Preparation and characterization of noble metal modified titanium dioxide hollow spheres – new insights concerning the light trapping efficiency

[Display omitted] •The unique morphology enhanced the activity compared to solid spherical reference.•Increased light harvesting was assumed and reinforced via calculations.•Hollow spheres with valid resonance condition was more beneficial to the activity.•The presence of noble metals was beneficial to the photocatalytic activity. Titanium dioxide hollow spheres (TiO2-HSs) were fabricated by applying carbon spheres (CSs) as templates, which were eliminated by calcination. The most suitable TiO2 was selected and an attempt was made to further increase its photocatalytic activity via noble metal (Au and Pt, at 0.25 wt%) deposition. The photocatalytic efficiency was determined by the decomposition of phenol and oxalic acid under both UV-A and visible light irradiation. It was established, that both the unique morphology and the presence of noble metals contributed to the photocatalytic activity gain compared to the solid spherical reference. For the elucidation of the observed phenol degradation performance under UV-A light irradiation, new insights were proposed: within the TiO2 samples the ratio of HSs with enhanced light trapping properties were demonstrated, and the data was compared to the observed photocatalytic activities and a direct correlation was found.