Design of multicomponent photocatalysts for hydrogen production under visible light using water-soluble titanate nanodisks

Abstract

We report the design of efficient multicomponent photocatalysts (MPs) for H₂ production under visible light by using water-soluble ultrathin titanate nanodisks (TNDs) stabilized by tetraethylammonium cations (TEA⁺) as building blocks. The photocatalysts are designed in such a way to significantly enhance simultaneously the efficiency of the three main steps in the photocatalytic process i.e., light absorption, charge separation and catalytic reaction. We show, as an example, the construction of water-soluble CdS–TND–Ni MPs. The designed CdS–TND–Ni MPs, in which CdS nanoparticles and TNDs are intimately assembled to enhance the charge transfer and surface area, are controlled in composition to optimize visible light absorption. The conception of the MPs allows them to be highly dispersed in water which markedly improves the photocatalytic H₂ production process. Most importantly, a Ni co-catalyst is selectively located on the surface of TNDs, enabling vectorial electron transfer from CdS to TND and to Ni, which drastically improves the charge separation. Consequently, under visible light illumination (λ ≥ 420 nm), the optimally designed CdS–TND–Ni MPs could generate H₂ from ethanol–water solution with rate as high as 15.326 mmol g⁻¹ h⁻¹ during a reaction course of 15 h and with an apparent quantum yield of 24% at 420 nm. Moreover, we also demonstrate that TNDs can be combined with other single or mixed metal sulfide to form water-soluble metal sulfide–TNDs composites which could also be of great interest for photocatalytic H₂ production.