Facile and rapid exfoliation of HTiNbO5 nanosheets for photocatalytic applications

•HTiNbO5 nanosheets are prepared with a facile hydrothermal method in acid solution.•Using this method, preparation time is reduced from several days to 12 h.•Both acid type and starting KTiNbO5 are keys to this preparation.•The prepared HTiNbO5 nanosheets show good photocatalytic activity. Due to the rich chemistry, HTiNbO5 nanosheets are interesting candidates in many applications but the long preparation time limits their uses. Here, we report a novel fast, and facile preparation of HTiNbO5 nanosheets by hydrothermal treatment of KTiNbO5 with acid solution. Investigation on various acids shows that the acid strength and structure determine the product. The bulky structure of citric acid promotes the exfoliation and stabilizes the nanosheets, preventing the decomposition. Nature of KTiNbO5 is also important as only KTiNbO5 prepared from molten salt, but not solid-state reaction, gives pure nanosheets. The obtained nanosheets have good crystallinity and photocatalytic activity. Therefore, this novel one-step hydrothermal preparation would play a role in realizing applications of HTiNbO5 nanosheets and might benefit the exfoliation of other layered oxides.