LAUSR

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.