Benzoquinone (BQ) is considered to be a desirable cathode material for aqueous zinc-based batteries. The major limitations of BQ electrode are the severe sublimation and poor electrical conductivity, which results in serious mass loss during electrode preparation and inferior rate performance. In this study, iodine (I 2 ) species are utilized as an efficient catalyst for the highly reversible conversion of BQ/BQ 2− couple in the Zn-BQ battery system, wherein N-doped porous carbon is employed as a host material for anchoring the BQ molecule. In the combination electrode (denoted as BQ-I@NPC) with 1wt% I 2 additive where I 2 can serve as a carrier to accelerates the Zn 2+ transmission, and reduce the voltage hysteresis of the electrode. As a result, the BQ-I@NPC cathode delivers a high specific capacity of ≈482 mAh g −1 at 0.25 A g −1 , realizing a high energy density of 545 Wh kg −1 (based on BQ), which is the highest values among reported organic cathode materials for aqueous Zn-based batteries. Also, a high BQ loading (8 mg cm −2 ) can be attained, and achieving a superior cycling stability with a capacity retention of ≈80% after 20,000 times at 10 C. The work proposes an effective approach toward high performance organic electrode materials.
The I2-catalyzed reaction of 1-(2-hydroxyphenyl)-propargyl alcohols with indoles and subsequent treatment with K2CO3 provided (benzofuran-3-yl)-1H-indoles in good to excellent yields with high regioselectivity. This one-pot and two-step strategy proved to be suitable for a wide range of substrates except for aliphatic alkynyl alcohols as well as the indoles bearing N-protected groups such as the Ts group possessing strong electron-withdrawing feature. The reaction procedure involved a cross-coupling and the construction of a benzofuran framework via 5-exo-dig cyclization.
Graphical A metal-free aerobic oxidative C–H sulfenylation of aryl-fused cyclic amines with various thiols was developed with excellent functional compatibility. While flavin I catalyzed the C–H sulfenylation of indolines to afford 3-sulfenylindoles, flavin II enabled transformations resulting in substitution at the position para to the N atom on the aryl ring to obtain 6-sulfenylquinolines. We report an aerobic oxidative C–H sulfenylation of aryl-fused cyclic amines with various thiols catalyzed by flavin/I 2 for the first time. While flavin I catalyzed the C–H sulfenylation of indolines to afford 3-sulfenylindoles, flavin II enabled transformations resulted in substitution at the position para to the N atom on the aryl ring to obtain 6-sulfenylquinolines. The advantages of this metal-free oxidative C–S coupling approach utilizing ambient oxygen as the terminal oxidant were that it was conducted under mild conditions with good atom-efficiency and excellent functional compatibility.
The vaporization-condensation-conversion method is the prominent technique used for synthesizing red phosphorus/carbon (P/C) composites. However, its practical application is limited by the inevitable formation of toxic white phosphorus (WP) residues, posing severe safety concerns. Theoretical calculations of the WP polymerization process performed in this study revealed that the introduction of iodine can considerably accelerate the polymerization of WP molecules, yielding P/C composites free of WP residues. Furthermore, in the resulting iodine-doped P/C (I-P/C) composites, iodine forms I-P bonds, considerably enhancing electronic conductivity and promoting faster Na-P redox kinetics compared to those in the original P/C composites. Consequently, an I-P/C electrode exhibited a capacity of 1193 mA h g⁻ 1 , retaining 100 % of its capacity after 100 cycles at 0.2 A g⁻ 1 . Furthermore, an assembled I-P/C||Na 3 V 2 (PO 4 ) 2 F 3 full cell retained 91.9 % of its capacity after 200 cycles at 0.5 A g⁻ 1 . Additionally, the full cell exhibited a high energy density of 132.2 W h kg⁻ 1 at a power density of 9942.1 W kg⁻ 1 , demonstrating potential to complete charging or discharging within ∼57 s. Finally, an I-P/C||Na 3 V 2 (PO 4 ) 2 F 3 pouch cell, with a capacity of 0.36 A h, demonstrated excellent cycling performance even after 150 cycles at 0.05 A g⁻ 1 .
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