Ligand-variable metal clusters charge transfer in Ce-Por-MOF/AgNWs and their application in photoelectrochemical sensing of ronidazole.

A photoelectrochemical sensing platform based on ligand-variable metal clusters charge transfer was established for the quantitative assay of ronidazole (RNZ) using Ce-porphyrin-metal-organic frameworks/silver nanowires (Ce-Por-MOFs/AgNWs). Rod-like Ce-Por-MOFs and well-dispersed sub-50 nm AgNWs were prepared using a hydrothermal method and polyol strategy, and then through simple drop coating to yield Ce-Por-MOFs/AgNWs nanocomposites. We investigated the intrinsic semiconducting properties of the composites. More importantly, it was found that the variable-valence metal node can provide electronic defect states similar to those caused by multi-metal doping, synergizing with the surface plasmon effect of AgNWs, which significantly improved the photoelectric conversion efficiency, thereby resulting in excellent optoelectronic properties. In combination with molecular imprinting, a competitive type trace photoelectrochemical sensor for RNZ was constructed using Fe2+ as the electron donor and probe. Under optimal conditions, the sensor response is proportional to the logarithm of RNZ concentration in the range 0.1-104 nM with a detected limit of 0.038 nM. The recoveries ranged from 87.2 to 116% with relative standard deviations (RSDs) < 6.5% (n = 3) in milk sample. This work reveals the charge-transfer process of variable-valence metal nodes in MOFs during photoelectrochemical processes, which will provide new insights for the sensing application of variable-valence metal MOFs.