Direct evidence of the efficient hole collection process of the CoOx cocatalyst for photocatalytic reactions: a surface photovoltage study

Abstract

The true effect of a cocatalyst on photocatalytic reactions is one of the major issues to resolve in photocatalysis research. Herein, the efficient hole collection role of the CoO_x cocatalyst grown on TiO₂-nanotubes has been directly proved by surface photovoltage (SPV) spectroscopy. Transient SPV measurements provide evidence that the CoO_x cocatalyst could significantly prolong the life-time of photogenerated holes. Furthermore, it is proposed that the hole collection effect can be attributed to the work function difference between the TiO₂ and CoO_x interface. These findings demonstrate that the development of a cocatalyst with a suitable work function can be a general strategy for photoconversion applications.