Structural, opto-electronic and photoelectrochemical properties of tin doped hematite nanoparticles for water splitting

Abstract

For application in photoelectrochemical water splitting, pristine and Sn doped (1%, 3% and 5%) hematite nanoparticles were prepared hydrothermally via a two step heating process. XRD results showed that the products match the rhombohedral crystal system. The peak broadening of hematite nanoparticles due to small crystallite size and strain were analyzed by Scherrer's equation and Williamson Hall plot method respectively. A decrease in crystallite size and an increase in lattice strain is observed with dopant addition. Structural change from nanorods to nanocorals is seen for the Sn doped hematite products. Selected Area Diffraction patterns reveal crystallinity of both the doped and undoped powders. Sn 3d XPS peak analysis reveals that Sn has been doped into the hematite lattice. Linear Sweep Voltammetry and Electrochemical Impedance Spectroscopy analysis confirm that 1% Sn doped hematite has the highest photocurrent density (3 mA/cm2 at 1 V vs. Ag/AgCl) and least charge transfer resistance among the doped products. UV-VIS, Photoluminescence and Mott-Schottky analysis further show that optimum optical and electrical properties are observed for hematite doped with 1% Sn.