Controlled Regulation of N‐Involved TiO2 Nanoflowers in Size and Morphology via Solvothermal Synthesis for Enhanced Photocatalytic Performance

Abstract The precise control of size and morphology of photocatalysts through solvothermal methods is a challenge in the basic research of 3‐D titanium dioxide (TiO 2 ) hierarchical structures. This study utilizes the solvothermal method to synthesize N‐involved TiO 2 nanoflowers with nanosheet‐assembled structures ranging from microscale (1.3 µm ± 0.2 µm) to nanoscale (200 nm ± 50 nm), achieved by varying the volume fraction (percentage by volume, vol%) of N‐N‐ dimethylformamide (DMF) from 0% to 75% in a mixed solution of DMF and isopropanol (IPA). The synthesized TiO 2 :VF DMF = 0–75% catalyst exhibits good monodispersity and uniform particle size. With increasing DMF volume percentage, the size of TiO 2 :VF DMF = 0–75% decreased regularly, and the number of nanosheets constructed with a single TiO 2 :VF DMF = 0–75% particle decreased without any stacking or reassembly occurring. This study monitors the solvothermal processes of DMF 5% and DMF 75%, revealing the changing rules of nanoparticle size and morphology. Furthermore, the photocatalytic degradation of methyl orange shows that TiO 2 :VF DMF = 50% and TiO 2 :VF DMF = 75% are structurally stable and exhibit good photocatalytic activity without any noble metal doping. The degradation efficiency reaches 99.9%, and after repeated use, the catalysts demonstrate excellent degradation performance.