Size dependent electrochemical properties of reduced graphite oxide

Direct Electrochemical Synthesis of Metal-Organic Frameworks: Cu3 (BTC)2 and Cu(TCPP) on Copper Thin films and Copper-Based Microstructures

Cu thin films and Cu2 O microstructures were partially converted to the Metal-Organic Frameworks (MOFs) Cu3 (BTC)2 or Cu(TCPP) using an electrochemical process with a higher control and at milder conditions compared to the traditional solvothermal MOF synthesis. Initially, either a Cu thin film was sputtered, or different kinds of Cu or Cu2 O microstructures were electrochemically deposited onto a conductive ITO glass substrate. Then, these Cu thin films or Cu-based microstructures were subsequently coated with a thin layer of either Cu3 (BTC)2 or Cu(TCPP) by controlled anodic dissolution of the Cu-based substrate at room temperature and in the presence of the desired organic linker molecules: 1,3,5-benzenetricarboxylic acid (BTC) or photoactive 4,4',4'',4'''-(Porphine-5,10,15,20-tetrayl) tetrakis(benzoic acid) (TCPP) in the electrolyte. An increase in size of the Cu micro cubes with exposed planes [100] of 38,7 % for the Cu2 O@Cu3 (BTC)2 and a 68,9 % increase for the Cu2 O@Cu(TCPP) was roughly estimated. Finally, XRD, Raman spectroscopy and UV-vis absorption spectroscopy were used to characterize the initial Cu films or Cu-based microstructures, and the obtained core-shell Cu2 O@Cu(BTC) and Cu2 O@Cu(TCPP) microstructures.

Dendrite Suppression Membranes for Rechargeable Zinc Batteries

Aqueous batteries with zinc metal anodes are promising alternatives to Li-ion batteries for grid storage because of their abundance and benefits in cost, safety, and nontoxicity. However, short cyclability due to zinc dendrite growth remains a major obstacle. Here, we report a cross-linked polyacrylonitrile (PAN)-based cation exchange membrane that is low cost and mechanically robust. Li₂S₃ reacts with PAN, simultaneously leading to cross-linking and formation of sulfur-containing functional groups. Hydrolysis of the membrane results in the formation of a membrane that achieves preferred cation transport and homogeneous ionic flux distribution. The separator is thin (30 μm-thick), almost 9 times stronger than hydrated Nafion, and made of low-cost materials. The membrane separator enables exceptionally long cyclability (>350 cycles) of Zn/Zn symmetric cells with low polarization and effective dendrite suppression. Our work demonstrates that the design of new separators is a fruitful pathway to enhancing the cyclability of aqueous batteries.

Electrochemical tuning of capacitive response of graphene oxide

The capacitance of graphene oxide can be maximized by precise control of the conditions of electrochemical reduction to balance the oxygen concentration and conductivity.