Discovery of Novel Delafossite-type Compounds Composed of Copper(I) Lithium Titanium with Photocatalytic Activity for H2 Evolution under Visible Light

Abstract Novel delafossite-type compounds Cu(Li1/3Ti2/3)O2 with 3R- and 2H-type structures have been discovered through the reaction between Li4Ti5O12 and Cu2O. Cu(Li1/3Ti2/3)O2 is the first Cu(I)-titanate containing no dn (n = 1–9) metal ions. It has been found that Cu(Li1/3Ti2/3)O2 with a band gap of 2.1 eV functions as a photocatalyst for H2 evolution under visible light irradiation.