Enhanced H-2 Generation of Au-Loaded, Nitrogen-Doped TiO2 Hierarchical Nanostructures under Visible Light

Abstract

Hierarchical N-doped TiO2 nanostructured catalysts with micro-, meso-, and macroporosity are synthesized by a facile self-formation route using ammonia and titanium isopropoxide precursor. UV-vis diffuse reflectance spectra confirm the red shift and band gap narrowing due to the doping of N species in the TiO2 nanoporous catalyst. Hierarchical macroporosity with fibrous channel patterning is observed and well preserved even after calcination at 800 degrees C, indicating thermal stability, whereas micro-and mesoporosity are lost after calcination at 500 degrees C. The photocatalytic activity of hiearchical N doped TiO2 catalysts loaded with Au is evaluated for H-2 production reaction in visible light. The enhanced photocatalytic activity is attributed to the combined synergetic effect of N doping for visible light absorption, micro-and mesoporosity for an increase of effective surface area and light harvestation, and hierarchical macroporous fibrous structure for multiple reflection and effective charge transfer.