Facile and mild preparation of brookite-rutile heterophase junction TiO2 with high photocatalytic activity based on deep eutectic solvent (DES)
The phase junction of nano-TiO2 plays an important role in enhancing its photocatalytic activity. How to achieve the green, mild and controllable synthesis of phase-junction nano-TiO2 still remains a big challenge for the large-scale preparation and application. Deep eutectic solvents (DESs) show many advantages in the green and mild preparation of high active nanomaterial due to their low cost, high green degree, easy large-scale preparation, tailored structures and tunable properties. In this study, by two H-bond acceptors sharing with one H-bond donor, we have successfully used DES as solvent, template, inhibitor and crystalline phase control agent at the same time to controllably synthesize heterophase-junction nano-TiO2 with different phase ratios under green and mild reaction conditions (at 180 ℃ for 18 h). The H2 production rate by photocatalytic water splitting of this catalyst reaches up to 14.51 mmol﹒h-1﹒g-1, which is 20-fold greater than that of commercial P25 TiO2 and also much higher than those of other TiO2 nanostructures. Such rate is the highest yield reported so far to the best of our knowledge for photocatalytic H2 production catalyzed by sole TiO2. The higher activity is mainly attributed to the phase junctions and defects. This study will provide a new way for the green, mild, easy-controllable and versatile preparation of phase-junction photocatalysts with high efficiency.