Chemical synthesis and super capacitance performance of novel CuO@Cu4O3/rGO/PANI nanocomposite electrode.

Copper oxide-based nanocomposites are promising electrode materials for high-performance supercapacitors due to their unique properties that aid electrolyte access and ion diffusion to the electrode surface. Herein, a facile and low-cost synthesis in situ strategy based on co-precipitation and incorporation processes of reduced graphene oxide (rGO), followed by in situ oxidative polymerization of aniline monomer has been reported. CuO@Cu4O3/rGO/PANI nanocomposite revealed the good distribution of CuO@Cu4O3 and rGO within the polymer matrix which allows improved electron transport and ion diffusion process. Galvanostatic charge-discharge (GCD) results displayed a higher specific capacitance value of 508 F g-1 for CuO@Cu4O3/rGO/PANI at 1.0 A g-1 in comparison to the pure CuO@Cu4O3 278 F g-1. CuO@Cu4O3/rGO/PANI displays an energy density of 23.95 W h kg-1 and power density of 374 W kg-1 at the current density of 1 A g-1 which is 1.8 times higher than that of CuO@Cu4O3 (13.125 W h kg-1) at the same current density. The retention of the electrode was 93% of its initial capacitance up to 5000 cycles at a scan rate of 100 mV s-1. The higher capacitance of the CuO@Cu4O3/rGO/PANI electrode was credited to the formation of a fibrous network structure and rapid ion diffusion paths through the nanocomposite matrix that resulted in enhanced surface-dependent electrochemical properties.

Evaluating the electrocatalytic activity of flower-like Co-MOF/CNT nanocomposites for methanol oxidation in basic electrolytes.

Efficient electrocatalysts, with high tolerance to methanol oxidation, good stability, and acceptable cost are the main requisites for promising direct methanol fuel cell (DMFC) electrode materials. This target can be achieved by the integration of different active materials with unique structures. In this work, a cobalt metal-organic framework (Co-MOF) flower structure was prepared by a hydrothermal method, and then a simple ultrasonication method was employed to anchor carbon nanotubes (CNTs) in between the MOF flower petals and fabricate a Co-MOF/CNT hybrid composite. Different ratios of CNTs were used in the composite preparations, namely 25, 50, and 75 wt% of the composite. The nanocomposites were entirely investigated using different characterization techniques, such as XRD, FTIR, SEM, TEM, and XPS. Comparative electrochemical measurements confirmed that due to the integration of highly conductive CNTs with the porous active fascinating structure of Co-MOF, Co-MOF/50% CNTs exhibited improved electrocatalytic activity with a current density of 35 mA cm-2 at a potential of 0.335 V and a scan rate of 50 mV s-1. The excellent electrochemical activity and stability could be due to the synergy between Co-MOF and the CNTs that conferred adequate active sites for methanol electro-oxidation and a lower equivalent series resistance, as revealed from the electrochemical impedance spectroscopy study. This study opens a new avenue to decrease the utilization of platinum and increase the methanol oxidation activity using low-cost catalysts.

Three-dimensional N-doped mesoporous carbon-MXene hybrid architecture for supercapacitor applications.

Hierarchical heterostructures of mesoporous carbon wrapped around MXene nanolayers, which combine a porous skeleton, two-dimensional nanosheet morphology, and hybrid characteristics, have attracted research attention as electrode materials for energy storage systems. Nevertheless, it remains a significant challenge to fabricate such structures due to a lack of control of material morphology with high pore accessibility for the mesostructured carbon layers. As a proof of concept, I report a novel layer-by-layer N-doped mesoporous carbon (NMC)MXene heterostructure through the interfacial self-assembly of exfoliated MXene nanosheets and block copolymer P123/melamine-formaldehyde resin micelles with subsequent calcination treatment. The incorporation of MXene layers in the carbon matrix not only creates a spacer to inhibit the MXene sheet restacking and high specific surface area, but it also renders composites with good conductivity and additional pseudo capacitance. The as-prepared electrode with NMC and MXene exhibits outstanding electrochemical performance, with a gravimetric capacitance of 393 F g-1 at 1 A g-1 in an aqueous electrolyte and remarkable cycling stability. More importantly, the proposed synthesis strategy highlights the benefit of using MXene as a buttress for organizing mesoporous carbon in novel architectures with the potential for energy storage application.

Synergy between iron oxide sites and nitrogen-doped carbon xerogel/diamond matrix for boosting the oxygen reduction reaction.

The innovative design and facile synthesis of efficient and stable electrocatalysts for the oxygen reduction reaction (ORR) are crucial in the field of fuel cells. Herein, the facile synthesis of an iron oxide@nitrogen-doped carbon diamond (FeO x @NCD) composite via an effective pyrolysis strategy is reported. The properties of this electrocatalyst, including a high density of active sites, nitrogen doping, accessible surface area, well dispersed pyramidal morphology of the iron oxide, and the porous structure of the carbon matrix, promote a highly active oxygen reduction reaction (ORR) performance. The electrocatalyst exhibits outstanding stability, with a half-wave potential of 0.692 V in alkaline solution (0.1 M KOH), as well as a limiting current density of -31.5 mA cm-2 at 0.17 V vs. RHE. This study highlights the benefits of hybridizing sp2 carbon xerogel and sp3 diamond carbon allotropes with iron oxide to boost the ORR activity. The proposed strategy opens up an avenue for designing advanced carbon-supported metal oxide catalysts that exhibit excellent electrocatalytic performance.

Design and Characterization of a Novel ZnO-Ag/Polypyrrole Core-Shell Nanocomposite for Water Bioremediation.

Incorporating nanostructured metal and metal oxide in a polymer matrix is a strategic way to develop a novel candidate for water bioremediation. In this study, under microwave irradiation, a ZnO-Ag/polypyrrole (PPy) nanocomposite with a core/shell structure was prepared by interfacial polymerization of pyrrole in the presence of ZnO nanoparticles and AgNO3 as an oxidant. The antimicrobial behavior of the ZnO-Ag core combined with the electrical properties of the conducting PPy shell created a special ZnO-Ag/PPy nanocomposite with inherent adsorption behavior and antimicrobial properties. More impressively, the as-prepared ZnO-Ag/PPy displayed enhanced adsorption of Cd2+ and PO43- ions in the mixed solution. At pH 8, it had overall removal efficiencies of 95% and 75% for Cd2+and PO43- ions, respectively. The Freundlich adsorption model, rather than the Langmuir adsorption model, better fits the adsorption isotherm results. The adsorption kinetics also followed the pseudo-second-order kinetic model. Additionally, the engineered nanocomposite demonstrated antifungal activity against different fungi, as well as remarkable antibacterial activity against Gram-negative and Gram-positive bacteria. The synergistic combination of crystallinity, coherence of the ZnO-Ag core in the PPy matrix, and the negative zeta potential all contribute to this nanocomposite's high efficiency. Our results have significant consequences in the wastewater bioremediation field using a simple operation process.

Controlled synthesis of mesoporous nitrogen-doped carbons with highly ordered two-dimensional hexagonal mesostructures and their chemical activation.

Ordered mesoporous nitrogen-doped carbon (OMNC) materials are considered as the most promising material for supercapacitors. In this study, a highly ordered two-dimensional (2D) hexagonal mesostructured polymer was synthesized through a facile assembly of triblock polymer micelles and phenol-melamine/formaldehyde resin via an organic-organic assembly process in aqueous solution. After calcination, the novel OMNC materials with 2D hexagonal mesostructures were obtained. By further KOH activation, the surface area and the porosity of the OMNC significantly improved, and the internal mesoporous structures were maintained. The activated OMNC-800A displayed a specific capacitance as high as 475.75 F g-1 at 0.5 A g-1 with an outstanding cycling stability (over 100% capacitance retention during 2000 cycling tests at 100 mV s-1). These results confirm that the tubular mesochannels inside the OMNC are very beneficial in providing an accessible path for diffusion of the electrolyte, thereby improving the specific capacitance of OMNC at a high current density.