TiO₂ nanoparticles anchored on hollow carbon spheres for enhanced photocatalytic antibacterial

TiO2 nanoparticles anchored on hollow carbon spheres (HCS) composites (HCS@TiO2) were prepared via a facile wet-chemistry and controllable pyrolysis using polystyrene@polypyrrole derived HCS as substrates and titanium oxide acetylacetone (TOAC) as Ti source, respectively. The crystalline structures, micro morphologies, and optical properties of HCS@TiO2 composites were characterized by powder X-ray diffraction, ultraviolet-visible spectra, X-ray photoelectron spectra, thermogravimetric analysis, scanning electron microscope, transmission electron microscope, photoluminescence spectra, and Mott-Schottky curves. The structural optimization of HCS@TiO2 composites was investigated by tuning the loading mass of TiO2 and pyrolysis temperatures. Antibacterial performances for E. Coli and S. aureus were evaluated by using HCS@TiO2 with different loading masses and control group (HCS and TiO2) under simulated sunlight irradiation conditions as well as different irradiation times. It was found that the optimized HCS@TiO2-15 (the mass ratio of TOAC to HCS was 15:1, the pyrolysis temperature was 650 degrees C) showed a high antibacterial efficiency (above 99%) which was far superior to that of HCS and TiO2. Moreover, the irradiation time was determined to 90 min having best antibacterial activity (the survival rate was less than 1%).