Revealing the Role of Defect in 3D Graphene-Based Photocatalytic Composite for Efficient Elimination of Antibiotic and Heavy Metal Combined Pollution

Defect engineering can give birth to novel properties for adsorption and photocatalysis in the control of antibiotics and heavy metal combined pollution with photocatalytic composites. However, the role of defects and the process mechanism are complicated and indefinable. Herein, TiO₂/CN/3DG was fabricated and defects were introduced into the tripartite structure with separate O₂ plasma treatment for the single component. We find that defect engineering can improve the photocatalytic activity, attributing to the increase of the contribution from h⁺ and OH. In contrast to TiO₂/CN/3DG with a photocatalytic tetracycline removal rate of 75.2%, the removal rate of TC with D-TiO₂/CN/3DG has increased to 88.5%. Moreover, the reactive sites of tetracycline can be increased by adsorbing on the defective composites. The defect construction on TiO₂ shows the advantages in tetracycline degradation and Cu²⁺ adsorption, but also suffers significant inhibition for the tetracycline degradation in a tetracycline/Cu²⁺ combined system. In contrast, the defect construction on graphene can achieve the cooperative removal of tetracycline and Cu²⁺. These findings can provide new insights into water treatment strategies with defect engineering.