One-step hydrothermal method to prepare nitrogen and lanthanum co-doped TiO2 nanocrystals with exposed {0 0 1} facets and study on their photocatalytic activities in visible light

•(0 0 1) dominated TiO2 nanosheets co-doped with N and La is synthesized.•N,La–TiO2 nanosheets shows higher visible light photocatalytic activity than N,La–TiO2 nanoparticles.•N and La co-doping could produce a synergistic effect.•N and La co-doping could increase BET surface area.

The photocatalytic activity of TiO2 can be mainly improved from three approaches: (1) enhancing the separation efficiency of photoelectrons and holes, (2) enhancing surface energy, and (3) increasing availability of visible light. Here, we report a one-step method to obtain nitrogen and lanthanum co-doped TiO2 nanosheets with dominant {0 0 1} facets through a hydrothermal process, using TBOT, triethylamine and LaCl3·nH2O as precursor and sources of N, La respectively in HF–HNO3 mixed aqueous solution, and the samples were characterized by XRD, SEM, TEM, XPS, UV-DRS and BET analyses. The XRD and XPS results confirmed that N was doped into the lattice of anatase TiO2, while La was not. N acts as an O–Ti–N structure or interstitial N and La exists as LaF3 in TiO2 nanosheets. The SEM and TEM results show that the percentage of {0 0 1} facets in the as-synthesized N,La–TiO2 nanosheets is estimated to be about 75% on average at RF = 1.0. N,La–TiO2 nanosheets can absorb visible light due to the red shift in the absorption edges, and compared with N–TiO2 nanosheets, N and La co-doping can further strengthen the absorption of visible light. N,La–TiO2 nanosheets exhibited higher photocatalytic activity for photodegradation of Rh B under visible light than pure TiO2, N–TiO2, La–TiO2 nanosheets and N,La–TiO2 nanoparticles. N and La co-doping could produce a synergistic effect. The N doping narrowed the band gap of TiO2, while the La doping could improve the separation efficiency of photoelectrons and holes. In addition, the La doping could enhance the adsorption property of photocatalyst for organic pollutants.