Trace surface fluorination and tungsten-intercalation cooperated dual modification induced photo-activity enhancement of titanium dioxide

General modification that utilizes insoluble tungstic acid or highly toxic hydrofluoric acid to improve charge separation and transfer in TiO2 results in considerable issues such as uneven doping, significant impacts on particle size and morphology, as well as environmental hazards. In the present work, an environmental benign one-pot dual-modification approach was demonstrated that uses soluble sodium tungstate and only trace-level sodium fluoride as replacements. The photoactivity efficiency for decoloration of methylene blue (MB) solution was improved by 33.6% and 119.5% under ultraviolet and visible light, respectively. Meanwhile, the photocurrent density reached an enhancement by 181.2% by this dual-modification. The dual-modification had negligible influence on the crystal structure and the surface area of the TiO2 nanoparticles. Density functional calculation suggested the remarkable improvements of the photocatalysis of TiO2 can be ascribed to the rapid charge separation and transfer owing to the down-shift of conduction band from the tungsten doping and localized spatial charge separation from the surface fluorination enabled by the dual-modification approach.