Superior atomic layer deposition of conformal ZnO shell on spherical SiO2 particles for enhanced photocatalytic activity

Abstract

Atomic layer deposition (ALD) was employed to obtain superior deposition of a conformal ZnO shell on SiO2 spherical particles passivating the limitations of wet-chemical deposition routes which yield inferior surface-related physicochemical characteristics of resultant SiO2-ZnO particles. It was established that ALD route for deposition of ZnO on SiO2 enables us to have reasonably crystalline ZnO shell over amorphous SiO2 (SZCSPs), without any evolution of corresponding silicates of zinc that may lower the performance of SZCSPs. Detailed scanning and transmission electron microscopy along with X-ray diffraction analysis were utilized to elucidate the morphological contrast of SZCSPs particles, concomitantly revealing the structural superiority, conformality and effectiveness of ALD deposition in comparison with the wet-chemical route. Concurrently, improved opto-electronic properties were recorded for superior photocatalytic performance of the SZCSPs under UV-irradiation for degradation of rhodamine-B dye. Furthermore, the dye degradation performance was investigated by scav-enging experiment, revealing the mechanism of generation of reactive species and their interaction with rhodamine-B dye molecules.