Mild solvothermal syntheses and characterizations of four quaternary layered sulfides AAgCdS2 (A = K, Rb, Cs) and Cs2Cu2Cd2S4

Abstract

Four layered quaternary sulfides KAgCdS2 (1), RbAgCdS2 (2), CsAgCdS2 (3), and Cs2Cu2Cd2S4 (4) have been successfully synthesized by mild solvothermal methods by employing excess sulfur as a mineralizer. Compound 1 possesses anionic [AgCdS2]nn− double layers. Compounds 2 and 3 are isostructural and contain anionic [AgCdS2]nn− single layers. Although both of the two structures are constructed by edge-sharing [MS4] (M = Ag/Cd) tetrahedral units, their condensation behaviors are totally different. The structure of 4 consists of infinite [Cd2S4]n4n− chains and [CuS2]2- dumbbells that linked to form [Cu2Cd2S4]n2n− layers. According to the UV–vis diffuse reflectance experiments, the band gaps of the title compounds are 1.92 eV (1), 2.16 eV (2), 2.42 eV (3), and 2.23 eV (4). Additionally, the photoelectrochemical experiments indicate that compounds 2 and 3 exhibit excellent photocurrent responsive properties.