Evaluation of Quality Properties of Brown Tigernut (Cyperus esculentus L.) Tubers from Six Major Growing Regions of China: A New Source of Vegetable Oil and Starch.

Tigernut has been recognized as a promising resource for edible oil and starch. However, the research on the quality characteristics of tigernut from different regions is lagging behind, which limits the application of tigernut in food industry. Tigernut tubers were obtained from six major growing regions in China, and the physicochemical properties of their main components, oil and starch, were characterized. Tigernut tubers from Baoshan contained the most oil (30.12%), which contained the most ß-carotene (130.4 µg/100 g oil) due to high average annual temperature. Gas chromatography analysis and fingerprint analysis results indicated that tigernut oil (TNO) consists of seven fatty acids, of which oleic acid is the major component. Changchun TNO contained the least total tocopherols (6.04 mg/100 g oil) due to low average annual temperature. Tigernut tubers from Chifeng (CF) contained the most starch (34.85%) due to the large diurnal temperature range. Xingtai starch contained the most amylose (28.4%). Shijiazhuang starch showed the highest crystallinity (19.5%). Anyang starch had the highest pasting temperature (76.0°C). CF starch demonstrated superior freeze-thaw stability (syneresis: 50%) due to low mean annual precipitation. The results could be further applied to support tigernut industries and relevant researchers that looks for geographical origin discrimination and improvements on tigernut quality, with unique physicochemical and technological properties.

Spray Pyrolysis Regulated FeCo Alloy Anchoring on Nitrogen-Doped Carbon Hollow Spheres Boost the Performance of Zinc-Air Batteries.

Low-cost and high-efficiency non-precious metal-based oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional catalysts are the key to promoting the commercial application of metal-air batteries. Herein, a highly efficient catalyst of Fe0.18Co0.82 alloy anchoring on the nitrogen-doped porous carbon hollow sphere (FexCo1-x/N-C) is intelligently designed by spray pyrolysis (SP). The zinc in the SP-derived metal oxides and metal-organic framework volatilize at high temperature to construct a hierarchical porous structure with abundant defects and fully exposes the FeCo nanoparticles which uniformly anchor on the carbon substrate. In this structure, the coexistence of Fe0.18Co0.82 alloy and binary metal active sites (Fe-Nx/Co-Nx) guarantees the Fe0.2Co0.8/N-C catalyst exhibiting an excellent half-wave potential (E1/2 ═ 0.84 V) superior to 20% Pt/C for ORR and a suppressed overpotential (280 mV) than RuO2 for OER. Assembled rechargeable Zn-air battery (RZAB) demonstrates a promising specific capacity of 807.02 mAh g-1, peak power density of 159.08 mW cm-2 and durability without electrolyte circulation (550 h). This work proposes the design concept of utilizing an oxide core to in situ consume the porous carbon shell for anchoring metal active sites and construct defects, which benefits from spray pyrolysis in achieving precise control of the alloy structure and mass preparation.

Redox-Active Metal-Organic Frameworks with Three-Dimensional Lattice Containing the m-Tetrathiafulvalene-Tetrabenzoate.

Metal-organic frameworks (MOFs) constructed by tetrathiafulvalene-tetrabenzoate (H4TTFTB) have been widely studied in porous materials, while the studies of other TTFTB derivatives are rare. Herein, the meta derivative of the frequently used p-H4TTFTB ligand, m-H4TTFTB, and lanthanide (Ln) metal ions (Tb3+, Er3+, and Gd3+) were assembled into three novel MOFs. Compared with the reported porous Ln-TTFTB, the resulted three-dimensional frameworks, Ln-m-TTFTB ([Ln2(m-TTFTB)(m-H2TTFTB)0.5(HCOO)(DMF)]·2DMF·3H2O), possess a more dense stacking which leads to scarce porosity. The solid-state cyclic voltammetry studies revealed that these MOFs show similar redox activity with two reversible one-electron processes at 0.21 and 0.48 V (vs. Fc/Fc+). The results of magnetic properties suggested Dy-m-TTFTB and Er-m-TTFTB exhibit slow relaxation of the magnetization. Porosity was not found in these materials, which is probably due to the meta-configuration of the m-TTFTB ligand that seems to hinder the formation of pores. However, the m-TTFTB ligand has shown to be promising to construct redox-active or electrically conductive MOFs in future work.

Poly(ethylene glycol)-functionalized 3D covalent organic frameworks as solid-state polyelectrolytes.

Existing lithium-ion-conducting covalent organic frameworks (COFs) are mainly two-dimensional, in which the one-dimensional channels are difficult to completely and uniformly stack in the same direction, particularly in the case of powdered COFs, resulting in the hindrance of ion transport at the grain boundary or at the interface of the powder contact. In this contribution, poly(ethylene glycol) (PEG)-functionalized three-dimensional COFs with 3D channels were successfully constructed for ion conduction in different directions, which is conducive to reducing the grain boundary and interface contact resistance. Combined with the coupling behaviour between the PEG chain segments and Li-ions, the 3D COF incorporated with LiTFSI achieves a high ionic conductivity of 3.6 × 10-4 S cm-1 at 260 °C. The maximum operating temperature is higher than the boiling point of commercial organic electrolytes, indicating the excellent security of PEG-based COFs as Li-ion polyelectrolytes at high temperature.