Synthesis, characterization and visible light-responsive photocatalysis properties of Ce doped CuO nanoparticles: A combined experimental and DFT+U study

Abstract

In this work, CuO and Ce doped CuO (Ce:CuO) nanoparticles (NPs) were prepared by the sol-gel auto-combustion process. The effect of the concentration of Ce doping (0, 2%, 4%, 6%, and 8%) on the structural properties, surface morphology, electronic properties, optical properties, and visible light assisted photocatalytic activities of NPs were studied experimentally and also with Density Functional Theory (DFT + U) simulation. The X-ray Diffraction (XRD), Raman and Fourier transform-infrared (FTIR) studies confirmed the presence of Cu-O bonding in the as-prepared nanoparticles. Incorporation of Ce was found to introduce intrinsic defects in the Ce:CuO NPs and reduces the optical bandgap from 1.72 eV to 1.40 eV. The photocatalytic performance of the NPs was assessed by studying the degradation of methylene blue (MB) under visible light irradiation. Ce:CuO NPs exhibit better photocatalytic efficiency compared to pure CuO NPs. Furthermore, DFT based simulation predicted that the incorporation of Ce narrowed down the bandgap of the NPs due to the creation of shallow doping states near the valance and conduction bands. The reduction of band gap together with the presence of shallow dopant states allows efficient charge separation together with improved photon adsorption of Ce doped CuO NPs yielding an enhanced photocatalytic activity.