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The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are cornerstone half reactions involved in many renewable energy technologies. High‐density single‐atom catalysts maximize the atom utilization and isolated active sites. Furthermore, introduction of pyri‐N into the carbon‐based nanostructures as an oxygen electrocatalyst creates an abundance of active sites. Here, an innovative strategy is reported based on atomic scale dispersion of Co atoms into the pyri‐N enriched carbon nanotube encapsulated Ni nanoparticles grown on 3D electrospun carbon nanofiber nano‐assemblies. Notably, the CoSANi‐NCNT/CNF electrocatalyst exhibited excellent OER and ORR activity in terms of low overpotentials and higher half‐wave potentials. The atomically distributed Co allows the maximum exposure of active sites on the pyri‐N dominated multidimensional carbon skeleton, and synergistic effects with Ni nanoparticles greatly reduced the delocalization around the metal centers and provided an ideal environment for interactions with oxygen intermediates, thus facilitating the 4e− pathway, as evidenced by the DFT calculations. Moreover, Zn‐air batteries using a CoSANi‐NCNT/CNF air cathode exhibited a high‐power density and admirable specific capacity. This studies may provide an avenue for the rational modulation of single‐atom catalysts and cost‐effective, large‐scale synthesis of bifunctional oxygen electrocatalysts for rechargeable Zn‐air batteries and anion exchange membrane fuel cell. [ABSTRACT FROM AUTHOR]

The electrocatalytic oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are the core reactions in reversible zinc-air batteries but are kinetically challenging because of their complex multielectron transfer process. In this case, the exploration and rational design of non-precious bifunctional oxygen electrocatalysts with dense active sites and optimized electronic structures can facilitate favorable 4e-transfer. In this study, we report a highly reversible bifunctional electrocatalyst for flexible Zn-air batteries featuring pyridinic-N exclusively enriched carbon-nanotube-encased nickel-iron (NiFe) interfacial alloy nanoparticles derived from an LDH template on knitted carbon fiber cloth. The NiFe nanoparticles were catalytically released from NiFe-MOFs to form CNT tentacles when pyrolyzed in an inert atmosphere. XPS and XAS studies revealed the dominant presence of pyridinic-N, which reduces electron localization around NiFe centers and improves the interaction with oxygenated species. As a result, NiFe-N-CNT-KCC catalysts exhibited a low operating overpotential (h10) of 173 mV for the OER and a half-wave potential (E1/2) of 0.87 V for the ORR, which are superior to benchmark electrocatalysts. As an air cathode for zinc-air batteries, the NiFe-N-CNT-KCC-based battery showed an excellent electrochemical performance, with an open circuit voltage (OCV) of 1.55 V, high power density of 153 mW cm-2, excellent specific capacity of 793.2 mA h g-1, and long-term stability. Impressively, a solidstate flexible zinc-air battery with the NiFe-N-CNT-KCC cathode showed an admirable rate performance and exceptional mechanical stability under arbitrary bending and twisting conditions, showing great potential for practical implementation in next-generation high-power and high-energydensity batteries wearable applications. [ABSTRACT FROM AUTHOR]

A functionally graded membrane (FGM) with a special spiral-structured cellulose acetate (CA) membrane was prepared by electrospinning under different collection distances. The membrane morphology was analyzed by scanning electron microscopy (SEM). FESEM images revealed that the high concentration shows the formation of fibers with an irregular diameter, with a large diameter distribution range. The fiber collected at a short distance of 10 cm experiences the strong electrostatic force, resulting in the short flight time for the polymer jet. This causes the bending instability of the polymer jet forming the comparatively thick fiber diameters, whereas the fiber collected at 15 cm shows the presence of a smooth, homogeneous diameter. Furthermore, the water flux of the membrane was determined using 50 mL of Amicon stirred cells. The fiber collected at different distances showed diameter variation, which is used to design a special spiral structure on the membrane by auto-moving the collector between the fixed distances of 10–20 cm. This technique will reveal a new approach for the fabrication of a special spiral structure on the nanofibrous membrane for different biomedical applications from different polymers. Meanwhile, the fabricated FGM with a special spiral-structure CA membrane demonstrates high water permeation flux. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ag@TiO 2 NFs were synthesized by solvothermal route followed by photoreduction method. • Antibacterial study was performed with Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) bacteria. • The Ag (2 wt%) @TiO 2 NFs has more antibacterial effect against both type of bacteria. Silver nanoparticles (Ag NPs) decorated Titanium dioxide nanoflakes (TiO2 NFs) were synthesized via solvothermal followed by photoreduction method. As synthesized TiO 2 NFs and Ag@TiO 2 NFs were characterized by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy. The impact of Ag@TiO 2 NFs as antibacterial agents against Gram positive Staphylococcus aureus and gram-negative Escherichia coli was investigated. The obtained results revealed that the Ag@TiO 2 NFs were potential antibacterial agents compared to TiO 2 NFs only. Moreover, among of various samples Ag (2 wt%) @TiO 2 NFs was more effective with compared to other samples. [ABSTRACT FROM AUTHOR]

We report a polyaniline-wrapped, manganese-doped titanium oxide (PANi/Mn-TiO2) nanoparticle composite for supercapacitor electrode and photocatalytic degradation. The PANi/Mn-TiO2 nanoparticles were synthesized using a solvothermal process, followed by oxidative polymerization of aniline. The structural properties of studied materials were confirmed by XRD, FTIR, HRTEM, FESEM, and UV visible spectroscopy. The as-prepared PANi/Mn-TiO2 nanoparticles revealed admirable electrochemical performance with a specific capacitance of 635.87 F g−1 at a current density of 1 A g−1 with a notable life cycle retention of 91% after 5000 charge/discharge cycles. Furthermore, the asymmetric cell with PANi/Mn-TiO2 as a positive electrode exhibited energy density of 18.66 W h kg−1 with excellent stability. Moreover, the PANi/Mn-TiO2 had promising photocatalytic activity for methylene blue degradation. The improved performance of PANi/Mn-TiO2 nanoparticles is attributed to the well-built synergetic effect of components that lead to significant reduction of band gap energy and charge transfer resistance, as revealed by UV visible spectroscopy and electrochemical impedance spectroscopy. [ABSTRACT FROM AUTHOR]

Environmental remedies, including adsorption-based water purification, are now being asked to meet the requirement for a low-carbon circular economy requiring low energy and low material consumption. In this regard, we tested the possibility of regenerating adsorbents via cold plasma (CP) treatment for less use of adsorbents and no washing solution. In the adsorption of methylene blue (MB) using carbonized rice husk (CRH) and five successive regeneration cycles by CP treatment, the removal efficiencies were maintained at a moderate level (∼70% of the initial performance), unlike five consecutive adsorption without CP treatment (∼9–13% of the initial performance). The regeneration of CRH by CP treatment was also double-checked by the FESEM, EDS, BET, FTIR, XPS, and surface zeta potential measurements. The successfully recovered adsorption capability is related to the remediation of adsorption sites. It is also worth noting that the required power consumption for recycling by CP treatment was about 6.4 times lower than carbonizing new rice husks. This work provides insights into recovering adsorbents using CP without rigorous, costly, and energy-intensive processes. [Display omitted] • Carbonized rice husk (CRH) was used for adsorption-based removal of dye molecules. • The adsorption kinetics was governed by the pseudo-second-order model. • Cold plasma (CP) treatment successfully regenerated the dye-adsorbed CRH. • CP treatment was workable for the five consecutive adsorption tests of the used CRH. • The regeneration mechanism was discussed in detail based on thorough analyses. [ABSTRACT FROM AUTHOR]