Dual-mode sensing of hydrogen peroxide on self-assembled Ag nanoparticles anchored on polydopamine wrapping 2D Cu-MOFs.

In this study, we have fabricated a dual-signal sensor for HO determination based on 2D Cu-MOFs decorated with Ag NPs. A novel polydopamine (PDA) reduction method was utilized to reduce [Ag(NH)] to highly dispersed Ag NPs without other reductive agents, and Cu-MOF@PDA-Ag was obtained. For the electrochemical sensor, the Cu-MOF@PDA-Ag modified electrode exhibits outstanding electrocatalytic properties toward HO reduction with a high sensitivity of 103.7 μA mM cm, a wide linear range from 1 μM to 35 mM and a low detection limit of 2.3 μM (S/N = 3). Moreover, the proposed sensor shows good feasibility in an orange juice sample. For the colorimetric sensor, colorless 3,3',5,5'-tetramethylbenzidine (TMB) can be oxidized by the Cu-MOF@PDA-Ag composite in the presence of HO. A Cu-MOF@PDA-Ag catalysis-based colorimetric platform is further established for the quantitative analysis of HO ranging from 0 to 1 mM with a lower detection limit of 0.5 nM. Importantly, such a dual-signal method for the detection of HO could potentially have wide practical applications.