Short rod-like Ni-MOF anchored on graphene oxide nanosheets: A promising voltammetric platform for highly sensitive determination of p-chloronitrobenzene

FeNP@MIL-101(Fe)-Based Carbon Nanotube Composite for Energy Storage Applications

Metal-organic frameworks (MOFs) are of great interest for energy applications due to their high porosity, high charge storage capacity, and large number of active redox sites. It is important to enhance the performance of metal-organic frameworks through modification in order to increase their potential applications. Unique Fe nanoparticle (NP) in the Materials of Institute Lavoisier (MIL) series embedded in the carbon nanotube (CNT), FeNP@MIL-101(Fe)/CNT-based, nanocomposites have been synthesized using suitable hierarchical micromesoporous structures. These were fabricated by simple and straightforward solvothermal methods, and their electrochemical charge storage performance was investigated. The energy storage application using the FeNP@MIL -101(Fe)/CNT composite as a supercapacitor electrode was implemented for the first time. Various techniques were used to characterize this composite. It has excellent electrochemical properties when used as electrode material in 1 M KOH solution, including a high capacitance of up to 1305 F g-1 at 1 A g-1 and a long cycling stability of 95.7% capacitance retention after 10,000 cycles. Moreover, symmetric two-electrode electrochemical experiments showed that the composite achieved an energy density of 98.65 Wh kg-1 and a power density of 9000 W kg-1, The combination of microporous and mesoporous structures, increased surface area, and higher electrical conductivity are the main reasons for the high performance. The integration of FeNP@MIL-101(Fe) with the CNT creates new ion diffusion pathways, improves the hierarchical pore properties, and exposes the FeNP@MIL-101(Fe) cluster to more redox active sites, which improves the charge storage performance.

A Review on Recent Trends and Future Developments in Electrochemical Sensing

Electrochemical methods and devices have ignited prodigious interest for sensing and monitoring. The greatest challenge for science is far from meeting the expectations of consumers. Electrodes made of two-dimensional (2D) materials such as graphene, metal-organic frameworks, MXene, and transition metal dichalcogenides as well as alternative electrochemical sensing methods offer potential to improve selectivity, sensitivity, detection limit, and response time. Moreover, these advancements have accelerated the development of wearable and point-of-care electrochemical sensors, opening new possibilities and pathways for their applications. This Review presents a critical discussion of the recent developments and trends in electrochemical sensing.

Controlling ultrafiltration membrane fouling in surface water treatment via combined pretreatment of O3 and PAC: Mechanism investigation on impacts of technological sequence

In this research, the effects of combined powdered activated carbon (PAC)-ozone (O3) pretreatment on ultrafiltration (UF) performance were comprehensively examined and compared with the conventional O3-PAC pretreatment. The performance of pretreatments on mitigating membrane fouling caused by Songhua River water (SHR) was evaluated by specific flux, membrane fouling resistance distribution, and membrane fouling index. Moreover, the degradation of natural organic matter in SHR was investigated by UV absorbance at 254 nm (UV254), dissolved organic carbon (DOC), and fluorescent organic matter. Results showed that the 100PAC-5O3 process was the most effective in improving the specific flux, with 82.89 % and 58.17 % reductions in the reversible fouling resistance and irreversible fouling resistance respectively. Additionally, the irreversible membrane fouling index was reduced by 20 % relative to 5O3-100PAC. The PAC-O3 process also exhibited superior performance in the degradation of UV254, DOC, three fluorescent components, and three micropollutants in the SHR system compared to O3-PAC pretreatment. The O3 stage played a major role in mitigating membrane fouling, while PAC pretreatment enhanced the oxidation in the subsequent O3 stage during the PAC-O3 process. Furthermore, the Extended Derjaguin-Landau-Verwey-Overbeek theory and pore blocking-cake layer filtration model fitting analysis were employed to explain the mechanisms of membrane fouling mitigation and fouling patterns transformation. It was found that PAC-O3 significantly increased the repulsive interactions between the foulants and the membrane, which restrained the formation of the cake layer filtration stage. Overall, this study evidenced the potential of PAC-O3 pretreatment in surface water treatment applications, providing new insights into the mechanism of controlling membrane fouling and improving the permeate quality.

Graphene Oxide Facilitates Transformation of Waste PET into MOF Nanorods in Ionic Liquids

Although though ionic liquids (IL) are rapidly emerging as highly efficient reagents for the depolymerization of waste plastics, their high cost and adverse impact on the environment make the overall process not only expensive but also environmentally harmful. In this manuscript, we report that graphene oxide (GO) facilitates the transformation of waste polyethylene terephthalate (PET) to Ni-MOF (metal organic framework) nanorods anchored on reduced graphene oxide (Ni-MOF@rGO) through NMP (N-Methyl-2-pyrrolidone)-based coordination in ionic liquids. Morphological studies using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed mesoporous three-dimensional structures of micrometer-long Ni-MOF nanorods anchored on reduced graphene substrates (Ni-MOF@rGO ), whereas structural studies using XRD and Raman spectra demonstrated the crystallinity of Ni-MOF nanorods. Chemical analysis of Ni-MOF@rGO carried out using X-ray photoelectron spectroscopy demonstrated that nickel moieties exist in an electroactive OH-Ni-OH state, which was further confirmed by nanoscale elemental maps recorded using energy-dispersive X-ray spectroscopy (EDS). The applicability of Ni-MOF@rGO as an electro-catalyst in a urea-enhanced water oxidation reaction (UOR) is reported. Furthermore, the ability of our newly developed NMP-based IL to grow MOF nanocubes on carbon nanotubes and MOF nano-islands on carbon fibers is also reported.

Preparation of a GO/MIL-101(Fe) Composite for the Removal of Methyl Orange from Aqueous Solution

The composite material graphene oxide (GO)/MIL-101(Fe) was prepared by a simple one-pot reaction method. MIL-101(Fe) grown on the surface of a GO layer was confirmed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The adsorption performance and the mechanism of MIL-101(Fe) and GO/MIL-101(Fe) for methyl orange (MO) were studied. The results have shown that the adsorption capacity of GO/MIL-101(Fe) for MO was significantly better than that of MIL-101(Fe), and its capacity was the highest when 10% GO was added. The Langmuir specific surface areas of MIL-101(Fe) and GO/MIL-101(Fe) were 1003.47 and 888.289 m²·g^-1, respectively. The maximum adsorption capacities of MO on MIL-101 (Fe) and 10% GO/MIL-101 (Fe) were 117.74 and 186.20 mg·g^-1, respectively. The adsorption isotherms were described by the Langmuir model, and the adsorption kinetic data suggested the pseudo-second order to be the best fit model. GO/MIL-101(Fe) can be reused at least three times.

Metal-organic framework precursors derived Ni-doping porous carbon spheres for sensitive electrochemical detection of acetaminophen

The sensitive and selective determination of acetaminophen (AP) in the human body is highly desirable to ensure human health. In this work, nickel-doping nanoporous carbon (Ni/C) was fabricated by directly calcining Ni based metal-organic framework (Ni-MOF). The Ni/C based electrochemical sensor was developed for sensitive and selective determination of AP in human blood serum and urine samples. The prepared Ni/C composite possess plentiful catalytic active sites, ordered mesoporous structure and large specific surface area, which endow the constructed Ni/C sensor with a prominent performance for acetaminophen sensing. Under the optimal conditions, the developed method offered good linearity in the range of 0.20-53.75 μM with a low detection limit (S/N = 3) of 4.04 × 10^-2 μM. The electrocatalytic performance of the sensor towards AP was further measured by differential pulse voltammetry and cyclic voltammetry. The results demonstrated that the Ni/C sensor can be feasibly employed for the determination of AP in human blood serum and urine samples with excellent anti-interference stability and good reproducibility. The research reveals a great promising of the Ni/C electrochemical sensor for clinical applications and paves a way for the construction of high-performance electrochemical sensors for AP determination.