Zinc-Mediated Template Synthesis of Hierarchical Porous N-Doped Carbon Electrocatalysts for Efficient Oxygen Reduction.

The development of highly active and low-cost catalysts for use in oxygen reduction reaction (ORR) is crucial to many advanced and eco-friendly energy techniques. N-doped carbons are promising ORR catalysts. However, their performance is still limited. In this work, a zinc-mediated template synthesis strategy for the development of a highly active ORR catalyst with hierarchical porous structures was presented. The optimal catalyst exhibited high ORR performance in a 0.1 M KOH solution, with a half-wave potential of 0.89 V vs. RHE. Additionally, the catalyst exhibited excellent methanol tolerance and stability. After a 20,000 s continuous operation, no obvious performance decay was observed. When used as the air-electrode catalyst in a zinc-air battery (ZAB), it delivered an outstanding discharging performance, with peak power density and specific capacity as high as 196.3 mW cm-2 and 811.5 mAh gZn-1, respectively. Its high performance and stability endow it with potential in practical and commercial applications as a highly active ORR catalyst. Additionally, it is believed that the presented strategy can be applied to the rational design and fabrication of highly active and stable ORR catalysts for use in eco-friendly and future-oriented energy techniques.

Modification of biochar by phosphoric acid via wet pyrolysis and using it for adsorption of methylene blue.

Algae biochar (ABC), coconut shell biochar (CSBC), and coconut coat biochar (CCBC) were prepared by wet pyrolysis in a phosphoric acid solvent under normal pressure. Materials were characterized for their micromorphology, specific surface area, and surface functional groups by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) nitrogen adsorption-desorption spectrum technique and Fourier transform infrared diffraction (FT-IR). The evaluation of the liquid-phase adsorption performance using methylene blue (MB) as a pigment model, and the effects of temperature, pH, adsorbent dosage, and pollutant concentration of the MB adsorption onto modified biochars were fully investigated. The adsorption mechanism was proposed based on the adsorption kinetics curve and adsorption isotherm. The synthetic biochar showed great adsorption properties toward cationic dyes rather than anionic dyes. Specifically, the adsorption abilities for algal biochar, coconut shell biochar, and coconut coat biochar were determined to be 97.5%, 95.4% and 21.2%, respectively. The isothermal adsorption of MB by the three kinds of biochar conformed to the Langmuir equation, and the adsorption process fitted to the quasi-second-order kinetic equation, which suggested that ABC and CSBC effectively adsorbed MB dye molecules through hydrogen bonding, π-π stacking, and electrostatic interactions.

Removal of methyl orange from water by Fenton oxidation of magnetic coconut-clothed biochar.

Water pollution has become a serious environmental problem to date. Advanced oxidation processes (AOP) have been widely applied in water treatments. However, the traditional Fenton reaction based on the Fe2+-H2O2 system has obvious drawbacks, limiting further practical applications. In this work, an Fe3O4 and nano-clothed biochar (Fe3O4/CBc) composite was prepared through a precipitation method and used for the degradation of methyl orange (MO) in water. The Fe3O4/CBc composite was characterized by FTIR, BET, SEM, TEM, XRD, and VSM. In addition, the adsorption/catalytic oxidation of MO were also tested. Specifically, Fe3O4/CBc had a rough surface, abundant porous structure, high surface area of 835.82 m2 g-1, and obvious magnetization. The catalyst showed rather high performance towards MO removal. The optimal conditions for MO removal were as follows: the dosage of hydrogen peroxide was 16 mmol L-1, pH = 3, the temperature was 35 °C, and the addition amount of adsorbent was 10 mg. Under optimal conditions, the MO removal rate can be higher than 99%. The synergistic effect between catalytic degradation and adsorption in removing MO was also observed. Besides high performance in removing MO, Fe3O4/CBc also exhibited high stability, easy magnetic separation, and great reusability, as well as the potential to be developed as a new heterogeneous Fenton catalyst.

Rechargeable Zinc-Air Battery with Ultrahigh Power Density Based on Uniform N, Co Codoped Carbon Nanospheres.

Highly efficient catalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key to the commercialization of rechargeable zinc-air batteries (ZABs). In this work, a catalyst with uniform nanospherical morphology was prepared from cobalt nitrate, acetylacetone, and hydrazine hydrate. The final catalyst possesses high ORR and OER performances, with a half-wave potential of 0.911 V [vs reversible hydrogen electrode (RHE)] for ORR and a low potential of 1.57 V (vs RHE) at 10 mA cm-2 for OER in 0.1 M KOH solution. Specially, a ZAB based on the catalyst demonstrates an ultrahigh power density of 479.1 mW cm-2, as well as excellent stability, and potential in practical applications.

Fog-like fluffy structured N-doped carbon with a superior oxygen reduction reaction performance to a commercial Pt/C catalyst.

A high-performance N-doped carbon catalyst with a fog-like, fluffy structure was prepared through pyrolyzing a mixture of polyacrylonitrile, melamine and iron chloride. The catalyst exhibits an excellent oxygen reduction reaction (ORR) performance, with a half-wave potential 27 mV more positive than that of a commercial Pt/C catalyst (-0.120 vs. -0.147 V) and a higher diffusion-limiting current density than that of Pt/C (5.60 vs. 5.33 mA cm(-2)) in an alkaline medium. Moreover, it also shows outstanding methanol tolerance, remarkable stability and nearly 100% selectivity for the four-electron ORR process. To our knowledge, it is one of the most active doped carbon ORR catalysts in alkaline media to date. By comparing catalysts derived from precursors containing different amounts of melamine, we found that the added melamine not only gives the catalyst a fluffy structure but also modifies the N content and the distribution of N species in the catalyst, which we believe to be the origins for the catalyst's excellent ORR performance.

2-(3-Oxo-2,3-dihydro-1,2-benzothia-zol-2-yl)acetic acid.

In the title compound, C(9)H(7)NO(3)S, the benzoisothia-zolone ring system is essentially planar, with a maximum deviation of 0.013 (2) Å. In the crystal, mol-ecules are linked via O-H⋯O hydrogen bonds, forming chains along [010]. In addition, weak inter-molecular C-H⋯O hydrogen bonds are present.

Ethyl 3-oxo-2,3-dihydro-1,2-benzothia-zole-2-carboxyl-ate.

The title compound, C(10)H(9)NO(3)S, was synthesized by the reaction of benzo[d]isothia-zol-3(2H)-one with ethyl carbonochloridate in toluol. The benzisothia-zolone ring system is approximately planar, with a maximum deviation from the mean plane of 0.020 (1) Šfor the N atom.

Propyl 3-oxo-2,3-dihydro-1,2-benzothia-zole-2-carboxyl-ate.

The title compound, C(11)H(11)NO(3)S, was synthesized by the reaction of benzo[d]isothia-zol-3(2H)-one with propyl carbono-chloridate in toluene. The benzoisothiazolone ring system is approximately planar with a maximum deviation from the mean plane of 0.0226 (14) Šfor the N atom. Weak inter-molecular C-H⋯O hydrogen bonding occurs in the crystal structure.