RuO2 photodeposited on W-doped and Cr-doped TiO2 nanotubes with enhanced photoelectrochemical water splitting and capacitor properties

In situ anodizing was used for the fabrication of highly ordered Cr-doped TiO2 (CT) and W-doped TiO2 (WT) nanotubes. For enhancing the photoelectrochemical performance, two series of RuO2 on Cr-doped TiO2 nanotubes (RCT) and on W-doped TiO2 nanotubes (RWT) electrodes were then prepared via a photodeposition method (during various times). Structures, morphologies, elemental compositions and optical properties of the samples were characterized with SEM, XRD, EDX, Raman, and UV-Vis techniques. In addition, photoelectrochemical (PEC) as well as capacitor behaviour of the samples were studied by different electrochemical measurements. The results showed that deposited RuO2 on the surface of CT and WT leads to an incredible decrease in the band gap of bare CT and WT and increase in PEC performance. RCT2 and RWT2 samples exhibited the maximum current density as well as H2 production by water splitting. In addition, RCT8 and RWT8 showed the maximum specific capacitance at a scan rate of 5 mV s−1.