Bimetallic oxygen electrocatalyst derived from metallocenes doped MOFs

Synthesis and Peroxide Activation Mechanism of Bimetallic MOF for Water Contaminant Degradation: A Review

Metal-organic framework (MOF) materials possess a large specific surface area, high porosity, and atomically dispersed metal active sites, which confer excellent catalytic performance as peroxide (peroxodisulfate (PDS), peroxomonosulfate (PMS), and hydrogen peroxide (H₂O₂)) activation catalysts. However, the limited electron transfer characteristics and chemical stability of traditional monometallic MOFs restrict their catalytic performance and large-scale application in advanced oxidation reactions. Furthermore, the single-metal active site and uniform charge density distribution of monometallic MOFs result in a fixed activation reaction path of peroxide in the Fenton-like reaction process. To address these limitations, bimetallic MOFs have been developed to improve catalytic activity, stability, and reaction controllability in peroxide activation reactions. Compared with monometallic MOFs, bimetallic MOFs enhance the active site of the material, promote internal electron transfer, and even alter the activation path through the synergistic effect of bimetals. In this review, we systematically summarize the preparation methods of bimetallic MOFs and the mechanism of activating different peroxide systems. Moreover, we discuss the reaction factors that affect the process of peroxide activation. This report aims to expand the understanding of bimetallic MOF synthesis and their catalytic mechanisms in advanced oxidation processes.

Iron cobalt-doped carbon nanofibers anode to simultaneously boost bioelectrocatalysis and direct electron transfer in microbial fuel cells: Characterization, performance, and mechanism

A self-supporting electrode (FeCo-MOF/CNFs) combining iron cobalt bimetallic metal-organic frameworks (FeCo-MOFs) with carbon nanofibers (CNFs) was applied as the anode of a microbial fuel cell (MFC). The introduction of FeCo-MOFs enhanced graphitization degree and electrical conductivity, which endowed FeCo-MOF/CNFs with excellent electrocatalytic performance and good biocompatibility. The hierarchical porous structure of FeCo-MOF/CNFs provided abundant attachment sites for electroactive bacteria (EAB) and facilitated rapid electron transfer. The MFC equipped with FeCo-MOF/CNFs anode (FeCo/CNFs-MFC) exhibited considerable power generation output (maximum power density: 5.3 ± 0.2 W/m², coulombic efficiency: 54 ± 4 %). In addition, FeCo/CNFs-MFC achieved a direct electron transfer (DET) catalytic current density of 0.63 A/m². FeCo-MOF/CNFs could simultaneously enhance the bioelectrocatalysis activity and promote the DET process of EAB, which provided an effective way to improve the sluggish extracellular electron transport process of the MFC anode.

One-dimensional cobalt oxide nanotubes with rich defect for oxygen evolution reaction

For the electrochemcial hydrogen production, the oxygen evolution reaction (OER) is a pivotal half-reaction in water splitting. However, OER suffers sluggish kinetics and high overpotential, leading to the increase of overall energy consumption and decrease of the energy efficiency. In this work, high-quality cobalt oxide porous nanotubes (Co₃O₄-PNTs) are easily obtained by simple self-template approach. One-dimensional (1D) porous structure provides the large specific surface area, enough abundant active atoms and effective mass transfer. In addition, Co₃O₄-PNTs also own self-stability of 1D architecture, benefitting the their durability for electrocatalytic reaction. Thus, Co₃O₄-PNTs with optimal annealing temperature and time reveal the attractive alkaline OER performance (Tafel slope of 56 mV dec^-1and 323 mV overpotential at 10 mA cm^-2), which outperform the Co₃O₄nanoparticles and benchmark commercial RuO₂nanoparticles. Furthermore, Co₃O₄-PNTs also exhibit excellent OER durability for least 10 h at the 10 mA cm^-2. Overall, Co₃O₄-PNTs with low cost can be serve as a highly reactive and economical catalyst for OER.