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

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 (lambda >= 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.