Assembly of Core-Shell Structures for Photocatalytic Hydrogen Evolution from Aqueous Methanol

We present a layer-by-layer assembly approach for the construction of core shell structures with photocatalytic activity for hydrogen evolution from aqueous methanol. Submicrometer silica spheres and ultrasonicated (TBA, H)Ca2Nb3O10 and PA(2)K(2)Nb(6)O(17) nanosheets are used as the building blocks to assemble core shell structures with single and double (homostacked and heterostacked) nanosheet layers via sequential electrostatic coupling with poly(diallyldimethylammonium) chloride (PDDA). The lateral nanosheet distribution on the SiO2 spheres is observed with SEM while the stacking is directly observed with TEM. Diffuse reflectance UV/vis spectra reveal the nanosheet absorbance edge at similar to 350 nm. All core-shell structures are active for photocatalytic H-2 evolution from aqueous methanol solution with gas evolution rates comparable or smaller than observed for individually dispersed nanosheets. Heterostacks were more active than homostacks, with the latter being comparable to single layers (at equal mass). Loading with Pt nanoparticles increases H-2 evolution rates, but reduces the activity differences between homostacked and heterostacked samples.