Fabrication of Self-Assembled Graphene Oxide Film and Its Application in Aqueous Zinc Metal Batteries.

Fabrication of well-dispersed thin graphene oxide (GO) films (GOFs) has always been a challenge. Herein, a quick preparation method for GOFs was developed using our homemade GO with a large lateral size. The film can be prepared in less than 2 h via a metal framework-induced self-assembly process. The thickness of the films can be as thin as ∼15.5 µm, which will be thinner with compression. When it is used as a flexible modification layer on the Zn metal for aqueous Zn-ion batteries, Zn can grow along the [010] direction in plane and stack orderly along the [002] direction even on the Cu substrate with GOF through epitaxial plating owing to negligible lattice mismatch between the (002) plane of Zn and the hexagonal ring [also (002) plane for graphite] of GO. Meanwhile, the rich O groups on the GO film can provide abundant zincophilic points and promote uniform distribution of Zn2+ around the anode. Finally, dendrite-free and dense Zn stripping/plating can be achieved and well remained. The GOF@Zn symmetric cell reveals long cyclic stability of 1300 h at 1 mA cm-2 and 1 mA h cm-2. It still can remain at 350 h even at a very high current density of 10 mA cm-2 accompanied by a high areal capacity of 10 mA h cm-2. With the same plating amount of 5 mA h cm-2, the thickness of the plated Zn is only ∼10 µm with GOF modification, very close to the theoretical value of 8.54 µm, much thinner than that without GOF (∼18 µm), indicating very dense deposition. Full cells assembled with the GOF@Zn anode and the MnO2 cathode exhibit a capacity retention rate of 71% over 1000 cycles at 0.7 A g-1, showing much better cycling performance than that using bare Zn.

Achievement of Efficient and Stable Nonflow Zinc-Bromine Batteries Assisted by Rational Decoration upon the Two Electrodes.

Aqueous zinc-bromine batteries (ZBBs) are highly promising because of the advantages of safety and cost. Compared with flow ZBBs, static ones without the assistance of pumping and tank components possess decreased cost and increased energy density and efficiency. Yet, the issues of Zn dendrites and shuttle effect of polybromide ions (Brn-) are more serious in nonflow ZBBs. Meanwhile, the hydrogen evolution reaction (HER) and the sluggish kinetics of the Br2/Br- couple are also in-negligible. Herein, a compressive approach, the cation-exchange membrane (CEM) coating on Zn anodes and N-defect decoration toward carbon felt cathodes, is developed. The CEM with cation-only function can inhibit the formation of Zn dendrites via tuning the Zn2+ flow at the interface, block the noncationic substances, and hence prevent the shuttle of Br2/Brn- and the water decomposition-concerned HER. The optimized nonflow ZBBs can deliver high Coulombic, voltage, and energy efficiencies of 94.1, 92.8, and 87.4%, respectively, which can be well remained in 1000 cycles. Meanwhile, the output voltage is as high as 1.7 V at 10 mA cm-2 with a high areal capacity of 2 mA h cm-2, and a LED with a rated voltage of 1.6 V can be powered successfully, exhibiting high application value.

Construction of Cation-Sieving Function Layers Enabling Dendrite-Free Zinc Metal Anodes for Durable Aqueous Systems.

Rechargeable aqueous zinc-ion batteries are considered as promising candidates for safe and green energy storage. Yet, Zn anodes still suffer from serious challenges. Herein, an effective cation-sieve of polyethersulfone-modified sulfonated polyether ether ketone is developed as protective coating layer of the Zn anodes. Cation-only transmission and dense property of the layer can protect the Zn from active water and anions, inhibiting corrosion, hydrogen evolution reaction (HER), and passivation. Zincophilic property of the layer can homogenize Zn2+ flow, and promote uniform plating of Zn. Therefore, protected symmetric Zn||Zn cell can maintain as long as 5600 h with a low polarization at 1.0 mA cm-2 and 0.5 mAh cm-2 , and still long as 800 h at 5.0 mA cm-2 and 5.0 mAh cm-2 . It is found that not only the dendrites but also the popular existed passivation product of Zn4 SO4 (OH)6 ·5H2 O can be inhibited effectively. In asymmetric Zn||Ti cells, average Coulombic efficiency can reach 98.2%, suggesting corrosion and HER are restrained effectively. Matched with MnO2 cathode, full cells using coated Zn exhibit much better cycling performance than that using bare Zn. Moreover, Zn4 O3 (SO4 )·7H2 O (ZSH)-assisted reversible conversion mechanism between the ZSH and Znx Hy MnO2 is revealed through operando Raman.

A 18ß-glycyrrhetinic acid conjugate with Vorinostat degrades HDAC3 and HDAC6 with improved antitumor effects.

Semisynthetic 18ß-glycyrrhetinic acid (GA) analogues bearing 1-en-2-cyano-3-oxo substitution on ring A have enhanced antitumor effects with reduced levels of HDAC3 and HDAC6 proteins. Aiming to inhibit both HDAC protein and activity, we developed a hybrid molecule by tethering active GA analogue methyl 2-cyano-3,11-dioxo-18ß-olean-1,12-dien-30-oate (CDODA-Me) and Vorinostat (SAHA). We tested the proper hybrid approaches of GA with hydroxamic acid and turned out that GA conjugated with SAHA by a piperazine linker was the best. The conjugate (15) of CDODA-Me and SAHA linked through a piperazine group was a potent cytotoxic agent against cancer cells with apoptosis induction. Compound 15 was more effective than the simple combination of CDODA-Me and SAHA to induce apoptosis. Mechanistic studies revealed that 15 was less effective than SAHA to inhibit HDAC activity, but was more effective than CDODA-Me to decrease the levels of HDAC3 and HDAC6 proteins with upregulated levels of acetylated H3 and acetylated α-tubulin. Compound 15 represents a new HDAC3 and HDAC6 inhibitor by reducing protein levels.