Dual modification of TiO₂ nanorods for selective photoelectrochemical detection of organic compounds

Selective detection of organic compounds in water body is both desirable and challenging for photoelectrocatalytic (PEC) sensors. In this work, tunable oxidation capability is designed and achieved by modifying titanium dioxide nanorod arrays (TiO₂) photoelectrodes with nano-sized plasmonic gold (Au) particle deposition and subsequent hydrogenation treatment (i.e. Au@H-TiO₂). The effective incorporation of Au nanoparticles onto the TiO₂ nanorods induces a plasmonic effect and extends light absorption from ultraviolet (UV) to the visible light range while the hydrogenation process dramatically improves PEC oxidation activity. Under visible light, the Au@H-TiO₂ electrode exhibits selective detection capability to labile organic compounds. This excellent selectivity is demonstrated by a wide linear relationship between photocurrent and the concentration of different types of sugars, including glucose, fructose, sucrose and lactose in the presence of various concentrations of the aromatic compound potassium hydrogen phthalate (KHP). Furthermore, the modified electrode can also undiscriminately detect all kinds of organic compounds in a rapid manner under UV irradiation due to the strong oxidation capability. Such a unique feature of the tunable oxidation capability bestows the Au@H-TiO₂ photoelectrodes a new generation of the PEC sensors for selective and collective degradation of organic compounds.