Flexible all-solid-state supercapacitors are fabricated with liquid-exfoliated black-phosphorus (BP) nanoflakes as an electrode material. These devices deliver high specific volumetric capacitance, power density, and energy density, up to 13.75 F cm(-3) , 8.83 W cm(-3) , and 2.47 mW h cm(-3) , respectively, and an outstanding long life span of over 30 000 cycles, demonstrating the excellent performance of the BP nanoflakes as a flexible electrode material in electrochemical energy-storage devices.

Black phosphorous (BP) is a unique layered p-type semiconducting material. The successful use of BP nanosheets in fi eld-effect transistors fueled research on BP atomic layers that focuses on, e.g., the exploration of their optical and electronic properties, and promising applications in (opto)electronics. However, BP fi lms are prone to degradation in ambient conditions, which prevents their commercial application. Here, a route to the application of BP fi lms as an environmental stable nonvolatile resistive random access memory is presented. The BP fi lms, which are prepared from exfoliated BP nanosheets in selected solvents, show solvent-dependent degradation upon ambient exposure, inducing the formation of an amorphous top degraded layer (TDL). The TDL acts as an insulating barrier just below the Al electrode. This property that was only obtained by degradation, confers a bipolar resistive switching behavior with a high ON/OFF current ratio up to ~3 × 10 5 and excellent retention ability over 10 5 s to the fl exible BP memory devices. The TDL also prevents propagation of degradation further into the fi lm, ensuring excellent memory performance even after three month of ambient exposure.

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Black phosphorus (BP) has drawn great attention owing to its tunable band gap depending on thickness, high mobility, and large I/ I ratio, which makes BP attractive for using in future two-dimensional electronic and optoelectronic devices. However, its instability under ambient conditions poses challenge to the research and limits its practical applications. In this work, we present a feasible approach to suppress the degradation of BP by sulfur (S) doping. The fabricated S-doped BP few-layer field-effect transistors (FETs) show more stable transistor performance under ambient conditions. After exposing to air for 21 days, the charge-carrier mobility of a representative S-doped BP FETs device decreases from 607 to 470 cm V s (remained as high as 77.4%) under ambient conditions and a large I/ I ratio of ∼10 is still retained. The atomic force microscopy analysis, including surface morphology, thickness, and roughness, also indicates the lower degradation rate of S-doped BP compared to BP. First-principles calculations show that the dopant S atom energetically prefers to chemisorb on the BP surface in a dangling form and the enhanced stability of S-doped BP can be ascribed to the downshift of the conduction band minimum of BP below the redox potential of O/O. Our work suggests that S doping is an effective way to enhance the stability of black phosphorus.

In this work, self‐supporting three‐dimensional hierarchical nanostructured MoS2@Ni(OH)2 nanocomposites are synthesized via a facile single‐mode microwave hydrothermal technique. The fabricated MoS2@Ni(OH)2 nanocomposites for supercapacitors in aqueous electrolyte exhibit higher specific capacitance and better cyclic stability than those of MoS2 and Ni(OH)2 due to the pronounced synergistic effect between MoS2 and Ni(OH)2. Further, the flexible all‐solid‐state supercapcitor is readily constructed by composing the PVA/KOH gel electrolyte in between two MoS2@Ni(OH)2 electrodes on the flexible PET substrates. The resulting supercapacitors can operate at high rate up to 1000 V/s, have excellent long‐life cycling stability, retaining 94.2% of the initial capacitance after 9000 cycles, and mechanical flexibility during extreme bending, respectively. Thereby, the MoS2@Ni(OH)2 nanocomposites are a promising electrode materials for flexible long‐life cycling all‐solid‐sate supercapacitors.