Fabrication of Ni Nanoclusters-Modified Brookite TiO₂ Quasi Nanocubes and Its Photocatalytic Hydrogen Evolution Performance

The development of low-cost, earth-abundant and highly-efficient cocatalysts is still important to promote the photocatalytic H₂ evolution reaction over semiconductors. Herein, a series of Ni nanoclusters (NCs) modified brookite TiO₂ quasi nanocubes (BTN) (marked as Ni/BTN) are fabricated via a chemical reduction process. It is found that the loading content and oxidation state of Ni NCs can significantly influence the optical absorption, photocat-alytic activity, and stability of Ni/BTN composites. Among the resultant Ni NCs-loaded products, 0.1%Ni/BTN composite delivers the best H₂ evolution activity (156 μmol/h), which is 4.3 times higher than that of the BTN alone (36 μmol/h). Furthermore, the Ni NCs with ultra ne size (∽2 nm) and high dispersity enable shorter charge transfer distance by quickly capturing the photoexcited electrons of BTN, and thus result in the improved activity even though the oxidization of some Ni NCs on BTN is harmful to the activity for H₂ evolution due to the much lower electron capturing capability of NiO than metallic Ni. This study not only clari es that brookite TiO₂ would be a promising high-efficient photo-catalyst for H₂ evolution, but also reveals vital clues for further improving its photocatalytic performance using low-cost Ni-based cocatalyst.