Sulfur doped ceria-titania (S-CeTiO_4−x) nanocomposites for enhanced solar-driven water splitting

In this work the synthesis of sulfur-doped cerium-titania based nanocomposites is carried out for photoelectrochemical (PEC) water splitting applications. Pristine ceria (CeO₂), titania (TiO₂) and S-CeTiO_4−x nanohybrid have been synthesized via facile hydrothermal technique. Additionally, sulfur doping is performed at 350 °C to achieve sulfidized-CeTiO_4−x (S-CeTiO_4−x) nanohybrid with improved optoelectronic properties. The energy disperse x-ray spectrometer (EDS) spectra and elemental mapping of S-CeTiO_4−x showed the presence of sulfur. The X-Ray Photoelectron Spectroscopy (XPS) and X-ray diffraction (XRD) analysis further confirm sulfur doping and composite formation. Additionally, the XRD patterns of S-CeTiO_4−x suggest the anatase phase of TiO₂, which is slightly mitigated with sulfidation. The Brunauer–Emmett–Teller (BET) isotherms indicate the average pore size decreases from 20.82 nm to 18.35 nm after sulfidation, which confirms successful sulfur incorporation in the pores. The Kubelka-Munk plots acquired from UV/Vis-diffuse reflectance spectroscopy (DRS) displayed a substantial red shift in the bandgap with sulfidization from 3.00 eV to 2.50 eV. The photoelectrochemical (PEC) water splitting of S-CeTiO_4−x photoanode in terms of photocurrent density suggesting more than 3-times increase as compared to pristine TiO₂ nanoparticles. These results affirm the photoelctrocatalytic nature of ceria-based nanostructures for PEC water splitting.