Self-photoreduced Ag⁰-doped Ag(I)–organic frameworks with efficient visible-light-driven photocatalytic performance

To investigate the facile synthesis strategy for MOF-based plasmonic photocatalysts, an Ag(I)–organic framework [Ag₃(psa)(4,4′-bpy)₃]·OH·2CH₃OH·2H₂O (JLNU-91) was prepared by employing phenylsuccinic acid (H₂psa) and 4,4′-bipyridine (4,4′-bpy) under room temperature. Under the irradiation of UV light, the separated Ag(I) sites in the framework can be reduced to metallic Ag⁰, producing a series of Ag⁰-doped JLNU-91/x. The photocatalytic experiments indicate that the JLNU-91/x samples display improved photocatalytic activities for the degradation of methyl orange (MO) and the optimal JLNU-91/1 has a 2.2 times higher degradation kinetic constant than pure JLNU-91. The photocurrent responses and EIS plots demonstrate that the SPR effect of the self-reduced Ag⁰ promotes the separation of photoinduced electron–hole pairs. Moreover, the electron spin resonance (ESR) spectra and capture experiments reveal that O²⁻, ˙OH and the holes play important roles in the photodegradation of MO. This work brings a new insight into the development of MOF-based plasmonic photocatalysts.