Photocatalytic H₂ evolution by layered perovskite Ca₃Ti₂O₇ codoped with Rh and Ln (Ln = La, Pr, Nd, Eu, Gd, Yb, and Y) under visible light irradiation

Abstract

Layered perovskite Ca₃Ti₂O₇ codoped with Rh and Ln (Ca_3-xLn_xTi_1.9Rh_0.1O₇; Ln = La, Pr, Nd, Eu, Gd, Yb, and Y; 0 ≤ x ≤ 0.15) was synthesized by a conventional solid-state reaction to investigate the effects of Rh and Ln codoping on the photocatalytic activity. Rh and Ln-codoped Ca₃Ti₂O₇ exhibited a higher photocatalytic activity than Rh-doped Ca₃Ti₂O₇ for H₂ production from an aqueous methanol solution under visible light irradiation (λ > 420 nm). In addition, the induction period for H₂ production was shortened by codoping with Rh and Ln. The codoped elements helped control the oxidation state of Rh ions and suppressed the formation of oxygen defects, improving the activity of the Rh-doped Ca₃Ti₂O₇ photocatalyst.