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A series of metal‐free imidazole‐benzimidazole catalysts (ImBenz‐H, ImBenz‐NO2, ImBenz‐OCH3) for oxygen reduction reaction (ORR) were prepared. We demonstrate that the electrocatalytic O2 reduction by ImBenz‐NO2 with the electron‐withdrawing group showed high selectivity toward H2O with the number of electrons transferred (n=3.7) in a neutral aqueous solution. The highest ORR selectivity toward H2O2 was achieved using ImBenz‐H (n=2.4) in an alkaline solution. Electrochemical studies of reaction kinetics disclosed that the highest turnover frequencies were obtained from ImBenz‐H in both neutral and alkaline aqueous solutions. The results prove that the ORR selectivity is tunable by modulating the substituent of the ImBenz catalysts. Furthermore, DFT calculations suggested that the ORR mechanism of ImBenz‐H involves the electron transfer from imidazole‐benzimidazole to O2 resulting in the formation of H2O2 which supports the redox active properties of the catalysts ImBenz. [ABSTRACT FROM AUTHOR]

Ensuring continuous and sustainable lithium supply requires the development of highly efficient separation processes such as LLE (liquid‐liquid extraction) for both primary sources and certain waste streams. In this work, 4‐phosphoryl pyrazolones are used in an efficient pH‐controlled stepwise separation of Li+ from Ca2+, Mg2+, Na+ and K+. The factors affecting LLE process, such as the substitution pattern of the extractant, diluent/water distribution, co‐ligand, pH, and speciation of the metal complexes involved, were systematically investigated. The maximum extraction efficiency of Li+ at pH 6.0 was 94 % when Mg2+ and Ca2+ were previously separated at pH<5.0, proving that the separation of these ions is possible by simply modulating the pH of the aqueous phase. Our study points a way to separation of lithium from acid brine or from spent lithium ion battery leaching solutions, which supports the future supply of lithium in a more environmentally friendly and sustainable manner. [ABSTRACT FROM AUTHOR]

Keywords: Ca/Mg/Li Separation; Di- and Trinuclear Complexes; Separation Science; pH-Regulated Receptors; 4-Phosphoryl Pyrazolone Ligands EN Ca/Mg/Li Separation Di- and Trinuclear Complexes Separation Science pH-Regulated Receptors 4-Phosphoryl Pyrazolone Ligands 1 1 1 03/15/23 20230320 NES 230320 B Receptors b . Ca/Mg/Li Separation, Di- and Trinuclear Complexes, Separation Science, pH-Regulated Receptors, 4-Phosphoryl Pyrazolone Ligands Frontispiece: Selective Separation of Lithium, Magnesium and Calcium using 4-Phosphoryl Pyrazolones as pH-Regulated Receptors. [Extracted from the article]