Self-assembly preparation of gold nanoparticles-TiO2 nanotube arrays binary hybrid nanocomposites for photocatalytic applications

Abstract

Increasing interest has been devoted to preparing gold nanoparticle (GNP) functionalized TiO 2 nanotube array (TNTA) nanocomposites (GNP/TNTA) for photocatalytic applications. Nonetheless, achieving accurate control of surface assemblies of GNPs tethered on the TNTA substrate is far from satisfactory. Thus, in our work, applying 3-mercaptopropionic acid (MPA) as an interconnecting ligand, tailor-made monodispersed GNPs are evenly deposited on the interior and exterior surfaces of TNTAs with significant monodispersity via a self-assembly approach. The intrinsic self-assembly mechanism leading to the GNP/TNTA hybrid nanostructure is highlighted and ascertained. The photocatalytic performances of GNP/TNTAs are systematically evaluated in the photodegradation of organic dye pollutants under UV light irradiation. The ensemble of results indicates that the hierarchical nanostructure of the GNP/TNTA nanocomposite obtained via this self-assembly approach exhibits remarkably enhanced photocatalytic performance compared to its counterparts of P25 particulate film, a flat anodic TiO 2 layer (FTL), and GNP/FTL, in which well-dispersed GNPs and conducting titanium substrate are proposed to play crucial roles as efficient ''electron traps'' for the transfer of the photogenerated electrons and thus retard the recombination of photogenerated electron-hole pairs during the harvesting of photon-energy. In addition, the detection of increased amounts of highly active species (especially hydroxyl radicals) on the GNP/TNTAs by photoluminescence (PL) and electron spin resonance spectra (ESR) techniques further confirms the proposed mechanism. It is hoped that our knowledge regarding this simple self-assembly approach may cast new insight into the design and fabrication of noble-metal NPs/1-D nanotubular semiconductor hybrid nanomaterials for a wide range of photocatalytic applications.

Nanocomposite materials for photocatalytic degradation of pollutants

“…Briefly, previously synthesised dodecanethiolcapped Au NPs were tethered to the interior and exterior surfaces of TNTAs by applying 3-mercaptopropionic acid (MPA) as an interconnecting bifunctional ligand. Overall results showed that the Au NPs/TNTA nanocomposite exhibited significantly enhanced performance in photocatalytic degradation of methyl orange compared to its counterparts, represented by blank TNTA, P25 particulate film, flat anodic TiO 2 layer (FTL), and Au NPs/FTL [73].…”

One-step electrochemical synthesis and visible-light photocatalytic activities of bismuth titanate coatings: Effect of voltage

“…Typical examples are TiO 2 -based photocatalytic detoxification of air and water for environmental remediation. However, TiO 2 only shows activity under ultraviolet irradiation due to its large band gap (3.2 eV) [3,4]. Therefore, the exploration of novel catalysts with visible light activity has gained prompted attention.…”

Ag@Ag2SO4 nanoparticles: simple microwave-assistance synthesis, characterization and its co-photocatalytic degradation of methylene blue

“…Nevertheless, this semiconductor has a few major drawbacks on its photoexcitation domain includes: (1) wide band gap energy 3.2 eV, (2) possess low absorption capability especially in the visible light region and (3) exhibit high recombination of photogenerated electron-hole thus hindering its visible light-driven photocatalytic performance [1,[12][13][14][15][16][17][18][19]. Thus, remarkable efforts have been devoted to overcome all these limitations by doping/composite with metal, non-metal (NPs), noble metal inclusion or deposition to gain plasmonic property [20][21][22][23][24][25][26][27][28] and etc. Among of them, doping with metal such as Ag/TiO 2 , Au/TiO 2 and etc.…”