Ligand-induced synthesis of two Cu-based coordination polymers and derivation of carbon-coated metal oxide heterojunctions for enhanced photocatalytic degradation.

Photocatalytic degradation of dyes is an extremely difficult but very important issue in the field of environmental protection. Two coordination polymers (CPs) [Cu(3-bpah)(HD)]n (1) and [Cu(3-dpye)0.5(HD)]n (2) [3-bpah = N,N'-bis(3-pyridinecarboxamide)-1,2-cyclohexane, 3-dpye = N,N'-bis(3-pyridinecarboxamide)-1,2-ethane, H2HD = hexanedioic acid] were successfully synthesized by tuning the auxiliary ligands under hydrothermal conditions. CPs 1 and 2 exhibited different compositions because of the different N-donor ligands, and were used as precursors for the preparation of metal oxide heterojunctions. Doping foreign elements into intrinsic CP-based materials is an effective way to enhance their photocatalytic activity, and thus we designed a facile method to synthesize a series of carbon-coated metal oxide heterojunctions which were derived from the two Cu-based CPs (Cu@V-1, Cu@V-2, Cu@Mo-1, Cu@Mo-2, Cu@W-1 and Cu@W-2) in this work for the first time. Benefiting from the formation of a carbon shell and regulation of the electronic structure through doping molybdenum and generating the Mo2C phase, the photocatalytic degradation rates were 94.84% for MB, 76.02% for RhB, 52.29% for MO, and 86.18% for CR after 4 h.

Synthesis of a 2D Cu@TiO2 composite via the design of a 1D Cu-based coordination polymer precursor for efficient and selective photodegradation of dyes.

A 2D Cu@TiO2 composite with a porous and crystalline structure was successfully synthesized via one-step and low-temperature calcination of a 1D Cu-based coordination polymer (Cu-CP), namely [Cu2(3-dpha)(1,4-NDC)2(H2O)3] n (3-dpha = N,N'-bis(3-pyridyl)adipamide and 1,4-H2NDC = 1,4-naphthalenedicarboxylic acid). Moreover, the Cu@TiO2 membrane was fabricated by a simple filtration of the as-grown Cu@TiO2 composite. Compared with the benchmark TiO2 photocatalyst, the Cu@TiO2 composite material with high specific surface area and reduced photogenerated electron-hole ratio exhibited good photodegradation activity and durability for gentian violet (GV), which could be attributed to the combined effect of co-doping of Cu and TiO2 structure. Furthermore, the ˙OH and ˙O2 - radicals were predicted to dominate the photocatalytic process. Therefore, this new efficient photocatalyst is a promising candidate for efficient and selective photodegradation of organic pollutants.

Cu-Organic framework-derived V-doped carbon nanostructures for organic dye removal.

Metal-organic frameworks (MOFs) have recently emerged as a type of uniformly and periodically atom-distributed precursor and efficient self-sacrificial template to fabricate hierarchical porous-carbon-related nanostructured functional materials. In this work, we used Cu(II) ions and aromatic dicarboxylic acid to construct [Cu3(4,4'-oba)2(µ2-OH)2(H2O)2]n (4,4'-H2oba = 4,4'-oxybisbenzoic acid) as a precursor for the preparation of carbon nanostructures. Doping foreign elements into intrinsic MOF-based nanomaterials is an effective way to enhance the adsorption property and photocatalytic activity; thus, we designed a facile method to synthesize a vanadium-doped mixture of Cu2O and Cu nanoparticles encapsulated in a Cu-MOF-derived carbon nanostructure (C-V-1) in this work for the first time. Benefiting from the protection of the carbon shell and regulation of the electronic structure by doping vanadium and phase-mixing Cu2O and Cu, the adsorption capacities of C-V-1 for MB, RhB, MO, CR and GV at room temperature are 174.13, 147.06, 179.92, 275.90 and 611.81 mg g-1 in 240 min, respectively, while the photocatalytic degradation rates are 88.14% for MB, 79.80% for RhB, 71.31% for MO, and 71.19% for CR after 4 h. In addition, the degradation rate is larger than 99.01% for GV after only 30 min of UV irradiation. This strategy of using a diverse MOF as a structural and compositional material to create a multifunctional composite/hybrid may expand the opportunities to explore highly efficient, fast and robust adsorbents and photocatalysts for water treatment.

Efficient and selective removal of Congo red by a C@Mo composite nanomaterial using a citrate-based coordination polymer as the precursor.

To research the effect of structural diversity on citrate-based coordination polymers (CPs), citric acid (H4cit) was selected to combine with Cu(ii) under hydrothermal conditions. A new CP [Cu2(cit)(H2O)2] (1) was synthesized and structurally characterized. The title complex shows a 3D 2,4,6-connected topology with the point symbol of {43·63}{44·66·85}{4}. Inspired by the decomposition and functional molybdenum component, 1 was used as a catalyst precursor to synthesize a carbon-based material (C-1) and a C@Mo material (C-Mo-1) by the chemical vapor deposition (CVD) method and characterized in detail. The selective removal of a contaminant (Congo red) by complex 1, C-1 and C-Mo-1 in the aqueous phase was also comparatively investigated.