Bio-inspired Hierarchical TiO₂: Synthesis And Photocatalytic Properties

The world's energy crisis and environmental problems continue to grow as civilization continues. Using photocatalyst to make use of solar energy seems to be a promising solution. Butterfly wings have a lot of periodical submicrometer structures in their scales coming from millions of years of evolution. Here we put forward a general strategy of borrowing nature's butterfly wing hierarchical architecture to get better photocatalytic performance of TiO2, a typical sunlight water splitting photocatalyst. This concept is of certain potential to be extended to many other relative species, thus give a broad scope of building prototypes to exploit solar energy for sustainable energy resources.Three kinds of butterflies: Papilio helenus Linnaeus,Papilio maackii&Euploea mulciber were chosen as bio-template. Bio-inspired hierarchical TiO2 samples were synthesized by a immersing-calcine method using TiCl3 solutions as precursor.Several kinds of characterizing methods like XRD, FESEM, TEM, UV-Vis Absorption were employed to characterize the products. The products are identified as being due to the anatase phase of TiO2, and their average grain size is about 10 nm. The mesoporous architectures from original butterfly wing scales were well borrowed with a proper size shrank. The products also have nanoporous architectures and the average pore size is about 8 nm. Compared to TiO2 made by the same method but without template, light harvesting efficiency of bio-inspired hierarchical TiO2 was enhanced by about 20 -35percent in wave range of about 380nm to 200nm.Experiments of organic dyes degradation under a 500W Xe lamp indicate that the photocatalytic activity of bio-inspired hierarchical TiO2 samples are 4.3, 2.6, and 1.9 times superior than that of TiO2 made by the same method but without template respectively. And H2 production performance in sunlight driven water splitting indicate that the photocatalytic activity of bio-inspired hierarchical TiO2 is 7 times superior than that of TiO2 made by the same method but without template, 2.24 times when both samples were loaded with 1.5wt.% Pt.