Enhanced Photocatalytic Activity of the Bi2O3-NiO Heterojunction for the Degradation of Methyl Orange under Irradiation of Sunlight

Recently, the development of visible-light-responsive catalysts for the photodegradation of organic pollutants has captured the attention of researchers globally. The ineffectiveness and high costs associated with conventional methods and techniques used for the abatement of water pollution have forced researchers to develop effective and low-cost innovative techniques for this purpose. Photocatalysis is considered an effective protocol for this purpose. Therefore, this study was conducted for the development of the Bi2O3-NiO heterojunction as a visible-light-responsive photocatalyst for the degradation of methyl orange. Ni(NO3)2∙6H2O (Fluka) and Bi(NO3)3∙5H2O (Merck) were used as precursor materials for the synthesis of NiO-Bi2O3. After fabrication, the Bi2O3-NiO heterojunction was characterized using XRD, EDX, SEM, FTIR, and TGA techniques. Then, it was employed as a catalyst for the photodegradation of methyl orange under sunlight irradiation. The fabricated Bi2O3-NiO showed higher photocatalytic activity than Bi2O3 and NiO with 100, 67, and 46% degradation of methyl orange, respectively. The rate constant determined by the non-linear method of analysis for the photodegradation of MO in the presence of Bi2O3-NiO was 3.2-fold and 1.7-fold of the rate constant with NiO and Bi2O3, respectively. The higher photocatalytic activity of Bi2O3-NiO than of its individual components in the present study is also attributed to the separation and transfer of positive holes and electrons. The recycling of spent Bi2O3-NiO under similar experimental conditions exhibited the same photocatalytic activity suggesting the stability of the fabricated Bi2O3-NiO photocatalyst.