination of hexagonal boron nitride nanosheets (h-BNNSs). It is of great significance to achieve the tunability of F content in the range from 4.09% to 14.6% by controlling dosage of fluorinating agent and fluorinating time. F-BNNSs(2.0-24) with the highest F content possess the best tribological performance: the average friction coefficient and wear rate can decrease by 32.3% and over 91%, respectively. The outstanding tribological properties are attributed to their special composition, physicochemical properties, nanostructure and interface behaviors, which promotes the formation of self-lubricating structure and dense protective tribo-films. F-BNNSs show promising potentials as a substitute of traditional h-BNNSs in industrial application. Prospectively, this method can also be applied in fluorination of other two-dimensional materials to improve the tribological behaviors, considering its advantages of conveniency, controllability and environmental friendliness.