Niobium oxide nanoscrolls as building blocks for dye-sensitized hydrogen production from water under visible light irradiation

Potassium hexaniobate nanoscrolls (NS-K₄Nb₆O ₁₇) formed by exfoliation of lamellar K₄Nb ₆O₁₇ were studied as building blocks for visible-light-driven H₂ production (λ > 420 nm) from water using tris(2,2′-bipyridyl)ruthenium(II) chloride (Ru(bpy)₃ ²⁺) as a sensitizer and ethylenediaminetetraacetic acid (EDTA) as an electron donor. The surface of NS-K₄Nb₆O₁₇ is negatively charged at pH 3-11, enabling cationic Ru(bpy)₃ ²⁺ molecules to be efficiently adsorbed onto the surface, allowing for rapid excited-state electron and subsequent H₂ evolution without any chemical bond linkage between the sensitizer and the oxide surface. The rate of visible light H₂ production in the nanoscroll-based system is 10 times higher than that of similarly sensitized K₄Nb₆O ₁₇. The difference can be primarily attributed to the strong adsorption of Ru(bpy)₃²⁺ in the case of the nanoscrolls. The maximum photocatalytic reactivity is found over a narrow range of pH and Pt-loading. This study highlights the utility of single-crystalline oxide nanosheets as components of photosystems for visible-light-driven H₂ production from water.