Elucidation of the enhanced photoactivity of melon calcined with MoO3

The charge separation efficiency of melon, a linear polymer of carbon nitride, is a key to enhancing its photoactivity. MoO3 is known to be an efficient co-catalyst to improve the charge separation efficiency. To elucidate the mechanism underlying the enhanced photoactivity of melon calcined with MoO3, the electronic structure of the interface at which melon and MoO3 are in direct contact has been investigated by ultraviolet and X-ray photoemission spectroscopy. The samples were further characterized via photocatalytic activity measurements, X-ray diffraction, and Fourier-transform infrared spectroscopy. Excellent photodegradation ability of an organic compound was observed for the melon:MoO3 sample prepared via calcination at 400 °C for 3 h, which had a blue-black color. From the obtained results, the origin of the high photoactivity of melon:MoO3 composites is consistently explained by taking account of gradient of energy levels in the heterojunction and the states of the oxygen vacancies in MoO3.