Activated Biocarbon from Paper Mill Sludge as Electrode Material for Supercapacitors: Comparative Performance Evaluation in Two Aqueous Electrolytes.

The valorization of a South African paper mill waste sludge into an activated biocarbon electrode material for energy storage application is reported. The valorization method is a two-step synthesis that comprises hydrothermal carbonization and NaOH activation of paper mill waste at 700 °C to produce activated biocarbon. The development of high porosity carbon material with a surface area of 1139 m2/g was observed. The synthesized biocarbon electrode exhibited good specific capacitance (C sp) values of 206 and 157 Fg-1, from a three-electrode cell in neutral (1 M Na2SO4) and alkali (3 M KOH) electrolytes, respectively. The electrolyte concentration purportedly has a considerable effect on specific capacitance. In both electrolytes, symmetric triangular curves in galvanostatic charge-discharge point to a quick charge-discharge process. Synthesized material testing with a two-electrode cell in 3 M KOH and 1 M Na2SO4 electrolytes, respectively, delivered specific capacitances of 125 and 152 Fg-1, with the corresponding energy densities of 17.4 and 21.1 Wh kg-1. The material had capacity retention efficiencies of 83 and 92% after 5000 cycles in 3 M KOH and 1 M Na2SO4 electrolytes, respectively. The electrode material performance of the activated biocarbon from paper sludge clearly shows its potential for electrochemical energy storage. The reported results present an exciting potential contribution of the pulp and paper industry toward the transition to green energy.

Synthesis, Characterization, and Supercapacitor Performance of a Mixed-Phase Mn-Doped MoS2 Nanoflower.

The fascinating features of 2D nanomaterials for various applications have prompted increasing research into single and few-layer metal dichalcogenides nanosheets using improved nanofabrication and characterization techniques. MoS2 has recently been intensively examined among layered metal dichalcogenides and other diverse transition metal-based materials, that have previously been studied in various applications. In this research, we report mixed-phase Mn-doped MoS2 nanoflowers for supercapacitor performance studies. The confirmation of the successfully prepared Mn-doped MoS2 nanoflowers was characterized by XRD, SEM-EDS, RAMAN, and BET research techniques. The mixed-phase of the as-synthesized electrode material was confirmed by the structural changes observed in the XRD and RAMAN studies. The surface area from the BET measurement was calculated to be 46.0628 m2/g, and the adsorption average pore size of the electrode material was 11.26607 nm. The electrochemical performance of the Mn-doped MoS2 electrode material showed a pseudo-capacitive behavior, with a specific capacitance of 70.37 Fg-1, and with a corresponding energy density of 3.14 Whkg-1 and a power density of 4346.35 Wkg-1. The performance of this metal-doped MoS2-based supercapacitor device can be attributed to its mixed phase, which requires further optimization in future works.

Green synthesis of silver nanoparticles using terrestrial fern (Gleichenia Pectinata (Willd.) C. Presl.): characterization and antimicrobial studies.

Novel silver nanoparticles from Gleichenia Pectinata (Willd.) C. Presl. was synthesized. A combination of spectroscopic and microscopic techniques were utilized to characterize the newly synthesized Gleichenia Pectinata Silver Nanoparticles (GPAgNPs) vis-à-vis UV-Vis Spectroscopy, Fourier Transform Infra-Red (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDX) and X-Ray Diffraction (XRD) Analyses. Significant absorption was observed at 460 nm resulting from the surface Plasmon resonance (SPR). A rapid rate of synthesis was observed and the best surface plasmon resonance was obtained at 105 minutes contact time. SEM and TEM showed an spherical shape of GPAgNPs with an average size of 7.51 nm. The XRD result revealed a crystalline and polydispersed GPAgNPs. GPAgNPs were effective against four antibiotic resistant pathogens and they exhibited excellent antimicrobial activity against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Candida albicans. GPAgNPs favorably competed with standard antibiotics. This therefore enlisted GPAgNPs as potential antimicrobial and therapeutic agents against multidrug resistant micro-organisms (MDRM).