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1.
ACS Appl Mater Interfaces ; 16(8): 10009-10018, 2024 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-38376956

RESUMO

Although aqueous zinc batteries have attracted extensive interest, they are limited by relatively low rate capabilities and poor cyclic stability of cathodes. The crystal orientation of the cathode is one important factor influencing electrochemical properties. However, it has rarely been investigated. Herein, VO2 cathodes with different crystal orientations are developed via tuning the number of hydroxyl groups in polyol, such as using glycerol, erythritol, xylitol, or mannitol. The polyols serve as a reductant as well as a structure-directing agent through a hydrothermal reaction. Xylitol-derived VO2 shows a (110)-orientated crystalline structure and ultrathin nanosheet morphology. Such features greatly enhance the pseudocapacitance to 76.1% at a scan rate of 1.0 mV s-1, which is significantly larger than that (61.6%) of the (001)-oriented VO2 derived from glycerol. The corresponding aqueous zinc batteries exhibit a high energy storage performance with a reversible specific capacity of 317 mAh g-1 at 0.5 A g-1, rate ability of 220 mAh g-1 at 10 A g-1, and capacity retention of 81.0% at 10 A g-1 over 2000 cycles. This work demonstrates a facile method for tailoring VO2 crystal orientations, offers an understanding of the Zn2+ storage mechanism upon different VO2 facets, and provides a novel method to develop cathode materials toward advanced aqueous zinc batteries.

2.
Nanomicro Lett ; 15(1): 126, 2023 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-37209237

RESUMO

Rechargeable aqueous zinc iodine (ZnǀǀI2) batteries have been promising energy storage technologies due to low-cost position and constitutional safety of zinc anode, iodine cathode and aqueous electrolytes. Whereas, on one hand, the low-fraction utilization of electrochemically inert host causes severe shuttle of soluble polyiodides, deficient iodine utilization and sluggish reaction kinetics. On the other hand, the usage of high mass polar electrocatalysts occupies mass and volume of electrode materials and sacrifices device-level energy density. Here, we propose a "confinement-catalysis" host composed of Fe single atom catalyst embedding inside ordered mesoporous carbon host, which can effectively confine and catalytically convert I2/I- couple and polyiodide intermediates. Consequently, the cathode enables the high capacity of 188.2 mAh g-1 at 0.3 A g-1, excellent rate capability with a capacity of 139.6 mAh g-1 delivered at high current density of 15 A g-1 and ultra-long cyclic stability over 50,000 cycles with 80.5% initial capacity retained under high iodine loading of 76.72 wt%. Furthermore, the electrocatalytic host can also accelerate the [Formula: see text] conversion. The greatly improved electrochemical performance originates from the modulation of physicochemical confinement and the decrease of energy barrier for reversible I-/I2 and I2/I+ couples, and polyiodide intermediates conversions.

3.
J Colloid Interface Sci ; 631(Pt B): 269-280, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36403382

RESUMO

AgI/g-C3N4 S-scheme heterojunction with a unique electron transfer pathway was developed as a catalyst for H2 evolution. We discussed the behavior of chemisorption and photoexcited charge carriers in photocatalytic reduction on the S-scheme AgI/g-C3N4 heterojunction. It was demonstrated that the path of charge transfer mediated by S-scheme AgI/g-C3N4 heterojunction was favorable for the improvement of electron utilization in photocatalysis. The advantage of S-scheme heterojunction was that the holes in the valence band (VB) of g-C3N4 could recombine with the electrons in the conduction band (CB) of AgI due to the built-in electric field. Electrons on the CB of g-C3N4 and holes on the VB of AgI were preserved for further photocatalytic reaction. Therefore, a distinctive electron transfer pathway was introduced in the S-scheme heterojunction. In addition, the lifetime of charge carriers was prolonged, and the reduced ability of electrons was increased as compared to reference g-C3N4. It not only decreased the energy required for electron excitation, but also reduced the energy consumption for the charge transfer. This paper provided a new strategy to improve the utilization of photogenerated electrons and chemisorption of water for photocatalytic H2O splitting.

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