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Graphene/metal oxide (rGO/MOx) heterostructures hold great promise for energy storage, yet a full understanding of their synthesis remains elusive. Herein, a general, efficient, and scalable synthesis strategy is designed for the preparation of various rGO/MOx heterostructure materials featuring robust interfacial interactions. The heterogeneous nucleation growth mechanism of metal oxides on graphene is elucidated through ex situ characterization and theoretical simulation. The surface of graphene oxide (GO) is enriched with reactive oxygen‐containing functional groups, serving as potent nucleation sites that facilitate the rapid and heterogeneous nucleation of MOx grains. Simultaneously, a stable interface (C−O−M bond) is in situ formed between graphene and adsorbed metal ions during heat treatment, producing rGO/MOx heterostructure materials. Notably, the resultant rGO/CoO heterostructure material is employed as an anode and LiCoO2 as a cathode to assemble a soft packaging quasi‐solid‐state battery, which has demonstrated an impressive energy density of 341.4 Wh kg−1 and maintains outstanding capacity retention at 93.4% after 300 cycles at a 1C current. These findings provide valuable insights into the preparation and potential applications of rGO/MOx heterostructure materials for energy storage. [ABSTRACT FROM AUTHOR]

The delicate structural engineering is widely acknowledged as a powerful tool for boosting the electrochemical performance of conversion‐type anode materials for lithium storage. Here, a general electrostatic self‐assembly strategy is proposed for the in situ synthesis of MnO nano‐cabbages on negatively charged reduced graphene oxide (rGO/MnO). The strong interfacial heterostructure and robust lithium storage mechanism related to fast Li+ diffusion kinetics and high Li‐adsorption ability of rGO/MnO heterostructure are confirmed through operando experimental characterizations and theoretical calculation. Owing to the rapid charge transfer, enriched reaction sites, and stable heterostructure, the as‐synthesized rGO/MnO anode delivers a high capacity (860 mAh g−1 at 0.1 A g−1), superior rate capability (211 mAh g−1 at 10 A g−1), and cycle stability. Notably, the as‐assembled flexible pouch cell of activated carbon//rGO/MnO solid‐state lithium‐ion capacitors (LICs) possesses an exceptional energy density of 194 Wh kg−1 and power density of 40.7 kW kg−1, both of which are among the highest flexible solid‐state LICs reported so far. Further, the LICs possess an ultralong life span with ≈77.8% retention after 10 000 cycles and extraordinary safety, demonstrative of great potential for practical applications. [ABSTRACT FROM AUTHOR]

High-loading atomic cobalt (12.8 wt%) dispersed on nitrogen-doped graphene was successfully synthesized via considerably low temperature pyrolysis. The catalyst exhibits excellent electrocatalytic performance towards the oxygen reduction reaction with a large limiting diffusion current density of 5.60 mA cm−2 (10% higher than that of commercial Pt/C), and when acting as the air catalyst of Zn–air batteries, a high open-circuit voltage of ＞1.40 V and excellent power density are also achieved. [ABSTRACT FROM AUTHOR]

Ni 2 P/GNS nanocomposite was synthesized by a facile and green hydrothermal technique. Microstructural characterizations demonstrated that Ni 2 P nanoparticles with an average size of about 5 nm were uniformly distributed in graphene nanosheets. The Ni 2 P/GNS nanohybrid exhibited enhanced effects on the dehydrogenation properties of MgH 2 compared to Ni 2 P and GNS individually. The onset desorption temperature of MgH 2 Ni 2 P/GNS composite reduced by 98 °C in contrast with the pure as-milled MgH 2 . Moreover, the MgH 2 Ni 2 P/GNS composite could release 6.1 wt% H 2 (only 0.2 wt% H 2 for the pure as-milled MgH 2 ) within 20 min at 325 °C. In addition, the relative hydrogen desorption mechanism of MgH 2 Ni 2 P/GNS composite has also been discussed. [ABSTRACT FROM AUTHOR]

A potential negative electrode material Co 3 O 4 @rGO is synthesized via a facile reflux condensation route. The electrochemical performances of Co 3 O 4 @rGO composite for alkaline rechargeable Ni/Co batteries have been systemically investigated for the first time. The reduced-graphene can remarkably enhance the electrochemical activity of Co 3 O 4 materials, leading to a notable improvement of discharge capacity, cycle stability and rate capability. Interestingly, the maximum discharge capacity of Co 3 O 4 @rGO-20 (additive amount of GO is 20 mg) electrode can reach 511.4 mAh g −1 with the capacity retention of 89.1% after 100 cycles at a discharge current of 100 mA g −1 . A properly electrochemical reaction mechanism of Co 3 O 4 @rGO electrode is also constructed in detail. [ABSTRACT FROM AUTHOR]

Exploring thermal transport in graphene–polymer nanocomposite is significant to its applications with better thermal properties. Interfacial thermal conductance between graphene and polymer matrix plays a critical role in the improvement of thermal conductivity of graphene–polymer nanocomposite. Unfortunately, it is still challenging to understand the interfacial thermal transport between graphene nanofiller and polymer matrix at small material length scale. To this end, using nonequilibrium molecular dynamics (NEMD) simulations, we investigate the interfacial thermal conductance of graphene–polyethylene (PE) nanocomposite. The influence of functionalization with hydrocarbon chains on the interfacial thermal conductance of graphene–polymer nanocomposites was studied, taking into account the effects of model size and thermal conductivity of graphene. An analytical model is also used to calculate the thermal conductivity of nanocomposite. The results are considered to contribute to the development of new graphene–polymer nanocomposites with tailored thermal properties. [ABSTRACT FROM AUTHOR]

Size-controlled Ag0.04@Co0.48@Ni0.48 core-shell nanoparticles (NPs) were synthesized by employing graphene (rGO) with different reduction degrees as supports. The number of CO and CO functional groups on the surface of rGO might play a major role in controlling the particle size. The strong steric-hindrance effect of CO resulted in the growth of large particles, whereas CO contributed to the formation of small particles. The particle size of Ag0.04@Co0.48@Ni0.48 NPs supported on rGO with different reduction degrees decreased as the number of CO functional groups decreased. The decrease in the particle size probably led to the increase in the catalytic activity towards the hydrolysis of ammonia borane (AB). The enhanced catalytic activity largely stemmed from the increasing active sites on the surface of catalysts owing to the decreasing particle size. [ABSTRACT FROM AUTHOR]

Piezoelectric composites comprising an active phase of ferroelectric ceramic and a polymer matrix have recently found numerous sensory applications. However, it remains a major challenge to further improve their electromechanical response for advanced applications such as precision control and monitoring systems. We here investigated the incorporation of graphene platelets (GnPs) and multi-walled carbon nanotubes (MWNTs), each with various weight fractions, into PZT (lead zirconate titanate)/epoxy composites to produce three-phase nanocomposites. The nanocomposite films show markedly improved piezoelectric coefficients and electromechanical responses (50%) besides an enhancement of ∼200% in stiffness. The carbon nanomaterials strengthened the impact of electric field on the PZT particles by appropriately raising the electrical conductivity of the epoxy. GnPs have been proved to be far more promising in improving the poling behavior and dynamic response than MWNTs. The superior dynamic sensitivity of GnP-reinforced composite may be caused by the GnPs’ high load transfer efficiency arising from their two-dimensional geometry and good compatibility with the matrix. The reduced acoustic impedance mismatch resulting from the improved thermal conductance may also contribute to the higher sensitivity of GnP-reinforced composite. This research pointed out the potential of employing GnPs to develop highly sensitive piezoelectric composites for sensing applications. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of battery-type anode limits the realization of high capacitance especially at elevated charge-discharge rates for lithium-ion capacitors (LICs). In this work, graphene wrapped carbon cages (G x P y) are obtained via a facile physical-confined pyrolysis approach from graphene oxide (GO)/polyvinylidene fluoride (PVDF), which exhibits great promise as a fast and large-capacity anode for LICs. The thermal degradation process analysis reveals that carbon cages with abundant mesopores derived from the dehalogenation of PVDF are formed spontaneously due to the HF releasing in the pyrolysis process with the aid of physical confined GO template. Hollow carbon cages could ameliorate the Li+ transport path, while 2D graphene serves as a conducting bridge connecting the isolated carbon cages to minimize the barrier of charge transfer. As a result, a LIC pouch-cell based on G x P y hierarchical carbon anode demonstrates high energy density and superior power density, as well as remarkable cycle life. This study may open a unique avenue for designing fast and large-capacity carbon anode and push the development of high-performance LICs. We report a physical-confined pyrolysis pathway to prepare hierarchical carbon anode composed of graphene wrapped carbon cages. Carbon cage structure can ameliorate the Li+ transport path, while graphene serves as a conducting bridge connecting the isolated carbon cages, resulting fast kinetics and large capacity as anode material. As a result, a LIC pouch-cell based on G x P y hierarchical carbon anode demonstrates impressive electrochemical performance. [Display omitted] • A physical-confined pyrolysis pathway is developed to prepare hierarchical carbon anode composed of graphene wrapped carbon cages. • The thermal degradation mechanism reveals that carbon cages are derived from the dehalogenation of PVDF due to the HF releasing in the pyrolysis process. • Cage structure can ameliorate Li + transport path, resulting fast kinetics and large capacity as anode material. [ABSTRACT FROM AUTHOR]

Abstract: Highly crumpled graphene nanosheets (GS) with a BET surface area as high as 722.1 m2 g−1 is prepared by a thermal exfoliation method. A systematical investigation is performed on the electrochemical performances of porous Ni2P/GS nanocomposite synthesized by the low temperature solid state reaction method. It is shown that Ni2P nanoparticles anchor on graphene sheets producing a porous structure and GS have beneficial effects on the electrochemical properties of Ni2P nanoparticles when investigated as pseudocapacitor materials. The novel Ni2P/GS composite electrode exhibits a superior specific capacitance of 1912 F g−1 and 888 F g−1 at current densities of 5 and 50mAcm−2, respectively. The specific capacitance decreases to 1473 F g−1 after 2500 cycles, suggesting its excellent cycling stability. It is confirmed that the GS with good electrical conductivity serve as a conducting network for fast electron transfer between the active materials and charge collector, as well as buffered spaces to accommodate the volume expansion/contraction during cycling, thus, leading to enhancement of the electrochemical properties of the Ni2P electrode. [Copyright &y& Elsevier]

Abstract: Well-dispersed Fe0.3Co0.7/rGO nanocatalysts have been synthesized utilizing the two-step reduction method and successfully employed in the hydrolysis of ammonia borane (NH3BH3 AB) at room temperature. The mass percent of the supported Fe0.3Co0.7 nanoparticles (NPs) on graphene (rGO) sheets can reach to the maximum value of 50 wt%. The as-synthesized catalysts exerted satisfying activity and reusability for the hydrolytic dehydrogenation of AB at 298 K, especially for the specimen of 50 wt% Fe0.3Co0.7/rGO NPs. The catalytic hydrolysis reaction was rapidly completed within 1 min. [Copyright &y& Elsevier]