Facile Synthesis of Cd–ZnO/TiO ₂ Nanocomposite for Enhanced UV‐Driven Photocatalytic Dye Degradation

ABSTRACT

The design of efficient heterostructure photocatalysts with superior light‐harvesting capability and effective charge separation continues to be a significant challenge in wastewater remediation. Herein, a Cd‐doped ZnO/TiO ₂ (Cd‐ZnO/TiO ₂ ) nanocomposite was synthesized using a chemical co‐precipitation method, and its photocatalytic performance was systematically compared with those of ZnO, TiO ₂ , Cd‐ZnO, and ZnO/TiO ₂ counterpart catalysts prepared under identical conditions. The synthesized catalysts were comprehensively characterized using X‐Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy dispersive X‐ray spectroscopy (EDS), Differential scanning calorimetry (DSC), and UV–vis spectroscopy. TEM and HRTEM analyses confirmed the formation of a Cd‐ZnO/TiO ₂ heterojunction with distinct interfacial contact between the crystalline domains. The Cd‐ZnO/TiO ₂ exhibited a reduced band gap of 2.52 eV, compared with of the reference catalysts. UV‐light‐driven photocatalytic degradation of Safranin‐O (SO) revealed that Cd‐ZnO/TiO ₂ attained 87.04% removal in 180 min, significantly outpacing the reference catalysts in degradation. The degradation kinetics followed both pseudo‐first‐order (PFO) and pseudo‐second‐order (PSO) models. The Cd‐ZnO/TiO ₂ demonstrated excellent stability/reusability, retaining a degradation efficiency of ∼87% over five consecutive photocatalytic cycles. The enhanced photocatalytic activity is attributed to the synergistic effect of Cd doping and ZnO/TiO ₂ heterojunction formation, which collectively promotes charge separation and suppresses electron‐hole recombination. The good photocatalytic activity and operational stability of Cd‐ZnO/TiO ₂ underscore its practical viability for treating dye‐contaminated wastewater.