Effect of Al doping on the structural and optical properties of CuO nanoparticles prepared by solution combustion method: Experiment and DFT investigation

Abstract

In this study, pure and Al doped CuO nanoparticles (NPs) has been synthesized using the solution combustion technique. The effect of the Al dopant on the structural, surface morphological, optical and electronic properties of the CuO NPs was studied. The crystalline structure of the NPs has been studied by X-ray diffraction (XRD) analysis. XRD studies indicate that the NPs produced are highly crystalline with tenorite phase. Al doping was found to modify the bond length, and lattice strain of the CuO NPs. The surface morphology of the NPs showed formation of spherical particles for lower Al doping while at higher doping concentration agglomeration of NPs occurs and the particle size changes. A reduction in the optical band gap of the NPs was observed due to Al doping and such a red shift in the band gap can be attributed to incorporation of the Al3+ ion doping effect. First principles calculations based on density functional theory (DFT) implemented in the VASP code was applied to study the electronic properties of pure and Al-doped CuO. The DFT study reveals that an impurity level is created within the energy gap of the NPs due to Al doping resulting in a reduction in the band gap, consistent with the experimental results.