Mixed-valence metal−organic frameworks (MOFs) have exhibited unique potential in fields such as catalysis and gas separation. However, it is still an open challenge to prepare mixedvalence MOFs with isolated Ce(IV, III) arrays due to the easy formation of Ce III under the synthetic conditions for MOFs. Meanwhile, the performance of Li−S batteries is greatly limited by the fatal shuttle effect and the slow transmission rate of Li + caused by the inherent characteristics of sulfur species. Here, we report a mixed-valence cerium MOF, named CSUST-1 (CSUST stands for Changsha University of Science and Technology), with isolated Ce(IV, III) arrays and abundant oxygen vacancies (OVs), synthesized as guided by the facile and elaborate kinetic stability study of , to work as an efficient separator coating for circumventing both issues at the same time. Benefiting from the synergistic function of the Ce(IV, III) arrays (redox couples), the abundant OVs, and the open Ce sites within CSUST-1, the CSUST-1/CNT composite, as a separator coating material in the Li−S battery, can remarkably accelerate the redox kinetics of the polysulfides and the Li + transportation. Consequently, the Li−S cell with the CSUST-1/CNT-coated separator exhibited a high initial specific capacity of 1468 mA h/g at 0.1 C and maintained long-term stability for a capacity of 538 mA h/g after 1200 cycles at 2 C with a decay rate of only 0.037% per cycle. Even at a high sulfur loading of 8 mg/cm 2 , the cell with the CSUST/CNT-coated separator still demonstrated excellent performance with an initial areal capacity of 8.7 mA h/cm 2 at 0.1 C and retained the areal capacity of 6.1 mA h/cm 2 after 60 cycles.
Cerium (IV)-based metal-organic frameworks (MOFs) are highly desirable due to their unique potential in fields such as redox catalysis and photocatalysis. However, due to the high reduction potential of Ce IV species in solution, it is still a great challenge to synthesize Ce IV -MOFs with novel structures, which are extremely dominated by the hexanuclear CeÀ O cluster inorganic building units (IBUs). Herein, a CeÀ O IBU chain containing Ce IV -MOF, CSUST-3 (CSUST: Changsha University of Science and Technology), was successfully prepared using the kinetic stabilization study of UiO-66(Ce)-NDC (H 2 NDC = 2,6naphthalenedicarboxylic acid). Furthermore, owing to the superior redox activity, Lewis acidity and semiconductor-like behavior owing to Ce 4 + , activated CSUST-3 was demonstrated to be an excellent catalyst for CO 2 chemical fixation. One-pot synthesis of styrene carbonate from styrene and CO 2 was achieved under mild conditions (1 atm CO 2 , 80 °C, and solvent free). Moreover, activated CSUST-3 was shown to be a remarkable co-catalyst-free photocatalyst for overall water splitting (OWS), rendering 59 μmol g À 1 h À 1 of H 2 and 22 μmol g À 1 h À 1 of O 2 under simulated sunlight irradiation (Na 2 S-Na 2 SO 3 as sacrificial agent).
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