[en] Three-dimensional carbon foam (CF) has been widely employed as a conductive framework for preparing self-supporting supercapacitor electrodes. Herein, based on the spin-drying mechanism of washing machine, a spin-coating method is developed to prepare carbon foam@graphene oxide (CF@GO) composites, in which a special centrifugation tube containing a macroporous shelf is used to separate the foam block and residual GO suspension during centrifugation. The GO fractions in CF@GO composites are controlled easily by tuning the spin speeds. As freestanding electrodes in two-electrode supercapacitors, the CF@GO-4500 (4500 rpm, 1.2 wt% GO) and CF@RGO-1000 electrodes (1000 rpm, 3.2 wt% GO) exhibit the specific capacitances of 159 Fg⁻¹ (258 mF cm⁻²) and 180 Fg⁻¹ (297 mF cm⁻²) at 0.5 Ag⁻¹, respectively, which are much higher than those of CF and CF@GO-4 or CF@RGO-4 sample (15.3 wt% GO) prepared by a conventional soaking–freeze-drying method. The results show that a few GO/RGO sheets loading in CF framework exhibit an enhanced electrochemical performance in supercapacitor, rather than filling much GO/RGO.

[en] Highlights: : • Spreading GO nanosheets-coated NF framework (NF@sGO) is fabricated. • NF@sGO provides more supporting surfaces and abundant oxygen-containing groups. • The superiority of NF@sGO is clarified by loading NiCo₂O₄ and NiCo₂S₄. • NF@sGO/NiCo₂O₄ composite delivers a capacity of 1135 C g⁻¹ at 1 A g⁻¹. • NF@sGO/NiCo₂O₄/NiCo₂S₄ electrode has a capacity of 1341 C g⁻¹ at 1 A g⁻¹. -- Abstract: : Porous nickel foam (NF) is often wrapped by reduced graphene oxide (rGO) for loading active nanomaterials. To clarify the influence of the dispersion of graphene nanosheets in NF framework on the electrochemical performance, herein, spreading GO nanosheets-coated NF (NF@sGO) is developed via negative pressure immersion method, in which, GO sheets spreading on the macropores adjust the pore structure and enlarge the supporting surface of NF framework. Compared to the NF@rGO prepared by hydrothermal method, NF@sGO scaffold exhibits a high capacitance for the pseudocapacitance contributed by GO. Acting as a porous scaffold for growing NiCo₂O₄ nanoneedles, the NF@sGO/NiCo₂O₄ composite delivers a specific capacitance of 2522 F g⁻¹ (1135 C g⁻¹) at 1 A g⁻¹, much higher than that of the control sample NF@rGO/NiCo₂O₄. To further improve the electrochemical performance of NF@sGO/NiCo₂O₄, thin NiCo₂S₄ nanosheets are decorated on NiCo₂O₄ nanoneedles. Optimized NF@sGO/NiCo₂O₄/NiCo₂S₄-0.02 sample delivers a maximum specific capacitance of 2980 F g⁻¹ (1341 C g⁻¹) at 1 A g⁻¹ and a superior long-term cycling stability. The performances of NF@sGO/NiCo₂O₄ and NF@sGO/NiCo₂O₄/NiCo₂S₄-0.02 are both higher than existing composites. The superior electrochemical performance is attributed to the combination of novel NF@sGO scaffold and NiCo₂O₄ nanoneedles or optimized NiCo₂O₄/NiCo₂S₄ hybrid nanostructures. In view of the easy preparation and superior performance, NF@sGO scaffold has a promising prospect for preparing high-performance integrated electrodes.

[en] Highlights: • Carbon nanosheets are obtained from direct carbonization of potassium citrate. • Bamboo-like carbon nanotubes are generated on carbon nanosheets. • PANI is polymerized on the surface of carbon nanotubes and carbon nanosheets. • Carbon nanosheets/carbon nanotubes/PANI ternary composite is developed. • Ternary composite delivers the maximum capacitance of 767 F g⁻¹ at A g⁻¹. -- Abstract: To improve the electrochemical performance of potassium citrate-derived carbon nanosheets (PCCs), herein, bamboo-like carbon nanotubes (CNTs) are generated on PCCs to prepare PCCs/CNTs composite. Based on interconnected porous PCCs/CNTs, polyaniline (PANI) is in-situ polymerized to fabricate PCCs/CNTs/PANI ternary composite. Through adjusting the aniline concentration, the optimized PCCs/CNTs/PANI composite is obtained at the aniline concentration of 0.4 M. The result confirms that much more N-containing groups are introduced after growing PANI on PCCS/CNTs, and the diameter of PANI-wrapped CNT is about three-time thicker than that of CNT. Served as working electrode in three-electrode system, the optimized PCCs/CNTs/PANI composite delivers the maximum capacitance of 767 F g⁻¹ at 1 A g⁻¹, with a high capacitance retention of 87.5% for 5000 cycles at 5 A g⁻¹. When assembled in asymmetric supercapacitor by using PCCs/CNTs/PANI as positive electrode and PCCs/CNTs as negative electrode, the device exhibits a specific capacitance of 102.5 F g⁻¹ at 0.5 A g⁻¹, and energy density is 56.9 Wh kg⁻¹ at the power density of 537 W kg⁻¹. Compared to existing carbon/PANI composites, PCCs/CNTs/PANI composite shows an outstanding electrochemical performance, due to the tailored pore structure of PCCs/CNTs and the high pseduocapacitance contributed by PANI wrapping layer.

[en] Highlights: • A new transshipment type model for inter-plant heat exchanger network is proposed. • New constraints are used to identify three inter-plant heat integration schemes. • A model with linear constraints is developed, allowing non-isothermal mixing. • Better results with lower total annual cost can be obtained by the proposed model.

[en] Highlights: • Self-supporting porous CoS₂/rGO film is prepared by a bottom-up assembly. • CoS₂ nanoparticles are uniformly dispersed on the conductive graphene framework. • The CoS₂/rGO film is served as binder-free sulfur host for Li-S battery. • The CoS₂/rGO cathode shows higher capacity and better cycling stability than rGO. Cobalt disulfide (CoS₂) has been revealed as strong adsorption and activation sites for polar polysulfides, which effectively accelerates the redox reactions of polysulfides in lithium-sulfur (Li-S) batteries. As an ideal sulfur host, a three-dimensional (3D) graphene framework is adopted for high-performance Li-S batteries. Considering the special function of the CoS₂ nanoparticles and the advantages of a 3D porous graphene framework, a porous CoS₂/reduced graphene oxide (CoS₂/rGO) binder-free sulfur host is prepared by a bottom-up assembly and hydrothermal treatment. The porous rGO film is stacked by interconnected graphene sheets, and the CoS₂ nanoparticles are dispersed on the graphene sheets uniformly, which effectively obstructs the stacking of graphene sheets. As a binder-free sulfur host, the porous CoS₂/rGO sulfur host combines the sufficient electron conductivity of the porous rGO framework and the sulfur immobilization interaction of the CoS₂ nanoparticles. This host material demonstrates an initial discharge capacity of 993.5 mAh g⁻¹ and a capacity of 806.7 mAh g⁻¹ after 110 cycles at 0.5 C. Both the capacity and cycling stability of the CoS₂/rGO cathode were greatly improved over that of rGO. Furthermore, the bottom-up assembly approach provides a novel opportunity for preparing self-supporting graphene-based nanocomposite electrodes.