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A facile and template-free solvothermal method was developed for the synthesis of microspheric g-C3N4/Bi2MoO6 photocatalysts. The obtained g-C3N4/Bi2MoO6 composites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photo-electron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and ultraviolet-visible diffuse reflection spectroscopy (DRS). The XRD, FTIR, and HRTEM characterization results confirmed the formation of heterojunction structures at the interfaces of g-C3N4 and Bi2MoO6. The DRS results showed that the absorption edges of g-C3N4/Bi2MoO6 composites were red shifted in the visible light region with the increase of g-C3N4 content. The SEM and TEM images revealed that the composites exhibited a microsphere-like morphology and were composed of smaller nanoplates. The elemental mapping images revealed that g-C3N4 and Bi2MoO6 nanoflakes uniformly assembled together to form hierarchical flowers. Compared with pure g-C3N4 and Bi2MoO6, the as-prepared samples exhibited superior photocatalytic activity towards the degradation of dyes (Rhodamine B and Methyl blue) under visible light irradiation. The enhanced photocatalytic activity of g-C3N4/Bi2MoO6 composites could be attributed to their strong visible light absorption, the high migration efficiency of photo-induced carriers, and the interfacial electronic interaction. The electrochemical impedance spectroscopy (EIS) confirmed that the interface charge separation efficiency was greatly improved by coupling g-C3N4 with Bi2MoO6. It was also confirmed that the photo-degradation of dye molecules is mainly attributed to the oxidizing ability of the generated holes (h+) and partly to the oxidizing ability of ·O2− and ·OH radicals. [ABSTRACT FROM AUTHOR]

A series of seven mixed-ligand coordination polymers, namely {[Cd4(H2L1)4(suc)4]·3H2O}n(1), {[Cd4(H2L1)3(suc)4]·5H2O}n(2), {[Cd2(HL1)2(suc)]·8H2O}n(3), {[Cd(H2L2)(suc)]·3H2O}n(4), {[Cd(H2L3)(suc)]·3H2O}n(5), {[Co(H2L1)(chdc)(H2O)]·H2O}n(6), {[Co(H2L2)(chdc)(H2O)]}n(7) have been produced by the reaction of three 2-amino-4,6-dipyridylpyrimidine isomers (H2L1, H2L2, H2L3) and secondary ligand 1,4-succinic acid (H2suc) or 1,4-cyclohexanedicarboxylic acid (H2chdc) with Cd(II) and Co(II) salts under hydrothermal conditions. All these compounds have been structurally determined by elemental analysis, IR and single-crystal X-ray diffraction. The three isomers are introduced in a mixed-ligand system for the first time. For the H2L1–H2suc–Cd(II) system, it is found that the structures of compounds 1–3exhibiting a 1-D double-chain, a rare 1-D quadruple nano-chain and a 2-D network with (6,3) topology, respectively, are influenced by the ratio of metal-to-ligand. When H2L2 and H2L3 were used instead of H2L1, two 1-D chains (compounds 4and 5) were obtained. Although they have the same molecular formula and structure motif, their supramolecular networks constructed by hydrogen-bondings and π–π stacking interactions are different. When H2L1 and H2L2 were introduced into the Co(NO3)2–H2chdc system, compounds 6and 7were successfully isolated, and display a zigzag chain and a helical chain, respectively. Interestingly, the cis- and trans-conformations of H2chdc were separated completely in the two compounds. The results reveal that both the coordination structure and the supramolecular assembly could be directed by the ligand isomers. Furthermore, several intriguing water clusters have been observed in these mixed-ligand compounds, such as a novel (H2O)10cluster in 2, a 2-D water net formed by (H2O)8clusters in 3, a 1-D undulated water chain in 4and a chair-shaped (H2O)6cluster in 5. The solid-state properties of compounds 1–7such as thermal stability and fluorescence have also been investigated. [ABSTRACT FROM AUTHOR]