The fabrication of two-dimensional (2D) metal−organic frameworks (MOFs) and Prussian blue analogues (PBAs) combines the advantages of 2D materials, MOFs and PBAs, resolving the poor electronic conductivity and slow diffusion of MOF materials for electrochemical applications. In this work, 2D leaflike zeolitic imidazolate frameworks (Co-ZIF and Fe-ZIF) as sacrificial templates are in situ converted into PBAs, realizing the successful fabrication of PBA/ZIF nanocomposites on nickel foam (NF), namely, CoCo-PBA/Co-ZIF/ NF, FeFe-PBA/Fe-ZIF/NF, CoFe-PBA/Co-ZIF/NF, and Fe/CoCo-PBA/Co-ZIF/NF. Such fabrication can effectively reduce transfer resistance and greatly enhance electron-and masstransfer efficiency due to the electrochemically active PBA particles and NF substrate. These fabricated electrodes as multifunctional sensors achieve highly selective and sensitive glucose and H 2 O 2 biosensing with a very wide detective linear range, extremely low limit of detection (LOD), and good stability. Among them, CoFe-PBA/Co-ZIF/NF exhibits the best sensing performance with a very wide linear range from 1.4 μM to 1.5 mM, a high sensitivity of 5270 μA mM −1 cm −2 , a low LOD of 0.02 μM (S/N = 3), and remarkable stability and selectivity toward glucose. What is more, it can realize excellent detection of glucose in human serum, demonstrating its practical applications. Furthermore, this material as a multifunctional electrochemical sensor also manifests superior detection performance against hydrogen peroxide with a wide linear range of 0.2−6.0 mM, a high sensitivity of 196 μA mM −1 cm −2 , and a low limit of detection of 1.08 nM (S/N = 3). The sensing mechanism for enhanced performance for glucose and H 2 O 2 is discussed and proved by experiments in detail.

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The fabrication of highly efficient and sustainable electrocatalysts used for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is exceedingly challenging and warranted for overall water splitting. In this work, we successfully synthesized a series of metal−organic frameworks (MOFs), namely, as Fe 2 M-MOF (M = Fe, Co, Ni, Zn, Mn; H 4 L = 3,3,5,5′-azoxybenzenetetracarboxylic acid) under a simple and mild condition, in which the Fe 3 cluster as a basic building unit was replaced by the second kind of metal center; at the same time, a redox-active organic linker was adopted. The Fe 2 M-MOF system as a multifunctional catalyst realizes great improvement of the OER and HER performances. Among of them, the Fe 2 Co-MOF catalyst exhibits an extremely low overpotential of 339 mV at a current density of 10 mA cm −2 and a very small Tafel slope of 36.2 mV dec −1 in an alkaline electrolyte for OER. This result has far exceeded the commercial catalyst IrO 2 . Meanwhile, Fe 2 Zn-MOF manifests excellent HER activity with a small overpotential of 221 mV at 10 mA cm −2 and a low Tafel slope of 174 mV dec −1 . In addition, the good long-term stability for these catalysts can be evaluated under working conditions. Systematic investigations are used to explain the enhanced electrocatalytic mechanism. In conclusion, we provide a simple and effective strategy for the preparation of multifunctional catalysts for energy conversion applications based on a pristine MOF material with redox-active metal centers and organic linkers.

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