Development of inexpensive, efficient, and stable nonprecious-metal-based bifunctional catalysts for oxygen reduction (ORR) and evolution (OER) reactions remains an enormous challenge. This work reports on an excellent bifunctional electrocatalyst consisting of ultrathin N-doped carbon (1–3 graphitic carbon layers) coated Fe1.2Co nanoparticles and N-doped carbon nanotubes (Fe1.2Co@NC/NCNTs). The Fe1.2Co@NC/NCNTs have an extremely low Fe/Co content (6.7 wt %), but with highly efficient and durable bifunctionality for ORR and OER. Specifically, the Fe1.2Co@NC/NCNT exhibits onset potential (E onset = 0.842 V vs RHE) and half-wave potential (E 1/2 = 0.82 V vs RHE) for ORR and onset potential of 1.43 V vs RHE and overpotential of 355 mV at 10 mA cm–2 for OER. The potential gap (ΔE) between E 1/2 of ORR and E OER at 10 mA cm–2 (E j=10) for the Fe1.2Co@NC/NCNTs is 0.765 V, which surpasses the commercial Pt/C and Ir/C catalysts and most state-of-the-art bifunctional catalysts previously reported. Most notably, when used in the Zn-air battery, the Fe1.2Co@NC/NCNT exhibits superior efficiency and durability to the Pt–Ir/C catalysts. This strongly suggests that the Fe1.2Co@NC/NCNT can be used as an efficient bifunctional catalyst with potential applications in the field of clean electrochemical energy storage and conversion technologies.

The aim of this work is to study the effect of reaction conditions using steamed ammonia liquid waste without the use of additives on the crystallization of calcium carbonate.

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The essential oil was obtained at yield of 0.30% by hydrodistillation from fresh leaf tissue of Solidago canadensis L. collected from Zhejiang Province, China. GC and GC/MS analysis identified 46 components, representing 94.6% of the leaf oil. The main components were (-)germacrene D (28.4%), bornyl acetate (9.2%), D-Limonene (5.0%). The essential oil was tested for cytotoxic activities against three tumor cell lines. The inhibitory concentrations of the essential oil at 50% effect level (IC50) were 68.1 μg/ml for SMMC-7721, 71.4 μg/ml for SGC-7901, and 156.9 μg/ml for Hala, respectively.