Pravin S. Shinde

Fabrication of a ternary CdS/ZnIn2S4/TiO2 heterojunction for enhancing photoelectrochemical performance: effect of cascading electron–hole transfer

A novel, three-dimensional, ternary CdS/ZnIn2S4/TiO2 heterojunction has been fabricated via a three-step facile hydrothermal method. In this structure, one-dimensional TiO2 nanorods were directly grown on conductive fluorine-doped tin oxide (FTO) substrates. Next, to form a ternary heterojunction of CdS/ZnIn2S4/TiO2, ZnIn2S4 nanosheets were designed on the TiO2 nanorods and sensitized by CdS nanograins. A systematic photoelectrochemical study shows that the photocurrent density of the ternary heterojunction architecture is as high as 1.4 mA cm−2 at a potential of 0.1 V versus Ag/AgCl (under optimized conditions). A more detailed study shows that the photocurrent density is more than two times higher than that of a single CdS/TiO2 heterojunction (0.615 mA cm−2) and three times higher than that of ZnIn2S4/TiO2 (at 0.1 V vs. Ag/AgCl). This excellent photoelectrochemical performance is ascribed to the way that the band structure of TiO2 nanorods synergistically cascades with ZnIn2S4 and CdS, which allows for the absorption of a wider portion of the solar spectrum and improves the effective separation of the generated electron–hole pairs. Electrochemical impedance spectroscopy (EIS) studies also reveal the significant changes in both the interface resistance and the charge transfer resistance of the CdS/ZnIn2S4/TiO2 heterostructure. This can be attributed to the efficient hierarchical cascading that occurs during the electron–hole transfer from the excited CdS to TiO2 through the enlarged interface of ZnIn2S4 upon visible light illumination.

A Synergistic Effect of Surfactant and ZrO2 Underlayer on Photocurrent Enhancement and Cathodic Shift of Nanoporous Fe2O3 Photoanode.

Augmenting the donor density and nanostructure engineering are the crucial points to improve solar water oxidation performance of hematite (α-Fe2O3). This work addresses the sluggish water oxidation reaction associated with hematite photoanode by tweaking its internal porosity. The porous hematite photoanodes are fabricated by a novel synthetic strategy via pulse reverse electrodeposition (PRED) method that involves incorporation of a cationic CTAB surfactant in a sulfate electrolyte and spin-coated ZrO2 underlayer (UL) on FTO. CTAB is found to be beneficial in promoting the film growth rate during PRED. Incorporation of Zr4+ ions from ZrO2 UL and Sn4+ ions from FTO into the Fe2O3 lattice via solid-state diffusion reaction during pertinent annihilation of surfactant molecules at 800 °C produced internally porous hematite films with improved carrier concentration. The porous hematite demonstrated a sustained photocurrent enhancement and a significant cathodic shift of 130 mV relative to the planar hematite under standard illumination conditions (AM 1.5G) in 1 M NaOH electrolyte. The absorption, electrochemical impedance spectroscopy and Mott-Schottky analyses revealed that the ZrO2 UL and CTAB not only increased the carrier density and light harvesting but also accelerated the surface oxidation reaction kinetics, synergistically boosting the performance of internally porous hematite photoanodes.

Data on the effect of improved TiO2/FTO interface and Ni(OH)2 cocatalyst on the photoelectrochemical performances and stability of CdS cased ZnIn2S4/TiO2 heterojunction

This data article presents the experimental evidences of the effect of TiO2-fluorine doped tin oxide interface annealing and Ni(OH)2 cocatalysts on the photoelectrochemical, structural, morphological and optical properties of Ni(OH)2/CdS/ZnIn2S4/TiO2 heterojunction. The Raman spectroscopy exhibits the sharp features of the rutile phase of TiO2 and in agreement with the X-ray diffraction data. The band gap energy of the 500 °C sample was found to be 3.12 eV, further it was increased to 3.20, 3.22 eV for samples annealed at 600 and 700 °C respectively. The decrease in the band gap energy at 500 °C related to the oxygen vacancies and was analysed by photoluminescence spectroscopy analysis. The synthesis, characterization methods and other experimental details of TiO2 based heterostructure are also provided. The presence of CdS and ZnIn2S4 coating on surface of TiO2 electrodes providing a high surface area, extended visible absorption and helps to improve the change separation. This data article contains data related to the research article entitled “Highly efficient and stable 3D Ni(OH)2/CdS/ZnIn2S4/TiO2 heterojunction under solar light: Effect of an improved TiO2/FTO interface and cocatalyst” (Mahadik et al., 2017) [1].