Enriched with oxygen vacancies, Mo-doped strontium cobaltite (SrCo Mo O , SCM) is synthesized as an oxygen anion-intercalated charge-storage material through the sol-gel method. The supplemented oxygen vacancies, good electrical conductivity, and high ion diffusion coefficient bestow the SCM electrode with excellent specific capacitance (1223.34 F g ) and specific capacity (168.88 mAh g ) at 1 A g . The decisive constant (b-value) deduced for the charge storage mechanism (low scan-rate region) is nearly 0.8, indicating a highly capacitive process. In the high scan-rate region, however, the b-value is almost 0.5, and a linear pattern of charge (q) versus the inverse of the square root of the scan rate (v ) is obtained. The results reveal O diffusion as the rate-limiting factor for charge storage. Furthermore, a hybrid cell (SCM∥LRGONR) is fabricated by using lacey, reduced graphene oxide nanoribbon (LRGONR) as the negative electrode, which exhibits a high energy density (74.8 Wh kg at a power density of 734.5 W kg ). With a charging time of only 20.7 s, the cell sustains a very high energy density (33 Wh kg ) with a high power delivery rate (6600 W kg ). The excellent cycling stability (165.1 % activated specific capacitance retention and 97.6 % of the maximum value attained) after 10 000 charge-discharge cycles, demonstrates SCM is a potential electrode material for supercapacitors.

Perovskite oxides are considered to be attractive catalysts for the electrocatalysis of water in an alkaline electrolyte. However, they suffer from low catalytic efficacy and stability that need to be further improved. Here we present a triple perovskite, Sr 3 NiFeMoO 9−δ (SNFM), as a promising oxygen evolution electrocatalyst with high durability that outperforms double and single perovskites. The high performance of the triple perovskite SNFM could be correlated to the high lattice oxygen participation observed via pHdependent oxygen evolution reaction (OER) activity on the reversible hydrogen electrode scale. Through the strong participation of the oxide lattice during O 2 evolution in SNFM, the kinetic limitation can be eliminated, as it occurs during the conventional adsorbate evolution mechanism. In addition to lattice oxygen participation, SNFM exhibits a low charge transfer resistance at different potentials, studied through operando electrochemical impedance spectroscopy, and a high oxygen diffusion rate that is related to its oxygen vacancy defects.

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A facile and rapid surfactant-free microwave-assisted route is developed to synthesize 10 nm sized NiO nanoflakes with high pseudocapacitive performance for supercapacitor cells. The NiO nanoflakes exhibit mesoporous channels and a surface area as high as 206 m 2 g −1 as revealed under BET study, while the structural identity verified by XRD and IR confirm the phase purity of NiO. NiO nanoflakes maintain ∼85% of their thermal stability at temperature 900 °C which can be related to strong intermolecular forces between the NiO nanoparticles held in the molecular matrix. Electrochemical performance investigated in 6 M KOH solution suggests maximum specific capacitance of 307 F g −1 for the NiO∥NiO cell at 0.5 A g −1 sustaining about 96% capacitance after being successfully cycled up to 3000 cycles. The NiO nanoflakes reveal high conductivity of 33.87 S cm −1 at room temperature. Precisely, nanosized NiO bearing "flake" morphology is of particular interest due to the high surface to volume aspect and porosity featuresthe determining factors for swift ion diffusion into an electrode and improved redox reaction. The illustrated microwave-assisted route unfolds as a direct synthesis method to obtain nanosized NiO flakes with high surface area facilitating excellent device performance characteristics without involving any surface-capping agents.