Photocatalytic Nanostructured Self-Assembled Poly(allylamine hydrochloride)/Poly(acrylic acid) Polyelectrolyte Films Containing Titanium Dioxide–Gold Nanoparticles for Hydrogen Generation

In this study, we developed a facile layer-by-layer (LbL) method of incorporating gold (Au) and titanium dioxide (TiO2) nanoparticles (NPs) into self-assembled photocatalytic films (SAPFs). The resulting SAPFs were then systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV–vis spectrophotometry, profilometry, and atomic force microscopy (AFM). The results revealed that the SAPFs incorporated TiO2 and Au NPs with sizes of 21.2 ± 0.30 and 12.5 ± 0.05 nm, respectively. Moreover, the SAPFs with 40, 60, 80, and 100 layers exhibited thicknesses of 410, 472, 917, and 945 nm, respectively. The hydrogen produced by the SAPFs increased with increasing UV irradiation time in a linear relationship. Hydrogen was also produced within the bulk of the polymer/TiO2–Au NP assemblies because water hydrates the network, allowing for facile hydrogen production in the bulk under irradiation. The present approach represents a significant advance over traditional nanostructured catalysts, for which the highest possible surface area is desired to maximize photocatalytic activity.