Construction of metallic nanocrystalline TaB2 coupled with TiO2 for enhanced photocatalytic degradation

The search for new low-cost co-catalysts that can replace precious metals is highly desirable and challenging. Transition metal diboride can be ideal candidates due to their excellent electrical conductivity and suitable work function. In this work, a novel TaB2@TiO2 heterostructure has been successfully constructed by a facile sol-gel method. The results show that TaB2 has a suitable work function and B-O bonds are formed at the interface of the TaB2@TiO2 heterojunction, which makes it easier for the photogenerated electrons of TiO2 to migrate to the surface of TaB2 and promotes the effective separation of photogenerated carriers. In addition, the metallic nanocrystalline TaB2 also significantly increases the specific surface area of the heterojunction. The above two points lead to more hydroxyl radicals and superoxide radicals production, thus substantially improving the photocatalytic degradation performance. Therefore, the 3 wt% TaB2 (TT3) catalyst degraded rhodamine B (RhB, 20 mg/L) with an efficiency of 100% under 90 min irradiation, which is much higher than pristine TiO2-92% and commercial TiO2 (P25)-64%. Furthermore, its photocatalytic rate is about 1.73 times and 3.77 times of pristine TiO2 and commercial TiO2 (P25), respectively. This finding can provide new insights for the replacement of photocatalytic noble metal co-catalysts.