Physicochemically tailored Ag2S QDs deposition on ZnO for improved photocatalytic and antibacterial performance

Abstract

Considering the optoelectronic contrast and compatible band structure between Ag2S (band gap ∼ 1.4 eV) and ZnO (band gap ∼ 3.2 eV), we developed Ag2S quantum-dot (QD) sensitized ZnO nanoflowers (ZnO-Ag2S) using a simplistic and efficient p-SILAR method. Aiming the variation in size dependent performance of Ag2S QDs, we carried out different number of p-SILAR deposition cycles so that we can improve the performance of ZnO-Ag2S as a consequence of the physicochemical tailoring of visible light absorbance which originally depends upon the size of Ag2S QDs. Intensive SEM and TEM were performed to establish the development of Ag2S QDs on ZnO surface. The developed materials were utilized for photocatalytic and antibacterial applications. Interestingly, increasing Ag2S deposition cycles on ZnO nanoflowers (NFs) directly decreases their band gap. Owing to the improved optoelectronic character of ZnO-Ag2S revealed by UV-Visible spectroscopy and photoluminescence, the photocatalytic degradation rate of Rhodamine B dye increased to 0.01 min−1 compared to 0.004 min−1 for pristine ZnO. In addition, antibacterial assay and atomic force microscopy was involved to reveal the effectiveness of ZnO-Ag2S for inhibition of Bacillus subtilis and Escherichia coli bacteria. Anti-bacterial response for ZnO-Ag2S (2 C) was the highest while all samples exhibited nominal (<10%) hemolytic activity, endorsing the effectiveness of p-SILAR process for the development of biocompatible, photocatalytic, and antimicrobial ZnO-Ag2S.