Design and Synthesis of Concentration Gradient Prussian Blue Analogues

Abstract

A synthetic route to mixed composition particles based on different Prussian blue analogues containing a gradient in either the divalent metal or the hexacyanometalate components is explored. Synthetic conditions and combinations of components that favor kinetically trapping the gradient structures are identified, and these are contrasted with cases for which gradients in composition are harder to achieve. By an exploration of several combinations, the relative rate of precipitation of the PBA components is shown to be the crucial determinant for achieving control over the gradient synthesis, a parameter that is complicated by differing crystallization mechanisms within the PBA family. For one combination, cobalt hexacyanoferrate with nickel hexacyanoferrate, a complete series of particles is demonstrated, including particles with differing divalent metal ion gradients, core particles with a gradient shell, and particles with discrete core and shell components separated by a gradient. The structural characteristics of the gradient heterostructures are compared to the individual single phases and to more standard core–shell particles.

How Does Ion Exchange Construct Binary Hexacyanoferrate? A Case Study

“…Compared with the pristine MnHCF, the unit cell volume slightly shrank due to the decrease of parameters a, b, and c. The ICP-OES measurement showed that the overall element ratio of Mn/Fe was 0.31, far lower than that of the pristine MnHCF, 1.03, indicating the Mn was successfully substituted by Fe. The EDS linear scanning was employed to analyze the local composition and distribution of transition metals, 9 which also showed the content of Fe was significantly higher than Mn (Figure 2a). As for the distribution of elements, Fe and Mn were homogeneously distributed at the center of particles; within a depth of tens of nanometers from the surface, the ratio of Fe to Mn seemed to be high comparatively.…”

“…To this end, various preparation methods have been explored, of which the commonly used one was the gradient control of the concentrations of the mother solution of M A and M B . In detail, M A solution feedstock was continuously introduced into the M B solution to form a time-dependent M A concentration in the mother solution, thus achieving the M A concentration-gradient crystal growth. − Besides, the one-pot coprecipitation reaction was also a common method to construct high-entropy structures. − For example, the MnHCF coated with a thin epitaxial surface layer of nickel-based Prussian blue was successfully constructed due to unequal affinity for Mn 2+ and Ni 2+ with sodium citrate . However, for these cases, it meets a challenge in practice due to a complicated feeding system or poor productivity.…”

Recent Advances of Prussian Blue-Based Wearable Biosensors for Healthcare

“…12 Coprecipitation for preparation of multicomponent PBAs is mainly based on the difference of the relative precipitation rates of single-phase PBA, and this growth mechanism can promote the design of various heterostructures. 13 In a general chemical deposition process, PB/PBAs films were prepared by modifying various electrodes including platinum, gold, glass carbon (GC), carbon paste, and screenprinted electrode. However, most formed PB/PBAs films have shown poor electrochemical stability and can easily lose their catalytic effect.…”

“…For example, Cu 2+ and Ni 2+ analogues were prepared through nucleated growth, and the synthesis of Co 2+ analogues included aggregation and crystalline by annealing . Coprecipitation for preparation of multicomponent PBAs is mainly based on the difference of the relative precipitation rates of single-phase PBA, and this growth mechanism can promote the design of various heterostructures …”

Co‐MOF derived MoSe 2 @ CoSe 2 /N‐doped carbon nanorods as high‐performance anode materials for potassium ion batteries

“…To explore the practical use of MC-Se@NC composite, a full KIB cell with MC-Se@NC as the anode, Prussian blue (PB) as the cathode, and 1 M KPF 6 in ethylene carbonate (EC)/diethyl carbonate (DEC) as the electrolyte were fabricated and tested. The PB was prepared by a co-precipitation method [50][51][52] and showed an irregular morphology (Figure S18a). From the CV curve of the full KIB cell (Figure S19), two major peaks were observed at 2.3 and 1.6 V, which are attributed to charge and discharge processes, respectively.…”