Two-dimensional atomically thin boron nitride (BN) nanosheets possess many distinctive properties but their applications are still being hindered by the technical difficulties in their synthesis methods, due to the strong lip-lip interactions between their basal planes. In this paper, we reported a facile and scalable bottom-up approach to synthsizing atomically thin BN nanosheets in a molten salt medium. As-prepared BN nanosheets can be used as an effective co-catalyst to improve the catalytic performance of carbon nitride photocatalyst, owing to the interfacial effect induced by their addition. In the case of photodegradation of rhodamine B, for example, the photodegradation rate of carbon nitride could be approximately doubled when 5 wt% as-prepared BN nanosheets were added. (C) 2018 Elsevier Inc. All rights reserved.