Hydrogen production by the layer-by-layer assembled films of PAni-TiO2-AuNPs

Abstract

The production of high-performance and low-cost nanomaterials enables scale-up within the production sector for green hydrogen. In this regard, polymer films, such as composite films that consist of polyaniline (PAni), titanium dioxide (TiO2), and gold (AuNP) nanoparticles assembled by a layer-by-layer (LbL) technique, have been applied for hydrogen production as efficient photocatalysts. These composite films have been shown to be suitable materials for photochemical and photoelectrochemical hydrogen production, wherein the film morphology and thickness control photocatalytic performance. In addition, reflectance diffuse spectroscopy (UV–vis) was used to establish the synthesis conditions by verifying the plasmon resonance surface of PAni (emeraldine salt - ES) and AuNPs. The presence of PAni-ES increases film crystallinity (XRD) and avoids electron-hole recombination, providing a high recombination time of 9.38 s (3.93 s and 4.2 s for lesser crystalline sample). Thus, the hydrogen photochemical production also increases up to 2 times due to fewer trap states. Furthermore, the composite films can be used as photoanodes in photoelectrochemical hydrogen production due to their current stability. The bands position were calculated through Mott-Schottky and showed increased overpotential for the hydrogen evolution reaction from −0.46 V for bare TiO2 to ∼1.9 V for the best thin film. These results have interesting implications for the synthesis of photocatalytic materials because they identify the crucial parameters necessary for obtaining high-performance and low-cost materials for hydrogen production.