Flexible planar microsupercapacitors (MSCs) have become one of the most crucial energy storage devices for wearable and portable electronics on account of the superiorities of miniature size and easy integration with on-chip electronics. Under this background, we creatively design a versatile and facile strategy for in situ fabrication of flexible shape-controllable, planar microsupercapacitors based on Co 3 O 4 -decorated laserinduced graphene (LIG) on various substrates. This laser direct writing (LDW) patterning technique with advantages of simplicity, convenience, and low budget is applicable to customized polyimide films containing metal heterogeneous precursors coated on different flexible substrates to in situ generate metal oxide nanoparticles embedded in LIG patterning electrodes. These flexible designable-shaped, planar-integrated Co 3 O 4 /LIG MSCs exhibit excellent electrochemical performances, including high area-specific capacitances, excellent cycling stability, outstanding flexibility, and mechanical stability. Using this universal route, it can be proposed that flexible planar MSCs with desired shapes are fabricated on a variety of substrates for facilitating modular integration and biocompatibility to satisfy the requirements of microelectronics in the future.

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One of the key challenges of integrated energy storage devices is to develop a simple, low‐cost, and environmental‐friendly planar patterning technology. Herein, an ingenious and feasible laser‐engraved flash foam–assisted stamp technique of preparing flexible paper‐based planar‐integrated micro‐supercapacitors based on interdigital electrodes of self‐depositing electrochemically exfoliated graphene is proposed. The as‐synthesized flexible paper‐based planar‐integrated graphene micro‐supercapacitors exhibit excellent electrochemical performances with a remarkable area‐specific capacitance of 3.1 mF cm−2, and an excellent cycling stability in that capacitance retention reaches 95.8% even after 10 000 cycles. Furthermore, the paper‐based graphene micro‐supercapacitors are bent at different angles without significant electrochemical performance loss, and thus have outstanding mechanical flexibility. Therefore, such flexible paper‐based planar‐integrated graphene micro‐supercapacitors are expected to be applied in flexible wearable and portable electronics.

Oxygen reduction reaction (ORR) is an important half reaction in many renewable energy conversion and storage sources. The development of efficient, cost‐effective and durable non‐precious ORR catalysts with their catalytic efficiencies close to expensive Pt‐based catalysts is promising towards large‐scale practical applications of fuel cells and metal‐air batteries. Herein, we report a facile and scalable in‐situ synthesis of Fe3O4 nanoparticles supported on carbon nanotubes hybrid material using arc‐discharge method in low‐pressure air and use Fe3O4/CNTs hybrid as a highly efficient ORR electrocatalyst. The as‐synthesized Fe3O4/CNTs catalyst shows excellent ORR catalytic activity with its performance close to or even better than the commercial 20wt% Pt/C in alkaline media due to the synergistic effect between Fe3O4 and CNTs. This study provides a new insight into non‐precious metal ORR catalysts that are feasible in alkaline membrane fuel cells and metal‐air batteries.

A detailed study of the structural, electronic and absorption properties of crystalline L-serine-L-ascorbic acid (SAA) in the pressure range of 0-300 GPa was performed by density-functional theory (DFT) calculations in this work. Our results show that the compressible crystal of SAA is anisotropic. Furthermore, specific analysis of the variation tendencies of bond lengths and bond angles under different pressures show that the main structural transformations occur at pressures of 40, 50, 70, 100, 130 and 150 GPa, accompanied by repeated formations and disconnections of covalent bonds between O2(P1) and C2(P2) as well as C3(P1) and O1(P2), and a newly formed five-atom ring at 100 GPa. In addition, from 40 to 230 GPa, complex hydrogen bond transformations occur in SAA under compression, while from 240 to 300 GPa, the curve of lattice constants, bond lengths and bond angles of SAA barely changes, suggesting structural stability after 230 GPa. Then, by analyzing the band gap and density of states of SAA, it was found that the crystal undergoes a phase transformation from insulator to semiconductor at 150 GPa and it becomes more sensitive under compression. In addition, a relatively high optical activity with the pressure increases of SAA was seen from the absorption spectra, and two obvious changes of absorption coefficients were also observed at 50 GPa and 130 GPa, respectively, indicating that structural transformations occur here. Graphical abstract Structural formation and breaking of the five-atom ring O1(P2)-C2(P2)-O2(P1)-C2(P1)-C3(P1) with increasing pressure.