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The currently reported bottom water sealing materials and fracturing technologies can hardly simultaneously achieve the high production and low water cut of gas reservoirs due to the complexity of various formation conditions. Therefore, without controlling the fracturing scale and injection volume, a kind of polylactide polymer water plugging material with a density of 1.15–2.0 g/cm3 is developed, which can be used to seal the bottom water of a gas–water differential layer by contact solidification with water and automatic degradation with natural gas. This technology can not only fully release the production capacity of the gas reservoir but also effectively control water production and realize the efficient fracturing development of the target gas reservoir. Laboratory test results show that the smart plugging agent has a bottom water plugging rate of 100%, and the low-density plugging agent has a dissolution rate of 96.7% in methane gas at 90 °C for 4 h and a dissolution rate of 97.6% in methane gas at 60 °C for 6 h, showing remarkable gas degradation performance. In addition, settlement experiments show that the presence of a proppant can increase the settlement rate of a plugging agent up to many times (up to 21 times) in both water and guanidine gum solution. According to the actual conditions of well J66-8-3, a single-well water plugging fracturing scheme was prepared by optimizing the length of fracture, plugging agent dosage, and plugging agent sinking time, and a post-evaluation method was proposed. It has guiding significance to the development of similar gas reservoirs. [ABSTRACT FROM AUTHOR]

The excellent electrical conductivity of graphene is due to its highly‐conjugated structures. Manipulation of the electronic and mechanical properties of graphene can be achieved by controlling the destruction of its in‐sheet conjugation system. Herein, we report the preparation of CoCeSx−SA@BPMW@RGO through π‐π stacking interactions at the molecular level. In this study, sodium alginate was reacted with Co2+ and Ce3+, and the composite was loaded onto a graphene surface. The graphene sheets were prepared using a bi‐pyrene terminated molecular wire (BPMW) to avoid re‐stacking of the grapheme sheets, thereby forming nanoscale spaces between sheets. The angle between the BPMW coplanar pyrene group and the phenyl group was 33.2°, and the graphene layer is supported in an oblique direction. Finally, a three‐dimensional porous composite was obtained after annealing and vulcanization. The obtained CoCeSx−SA@BPMW@RGO exhibited excellent electrical conductivity and remarkable cycle stability. When the current density was 1 A g−1, its specific capacitance was as high as 1004 F g−1. BPMW modifies graphene through the synergistic effect of π‐π stacking interaction and special structure to obtain excellent electrochemical performance. Moreover, a solid‐state asymmetric supercapacitor device was fabricated based on the synthesized CoCeSx−SA@BPMW@RGO hybrid, which exhibited a power density of 979 W kg−1 at an energy density of 23.96 Wh kg−1. [ABSTRACT FROM AUTHOR]

Transition-metal selenides (TMSs) have great potential in the synthesis of supercapacitor electrode materials due to their rich content and high specific capacity. However, the aggregation phenomenon of TMS materials in the process of charging and discharging will cause capacity attenuation, which seriously affects the service life and practical applications. Therefore, it is of great practical significance to design simple and efficient synthesis strategies to overcome these shortcomings. Hence, P-doped Cu 3 Se 2 nanosheets are loaded on vertically aligned Cu 2 S nanorod arrays to synthesize CF/Cu 2 S@Cu 3 Se 2 /P nanocomposites with a unique core-shell heterostructure. Notably, the Cu 2 S precursors can be rapidly converted into Cu 3 Se 2 nanorod arrays in situ in just 30 min at room temperature. The unique core-shell heterostructure effectively avoids the aggregation phenomenon, and the doped P elements further enhance the electrochemical properties of the electrode materials. Therefore, the as-prepared CF/Cu 2 S@Cu 3 Se 2 /P electrode exhibits a high areal capacitance of 5054 mF cm -2 (1099 C g -1 ) at 3 mA cm -2 and still retains 90.2% capacitance after 10 000 galvanostatic charge-discharge (GCD) cycles. The asymmetric supercapacitor (ASC) device assembled from synthetic CF/Cu 2 S@Cu 3 Se 2 /P and activated carbon (AC) possesses an energy density of 41.1 Wh kg -1 at a power density of 480.4 W kg -1 . This work shows that the designed CF/Cu 2 S@Cu 3 Se 2 /P electrode has broad application prospects in the field of electrochemical energy storage.

Ternary layered double-hydroxide-based active compounds are regarded as ideal electrode materials for supercapacitors because of their unique structural characteristics and excellent electrochemical properties. Herein, an NiCeCo-layered double hydroxide with a core-shell structure grown on copper bromide nanowire arrays (CuBr 2 @NCC-LDH/CF) has been synthesized through a hydrothermal strategy and calcination process and utilized to fabricate a binder-free electrode. Due to the unique top-tangled structure and the complex assembly of different active components, the prepared hierarchical CuBr 2 @NCC-LDH/CF binder-free electrode exhibits an outstanding electrochemical performance, including a remarkable areal capacitance of 5460 mF cm -2 at 2 mA cm -2 and a capacitance retention of 88% at 50 mA cm -2 as well as a low internal resistance of 0.163 Ω. Moreover, an all-solid-state asymmetric supercapacitor (ASC) installed with CuBr 2 @NCC-LDH/CF and activated carbon electrodes shows a high energy density of 118 Wh kg -1 at a power density of 1013 W kg -1 . Three assembled ASCs connected in series can operate a multifunctional display for over three and a half hours. Therefore, this innovative work provides new inspiration for the preparation of electrode materials for supercapacitors.

The excellent electrical conductivity of graphene is due to its highly-conjugated structures. Manipulation of the electronic and mechanical properties of graphene can be achieved by controlling the destruction of its in-sheet conjugation system. Herein, we report the preparation of CoCeS x -SA@BPMW@RGO through π-π stacking interactions at the molecular level. In this study, sodium alginate was reacted with Co 2+ and Ce 3+ , and the composite was loaded onto a graphene surface. The graphene sheets were prepared using a bi-pyrene terminated molecular wire (BPMW) to avoid re-stacking of the grapheme sheets, thereby forming nanoscale spaces between sheets. The angle between the BPMW coplanar pyrene group and the phenyl group was 33.2°, and the graphene layer is supported in an oblique direction. Finally, a three-dimensional porous composite was obtained after annealing and vulcanization. The obtained CoCeS x -SA@BPMW@RGO exhibited excellent electrical conductivity and remarkable cycle stability. When the current density was 1 A g -1 , its specific capacitance was as high as 1004 F g -1 . BPMW modifies graphene through the synergistic effect of π-π stacking interaction and special structure to obtain excellent electrochemical performance. Moreover, a solid-state asymmetric supercapacitor device was fabricated based on the synthesized CoCeS x -SA@BPMW@RGO hybrid, which exhibited a power density of 979 W kg -1 at an energy density of 23.96 Wh kg -1 ., (© 2021 Wiley-VCH GmbH.)