Enhanced photoelectrochemical properties of TiO2 nanotubes co-sensitized with CdS nanoparticles and tetrasulfonated copper phthalocyanine

TiO2 nanotubes (TiNTs) with high specific surface area were prepared in a hydrothermal process. The XRD analysis indicated that the TiNTs calcined at 300 °C were mainly composed of anatase TiO2. The TiNTs co-sensitized with CdS nanoparticles and tetrasulfonated copper phthalocyanine (TiNTs/CdS-CuTsPc) were prepared via an in situ formation of CdS nanoparticles followed by adsorption of CuTsPc molecules. The co-sensitized TiNTs showed better photoresponse from ultraviolet to the near infrared. The results of photoelectrochemical measurements demonstrated that the co-sensitized TiNTs electrode (FTO/TiNTs/CdS-CuTsPc) possessed higher short circuit current Jsc and IPCE values than those of single-sensitized electrodes, as well as its counterpart fabricated with copper phthalocyanine (FTO/TiNTs/CdS-CuPc). The excellent light-harvesting and efficient spatial separation of the photogenerated charges were considered to be the main reasons responsible for the enhanced photoelectrochemical performance of TiNTs.