One-Step Hydrothermal Synthesis of Nitrogen-Doped Reduced Graphene Oxide/Hausmannite Manganese Oxide for Symmetric and Asymmetric Pseudocapacitors

In this paper, the pseudocapacitive performance of nitrogen-doped and undoped reduced graphene oxide/tetragonal hausmannite nanohybrids (N-rGO/Mn₃O₄ and rGO/Mn₃O₄) synthesized using a one-pot hydrothermal method is reported. The nanohybrid electrode materials displayed exceptional electrochemical performance relative to their respective individual precursors (i.e., reduced graphene oxide (rGO), nitrogen-doped reduced graphene oxide (N-rGO), and tetragonal hausmannite (Mn₃O₄)) for symmetric pseudocapacitors. Among the two nanohybrids, N-rGO/Mn₃O₄ displayed greater performance with a high specific capacitance of 345 F g^-1 at a current density of 0.1 A g^-1, excellent specific energy of 12.0 Wh kg^-1 (0.1 A g^-1), and a high power density of 22.5 kW kg^-1 (10.0 A g^-1), while rGO/Mn₃O₄ demonstrated a high specific capacitance of 264 F g^-1 (0.1 A g^-1) with specific energy and power densities of 9.2 Wh kg^-1 (0.1 A g^-1) and 23.6 kW kg^-1 (10.0 A g^-1), respectively. Furthermore, the N-rGO/Mn₃O₄ nanohybrid exhibited an impressive pseudocapacitive performance when fabricated in an asymmetric configuration, having a stable potential window of 2.0 V in 1.0 M Na₂SO₄ electrolyte. The nanohybrid showed excellent specific energy and power densities of 34.6 Wh kg^-1 (0.1 A g^-1) and 14.01 kW kg^-1 (10.0 A g^-1), respectively. These promising results provide a good substance for developing novel carbon-based metal oxide electrode materials in pseudocapacitor applications.

Nanoparticles Functionalised with Re(I) Tricarbonyl Complexes for Cancer Theranostics

Globally, cancer is the second (to cardiovascular diseases) leading cause of death. Regardless of various efforts (i.e., finance, research, and workforce) to advance novel cancer theranostics (diagnosis and therapy), there have been few successful attempts towards ongoing clinical treatment options as a result of the complications posed by cancerous tumors. In recent years, the application of magnetic nanomedicine as theranostic devices has garnered enormous attention in cancer treatment research. Magnetic nanoparticles (MNPs) are capable of tuning the magnetic field in their environment, which positively impacts theranostic applications in nanomedicine significantly. MNPs are utilized as contrasting agents for cancer diagnosis, molecular imaging, hyperfusion region visualization, and T cell-based radiotherapy because of their interesting features of small size, high reactive surface area, target ability to cells, and functionalization capability. Radiolabelling of NPs is a powerful diagnostic approach in nuclear medicine imaging and therapy. The use of luminescent radioactive rhenium(I), 188/186Re, tricarbonyl complexes functionalised with magnetite Fe3O4 NPs in nanomedicine has improved the diagnosis and therapy of cancer tumors. This is because the combination of Re(I) with MNPs can improve low distribution and cell penetration into deeper tissues.

Bovine Serum Albumin-Dependent Charge-Transfer Kinetics Controls the Electrochemical Immunosensitive Detection: Vibrio cholerae as a Model Bioanalyte

This work investigates how bovine serum albumin (BSA), a commonly used protein in the fabrication of electrochemical immunosensors, can impact on the sensitivity of detection when integrated with antibody (Ab) pre-encapsulated with (i) insulating polyacrylonitrile (PAN) fibre (i.e., GCE-PAN-Ab-BSA immunosensor) or (ii) conducting PAN-grafted iron (II) phthalocyanine (FePc) (i.e., GCE-PAN@FePc-Ab-BSA immunosensor), using Vibrio cholerae toxin as a case study bioanalyte. Both immunosensors show different charge-transfer kinetics that strongly impact on their immunosensitive detection. From the electrochemical data, GCE-PAN-Ab-BSA is more insulating with the presence of BSA, while the GCE-PAN@FePc-Ab-BSA is more conducting with BSA. The CV of the GCE-PAN-Ab-BSA is dominated by radial diffusion process, while that of the GCE-PAN@FePc-Ab-BSA is planar diffusion process. The behaviour of GCE-PAN@FePc-Ab-BSA has been associated with the facile coordination of BSA and FePc that permits co-operative charge-transport of the redox probe, while that of the GCE-PAN-Ab-BSA is related to the interaction-induced PAN-BSA insulating state that suppresses charge-transport. As a consequence of these different interaction processes, GCE-PAN-Ab-BSA immunosensor provides higher electroanalytical performance for the detection of Vibrio cholerae toxin (with sensitivity of 16.12 Ω/log [VCT, g/mL] and limit of detection (LoD) of 3.20 × 10⁻¹³ g/mL compared to those of the GCE-PAN@FePc-Ab-BSA (4.16 Ω/log (VCT, g mL⁻¹) and 2.00 × 10⁻¹² g/mL). The study confirms the need for a thorough understanding of the physico-chemistries of the electrode platforms for the construction of immunosensors. Although this work is on immunosensors for cholera infection, it may well apply to other immunosensors.

The crystal structure of fac-tricarbonyl(4,4-dimethyl-2,2-dipyridyl-κ2 N,N′)- (pyrazole-κN)rhenium(I) nitrate, C18H16O3N4Re

C18H16O3N4Re, monoclinic, P21/c (no. 14), a = 9.8409(6) Å, b = 14.0933(9) Å, c = 13.9153(9) Å, β = 90.558(2)°, V = 1929.8(2) Å3, Z = 4, R gt(F) = 0.0266, wR ref(F 2) = 0.0584, T = 100(2) K.

Poly(3-aminobenzoic acid) Decorated with Cobalt Zeolitic Benzimidazolate Framework for Electrochemical Production of Clean Hydrogen

A novel composite of poly(3-aminobenzoic acid) (PABA) and a cobalt zeolitic benzimidazolate framework (CoZIF) has been studied for the production of hydrogen through the hydrogen evolution reaction (HER). The structural characteristics and successful synthesis of PABA, CoZIF and the PABA/CoZIF composite were confirmed and investigated using different techniques. Probing-ray diffraction for phase analysis revealed that the composite showed a decrease and shift in peak intensities, confirming the incorporation of CoZIF on the PABA backbone via in situ polymerization, with an improvement in the crystalline phase of the polymer. The thermal stability of PABA was enhanced upon composite formation. Both scanning electron microscopy and transmission electron microscopy showed that the composite had a rough surface, owing to an interaction between the CoZIF and the external surface of the PABA. The electrochemical hydrogen evolution reaction (HER) performance of the synthesized samples was evaluated using cyclic voltammetry and Tafel analysis. The composite possessed a Tafel slope value of 156 mV/dec and an α of 0.38, suggesting that the Volmer reaction coupled with either the Heyrovsky or Tafel reaction as the rate determining step. The fabricated composite showed high thermal stability and excellent tolerance as well as high electroactivity towards the HER, showing it to be a promising non-noble electrocatalyst to replace Pt-based catalysts for hydrogen generation.