Electrochemical water splitting is of prime importance to green energy technology. Particularly, the reaction at the anode side, namely the oxygen evolution reaction (OER), requires a high overpotential associated with OO bond formation, which dominates the energy‐efficiency of the whole process. Activating the anionic redox chemistry of oxygen in metal oxides, which involves the formation of superoxo/peroxo‐like (O2)n−, commonly occurs in most highly active catalysts during the OER process. In this study, a highly active catalyst is designed: electrochemically delithiated LiNiO2, which facilitates the formation of superoxo/peroxo‐like (O2)n− species, i.e., NiOO*, for enhancing OER activity. The OER‐induced surface reconstruction builds an adaptive heterojunction, where NiOOH grows on delithiated LiNiO2 (delithiated‐LiNiO2/NiOOH). At this junction, the lithium vacancies within the delithiated LiNiO2 optimize the electronic structure of the surface NiOOH to form stable NiOO* species, which enables better OER activity. This finding provides new insight for designing highly active catalysts with stable superoxo‐like/peroxo‐like (O2)n− for water oxidation.

AbstarctThe thin film Li-ion batteries have been extensively used in micro-electronic devices due to their miniaturization, high capacity density and environmental friendliness, etc. In order to further prolong the lifetime of the film batteries, one of important tasks is to explore the aging mechanisms of the cathode films. In this paper, we especially focused on the multi-characterization of the LiCoO2 film in nanoscale, which is carried out by combining advanced AFM-based techniques with capacity measurement. The surface morphology, contact stiffness as well as surface potential were measured by amplitude modulation-frequency modulation (AM-FM) and kelvin probe force microscope (KPFM), respectively. Remarkable changes after different numbers of charge/discharge cycling were observed and the intrinsic reasons of them were discussed in detail. To acknowledge the relationship with these microscopic changes, the macro-capacity of the thin films was also measured by the galvanostatic charge/discharge method. These comprehensive results would provide a deep insight into the fading mechanism of the cathode film, being helpful for the design and selection of the cathode film materials for high performance batteries.

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A bio-inspired, amorphous-reinforced interfacial design and layer-by-layer assembly of synergistically interacting amorphous alumina nanosheets/polylactic acid (AAs/PLA) building blocks show a several-fold enhancement in PLA toughness and outstanding improvement in load-bearing capacity and viscoelastic figure of merit. This design strategy takes advantage of the efficient interactions between AAs and PLA adlayers and highly ordered lamellar arrangement, causing a toughening and strengthening mechanism. Such a framework will open a promising route to synthesize high-performance amorphous composites.