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Cerium, a unique rare earth element, possesses a relatively high abundance, low cost, and high redox voltage, making it an attractive candidate for redox flow batteries. However, the sluggish kinetics and corrosion nature of the Ce3+/Ce4+ electrolyte result in overpotential and degradation of carbon felt (CF) electrodes, which hinders the development of cerium‐based flow batteries. Therefore, it is essential to develop an electrode with high catalytic activity and corrosion resistance to the Ce3+/Ce4+ electrolyte. Herein, a TiC/TiO2 coated carbon felt (TiC/TiO2‐CF) electrode is proposed. Remarkably, the TiC/TiO2 coating effectively minimizes the exposure of the CF to the highly corrosive cerium electrolyte, consequently enhancing the electrode's corrosion resistance. Additionally, X‐ray photoelectron spectroscopy and high‐resolution transmission electron microscopy characterizations reveal the formation of a heterojunction between TiC and TiO2, which significantly enhances the redox reaction kinetics of the Ce3+/Ce4+ redox couple. Eventually, the practical application of TiC/TiO2‐CF catalytic electrode in a Ce–Fe flow battery is demonstrated. This study sheds light on the synthesis conditions of the TiC/TiO2‐CF electrode, elucidates its heterojunction structure, and presents a novel Ce–Fe flow battery system. [ABSTRACT FROM AUTHOR]

Highlights from the article: Keywords: high energy density; Na3V2(PO4)3; redox flow batteries; redox-targeting; sodium batteries In article number 1901188, Yong-Sheng Hu, Qing Wang and co-workers report a flow battery based on the redox-targeting reactions of methylphenothiazine and fluorenone with Na SB 3 sb V SB 2 sb (PO SB 4 sb ) SB 3 sb as the sole capacity booster in both cathodic and anodic compartments. High energy density, redox flow batteries, sodium batteries, Na3V2(PO4)3, redox-targeting.

Conventional water electrolyzer simultaneously generates H 2 and O 2 in neighboring electrode compartments which raises various issues by gas mixing. Thus, decoupled water electrolysis is desired to avoid the problems. Motivated by the above, spatially decoupled hydrogen evolution reaction (HER) is demonstrated in this work, leveraging a redox targeting-based flow battery employing iron triethanolamine (Fe(III)TEA)-K 2 MnO 4 redox couple. This system spatially separates HER from the electrode compartment. Sustained hydrogen is achieved by reaction between regenerated Fe(II)TEA and water in the negative electrolyte storage tank. The Faradaic efficiency of the decoupled HER is 70% and keeps stable upon prolonged operation. The onset overpotential of HER is 24 mV which is lower than previous studies. We anticipate the approach presented in this work would offer an alternative solution to water electrolysis for scalable and safe hydrogen production with improved gas purity. • Spatially decoupled hydrogen evolution is demonstrated by redox targeting concept. • It lowers the risk of H 2 /O 2 gas mixing in conventional water electrolysis. • Sustained hydrogen evolution is achieved under low overpotential. [ABSTRACT FROM AUTHOR]