Controlled synthesis of NbO-type metal-organic framework nano/microcrystals with superior capacity and selectivity for dye adsorption from aqueous solution

NbO-type MOF nano/microcrystals were facilely achieved by tuning the volume ratio of DMF and H2O mixed solvent under solvothermal conditions. It was found that NOTT-102 rhombohedral sample obtained with DMF:H2O volume ratio of 15:5 has the largest BET surface area (3006 m(2) g(-1)), compared to the samples with the DMF:H2O volume ratio of 12:8 (2263 m(2) g(-1)) and 20:0 (1962 m(2) g(-1)) as well as the bulk NOTT-102, namely [Cu-2(QPTC)] (H(4)QPTC = [1,1':4',1 '':4 '',1'''-quaterphenyl]-3,3''',5,5'''-tetracarboxylic acid), crystals (2942 m(2) g(-1)). Furthermore, dye adsorption results indicate that NOTT-102 rhombohedral sample exhibits superior adsorption capacity (850 mg g(-1)) and adsorption selectivity for methylene blue (MB) in contrast to methyl orange, rhodamine B, and acid chrome blue K dyes, which may be one of the promising candidates for potential application in removal of organic dyes from aqueous solution.