Abstract
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.
Highlights
A large number of methods have been suggested to remedy the problem of wastewater treatment from which heterogeneous photo catalysis is a suitable candidate to be used as an alternative technique
Based on the publication of Xiang and Zhao, in which methyl blue was applied as model con taminant, the light harvesting of the titania cannot be increased effectively only by controlling the morphology, but it is possible to en hance it by combining morphology control with noble metal deposition [19]
Even though there are nu merous publications in the literature for the explanation of the photocatalytic enhancement caused by the deposition of noble metals, but in the case of photocatalytic activity gain caused by the unique hollow spherical morphology the enhanced light trapping properties are only implied in these publications to the best of our knowledge
Summary
A large number of methods have been suggested to remedy the problem of wastewater treatment from which heterogeneous photo catalysis is a suitable candidate to be used as an alternative technique. The preparation of hollow structural semiconductors has attracted considerable attention due to their unique chemical, thermal, optical, electrical and optoelectronic properties [22] Semiconductors possessing such morphology may have enhanced light harvesting cap ability due to the multiple reflections of incident light within the hollow cavity which can lead to the improved utilization of light source [23,24], yielding more photogenerated charge carriers, resulting in enhanced photocatalytic efficiency of the semiconductor. Even though there are nu merous publications in the literature for the explanation of the photocatalytic enhancement caused by the deposition of noble metals, but in the case of photocatalytic activity gain caused by the unique hollow spherical morphology the enhanced light trapping properties are only implied in these publications to the best of our knowledge. In this paper an attempt was made to establish connection be tween the observed photocatalytic activity and the properties of the TiO2 hollow spheres based on calculations
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