CdS Sensitized Solvothermal Phase Change Assisted Synthesis of CoTiO₃ @ TiO₂ Nanorods As a Ternary Heterojunction Photoanode for Photoelectrochemical Water Splitting

Abstract

Development of efficient semiconductor heterostructures with adequate band alignment for enhanced charge separation and increased light absorbance has been at the forefront of research on photoelectrodes. In this work we demonstrate the fabrication of CdS sensitized CoTiO3 @ TiO2 photoanodes for photoelectrochemical water splitting. TiO2 nanorods were synthesized by a hydrothermal method followed by surfactant assisted solvothermal impregnation of Co2+ ions into the TiO2 lattice resulting in development of a core-shell CoTiO3 @ TiO2 p-n junction heterostructure. The photoanodes were further sensitized by CdS nanoparticles by a facile SILAR method not only to increase light absorbance in the visible region but also to form a ternary heterojunction photoanode with cascade type electron transfer. The fabricated photoanodes showed an ABPE % of 0.43% at 0.6 V vs Ag/AgCl reference electrode using 0.5 M Na2S and 0.5M Na2SO3 electrolyte under A.M 1.5 G simulated solar illumination. Optical properties were analyzed using UV-Vis Absorbance and Photoluminescence Spectroscopy. Transient photocurrent, EIS and Mott-Schottky analysis were carried out to analyze charge transport processes occuring at the semiconductor / electrolyte interface. Structure and morphological analysis was carried out using XRD and FESEM. Band structure and DOS was analyzed using DFT calculations.This work hopes to inspire new research in development of ternary heterojunctions for photoelectrochemical water splitting.