Zn-doped MnO2 ultrathin nanosheets with rich defects for high performance aqueous supercapacitors

Doping Engineering in Manganese Oxides for Aqueous Zinc-Ion Batteries

Manganese oxides (MnxOy) are considered a promising cathode material for aqueous zinc-ion batteries (AZIBs) due to their high theoretical specific capacity, various oxidation states and crystal phases, and environmental friendliness. Nevertheless, their practical application is limited by their intrinsic poor conductivity, structural deterioration, and manganese dissolution resulting from Jahn-Teller distortion. To address these problems, doping engineering is thought to be a favorable modification strategy to optimize the structure, chemistry, and composition of the material and boost the electrochemical performance. In this review, the latest progress on doped MnxOy-based cathodes for AZIBs has been systematically summarized. The contents of this review are as follows: (1) the classification of MnxOy-based cathodes; (2) the energy storage mechanisms of MnxOy-based cathodes; (3) the synthesis route and role of doping engineering in MnxOy-based cathodes; and (4) the doped MnxOy-based cathodes for AZIBs. Finally, the development trends of MnxOy-based cathodes and AZIBs are described.

Defective core-shell NiCo2S4/MnO2 nanocomposites for high performance solid-state hybrid supercapacitors

The roles of oxygen vacancies to enhance the electrochemical performance were not clearly explained in comprehensive research. Herein, the vertically oriented NiCo₂S₄/MnO₂ core-shell nanocomposites are in situ grown on the nickel foam (NF) surface and activated by oxygen vacancy engineering via a chemical reduction method. The scanning electron microscope (SEM) and transmission electron microscope (TEM) results show the shell-MnO₂ is well coated on the core-NiCo₂S₄. The hierarchical core-shell nanostructures synergistically increase conductivity and provide rich faradaic redox chemical reactions. Moreover, the density functional theory (DFT) calculations further indicate that the electronic properties and structure properties in NiCo₂S₄/MnO₂ electrode of reduction for 60 min (NiCo₂S₄/MnO₂-60) are effectively adjusted by introducing oxygen vacancies. Impressively, the NiCo₂S₄/MnO₂-60 electrode delivers substantially appreciable areal capacity of 2.13 mAh·cm^-2 couple with superior rate capability. The as-prepared high-performance electrode material can assemble into solid-state hybrid supercapacitor. The fabricated NiCo₂S₄/MnO₂-60//AC device exhibits an exceptional energy density of 43.16 Wh·kg^-1 at a power density of 384.21 W·kg^-1 and satisfactory cyclic stability of 92.1 % at current density of 10 mA·cm^-2 after 10,000 cycles. In general, the work demonstrates the significance of NiCo₂S₄/MnO₂-60 as a highly redox active electrode material for future practical application in supercapacitors.

Effective drug combinations of betulinic acid and ceranib-2 loaded Zn:MnO2 doped-polymeric nanocarriers against PC-3 prostate cancer cells

The development of theranostic nanocarriers with synergistic drug combinations has received considerable attention due to their improved pharmaceutical activity. Herein, we reported an investigation about the in-vitro anticancer activity of ceranib-2 (Cer), betulinic acid (BA), and the combination of betulinic acid and ceranib-2 (BA-Cer) against PC-3 prostate cancer cells. For this purpose, first we designed a suitable nanocarrier using a novel Zn:MnO₂ nanocomposite (NCs) and gallic acid (GA)-polylactic acid (PLA)-Alginate polymeric shell with nanoscale particle size and good stability. Chemical statements, morphology, and physicochemical properties of the nanocarrier have been illuminated with advanced characterization techniques. According to the transmission electron microscopy (TEM) results, Zn:MnO₂ NCs had a spherical and monodispersed morphology with a 2.03 ± 0.67 nm diameter. Moreover, vibrating-sample magnetometer (VSM) results showed that Zn:MnO₂ had paramagnetic properties with a saturation magnetization (Ms) value of 1.136 emu/g. Additionally, the in-vitro cytotoxic effects of the single and binary drugs loaded Zn:MnO₂-doped polymeric nanocarriers against PC-3 prostate cancer cells were investigated. According to the results, there was no significant cytotoxic effect of free BA and Cer against PC-3 prostate cancer cells. However, BA/Zn:MnO₂@GA-PLA-Alginate NCs, BA-Cer/Zn:MnO₂ @GA-PLA-Alginate NCs and free BA-Cer had IC₅₀ values of 6.498, 7.351, and 18.571 μg/mL, respectively. Consequently, BA-Cer/Zn:MnO₂@GA-PLA-Alginate is a nanocarrier with good stability, enhanced drug loading and release capacity for hydrophobic drugs, as well as being used as both imaging and treatment agent due to its magnetic properties. Furthermore, BA and Cer drug combination showed great promise in prostate cancer therapy which is known to be resulted high drug resistance. We strongly believed that this work could lead to an investigation of the molecular mechanisms of BA-mediated cancer theapy.