Synthesis of gold nanoparticles (AuNPs) onto anodized titania nanotubes (TNTs) by spin coating technique

Abstract

Gold nanoparticles (AuNPs) have received copious interests due to their unique properties such as small in size, reactive, high surface area and can be potentially applied in myriad fields including physics, chemistry, medicine and material sciences. However, the nanosized of gold particles makes them very reactive and undergo aggregation without protection. For that reason, supporting materials are introduced to prevent the aggregation of the AuNPs. In particular, metal oxide for example, titanium dioxide or titania nanotubes (TNTs) has been used as a support material because of its inertness, high porosity and great surface areas. Nevertheless, achieving precise control of attachment AuNPs on the TNTs substrate by conventional methods such as thermal evaporation and conservative heating are far from satisfactory. Herein, in this work, a new approach has been developed to synthesize controlled and uniformed attachment of AuNPs onto fabricated electrochemically-anodized TNTs by a spin coating technique. This preliminary work used different spin rate of 500, 1000 and 2000 revolutions per minute (rpm), following by heat treatment at 250 °C for 2 hours. The FESEM micrograph showed the anodized TNTs with good morphological structures were successfully fabricated at a voltage of 50 V in a mixture of ethylene glycol containing 0.5 wt. % ammonium fluoride solution, with an average nanotubes diameter of 150 nm. Meanwhile, the attachment of AuNPs on the fabricated TNTs has been effectively achieved at a higher spin rate of 2000 rpm and the EDX analysis confirmed the deposition of AuNPs over the TNTs. The AuNPs-TNTs also were tested for the catalytic reduction of p-nitrophenol (p-NP), in which is discussed shortly in this paper.