CoNi–MOF–Graphene Magnetic Nanocomposites for the Electrocatalytic Detection of Glucose and the Efficient Removal of Organic Dyes

Abstract

The design of a nanocomposite with electrocatalytic activity and recyclable development for the detection of small biomolecules and the removal of environmental pollutants has received enormous attention. A magnetic nanocomposite was synthesized by the hydrothermal approach comprising two building units: metal–organic frameworks (MOFs) and graphene (GR). GR accumulated organic ligands through the large specific surface area and cobalt (Co) and nickel (Ni) served as coordination ions to seamlessly connect with the former for forming CoNi–MOFs–GR (CNMs–GR) to improve the conductivity of MOFs and the electrocatalytic activity of GR. The nanocomposite was utilized to construct an electrochemical sensing platform for the detection of glucose in human blood serum and the removal of organic dyes (methylene blue (MB), congo red (CR), and neutral red (NR)) in water. The CNMs–GR-modified electrode exhibited good electrochemical performance toward glucose in a wide linear range of 10–2900 μM with a detection limit of 1.27 μM. The maximum uptake capacity of CNMs–GR for MB, CR, and NR was 184.29, 912.47, and 894.36 mg/g, respectively. Most obviously, this work provided a strategy for the design of an effective bifunctional nanocomposite, which not only demonstrated the enormous potential for detection of glucose but also realized the removal of organic dyes.

Single-Atom Ru Biomimetic Nanozyme for the Electrochemical Sensing of Hydrogen Peroxide

“…These three samples’ high-resolution C 1s spectra (Figure b) exhibit four prominent peaks accordingly signifying CC, C–OH, C–O–C, and HO–CO bonds. Meanwhile, Figure b also shows that the Ru 3d and C 1s signals overlapped, and the fitted Ru 3d signal is divided into the Ru 3d 3/2 and Ru 3d 5/2 peaks for Ru SA/GFs (285.20 and 281.70 eV) and Ru NPs/GFs (285.10 and 281.60 eV), respectively. , In the O 1s spectra (Figure c), aside from the existence of O–H and C–O bonds in three of them, , the emergence of the peak around 530.20 eV corresponding to Ru–O appeared in both Ru SA/GFs and Ru NP/GFs, while the peak located about 533.33 eV attributed to HO–CO observed in GFs diminishes. This alteration suggests that the Ru species anchored on the GFs through chemical bonding. , Furthermore, the signal of Na in GFs is relatively strong, whereas the Na signal decreases after the deposition of Ru (Figure S3), suggesting that the Na element probably indeed exerts a pronounced influence on the formation of the Ru single atom …”

“…To ascertain the atomic dispersion of Ru on the Ru SA/GFs, a more thorough examination of Ru SA/GFs was conducted using spherical aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM). As depicted in Figure 1e,f, the conspicuously white dots were 31,32 In the O 1s spectra (Figure 2c), aside from the existence of O−H and C−O bonds in three of them, 33,34 the emergence of the peak around 530.20 eV corresponding to Ru−O appeared in both Ru SA/GFs and Ru NP/GFs, 35 while the peak located about 533.33 eV attributed to HO−C�O observed in GFs diminishes. This alteration suggests that the Ru species anchored on the GFs through chemical bonding.…”