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Engineering can be used to create uniquely oriented 2D materials, especially graphene, and can play a crucial role in the development of multifunctional films for applications in supercapacitors and thermal management, imparting excellent electrical and thermal properties to the films. However, the preparation of a uniquely structured graphene film with high-quality often requires a complex multi-step technique. Herein, we propose a facile and efficient one-step laser irradiation process for the synthesis of multifunctional laser-induced graphene electrodes consisting of L-shaped reduced graphene oxide nanosheets with vertical alignment (VrGO). Notably, the instantaneous high thermal energy of the laser irradiation can heal the defects of graphene oxide (GO) nanosheets, thus, enhancing the electrical conductivity and crystallinity while inducing the vertical alignment. Additionally, the vertical alignment of high-quality GO nanosheets leads to more isotropic thermal transport, thus, enhancing the out-of-plane thermal conductivity to 6.202 W m−1K−1. GO nanosheets also exhibited superior performances as supercapacitor electrodes, demonstrating an outstanding areal capacitance of 36.8 mF cm−2 at 1.2 mA cm−2, and excellent stability up to 10,000 cycles of charging/discharging. This simple laser technique opens up new possibilities for engineering the structural and physical properties of graphene for applications in various fields that require functional thin films. [Display omitted] • The rapid reduction of graphen oxide (GO) by CO 2 -laser is performed. • Defect-healing and vertical alignment of GO nanosheets were achieved. • Enhancement of out-of-plane thermal conductivity with the vertical alignment. • Defect-less, vertical graphene sheets exhibit excellent supercapacitor performance. [ABSTRACT FROM AUTHOR]

Structurally engineered carbon allotropes and their composites are widely applicable in various electronic/electrochemical devices including energy storage. Herein, we develop an efficient method to fabricate graphene/ceramic hybrid nanostructure based in-plane micro-supercapacitors (MSCs). Via CO 2 -laser irradiation method, MSCs patterns consisting of CoMn 2 O 4 nanoparticles incorporated in vertically structured laser-induced graphene (CMOLIG) were formed on a freestanding graphene oxide film. The process is extremely convenient, since the laser irradiated CMOLIG patterns serve as the in-plane MSCs electrode, while the untreated graphene oxide acts as the substrate. MSCs with enhanced performance can be fabricated with the CMOLIG hybrid electrode patterns that are made of CoMn 2 O 4 nanoparticles with pseudocapacitive properties anchored on vertically structured high-quality graphene film with excellent electrical property and high surface area. Notably, the CMOLIG electrode patterns exhibit enhanced specific capacitance with fast redox kinetics. Using the technique, customized in-plane MSCs arrays are also fabricated, which demonstrated controllable output voltage and capacitance depending on the array configuration to suit the requirements of various wearable microelectronics. [Display omitted] • Vertically structured high-quality graphene electrode via laser irradiation. • In-situ formation of CoMn 2 O 4 nanoparticle embedded in vertical graphene. • Enhanced specific capacitance and reaction kinetics by pseudocapacitive behavior. • Customized MSC arrays with controllable output voltage and capacitor performances. [ABSTRACT FROM AUTHOR]

Abstract The microstructure and electrochemical behavior of MnO x @reduced graphene oxide (rGO) composites derived from a MnO 2 /GO template are thoroughly investigated. An as-prepared MnO 2 /GO mixture is gradually converted to MnO 2 /rGO in a reduction process and is subsequently annealed under specific conditions to form the Mn 3 O 4 /rGO composites. The overall Li+ conversion reactions are visualized and the stability of the transformed MnO x phases is evaluated using density function theory calculations. The semispherical Mn 3 O 4 anchored composite exhibits stable electrode performances, including both the Li+ anode and the Li+-air cathode catalyst, induced by the electrochemically favorable composite with an effective large contact area between the active materials and the electronic conductive rGO. This provides a comparative way of designing the electrode for multiphase metal oxide-based composite electrodes considering the specific electrochemical reactions in view of materials engineering. Graphical abstract Image 1 Highlights • Comparative evaluating the electrochemical behaviors for MnO 2 / and Mn 3 O 4 /rGO. • Providing the cycle performance for polymorphic MnO x /rGO composites electrode. • GO reduction with well-stacked frame is crucial for MnO x /GO composite electrodes. [ABSTRACT FROM AUTHOR]

In order to realize the most suitable hybrid structure for air-stable graphene-based transparent and flexible electrodes, we systematically compared graphene oxide (GO)/Au/graphene and graphene/Au/GO hybrid films fabricated by layer-by-layer assembly. The sheet resistance of graphene/Au/GO was proportional to the concentration of AuCl 3 (1–5 mg/ml), which can be understood by a significant blue-shift in the G-band associated with the phonon stiffening. The size and density of formed Au nanoparticles strongly influenced their reduction reaction, which is a crucial factor for maximizing the doping effects. The optimized optical transmittance and sheet resistance of GO/Au/graphene were 94.9% and 198 ± 29 Ohm/sq, respectively. Furthermore, the hybrid films revealed stable doping effects (sheet resistance variation: 23–55%) against ambient conditions after 1 month. The variation in sheet resistance for GO/Au/graphene hybrid films corresponds to 30% with a bending radius of 10 mm after repeated bending tests (bending cycles of 10 5 ). [ABSTRACT FROM AUTHOR]

Recently, the importance of developing an effective catalyst for hydrogen evolution reaction is emphasized because hydrogen fueled energy conversion processes are gaining attention as the next generation energy production method. We propose a transition metal dichalcogenide composite catalyst based on molybdenum disulfide (MoS 2 ) and tungsten disulfide (WS 2 ) on reduced graphene oxide coated nickel (rGO-Ni) foams. The composite exhibited enhanced catalytic activity with observed on-set potential of ∼275 mV at −10 mA/cm 2 and Tafel slope of 54.1 mV/dec when the composition of the composite was 50%MoS 2 -50%WS 2 . The composite catalyst demonstrated high-stability up to 300 cycles. In order to understand the enhanced catalytic activity, X-ray photoelectron spectroscopy compositional analysis was utilized. We propose that the enhancement of catalytic activities exhibited by the composited samples were achieved due to introduction of new type of interface between MoS 2 and WS 2 grains, regional transition of 2H phase MoS 2 and WS 2 to 1T phase, and formation of excess sulfur which depended directly on the composition. [ABSTRACT FROM AUTHOR]

Abstract Reduced graphene oxide (rGO) has potential as a mass-producible and cost-effective substitute for graphene, but displays poor crystal quality due to various types of structural defects. Though many attempts have been reported to improve the quality of rGO, most of them require sophisticated equipment or severe conditions such as toxic chemicals, high temperature, and electron beam or plasma treatment in ultra-high vacuum (UHV) conditions. Here, we report a mild and simple solution-based healing method for obtaining high-quality rGO, with this method involving the use of a simple camera flash light treatment and the nontoxic chemicals l -ascorbic acid and ethanol. Exposing a GO solution containing l -ascorbic acid and ethanol to the flash light irradiation for a short amount of time (<10 min) resulted in the formation of rGO displaying high quality both with respect to its chemical composition and its crystallinity. To elucidate the mechanism of the flash-light-induced healing of rGO, we acquired and analyzed the transient absorption spectrum for the healing reaction by using femtosecond pump-probe spectroscopy; this analysis revealed the photo-catalytic activity of GO by itself to repair chemical and topological defects, and we hence named this process 'self-catalytic healing'. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]