A Ternary Photocatalyst With Double Heterojunctionsfor Efficient Diesel Oil Degradation

The photodegradation is a potential technology to solve environmental issues such as the diesel oil pollution. The titanium dioxide/graphitic carbon nitride (TiO2/g-C3N4) photocatalyst is widely used for the photodegradation of pollutants. However, the performances of this binary photocatalyst such as the degradation efficiency and cyclic stability are still unsatisfactory for real applications. In our work, we introduce a p-type NiO semiconductor into the binary TiO2/g-C3N4 (98: 2) photocatalyst by a simple dipping method. The NiO semiconductor can form double heterojunctions with the TiO2 and g-C3N4 (dual Z-scheme and Z-scheme+p-n), which can accelerate the separation of photo-generated electron-hole pairs effectively. Thus, the as-obtained ternary TiO2/NiO/g-C3N4 (TCN) sample delivers a good photocatalytic performance for diesel oil degradation under a simulated sunlight. Specifically, the TCN (7 : 3) photocatalyst exhibits a 98.94 % degradation efficiency after 2 h of visible-light, largely outperforming the single-component photocatalysts (TiO2, g-C3N4, NiO,) and the binary TiO2/g-C3N4 (98 : 2) photocatalyst. The free radical capture test manifests that center dot O2- is the major factor on the degradation. This work presents a typical example to boost the photodegradation performance via a ternary catalyst design, which will provide valuable insight for the future high-performance diesel oil degradation.