Improving photoelectrochemical performance of transferred TiO2 nanotubes onto FTO substrate with Mo2C and NiS as Co-catalyst.

The photoelectrochemical (PEC) performance of titanium dioxide nanotube (TiO 2 NT) photoelectrodes for sustainable hydrogen production has garnered significant research interest. Despite the advantages of TiO 2 NT fabricated via anodization of titanium metal, such as their well-ordered vertical structure, challenges persist including the thick oxide barrier layer, limited optical transparancy, and the wide energy band gap (∼3.0 eV), which constrain their practical efficiency in PEC applications. This study addresses these limitations by introducing a novel approch to transfer TiO 2 NT onto a fluorine-doped tin oxide (FTO) substrate. TiO 2 NTs were synthesized with varying anodization times and steps to achieve optimal free-standing structures. To further enhance PEC performance, co-catalyst including molybdenum carbide (Mo 2 C) and nickel sulfide (NiS) were incorporated using immersion and successive ionic layer adsorption reaction (SILAR) methods, respectively. Comprehensive characterization using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultraviolet–visible–near infrared (UV–Vis–NIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) provided insights into the crystal phase, morphological structure, band gap, and elemental composition of the photoelectrodes. Photoelectrochemical and photostability evaluations were conducted through linear scan voltammetry (LSV) and chronoamperometry under dark and light conditions. Results indicate that transferring TiO 2 NTs onto FTO significantly enhanced photocurrent density, achieving a 2.5-fold increase at 0.7 V versus a TiO 2 NT/Ti substrate. The incorporating of co-catalysts Mo 2 C, NiS and the combined NiS/Mo 2 C further enhanced the photocurrent density to 2.20, 3.00 and 8.00 mA cm−2 respectively, with a remarkable 31-fold enhancement compared to the TiO 2 NT/Ti substrate. This findings underscore the potential of the TiO₂ NT/FTO photoelectrode with optimized co-catalyst integration for advanced photoelectrochemical applications. [Display omitted] • Enhanced TiO 2 NTs efficiency by transferring from Ti foil substrate onto FTO. • Mo 2 C and NiS as co-catalysts of TiO 2 NTs prepared by immersion and SILAR methods. • Mo 2 C and NiS contribute in enhancing PEC water-splitting efficiency of TiO 2 NTs. • The two co-catalyst synergistically increase a 31-fold in photocurrent efficiency. [ABSTRACT FROM AUTHOR]