Magnetically Separable Visible Light-Active Ag_0.75Ni_0.25 Binary Alloy Nanoparticles as a Highly Efficient Photocatalyst for the Selective Oxidative Coupling of Aniline to Azobenzene

Abstract

Aniline wastes can be converted to useful pharmaceutical and industrial compounds like azobenzene. For this purpose, a bimetallic Ag0.75Ni0.25 alloy is designed in the nanoscale range resembling a fivefold twinned morphology using water as the solvent. These newly developed alloy nanoparticles (NPs) are employed for the first time as an efficient visible light-active photocatalyst for the oxidative homocoupling of aniline to azobenzene. Our catalytic protocol is highly sustainable for a large number of aniline substrates with a high yield of the product (up to 95%), which might be attributed to the combinational and superior properties achieved on alloy formation in comparison to the monometallic counterparts. High-electron density amines (p-anisidine) display greater photocatalytic proficiency than that of low-electron density amines (4-fluoroaniline). The developed photocatalyst is magnetically well-separable and can be reused for at least five catalytic cycles without appreciable loss in its activity.