Ru(Ⅱ) Bipyridyl Complex and TiO2 Nanocomposite Based Biomolecule-free Photoelectrochemical Sensor for Highly Selective Determination of Ultra-trace Hg2+ in Aqueous Systems

摘要

A biomolecule-free photoelectrochemical(PEC) probe(denoted as Ru-1) was designed,synthesized and coupled with TiO2 nanoparticles(NPs) for the highly sensitive and selective PEC detection of Hg2+,a model analyte with hypertoxicity to both human health and ecosystem.The probe Ru-1 was designed with Ru(II) bipyridyl complex as the chromophore,thiocyanate ligand as the recognition unit,and carboxylate group as the linkage site to connect Ru-1 to TiO2 nanoparticles.Under irradiation,Ru-1 shows strong affinity to TiO2 and good photophysical properties of strong visible light absorption,slow electron-hole(e-h+) recombination,and fast photoelectron injection to TiO2 nanoparticles via the π-bridge of 4-(2,2′-bipyridin)-4-yl-thiophene moiety.However,the specific coordination of Hg2+ with Ru-1 via the thiol moiety in the thiocyanate enlarges the band gap of the complex and reduces the photocurrent significantly.The synergistic interaction between TiO2 nanoparticles and the Ru-1 complex led to a selective PEC sensing strategy for Hg2+ detection.Detectable linear ranges from 10 12 g/mL to 10-7 g/mL and from 10-7 g/mL to 10-3 g/mL were obtained without the interference from possibly co-existed metal ions.The good analytical performances indicate the chemical probe based biomolecule-free PEC platform may offer a new route for the detection of biologically and environmentally important small molecules.