Fig. 1 SEM images of as-synthesized TiO2 samples before a and after b calcinations treatment at lower magnification. The high magnification SEM image c, TEM d, HR-TEM images e, SAED pattern f of the samples after calcinations treatment. SEM image g of the products that obtained in the absence of halloysite nanotubes

Fig. 2 XPS spectra of the as-prepared square-like TiO2 nanobiscuits before a and after b calcinations treatment a, high-resolution XPS spectra of F1s b, O1s c, Ti2p d

 Fig. 3 XRD patterns a, BET specific surface area and pore size distribution curves b of the products

Fig. 4 The photo-catalytic degradation of RhB a; methylene blue (MB) b over square-like TiO2 nanobiscuits under UV irradiation

Fig. 5 The photo-catalytic degradation of methanol over square-like TiO2 nanobiscuits under UV irradiation a, GC analysis b, a trapping experiment of active species during the photo-catalytic reaction using calcined sample as catalyst c