Influence of CVD parameters on Co-TiO2/CNT properties: A route to enhance energy harvesting from sunlight

Carbon nanotubes (CNTs) have been employed to enhance the photoactivity of titanium dioxide (TiO₂). In this work, CNTs were deposited by chemical vapor deposition (CVD) onto the surface of anodized Co-TiO₂ nanotubes. The influence of CVD parameters (time and temperature) on the Co-TiO₂/CNT structure and properties was investigated. We studied three synthesis times (10, 20, and 30 min) and two synthesis temperatures (700 and 800°C). The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and X-ray diffraction (XRD). The photocurrent performance of the electrodes was determined by linear voltammetry. The results showed the successful formation of Co-TiO₂/CNT hybrid structures. The shortest synthesis time produced higher quality CNTs. The samples synthesized at 700 and 800°C for 10 min exhibited a current density of 1.13 mA.cm^?2 and 7.84 mA.cm^?2, respectively, which is 9 and 65 times greater than the Co-TiO₂ sample. The synergistic effect of the CNT deposition and the crystalline phase composition significantly improved the photoresponse of TiO₂. The proper choice of synthesis parameters allowed the control of the sample structure, leading to the production of electrodes with better light-harvesting performance.