Na–O2 batteries have been attracting attention owing to their intrinsically high theoretical energy density. Several Na–O2 systems can produce various discharge products with different electrochemical performances. For example, sodium superoxide (NaO2) batteries have a low overpotential, and sodium peroxide (Na2O2) batteries have a high capacity. Studies of Na2O2 batteries are relatively scarce, owing to the difficulty of forming pure Na2O2 discharge products. A pure Na2O2 battery system is highly desirable for fully exploring the formation and decomposition of Na2O2 in Na–O2 batteries and evaluating their potential. This model of a Na2O2 battery should also be compatible with in situ characterization. To this end, we constructed a simple rechargeable all-solid-state Na2O2 battery. Using a nanoporous gold film as the cathode and Na–β″-Al2O3 as a solid electrolyte, we assembled a Na–O2 battery that can produce and decompose Na2O2. The all-solid-state Na–O2 battery is a simple model for conducting in situ ambient-pressure x-ray photoelectron spectroscopy (APXPS) investigations. The battery can be cycled at a low overpotential (≈450 mV). Qualitative and quantitative analyses of the APXPS and Raman results demonstrated that Na2O2 was the main discharge product and its transformation occurred during the charge and discharge periods. The operando investigation of this type of all-solid-state Na2O2 battery can help in the comprehensive exploration of the potential of Na–O2 batteries.
Understanding the structure–activity relationship of surface lattice oxygen is critical but challenging to design efficient redox catalysts. This paper describes data‐driven redox activity descriptors on doped vanadium oxides combining density functional theory and interpretable machine learning. We corroborate that the p‐band center is the most crucial feature for the activity. Besides, some features from the coordination environment, including unoccupied d‐band center, s‐ and d‐band fillings, also play important roles in tuning the oxygen activity. Further analysis reveals that data‐driven descriptors could decode more information about electron transfer during the redox process. Based on the descriptors, we report that atomic Re‐ and W‐doping could inhibit over‐oxidation in the chemical looping oxidative dehydrogenation of propane, which is verified by subsequent experiments and calculations. This work sheds light on the structure–activity relationship of lattice oxygen for the rational design of redox catalysts.
Efficient rhodium-catalyzed
oxidative decarboxylation annulation
reactions between mandelic acids and alkyne derivatives are described.
The desired indenone products were obtained in medium to good yields
under the optimized reaction conditions, which were a [RhCp*Cl2]2 catalyst (10.0 mol %) in combination with a
PCy3 ligand (10.0 mol %) and AgSbF6 (10 mol
%) and Cu(OAc)2 (20 mol %) additives. Many functional groups
are compatible with the reaction under the optimized reaction conditions.
This strategy provides a promising method for the construction of
indenones from cheap and commercially available starting materials.
The rechargeable all-solid-state Na-O 2 battery is one of the most promising candidates for next-generation energy storage devices owing to its high theoretical specific energy, safety, electrochemical stability, and abundant Na resources. However, the practical implementation of current all-solidstate Na-O 2 batteries is still limited by low-resistance interfaces, low energy efficiency, and poor cycle life. Herein, an all-solid-state Na-O 2 /H 2 O battery that can sustain highly reversible cycling with a low overpotential is reported. Using a customized silver-polymer composite cathode, this battery can be operated under ≈7% relative humidity (RH) at 80 °C and cycled for more than 100 times with a low overpotential (≈75 mV at 100th cycle) and high round trip efficiency >97% at 100th cycle) at an energy density of 20 mA g −1 . Furthermore, mechanistic insight that the RH intimately controls the type and hydration state of the discharge product is also provided, and thereby the charge kinetics and battery performance are modulated. It is also revealed that silver catalyst can efficiently reduce the reaction barrier of NaOH decomposition. With the further optimization, this battery potentially can be implemented in real-world applications and confer practical applicability that can extend to other energy-storage systems, such as other metal-air batteries.
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