Preparation of Type I n-n Heterojunction Cd(OH)<sub>2</sub>/Bi<sub>10</sub>Cd<sub>3</sub>O<sub>20</sub> and its Enhanced Photocatalytic Properties

The heterojunction structure Cd(OH) 2 /Bi 10 Cd 3 O 20 was successfully constructed through a straightforward hydrothermal method. The product was characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), high resolution transmission electron microscope (HRTEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), Diffuse reflectance spectrum (DRS), Raman analysis, photocurrent and electrochemical impedance spectroscopy (EIS) measurements. SEM, HRTEM and Raman analysis confirmed that the nanorod Bi 10 Cd 3 O 20 was effectively stacked on the surface of the hexagonal microblock Cd(OH) 2 , forming the heterojunction composite. This composite demonstrated exceptional photocatalytic performance in the degradation of azo dye pollutants, with a degradation rate for Rhodamine B reaching 98% under optimal synthesis conditions. A plausible photocatalytic mechanism for the heterojunction composite, based on a type I n-n heterojunction, was also proposed. The heterostructure significantly facilitates the migration and separation of charge carriers, thereby enhancing the photoactivity and stability.