In-situ calcination of polyoxometallate-based metal organic framework/reduced graphene oxide composites towards supercapacitor electrode with enhanced performance

Progress and opportunities for metal-organic framework composites in electrochemical sensors

Metal-organic framework composites have the advantages of large surface area, high porosity, strong catalytic efficiency and good stability, which provide a great possibility of finding excellent electrode materials for electrochemical sensors. However, MOF composites still face various challenges and difficulties, which limit their development and application. This paper reviews the application of MOF composites in electrochemical sensors, including MOF/carbon composites, MOF/metal nanoparticle composites, MOF/metal oxide composites and MOF/enzyme composites. In addition, the application challenges of MOF composites in electrochemical sensors are summarized. Finally, the application prospect for MOF composites is considered to promote the synthesis of more MOF composites with excellent properties.

MOFs-Graphene Composites Synthesis and Application for Electrochemical Supercapacitor: A Review

Today's world requires high-performance energy storage devices such as hybrid supercapacitors (HSc), which play an important role in the modern electronic market because supercapacitors (Sc) show better electrical properties for electronics devices. In the last few years, the scientific community has focused on the coupling of Sc and battery-type materials to improve energy and power density. Recently, various hybrid electrode materials have been reported in the literature; out of these, coordination polymers such as metal-organic frameworks (MOFs) are highly porous, stable, and widely explored for various applications. The poor conductivity of classical MOFs restricts their applications. The composite of MOFs with highly porous graphene (G), graphene oxide (GO), or reduced graphene oxide (rGO) nanomaterials is a promising strategy in the field of electrochemical applications. In this review, we have discussed the strategy, device structure, and function of the MOFs/G, MOFs/GO, and MOFs/rGO nanocomposites on Sc. The structural, morphological, and electrochemical performance of coordination polymers composites towards Sc application has been discussed. The reported results indicate the considerable improvement in the structural, surface morphological, and electrochemical performance of the Sc due to their positive synergistic effect. Finally, we focused on the recent development in preparation methods optimization, and the opportunities for MOFs/G based nanomaterials as electrode materials for energy storage applications have been discussed in detail.

Polyelectrolyte-functionalized reduced graphene oxide wrapped helical POMOF nanocomposites for bioenzyme-free colorimetric biosensing

For the sake of effective colorimetric sensing-pattern, a sensitive colorimetric sensor was conceived based on polyoxometalates based metal-organic frameworks (POMOFs) and polydiallyldimethylammonium chloride functionalized reduced graphene oxide (PDDA-rGO) for the first time, in which PDDA as a "glue" molecule turns rGO nanosheets into general platforms for bonding POMOFs nanoparticles. Herein, a new POMOF compound with fascinating helices-on-helices feature, [Ni₄(Trz)₆(H₂O)₂][SiW₁₂O₄₀]^.4H₂O (Trz = 1,2,4-triazole) (abbreviated as Ni₄SiW₁₂), was synthesized and characterized, then PDDA-rGO sheet as dispersive and conductive material was successfully introduced to Ni₄SiW₁₂ fabricating new PDDA-rGO/Ni₄SiW₁₂-n nanocomposites, (abbreviated as PMPG-n). The resulting PMPG-n nanocomposites as peroxidase mimetic show excellent catalytic activities under extreme condition (pH value 2.5), attributed to the nature and synergies from POMs, MOFs and PDDA-rGOs. Note that the peroxidase-like activity of PMPG-1 (the mass ratio of Ni₄SiW₁₂ to PDDA-rGO is 1:1) exhibits higher sensitivity (1-60 μM), faster response (10 min) and the lowest limit of detection (2.07 μM) among all reported materials to citric acid (CA) to date. This work opens up new application prospects in colorimetric sensing system for food quality control and safety, biotechnology and clinical diagnosis.

Fabrication of double-shell hollow NiO@N-C nanotubes for a high-performance supercapacitor

Rational fabrication of carbon-based materials hybridized with transition-metal oxides is crucial for the design of supercapacitor electrodes with superior properties.