Atomic layer deposition with rotary reactor for uniform hetero-junction photocatalyst, g-C3N4@TiO2 core–shell structures†
A heterojunction of TiO2 grown on g-C3N4 particles is demonstrated using atomic layer deposition (ALD), equipped with a specifically designed rotary reactor for maintaining stable mechanical dispersion of g-C3N4 particles during ALD. The photocatalytic activity of the g-C3N4@ALD-TiO2 core–shell composites was examined using the degradation of rhodamine B dye under visible light irradiation. The optimal composite with 5 ALD cycles of TiO2 exhibited the highest photocatalytic reaction rate constant among the composites with a range of ALD cycles from 2 to 200 cycles, which was observed to be 3 times higher than that of pristine g-C3N4 and 2 times higher than that of g-C3N4@TiO2 composite prepared using a simple impregnation method. The ALD-TiO2 were well-dispersed on the g-C3N4 surface, while TiO2 nanoparticles were agglomerated onto the g-C3N4 in the g-C3N4@TiO2 composite prepared by the impregnation method. This created uniform and stable heterojunctions between the g-C3N4 and TiO2, thus, enhancing the photocatalytic activity.