A “copolymer-co-morphology” conception for shape-controlled synthesis of Prussian blue analogues and as-derived spinel oxides

Abstract

The morphologically and compositionally controlled synthesis of coordination polymers and spinel oxides is highly desirable for realizing new advanced nanomaterial functionalities. Here we develop a novel and scalable strategy, containing a “copolymer-co-morphology” conception, to shape-controlled synthesis of various types of Prussian blue analogues (PBAs). Three series of PBAs M_yFe_1−y[Co(CN)₆]_0.67·nH₂O (M_yFe_1−y–Co, M = Co, Mn and Zn) with well-controlled morphology have been successfully prepared through this strategy. Using Mn_yFe_1−y–Co PBAs as the model, by increasing the relative content of Mn, flexible modulation of the morphology could be easily realized. In addition, a series of porous Mn_xFe_1.8−xCo_1.2O₄ nano-dices with well-inherited morphologies and defined cation distribution could be obtained through a simple thermal treatment of the PBAs. All these results demonstrate the good universality of this novel strategy. When evaluated as an electrocatalyst, the octahedral-site Mn^III/Mn^IV content in Mn_xFe_1.8−xCo_1.2O₄, mainly determined by sensitive ⁵⁷Fe Mössbauer in combination with X-ray photoelectron spectroscopic techniques, was discovered to be directly correlated with the oxygen reduction/evolution reaction (ORR/OER) activity.