Flowerlike Copper(II)-Based Coordination Polymers Particles: Rapid Room-Temperature Fabrication, Influencing Factors, and Transformation toward CuO Microstructures with Good Catalytic Activity for the Reduction of 4‑Nitrophenol

A facile and environment-friendly approach for synthesis of flowerlike copper-based coordination polymer particles (CPPs) was reported. Copper acetate (CuAc₂) and sodium pyridine-2,3-dicarboxylate (2,3-Na₂PDC) were used as the initial reactants. The flowerlike Cu-PDC microstructures were obtained based on a simple direct precipitation between CuAc₂ and 2,3-Na₂PDC in a mixed solution of water and methanol with the volume ratio of 20:10 at room temperature. The as-obtained products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and elemental analysis. Some factors to affect the morphology and size of the Cu-PDC microstructures were systematically investigated such as the molar ratio of reactants, the volume ratio of water/methanol, acetic groups, and the reaction time. It was found that flowerlike Cu-PDC microstructures could be transformed into flowerlike CuO microstructures by heat-treating in air at 350 °C for 30 min. Experiments showed that the as-obtained flowerlike CuO microstructure exhibited a high catalytic activity for the reduction of 4-nitrophenol in excess NaBH₄ solution