A novel Ag deposited nanocoordination polymer derived porous SnO2/NiO heteronanostructure for the enhanced photocatalytic reduction of Cr(vi) under visible light

Abstract

The fabrication of a novel porous Ag deposited SnO₂/NiO (Ag/SnO₂/NiO) heteronanostructure for the photoreduction of toxic aqueous Cr(VI) to non-toxic Cr(III) is reported. The material is prepared by depositing metallic Ag nanoparticles into the SnO₂/NiO heteronanostructure by the reduction of Ag⁺ under UV irradiation. The SnO₂/NiO heteronanostructure is obtained by a facile solid-state transformation of the novel nanocoordination polymer (NCP). The prepared Ag/SnO₂/NiO is characterized by different techniques such as PXRD, XPS, EDX, FESEM, TEM, HRTEM, BET, UV-Vis DRS and PL measurements. The PXRD and XPS studies confirm the formation of a Sn(IV) state of SnO₂ in the heterostructure. TEM images reveal the spherical morphology of Ag nanoparticles with an average particle size of 15 nm, and hexagonal shaped SnO₂ and NiO with an average particle size of 10 and 5 nm in Ag/SnO₂/NiO, respectively. The incorporation of Ag enhances visible light absorption and higher electron–hole separation of Ag/SnO₂/NiO by Surface Plasmon Resonance (SPR). Besides, the material exhibits a high surface area and porous nature, which facilitates the effective photocatalytic reduction of toxic aqueous Cr(VI) to non-toxic Cr(III) under visible light. Furthermore, the photocatalytic reduction of Cr(VI) is optimized under different conditions. The photostability of Ag/SnO₂/NiO is tested up to five successive runs indicating its promising applications for wastewater treatment. Finally, a photocatalytic mechanism is proposed for the reduction of aqueous Cr(VI) over Ag/SnO₂/NiO under visible light.