Construction of novel bimetallic Ti/Ce-MOFs for ratiometric fluorescence sensing of trace copper and photocatalytic reduction of chromium (Ⅵ)

A new bimetallic-centered MOFs, NH2-MIL-125(Ti/Ce), was synthesized by partially replacing Ti with Ce. The doping of Ce endowed the MOFs oxidase-like activity and enabled the construction of a ratiometric fluorescence sensing system in combination with o-phenylenediamine (OPD) for detecting trace Cu2+ with a limit of detection of 16 nM and a linear range of 0.02–50 μM. Trace Cu2+ was successfully quantified in real water samples. The doping of Ce also increased the photocatalytic capability of the MOFs by about 2 times, achieving excellent reduction of Cr(Ⅵ) under natural light conditions.