Enhanced Light-Harvesting and Photocatalytic Properties in Morph-TiO2 from Green-Leaf Biotemplates

The unique structure of green leaves endows them with an extremely high light-harvesting efficiency. In this work, green leaves are applied as biotemplates to synthesize morph-TiO2. The structural features favorable for light harvesting from the macro- to the nanoscale are replicated in morph-TiO2 through a two-step infiltration process and the N contained in the original leaves is self-doped into the resulting samples. The absorbance intensities within the visible-light range of morph-TiO2 derived from different leaves increase by 103-258% and the band-gap-absorption onsets at the edge of the UV and visible-light range show a red-shift of 25-100 nm compared to those in TiO2 without the template. The photocatalytic activity of morph-TiO2 is also improved, as proven by an electron paramagnetic resonance (EPR) study and degradation of rhodamine dye under irradiation with UV and visible light. The present work, as a new strategy, is of far-reaching significance in learning from nature, driving us to make full use of the most-abundant resources and structure-introduced functions endowed by nature,opening up possibilities for extensive study of the physical and chemical properties of morph-structured oxides and extending their potential for use in applications such as solar cells, photoeatalysts, photoelectrical devices, and photoinduced sensors.