Understand the role of nanostructure for efficient hydrogen generation on immobilized photocatalysts

Abstract

For the purpose of efficiently utilizing the renewable solar energy, it is of vital importance to understand the key factors that contribute to the performance merits for photocatalysis applications. The efficiencies toward photocatalytic water splitting were measured on three distinct immobilized titania nanostructures. Different trends in the nanostructure – water splitting efficiency relationship were observed, depending on the specific application mode being either photoelectrochemical cell (PEC) or direct heterogeneous reaction (DHR). Investigations were carried out to elucidate on how PEC and DHR benefit to a varying degree from the hydrothermal processing history, electronic properties, interface structures, and reactive facets of the resultant nanostructures. Good PEC cell performance was identified to be related to topotactically formed samples with intimate-contacting surfaces that eased inter-particle charge transfer. Additional benefit for PEC cell was found to be achieved from the vectorial conduction pathway in pseudo-one dimensional structure. On the other hand, high activity of DHR photocatalysis is attributed mainly to the exposed high reactivity crystal facets. The presence of anatase TiO2 {010} facets was identified to enhance electron-hole separation and create specific surface states that facilitate interactions across the semiconductor/electrolyte interfaces.