HF-based surface modification for enhanced photobiological and photochemical performance of ZnO and ZnO/CdS hierarchical structures

Abstract

In this work, we modified the conventional wet chemical route used for synthesis of ZnO hierarchical structure (HS), and successfully obtained superior optical, photochemical and antimicrobial characteristics for ZnO-HS as a consequence of incorporation of hydrofluoric acid (HF). ZnO-HS is unique owing to its morphology with 2D interconnected nanosheets. Strategic use of HF led to appreciable reduction in sheet thickness (up to ~15 nm) of ZnO-HS while physicochemical attachment of Fluorine (F) was also realized. Antimicrobial activity of ZnO-HS against Escherichia coli was measured via pour plate method, and found to be significantly increased as a consequence of HF-based modification of ZnO-HS. In addition, resultant ZnO-HS exhibited higher deposition of CdS quantum-dots via pseudo-successive ionic layer adsorption and reaction (p-SILAR), affirming higher photocatalytic performance of ZnO/CdS hierarchical composite (HC). It was established that congo red (CR) dye was degraded ~15% more, when ZnO/CdS HC incorporating HF-based surface modification was used as a photocatalyst. Characteristic improvements in ZnO-HS were affirmed using diffuse reflectance spectroscopy, FTIR spectroscopy and SEM.