Iron-doped novel Co-based metal-organic frameworks for preparation of bifunctional catalysts with an amorphous structure for OER/HER in alkaline solution

An aptamerelectrochemical sensor based on functional carbon nanofibers for tetracycline determination

Fe-Co@CNF was synthesized by electrospinning technology, and AuNPs was loaded onto Fe-Co@CNF by in-situ reduction to obtain Fe-Co@CNF@AuNPs composite material, which was used as the working electrode based on Au-S bond cooperation. The tetracycline electrochemical sensing interface Fe-Co@CNF@AuNPs@Apt was constructed by connecting mercaptoylated tetracycline (TC) aptamers on Fe-Co@CNF@AuNPs surface. The morphology and composition of Fe-Co@CNF@AuNPs composites were characterized by SEM, TEM, EDS, XRD and XPS, and the electrochemical properties of tetracycline were evaluated by CV and DPV. The results showed that the addition of Fe and Co did not destroy the structure of the original carbon nanofibers, and their synergistic effect enhanced the electrocatalytic performance, effective electrode area and electron transfer ability of carbon nanofibers. AuNPs are evenly distributed over the fibers, which effectively improves the electrical conductivity of the material. Under the optimal conditions, the theoretical detection limit of tetracycline was 0.213 nM, and the linear detection range was 5.12-10 mM, which could successfully detect tetracycline in milk.

Bimetallic CPM-37(Ni,Fe) metal-organic framework: enhanced porosity, stability and tunable composition

A newly synthesized series of bimetallic CPM-37(Ni,Fe) metal-organic frameworks with different iron content (Ni/Fe ≈ 2, 1, 0.5, named CPM-37(Ni2Fe), CPM-37(NiFe) and CPM-37(NiFe2)) demonstrated high N2-based specific SBET surface areas of 2039, 1955, and 2378 m2 g-1 for CPM-37(Ni2Fe), CPM-37(NiFe), and CPM-37(NiFe2), having much higher values compared to the monometallic CPM-37(Ni) and CPM-37(Fe) with 87 and 368 m2 g-1 only. It is rationalized that the mixed-metal nature of the materials increases the structural robustness due to the better charge balance at the coordination bonded cluster, which opens interesting application-oriented possibilities for mixed-metal CPM-37 and other less-stable MOFs. In this work, the CPM-37-derived α,β-Ni(OH)2, γ-NiO(OH), and, plausibly, γ-FeO(OH) phases obtained via decomposition in the alkaline medium demonstrated a potent electrocatalytic activity in the oxygen evolution reaction (OER). The ratio Ni : Fe ≈ 2 from CPM-37(Ni2Fe) showed the best OER activity with a small overpotential of 290 mV at 50 mA cm-2, low Tafel slope of 39 mV dec-1, and more stable OER performance compared to RuO2 after 20 h chronopotentiometry at 50 mA cm-2.

A hierarchical carbon foam-hosted Co2P nanoparticles monolithic electrode for ampere-level and super-durable electrocatalytic hydrogen production

In this work, we develop a hierarchical carbon foam-based monolithic electrode (Co2P@HCF) from Co2+-adsorbed polyvinyl alcohol (PVA) sponge via the successive carbonization and phosphorization. Owing to the 3D hierarchical porous structure, excellent electrolyte wettability, good mechanical strength, and intimate embedding of highly dispersed Co2P nanoparticles, the Co2P@HCF electrode delivers a high current density of 1.0 A cm-2 for the hydrogen evolution reaction (HER) at ultralow overpotentials of 189.6 and 218.6 mV in 0.5 M H2SO4 and 1.0 M KOH solutions, respectively, with remarkable durability for 100 h.

Interfacial engineering and chemical reconstruction of Mo/Mo2C@CoO@NC heterostructure for promoting oxygen evolution reaction

Chemical reorganization and interfacial engineering in hybrid nanomaterials are promising strategies for enhancing electrocatalytic performance. Herein, MoO₃@zeolitic imidazolate framework-67 (ZIF-67) heterogeneous nanoribbons are designed through coordination assembly. By following heat treatment, a Mo/Mo₂C@CoO@NC heterostructure with nitrogen-doped carbon-encapsulated CoO hexagons (CoO@NC) anchored on the Mo/Mo₂C jag matrix was fabricated. Notably, through controllable experimental optimization, the as-prepared Mo/Mo₂C@CoO@NC heterostructure exhibits numerous active centers (e.g. Mo, Mo₂C, CoO, and NC), fully exposed active sites (numerous pores and jagged structures), and abundant heterointerfaces (Mo/Mo₂C, Mo₂C/CoO@NC, Mo₂C/amorphous, and CoO@NC/amorphous), and exhibits good conductivity (localized single-crystal behavior, graphitized carbon). As a result, the as-developed Mo/Mo₂C@CoO@NC heterostructures inherit impressive oxygen evolution reaction (OER) performance with an overpotential of only 215 mV at 10 mA cm^-2. Furthermore, Mo/Mo₂C@CoO@NC heterostructures exhibit excellent stability with a current density retention of 98.4% after 20 h chronoamperometry. This work provides deep insights into chemical reconstructions and tuning heterointerfaces to efficiently enhance the OER activity of heterostructure-based electrocatalysts.

MOFs for Electrochemical Energy Conversion and Storage

Metal organic frameworks (MOFs) are a family of crystalline porous materials which attracts much attention for their possible application in energy electrochemical conversion and storage devices due to their ordered structures characterized by large surface areas and the presence in selected cases of a redox-active porous skeleton. Their synthetic versatility and relevant host-guest chemistry make them suitable platform for use in stable and flexible conductive materials. In this review we summarize the most recent results obtained in this field, by analyzing the use of MOFs in fuel and solar cells with special emphasis on PEMFCs and PSCs, their application in supercapacitors and the employment in batteries by differentiating Li-, Na- and other metal ion-batteries. Finally, an overview of the water splitting reaction MOF-catalyzed is also reported.