Electrochemical sensor for detection of hydrazine based on Au@Pd core-shell nanoparticles supported on amino-functionalized TiO2 nanotubes

In this paper, we reported a simple strategy for synthesizing well-defined TiO2NTs-Au@Pd hybrid nanostructures with prior TiO2 nanotube functionalization (F-TiO2NTs). TiO2NTs with larger surface area (BET surface area is 184.9 m(2) g(-1)) were synthesized by hydrothermal method, and the NTs are anatase phase with a range of 2-3 mu m in length and 30-50 nm in diameter after calcined at 400 degrees C for 3 h. 3-Aminopropyl-trimethoxysilane (APTMS) as a coupling agent was reacted with the surface hydroxyl groups as anchoring sites for flower-shaped bimetallic Au@Pd nanostructures, self-assembling amine functionality on the surface of TiO2NTs. Note that two faces at the interface between F-TiO2NTs with (004) plane and Au@Pd nanostructures with (111) one of cubic Au and Pd nanoparticles are compatible, benefiting to the charge transfer between two components due to their crystalline coordination. The results showed that as-prepared F-TiO2NTs-Au@Pd hybrid nanostructures modified glassy carbon electrode (GCE) exhibits high electrocatalytic activity toward hydrazine (N2H4) at low potential and a linear response from 0.06 to 700 mu M with the detection limit for N2H4 was found to be 1.2 x 10(-8) M (S/N = 3). Based on scan rate effect during the hydrazine oxidation, it indicates that the number of electrons transferred in the rate-limiting step is 1, and a transfer coefficient (a) is estimated as 0.73. The self-assembled F-TiO2NTs-Au@Pd hybrid nanostructures as enhanced materials present excellent electrocatalytic activity, fast response, highly sensitive and have a promising application potential in nonenzymatic sensing. (C) 2013 Elsevier B.V. All rights reserved.