Silver nanoparticles on titanate nanobelts via the self-assembly of weak polyelectrolytes: synthesis and photocatalytic properties

A weak-polyelectrolyte multilayer on a surface of titanate nanobelts (Ti-NBs) was utilized as a template for in situ Ag nanoparticle formation in the fabrication of Ag-loaded Ti-NBs nanocomposites. The polyelectrolyte multilayer (PEM) was fabricated using layer-by-layer self-assembly of poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) on the surface of high-surface-area titanate nanobelts (Ti-NBs) synthesized using a hydrothermal procedure. The concentration of Ag nanoparticles in the PEM was controlled by repeating the ion-loading/reduction cycle. The subsequent annealing of the Ag/Ti-NBs-PEM nanocomposites yielded nanostructured crystalline Ag/Ti-NBs. Transmission electron microscopy (TEM) techniques (HRTEM, SAED) and x-ray powder diffraction (XRD) were employed to evaluate the morphological, structural and growth characteristics of the silver nanocrystallites in the Ag/Ti-NBs nanocomposites. The UV-vis photoactivity of the as-fabricated nanocomposites was monitored by the degradation of the cationic dye methylene blue (MB). An enhanced UV photo-efficiency was observed for the Ag/Ti-NBs nanocomposites compared with pure Ti-NBs. As-fabricated Ag(x)/Ti-NBs nanocomposites also exhibited visible photoactivity assisted by the near-field amplitudes of the localized surface plasmon resonance (LSPR) of the silver nanoparticles in the 1D nanocomposite.