Layer-by-Layer Assembly of TaO₃ Nanosheet/Polycation Composite Nanostructures: Multilayer Film, Hollow Sphere, and Its Photocatalytic Activity for Hydrogen Evolution

Multilayer composite films comprising of TaO 3 nanosheet crystallites and poly(diallyldimethylammonium chloride) (PDDA) were assembled via layer-by-layer sequential adsorption. Exposure of the resulting films to UV light promoted photocatalytic decomposition of PDDA in the nanosheet gallery to yield inorganic films. Novel hollow microspheres of Ta 2 O 5 were fabricated by the deposition of a PDDA/TaO 3 multilayer nanoshell on polystyrene (PS) beads and the subsequent removal of the PS core and PDDA layers via calcination. The hollow microspheres showed photocatalytic properties effective for hydrogen evolution from an aqueous methanol solution. The shape control into hollow microsphere greatly enhanced the photocatalytic activity. The results highlight the role of the surface area and crystallinity of the catalyst in photocatalytic activity.