Fabrication of ruthenium doped Ag@TiO2 core-shell nanophotocatalyst for the efficient reduction of nitrophenols

In the present study, a novel Ag@Ru/TiO2 core-shell nanophotocatalyst with silver metal cores and ruthenium-doped TiO2 semiconductor shells has been fabricated via an impregnation method and was characterized by XRD, Raman spectroscopy, XPS, UV-vis DRS, STEM, EDX, photoluminescence (PL) spectroscopy, FTIR, and BET analysis. In Ag@Ru/TiO2, the Ag NPs core serves as electron traps to prevent the electron-hole pairs recombination, and Ru doping significantly increases the absorption of visible light of the TiO2. The photocatalytic efficiency of Ag@Ru/TiO2 was assessed by the reduction of 4-nitrophenol (4-NP), 2,4-dinitrophenol (2,4-DNP), and 2,4,6-trinitrophenol (2,4,6-TNP) in presence of visible light. Ag@Ru/TiO2 demonstrated superior photocatalytic performance and attained 100% photocatalytic reduction of 4-NP in 2 min, 2,4-DNP in 3 min, and 2,4,6-TNP in 4 min to their corresponding aminophenols, which was almost 58 and 2.35 times higher than TiO2 and Ag@TiO2. Different experimental parameters including the NaH4 concentration, and the catalyst quantity were also explored. The order of reduction rate constant has been found to be: 4-NP (2.33 min(-1)) > 2,4-DNP (1.99 min(-1)) > 2,4,6-TNP (1.4 min(-1)). Reusability studies revealed the high stability and excellent photocatalytic efficiency of Ag@Ru/TiO2. This novel and highly efficient nanophotocatalyst is a good material for photoreduction of aromatic nitro compounds.