Evolution of Ni-induced orthorhombic phase in SnO2: Influence of Ni on the optical and photocatalytic properties

This paper presents the impact of nickel doping on the structural, optical and photocatalytic characteristics of Sn1-xNixO2 (x = 0, 0.3, 0.05, 0.07) nanoparticles. The samples are synthesized via the chemical co-precipitation method. Information on the structural properties of the samples is obtained via the Rietveld refinement technique. As the dopant concentration increases, a partially stable orthorhombic phase emerges and becomes prominent, indicating a correlation with the amount of Ni dopant. This orthorhombic phase arises during the transformation from the amorphous state to a more stable crystalline phase. The FESEM-EDAX analysis demonstrates the uniform distribution of agglomerated particles. Additionally, the Raman data provides information related to surface defects and vacancies. A minor increase in the band gap value is detected, and this observed blue shift can be attributed to the Burstein-Moss effect. The samples exhibit a strong blue emission, primarily attributed to surface defects and states, particularly due to the oxygen vacancies. The CIE coordinates show an increase in blue colour purity, making the samples suitable for blue components in white-light emitting diodes. However, the photocatalytic study reveals only partial degradation of methylene blue under visible light conditions.