Rational design of hollow Prussian blue analogues with enhanced catalytic activity via Kirkendall Effect for...

Hollow Prussian blue analogues (PBAs) exhibit excellent specific surface area and stability, and have demonstrated outstanding performance. In the work, a series of MnFe bimetallic hollow Prussian blue analogues (MnFePBA) were synthesized via a hydrothermal method. By investigating the effects of manganese content and synthesis reaction time, it was found that the morphology of the material gradually changes from regular solid to hollow structure. Various characterization techniques were used to discuss the mechanism of structural change in detail, namely Kirkendall effect. Furthermore, the doping amount of transition metal Mn affected the concentration gradient in the solution, thereby regulating the intensity of diffusion. The reaction time controlled the progress of the diffusion process. This superiority is ascribed to the uniform hollow structure of the material prepared under these conditions, where the concentrations of Fe^3 + /Fe²⁺ and Mn³⁺/Mn²⁺ achieve an optimal synergistic state, which can provide more active sites and thus significantly enhance the peroxidase-like activity. Based on MnFePBA-TMB system, a simple and sensitive colorimetric method for the assay of uric acid (UA) was constructed. The sensor achieved quantitative detection of UA in the range of 0.4-80 μM with a detection limit of 0.16 μM. Additionally, the sensor was successfully applied to the detection of UA in human serum, demonstrating its potential for clinical application and home monitoring.