Optoelectronic and Photocatalytic investigations of chitosan (CS) modified Platinum decorated ceria (Pt-CeO2-CS) composite

Herein, a comparative study is performed to evaluate the Photodegradation of Methyl Orange (MO) and Photoelectrochemical (PEC) activities of novel ternary Pt–CeO₂/Chitosan (Pt–CeO₂/CS), and binary Pt/Chitosan (Pt/CS) and CeO₂/Chitosan (CeO₂/CS) composites synthesized via the chemical reduction and sol-gel methods. The structural, thermal, morphological, and optical characteristics of composite were examined using Fourier Transform Infra-Red (FTIR) Spectroscopy, Thermogravimetry (TG), Field Emission Scanning Electron Microscopy (FESEM) coupled with Electron Diffraction Spectroscopy (EDS), X-ray Diffraction (XRD), X-ray Photoelectron (XPS), UV–visible (UV–Vis), photoluminescence (PL) and Raman Spectroscopy. The UV–vis band gap analysis revealed that the reduction in the bandgap value E_g value (2.7eV) increases the light absorption property. The as synthesized ternary Pt–CeO₂/CS composite acts as a photocatalyst for dye decolourisation, with a maximum of 84 % of methyl orange (MO) decolourisation at λ_max of 464 nm under light irradiation. The kinetics of ternary composite was found to follow pseudo-first-order with rate constant of 0.01279 min⁻¹. Moreover, the photoelectrochemical performance of Pt–CeO₂/CS hybrid composite with 1.3 ∼ 2.5-fold higher value of current density (1.8 mA/cm² at 0.67 V vs. Ag/AgCl) is attained as compared to binary CeO₂/CS and Pt/CS composites. The probable enhanced charge transfer process in Pt–CeO₂/CS has been proposed responsible for the enhanced photodegradation of MO dye and improved PEC water splitting performance.