Surface-modified, dye-sensitized niobate nanosheets enabling an efficient solar-driven Z-scheme for overall water splitting

While dye-sensitized metal oxides are good candidates as H-2 evolution photocatalysts for solar-driven Z-scheme water splitting, their solar-to-hydrogen (STH) energy conversion efficiencies remain low because of uncontrolled charge recombination reactions. Here, we show that modification of Ru dye-sensitized, Pt-intercalated HCa2Nb3O10 nanosheets (Ru/Pt/HCa2Nb3O10) with both amorphous Al2O3 and poly(styrenesulfonate) (PSS) improves the STH efficiency of Z-scheme overall water splitting by a factor of similar to 100, when the nanosheets are used in combination with a WO3-based O-2 evolution photocatalyst and an I-3(-)/I- redox mediator, relative to an analogous system that uses unmodified Ru/Pt/HCa2Nb3O10. By using the optimized photocatalyst, PSS/Ru/Al2O3/ Pt/HCa2Nb3O10, a maximum STH of 0.12% and an apparent quantum yield of 4.1% at 420 nm were obtained, by far the highest among dye-sensitized water splitting systems and comparable to conventional semiconductor-based suspended particulate photocatalyst systems.

Automated summary

Researchers have improved the energy conversion efficiency of solar-driven water splitting for hydrogen production by modifying metal oxides. The use of the optimized photocatalyst achieved the highest STH and apparent quantum yield.