Cu clusters modified aligned titania nanotubes for photoelectrochemical water splitting

Limited availability of the fossil fuel resources, and their environmental impact has led to a rapid increase in the scientific interest towards renewable energy sources. Photoelectrochemical water splitting to produce hydrogen is one such technology. In the current work, aligned titania nanotubes were fabricated by electrochemical anodization and surface engineered with sub-nanometer Cu clusters for the enhanced photoelectrochemical responses. The nanotubes have anatase crystalline structure and are well covered on the surface as shown by X-ray diffraction and scanning electron microscopy, respectively. The surface modification of the nanotubes using Cu clusters enhanced the photoelectrochemical responses, indicative of improving the water splitting yield. The enhancement in photocurrent could be explained due to an extended absorption range or reduced recombination. As the enhancement was limited to the UV region and no visible response was observed, it was considered unlikely the surface modification altered the materials band gap. Instead, the enhancement is considered to be due to reduced recombination.