Tuning of morphological and electronic properties of In2S3 nanosheets by cerium ion intercalation for optimizing photocatalytic activity
In2S3 based nanocompounds have received notable scientific focus because of their electronic properties which have yielded promising results in harvesting solar energy for photocatalytic and photovoltaic applications. Apart from their visible light active band, their highly tunable structural and optical properties give immense scope to enhance their potential as solar energy materials. This work demonstrates a novel approach in optimizing the morphological and electronic properties of β-In2S3 by lanthanide element cerium ion intercalation for photocatalytic and photoelectrocatalytic applications. A facile hydrothermal treatment has been followed to develop In2S3 nanosheets doped with 0-2 mol% Cerium. Morphological and structural analysis have revealed development of highly crystalline smooth In2S3 nanosheets upon 1 mol% cerium doping. Along with modifying the morphological characteristics, the substitutionally doped cerium ions have led to hybridization of Ce 4f and In 5p orbitals resulting in downshift of the conduction band edge thus aiding in higher photon absorption for enhanced photocatalytic activity. Such characteristics have been deduced from the UV Vis spectra and have been further theoretically verified by employing first principles density functional theory (DFT) calculations to obtain density of state (DOS) plots of computationally constructed 1 mol% Ce doped In2S3 structures. The 4f to 5d transitions in the Ce3+ ions may also have resulted in efficient electron hole separation in the 1 mol% Ce doped samples, as revealed from the PL spectra. Transient photocurrent responses have been obtained and photocatalytic degradation of neurotoxic drug ciprofloxacin has been performed to demonstrate the enhanced photocatalytic and photoelectrocataytic potential of cerium doped samples. The marked improvement showed a rapid decline in 2 mol% Ce doped samples, due to limited solubility of cerium ions in the In2S3 lattice leading to structural deformities upon excess cerium doping. Thus the synergistic influence of indium and cerium atoms in In2S3 nanocompounds for solar energy applications has been established by various experimental analyses complemented with theoretical investigations via DFT calculations.