Fabrication of a high-efficiency CdS@TiO2@C/Ti3C2 composite photocatalyst for the degradation of TC-HCl under visible light

Abstract

A novel CdS@TiO₂@C/Ti₃C₂ composite as a high-efficiency photocatalyst for the degradation of tetracycline hydrochloride (TC-HCl) was fabricated by in situ oxidizing two-dimensional (2D) layered transition metal Ti₃C₂ MXene and subsequently compounding with CdS nanoparticles (NPs) via a two-step hydrothermal method. Benefitting from the in situ oxidation of Ti₃C₂ MXene, the derived TiO₂@C/Ti₃C₂ composites possess excellent interface contact and uniform morphology distribution. Furthermore, the in situ grown TiO₂ displays a nanosheet (NS) structure with high-energy (001) facets, which could bring about unique surface heterojunctions between the (101) and (001) facets of the TiO₂ NSs. On the above basis, CdS NPs are introduced to effectively improve the light-harvesting ability in the visible region due to the narrow band gap and enlarged surface area. Meanwhile, the separation and transfer efficiencies of photo-generated carriers are significantly enhanced by the synergistic effect of the C/Ti₃C₂ matrix, surface heterojunctions of the TiO₂ NSs and heterojunctions of CdS/TiO₂. Therefore, the CdS@TiO₂@C/Ti₃C₂ composites display remarkably enhanced photocatalytic ability for TC-HCl degradation under the irradiation of visible light, and the CdS@TiO₂@C/Ti₃C₂-2 sample exhibits optimal photodegradation efficiency with a value of 85% within 60 min, which is 8.5 times higher than that of the TiO₂@C/Ti₃C₂ sample. Additionally, the corresponding improved mechanism is also deeply discussed in the present paper.