K⁺‑Doped ZnO/g‑C₃N₄ Heterojunction: Controllable Preparation, Efficient Charge Separation, and Excellent Photocatalytic VOC Degradation Performance

The K⁺-doped ZnO/g-C₃N₄ heterojunction had been prepared by an electrostatic attraction self-assemble method. The charge separation efficiency of the K⁺-doped ZnO/g-C₃N₄ heterojunction was 17.6 and 2.9 times those of g-C₃N₄ and KZO. As expected, the K ion-doped ZnO/g-C₃N₄ heterojunction possessed better photocatalytic isopropanol degradation performance. The highest acetone evolution rate of K⁺-doped ZnO/g-C₃N₄ heterojunction was 28.5 ppm·min^–1, which was 2.7 times better than that of g-C₃N₄ and 1.7 times better than that of KZO. The improvement of charge separation efficiency and photocatalytic performance of K⁺-doped ZnO/g-C₃N₄ heterojunction is mainly due to the following two points. K⁺-doped ZnO/g-C₃N₄ heterojunction with a staggered band structure could effectively improve the carrier separation. The high surface area and mesoporous structure could realize the high efficiency of mass transfer and rapid surface reaction of reactants. These K⁺-doped ZnO/g-C₃N₄ heterojunctions with high photocatalytic activities could be widely used in air purification.