Double perovskite compounds A2CuWO6 (A = Sr and Ba) with p-type semiconductivity for photocatalytic water oxidation under visible light illumination

Abstract

Herein, the double perovskite compounds Sr₂CuWO₆ and Ba₂CuWO₆ were investigated and compared with CuWO₄. These perovskites have a tetragonal symmetry with a 1 : 1 ordering of Cu and W at the B site. The elongation of the CuO₆ octahedrons along the c direction due to the Jahn–Teller effect lowered their structure symmetry from cubic to tetragonal. Both perovskites have stronger visible light absorption than CuWO₄ as well as a more hydrophilic surface. Photocatalytic oxygen evolution under visible light illumination (λ ≥ 420 nm) was achieved for Sr₂CuWO₆ and Ba₂CuWO₆, which clearly outperformed CuWO₄. The photoelectrochemical analysis suggests a p-type semiconductivity for these double perovskite compounds as compared to the case of CuWO₄, which has a n-type semiconductivity. Similar to that of CuWO₄, their conduction band edge is located more positively than the water reduction potential, which is inapplicable for photocatalytic hydrogen production.