Synthesis, characterization and properties of sulfate-modified silver carbonate with enhanced visible light...

Sulfate-modified Ag₂CO₃ was successfully synthesized via a simple precipitation method. Its visible light photocatalytic performance against the removal of Orange G was found to be significantly enhanced in comparison with the one of pure Ag₂CO₃. While SO₄^2--Ag₂CO₃ ensured a removal efficiency of 100% of OG within 30 min, the unmodified Ag₂CO₃ exhibited a degradation threshold at hardly 60%. Likewise, the degradation rate constant in the presence of SO₄^2--Ag₂CO₃ photocatalyst was assessed to be twice that determined upon the involvement of pristine Ag₂CO₃. Furthermore, Total Organic Carbon (TOC) measurements evidenced the occurrence of a quasi-total mineralization of the dye pollutant upon the use of SO₄^2--Ag₂CO₃ photocatalyst. Scavenger experiments highlighted the dominant role of photo-induced h⁺ along with ˙O₃^- ozonide radicals in the OG photocatalytic oxidation mechanism. Reuse cycles revealed that the modification by SO₄^2- is a promising route to improve the stability of silver carbonate against photocorrosion. All these improvements could be ascribed to electronic transfer from the upper SO₄^2- HOMO to the lower Ag₂CO₃ conduction band.