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

Shunta Nishioka; Koya Hojo; Langqiu Xiao; Tianyue Gao; Yugo Miseki; Shuhei Yasuda; Toshiyuki Yokoi; Kazuhiro Sayama; Thomas E Mallouk; Kazuhiko Maeda

doi:10.1126/sciadv.adc9115

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

Sci Adv. 2022 Aug 12;8(32):eadc9115. doi: 10.1126/sciadv.adc9115. Epub 2022 Aug 10.

Authors

Affiliations

¹ Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1-NE-2 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
² Department of Chemistry, University of Pennsylvania, 231 S. 34th Street Philadelphia, PA 19104, USA.
³ Global Zero Emission Research Center (GZR), National Institute of Advanced Industrial Science and Technology (AIST), West, 16-1, Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
⁴ Nanospace Catalysis Unit, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan.
⁵ International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan.

Abstract

While dye-sensitized metal oxides are good candidates as H₂ 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 ~100, when the nanosheets are used in combination with a WO₃-based O₂ evolution photocatalyst and an I₃^-/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.