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This mini‐review summarises and discusses recent findings form the literature on the degradation of carbon‐based electrodes for vanadium redox flow batteries (VRFBs). It becomes evident that the focus of current investigations is on carbon paper, carbon felt and graphite felt electrodes, which is understandable from a practical point of view. However, the structural complexity of these materials often prohibits doubtless attribution of observed performance reduction (or increase) to changes in the electrode materials. Among the discussed major causes for degradation are formation or change of surface functional groups, changes in the carbon sp2/sp3 ratio, intercalation of ions as well as formation of inhibiting adsorbates. In order to gain deeper insight into the changes of carbon electrodes in VRFBs under relevant operation conditions, the authors suggest reducing complexity of the investigated materials and applying in situ‐studies under well‐defined and controllable conditions on model electrodes. These studies then should be extended towards more practical systems and may finally help to reduce degradation phenomena including enhanced overvoltages and thus could improve cycling and energy efficiency as well as long‐term stability of vanadium redox flow batteries. [ABSTRACT FROM AUTHOR]

Functionalization of nanocarbon materials with heteroatoms is of paramount interest as doping of carbon with electron withdrawing groups results in change of electrochemical properties of the potential catalyst. Adding fluorine, as the most electronegative element into the doping process next to boron is expected to have significant effect on the design of novel nanocarbon‐based electrocatalysts. In this paper boron and fluorine co‐doped reduced graphene oxide/few‐walled carbon nanotube (BF‐rGO/FWCNT) catalysts are synthesized via simple and low‐cost direct pyrolysis method using boron trifluoride diethyl etherate (BTDE). Composition analysis confirmed that boron and fluorine have been grafted onto the carbon support. Rotating disk electrode (RDE) measurements revealed that BF‐rGO/FWCNT has remarkable electrocatalytic activity toward the oxygen reduction reaction (ORR) both in alkaline and acid media. The onset potential of the best BF‐rGO/FWCNT catalyst was 50 mV more positive in alkaline and 600 mV more positive in acidic media compared with un‐doped rGO/FWCNT. The half‐wave potential was 100 mV more positive in alkaline media and 700 mV more positive in acidic media in comparison with un‐doped rGO/FWCNT. [ABSTRACT FROM AUTHOR]

Cu thin films and Cu2O 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 Cu2O 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 Cu2O@Cu3(BTC)2 and a 68,9 % increase for the Cu2O@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 Cu2O@Cu(BTC) and Cu2O@Cu(TCPP) microstructures. [ABSTRACT FROM AUTHOR]