Novel mesoporous NiO/TiO2 nanocomposites with enhanced photocatalytic activity under visible light illumination

The development of active semiconductor photocatalysts with desirable material properties and efficient carrier transformation is indispensable for better photocatalyst utilization and performance optimization. Here, we demonstrate the synthesis of novel mesoporous NiO-TiO2 nanocomposites at different NiO contents through a modified sol-gel method in the presence of triblock copolymer as a structure directing agent, followed by a simple ultrasonication process for enhancement of the photocatalytic properties under visible light illumination. The results indicated that XRD patterns of the NiO/m-TiO2 nanocomposites at different NiO contents show a biphasic anatase-rutile structure. TEM images of the NiO/m-TiO2 nanocomposites showed the formation of very fine TiO2 nanoparticles and NiO sheet-like structure with particle sizes ranging between 10 and 15 nm and 30-50 nm, respectively. The mesoporous NiO/TiO2 nanocomposites have large surface areas of 111.3 m(2)/g and wide pore volumes of 0.376 cc/g. NiO/m-TiO2 nanocomposites exhibit highly enhanced photocatalytic performance for Methylene Blue (MB) decomposition under visible light illumination, compared with either pure mesoporous TiO2 or pure NiO nanoparticles. The optimum NiO loading content was amounted to be 0.5 wt%, giving a photodegradation rate of 3.3 x 10(-7) mol L-1 min(-1) with a photocatalytic efficiency of 90%, exceeding that of pure NiO and pure mesoporous TiO2 by more than 10 and 1.5 times, respectively. Additionally, the optimal photocatalyst exhibited extremely high degradation ability towards the gemifloxacin mesylate (GFM: antibiotic drug), complete degradation of molecule was obtained after 180 min. The enhancement of the photocatalytic performance of prepared photocatalysts is explained by the synergistic effect, high surface area, low bandgap values, meso-structure and the formation of p-n junction at the interface of NiO and TiO2. The facile synthesis route, along with superior photocatalytic activity and proper reusability make the current mesoporous NiO/TiO2 nanocomposite a potential candidate in photocatalysts related fields.