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In the art museum, lighting plays a crucial role in visitors' understanding and appreciation of exhibits. This paper mainly explores the influence of different lighting mode (general lighting, accent lighting, and mixed lighting) and correlated color temperature (CCTs) (4000 K and 2700 K) changes on the observers' psychology to find the best lighting environment. Based on the simulation carried out at the National Museum of Western Art in Japan, we made six diverse lighting designs. 31 observers were invited to evaluate each scheme, and the results of subjective evaluation were analyzed by means of one-way analysis of variance and the paired sample T-test. According to the results of data analysis, suggestions can be given for art gallery lighting design. It is not recommended to use general lighting alone in art museums, and it is better to use mixed lighting. When the CCT is 4000 K, only accent lighting can be used. When the CCT is 2700 K, the mixed lighting effect is better. [ABSTRACT FROM AUTHOR]

Secondary settling tanks (SSTs) are a crucial process that determines the performance of the activated sludge process. However, their performance is often far from satisfactory. In the last 30 years, computational fluid dynamics (CFD) has become a robust and cost‐efficient tool for designing new SSTs, modifying the geometries of existing SSTs and improved control techniques in wastewater treatment plants. The first part of this review paper discusses the different approaches to model the motion of particles in SSTs. The applications of different multiphase approaches and the widely applied single‐phase approach in different SST studies are reviewed. The second part reviews current CFD research and engineering practice, focusing on the formation and the effect of density currents, effects of different design variables, parameter uncertainties in modeling structures, and atmospheric conditions. Finally, challenges and future improvements of sub‐models (sludge settling, rheology, turbulence, and flocculation) in the SST model framework are identified. Practitioner points: The first journal review for the CFD applications in SSTs over the last decade.The controversy over the relationship between SOR and SST performance can be largely explained by the prediction of the CFD model.Density decoupling in the turbulence model is possible for well‐baffled SSTs.The relative importance of three modeling parameters is summarized.Recommendations for future data collection are provided. [ABSTRACT FROM AUTHOR]

Computational fluid dynamics (CFD) model is used to study the effect of wind on the performance of a rectangular secondary sedimentation tank (SST) in a wastewater treatment plant (WWTP). Unlike most of the previous CFD modeling studies which evaluated the wind effect on the sedimentation tank in only water treatment plants, this study evaluates a rectangular SST in a WWTP at different wind speeds and directions, and under different inflow loading conditions. The wind is qualitatively and quantitatively analyzed for a range of wind speeds and directions as well as loading rates. The net effect is to change the three‐dimensional hydrodynamics profiles, effluent suspended solids, and sludge blanket height. The simulation results show that the wind deteriorates overall clarification performance of the rectangular SST and has little effect on the sludge thickening under mild wind conditions until the speed increases an extreme windy condition. These CFD simulation results suggest that in strong windy climates, covering SSTs or protecting them from strong winds may be justified. Practitioner points: This is the first comparison of wind effects on a rectangular secondary sedimentation tankThe effects of varied flow conditions, wind directions, and velocities are comparedWind‐induced currents in the settling tank negatively affect removal efficiencyWinds have strong negative impact on the performance of sedimentation tanks [ABSTRACT FROM AUTHOR]

Computational fluid dynamics model is used to understand the impact of wind on the performance of a secondary settling tank (SST) in a wastewater treatment plant (WWTP). Unlike most of the previous modeling studies which evaluated the wind effect on the settling tank in a water treatment plant, this study evaluates a circular SST in a WWTP at different current velocities and flow conditions. Performance indicators, such as effluent suspended solids and sludge blanket height, and three‐dimensional hydrodynamics profiles are compared among different windy conditions and the calm condition and under different wind directions and flow conditions. The simulation results show that the existence of wind has strong negative impacts on the overall performance of the circular SST. The prediction of ESS is doubled in the circular SST under the mild wind condition. Moreover, the circular SST is more sensitive to the wind along the inlet port direction. Practitioner points: This is the first comparison of wind effects on a circular secondary settling tankDetailed computational fluid dynamics solution procedures to simulate a secondary settling tankWind effects are investigated under multiple flow conditions, current velocities, and wind directionsThe performance of a circular secondary settling tank is very sensitive to the windWind along the inlet port direction has stronger negative impacts than it along 45° to the inlet direction [ABSTRACT FROM AUTHOR]

Highlights • Effects of eleven baffling structures on buoyancy-induced turbulence flow were evaluated. • The models were simulated and solved using a commercial CFD software program. • Both buoyancy-decoupled and buoyancy-coupled turbulence models were applied. • Turbulent kinetic energy difference and densimetric Froude number can evaluate the baffling effects. • Results of the baffling structre can be divided into three zones by the turbulent kinetic energy. Graphical abstract Abstract Computational fluid dynamics (CFD) models are applied to understand the effects of baffling structures on the buoyancy-induced turbulence flow in secondary settling tanks (SSTs). Eleven SST geometries, including four circular SSTs and seven rectangular SSTs, are evaluated in this study. The main research tool is a Fluent-based two-dimensional SST model. The model is verified with observations from literature. The validated model is then applied to compare the predictions of the effluent suspended solids (ESS) by the buoyancy-decoupled and buoyancy-coupled turbulence models on each SST geometry. Next, the effects of the SST baffling structures on the turbulence properties are compared and quantified. Additionally, stress tests are simulated on the SSTs, to predict their performances using both the buoyancy-decoupled and buoyancy-coupled turbulence models. The results for the original flow conditions show that the effects of the SST baffling structures on the buoyancy-induced turbulence can be divided into three zones: Zones A, where the baffling structures have negligible damping effects, and only the buoyancy-coupled turbulence model provides accurate predictions; Zone B, where the baffling structures partially dissipate the effect of buoyancy on turbulence, and the buoyancy-coupled model continues to provide accurate predictions but the buoyancy-decoupled turbulence model only provides qualitative but similar predictions; and Zone C, where the baffling structures fully dissipate the effect of buoyancy on turbulence, and both models provide similar, accurate predictions. Two indicators, the densimetric Froude number and the differences in turbulent kinetic energy can be used to predict the need for buoyancy coupling. [ABSTRACT FROM AUTHOR]

Secondary settling tanks (SSTs), also known as secondary sedimentation tanks or secondary clarifiers, are a basic yet complicated process in a biological water resource recovery facility. In order to understand and improve SST performance, computational fluid dynamics methods have been employed over the last 30 years. In the present investigation, a Fluent‐based two‐dimensional axisymmetric numerical model is applied to understand the effects of the buoyancy term (Gb) in the turbulent kinetic energy (TKE) equation and two model parameters (the coefficient of buoyancy term (C3) in the turbulent dissipation rate equation and the turbulent Schmidt number (σc) in the sludge transport equation) on the performance of an SST. The results show that the hydrodynamics can only be correctly predicted by buoyancy‐coupled TKE equation, unless the mixed liquor suspended solids is low and sludge settling velocity is extremely high. When the field observations show the SST is operating well, the buoyancy‐decoupled TKE equation predicts the correct result, but the buoyancy‐decoupled TKE equation may predict failure. Care is required in selecting the correct modeling technique for various conditions. This study provides guidance on how to avoid modeling problems and increase rates of convergence. Practitioner points: C3 can be set to zero to improve rate of convergence and reduce computing time.σc can be used to adjust SBH, when ESS and RAS concentrations are well calibrated to the field data, but the SBH does not fit field observation. [ABSTRACT FROM AUTHOR]

Abstract Graphene oxide derived from Hummer method has some irreversible defects such as easy accumulation and excessive oxygen-containing groups, which leads to deterioration of the electrochemical performance of graphene oxide, and sulfonated graphene can effectively overcome aforementioned shortcomings. Herein, sulfonated graphene is obtained by modifying graphene oxide with aryl diazonium salt of sulfanilic acid, and the hydrogel composite formed by anchoring Ni(OH) 2 on sulfonated graphene is prepared by means of hydrothermal method. The results show that, when the mass ratio of sulfonated graphene to Ni(OH) 2 is 1:5, the hydrogel composite can provide excellent electrochemical performance. The electrode material achieves a high specific capacitance of 1817.5 F g−1 at a current density of 1 A g−1, and still has excellent cycle stability at higher current densities. At a current density of 10 A g−1, its capacitance retention rate is as high as 89.5% after 1000 cycles, indicating that the electrode material has great potential in the field of supercapacitors. A laboratory-made all-solid-state flexible SGN//AC asymmetric supercapacitor exhibits a high specific capacitance of 80.44 F g−1 at 50 mA g−1, a large energy density and power density, and a stable cycle life. Three supercapacitors in series can lighten up a green LED indicator. Graphical abstract Hydrothermal Construction of Ni(OH) 2 /Sulfonated Graphene Hydrogel Composites for Supercapacitor Electrode. Image 1 Highlights • SGH can introduce oxygen-containing groups and accelerate the reaction rate of ions. • A simple and effective method for the preparation of SGN composite electrode materials. • The SGN compounds exhibits excellent electrochemical capability and cycling stability. • The supercapacitor device shows great flexibility, excellent capacitance and high power density. [ABSTRACT FROM AUTHOR]

The secondary sedimentation tank (SST) is a sensitive and complicated process in an activated sludge process. Due to the importance of its performance, computational fluid dynamics (CFD) methods have been employed to study the underflow hydrodynamics and solids distribution. Unlike most of the previous numerical studies, in the present investigation, the performance of three different types of turbulence models, standard k-ε , RNG k-ε and Realizable k-ε , are evaluated. Firstly, two-dimensional axisymmetric CFD models of two circular SSTs are validated with the field observations. Next, comprehensive comparisons are presented of the model predictions of the key physical quantities, such as the concentration of effluent suspended solids (ESS), and returned activated sludge (RAS), sludge blanket height (SBH), turbulent properties and flow and concentration patterns. A surprising result shows that the prediction of the ESS concentration is not sensitive to the change of turbulence models; while remarkable prediction difference can be observed in the inlet zone and near-field of sludge hopper and SBH. The results suggest that more observations inside the inlet zone are needed to achieve better model calibration and correct application of the turbulence model, which can be crucial to optimizing the geometry of inlet structure and sludge hopper as well as changing return solids concentration for the operation. [ABSTRACT FROM AUTHOR]

Abstract In this work, the high conductivity nanocomposite of NiMoO 4 -PANI (polyaniline) is synthesized via chemical polymerization, while NiMoO 4 nanorods are prepared with a solvothermal method. Furthermore, based on NiMoO 4 -PANI nanocomposite, we fabricate supercapacitor electrode, which shows an excellent chemical stability of 80.7% and a good specific capacitance of 1214 F g−1. In addition, we assemble an all-solid-state asymmetric supercapacitor (ASC) device, which uses NiMoO 4 -PANI and activated carbon (AC) as positive electrode and negative electrode, respectively. The ACS device demonstrates 33.07 Wh kg−1 at 240 W kg−1, 93 F g−1 at 0.3 A g−1 and a high retention value (about 98.6% of original value after 5000 cycles) of capacitance. Finally, two white LEDs can work for 15 min by using the ASC device (finished charging). Thus it can be seen that such unique properties of the binary nanocomposite strongly couple the advantages of the impressively high cyclic stability of NiMoO 4 and good electrical conductivity of PANI, respectively, which mainly give credit to synergistic effects of NiMoO 4 and PANI. Graphical abstract Image 1 Highlights • NiMoO 4 -PANI nanocomposite was synthesized by in situ oxidative polymerization method. • The NiMoO 4 -PANI nanocomposite electrode showed a good reversibility. • The NiMoO 4 -PANI//AC ASC exhibited an excellent cycling stability. • The NiMoO 4 -PANI//AC ASC device can support two white LEDs to work for 15 min. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three-dimensionally ordered mesoporous NiCo 2 O x @CeO y was developed by a hard template method. • Ce-doping can effectively adjust the electronic structure and bonding configuration of NiCo 2 O x electrode material. • The hollow cubic structure has high permeability and excellent bearing capacity. • The designed architecture has high specific surface area and abundant paths for electron/ion transport. • The NiCo 2 O x @CeO y //AC exhibits superior activity and stability for asymmetric supercapacitors. From the perspective of nano science and nanotechnology, it is very interesting and important to develop a reasonable and practical synthesis route of nanomaterials for production and life. Here, we develop a strategy of hollow cubic metal oxide nanocages. The method was inspired by Pearson's Hard-Soft-Acid-Base (HSAB) theory, and nanocages with excellent performance were prepared by coordination etching and optimization of reaction conditions. Firstly, Cu 2 O nanocubes were prepared by redox reaction at room temperature. Then, the hollow cubic NiCo 2 O x /CeO y nanocages were obtained by HSAB theory and cerium doping. The nanomaterial has a specific capacitance of up to 1976 F/g at the current density of 1 A/g. In addition, the asymmetric supercapacitor (ASC) prepared with hollow cubic NiCo 2 O x /CeO y nanocage as cathode and active carbon as anode exhibits an energy density as high as 37.1 Wh kg−1 at the power density of 375 W kg−1. The capacitance retention rate of the device is 91.5 % after 10,000 cycles. The device can be charged to light up LED lights. These excellent electrochemical properties, due to their unique structure and synergistic effect between materials, indicate the potential application value of hollow cubic NiCo 2 O x /CeO y nanocages in high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

This work reports a core–shell structure-dependent conversion to construct hollow Ni-Co-Fe-P nanoboxes with well-defined interior spaces on the basis of the interface-induced contraction mechanism, and demonstrates the electronic regulation of precatalyst-derived (oxy)hydroxides for boosting electrocatalytic oxygen evolution reaction. [Display omitted] • A interface-induced contraction of core–shell PBAs is used to prepare hollow Ni-Co-Fe-P nanoboxes. • Derived (oxy)hydroxides are the key to boost catalytic activity of hollow Ni-Co-Fe-P for OER. • The optimum hollow Ni-Co-Fe-P nanoboxes exhibit superior electrocatalytic OER performance. Hollow metal phosphides play an important role in electrocatalytic oxygen evolution reaction (OER), but directly phosphatizing solid precursors into well-defined hollow structures and further regulating electronic structures of their derived (oxy)hydroxides for boosting OER performance remain great challenges. Herein, we report hollow Ni-Co-Fe phosphide (Ni-Co-Fe-P) nanoboxes with well-defined interior spaces via a core–shell Prussian blue analogue (PBA)-dependent conversion. Starting from Ni-Co PBA nanocubes, a chemical reduction and decomposition process is utilized to fabricate core–shell Ni-Co@Fe PBA nanocubes based on the lattice matching principle, which are then phosphatized into hollow Ni-Co-Fe-P nanoboxes through an interface-induced contraction process. Thanks to well-designed hollow structures, polymetallic compositions, and doping of carbon, hollow Ni-Co-Fe-P nanobox catalyst shows a remarkable OER activity with a small overpotential of 277 mV at 20 mA cm−2. Notably, this catalyst is also highly stable with only 5 % activity decay over 24 h for the OER. Mechanism studies reveal that the electronic regulation of precatalyst-derived (oxy)hydroxides is the key to boost their OER activity. This work demonstrates a novel and effective protocol for designing polymetallic phosphides with well-defined hollow structures towards various targeted applications. [ABSTRACT FROM AUTHOR]

A virus-like hybrid material constituted by CoP nanoparticles confined in porous N-doped carbon framework decorated with N-doped carbon nanotubes for efficient water splitting. [Display omitted] Exploration of catalysts for water splitting is critical for advancing the development of energy conversion field, but designing bifunctional catalysts remains a major challenge. Herein, we demonstrate the N-doped carbon nanotube (NCNT)-grafted N-doped carbon (NC) framework embedding CoP nanoparticles (CoP@NC/NCNT) as hydrogen and oxygen evolution reaction (HER and OER) catalysts for water splitting. As a result, the CoP@NC/NCNT electrode requires the overpotentials of 106 and 177 mV at 10 mA cm−2 in 0.5 M H 2 SO 4 and 1.0 M KOH solutions for HER, respectively. Moreover, an overpotential of 324 mV for OER can drive 10 mA cm−2 in 1.0 KOH. The CoP@NC/NCNT-based electrolyzer derives a current density of 10 mA cm−2 at a low voltage of 1.72 V in 1.0 M KOH and remains stable for 10 h. The outstanding electrocatalytic performance is mainly attributed to the hierarchical structure with rich branches and highly active component of CoP. The intimate contacts between hierarchical porous NC frameworks by cross-linked NCNTs create a 3D conductive network, which facilitates electron or mass transfer and activates CoP. This work offers a novel route for preparing hierarchical carbon framework encapsulated metal phosphide particles for potential applications in energy conversion field. [ABSTRACT FROM AUTHOR]

The synthesis of multi‐carbon products through electrochemical CO2 reduction reactions has attracted great interest from researchers. Herein, nitrogen‐ and carbon‐doped copper nanocatalyst (NC−Cu) containing abundant Cu−N−C active sites was prepared by thermal decomposition of the complexes containing copper and melamine. The NC−Cu catalyst exhibited an ideal current density of 22 mA cm−2 at −0.93 V versus reversible hydrogen electrode (vs. RHE) in CO2‐saturated 0.5 M KHCO3 medium, with ethanol as the predominant product at −0.93 V (vs. RHE) and a maximum Faraday efficiency of 31 %. The current density of the catalyst remained almost unchanged after 20 h of electrolysis, indicating its excellent stability. The excellent catalytic ability is attributed to the abundant Cu−N−C active sites of NC−Cu with 3D porous microstructure. [ABSTRACT FROM AUTHOR]

Long-cycle stability and high-energy density are big challenges for developing high-performance hybrid supercapacitor (HSC) electrode materials. In this work, molybdenum-doped Co3O4 nanosheets arrays on nickel foam (noted as MoxCo1.5−xO/NF) are successfully prepared via facile one-step electrodeposition followed by annealing for hybrid supercapacitors. The experimental and calculated results indicate that the band gap modification and conductivity enhancement of MoxCo1.5−xO lead to excellent capacitive performance due to the doping of Mo into Co3O4. The as-prepared Mo0.25Co1.25/NF electrode demonstrates a high specific capacity of 128.2 mAh g−1 (923 F g−1) at 1 A g−1 (60% higher than the undoped Co3O4) and superior cycle stability with 95.2% capacity retention after 10,000 cycles at 10 A g−1. The assembled HSC delivers high-energy density of 64.3 Wh kg−1 at the power density of 794.1 W kg−1 and with 87.7% capacity retention after 10,000 cycles. This work can present a new strategy to fabricate the three-dimensional high-performance integrated electrode materials by a facile electrodeposition for heteroatom-doped transition metal oxide for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

• NF/ZnCo 2 O 4 @NiCo 2 O 4 heterostructures electrodes are fabricated via facile two-step methods. • The impact of all components in integrated electrode was investigated and discussed. • The integrated electrode exhibits excellent specific capacitance and cycling stability. • The hybrid supercapacitor delivers high energy and power densities. [Display omitted] The hierarchical core-shell heterostructures ZnCo 2 O 4 @NiCo 2 O 4 on Ni foam (NF) for supercapacitors were prepared via two-step hydrothermal and electrodeposition reactions followed by two post-annealing treatments. The effect of deposition time on its morphology and electrochemical performance was investigated in detail. Combining high electric conductivity of ZnCo 2 O 4 with high stability of NiCo 2 O 4 as well as synergistic effect, the NF/ZnCo 2 O 4 @NiCo 2 O 4 -100 (NF/ZCO@NCO-100) integrated electrode exhibited high specific capacitance of 1728.1 F g−1 (240.0 mAh g−1) at 1 A g−1, and excellent long-term stability with 97.8% capacitance retention after 10,000 cycles. The assembled hybrid supercapacitor (HSC) delivered the specific capacitance of 133.6 F g−1 (55.7 mAh g−1) at 1 A g−1 and high energy density of 40.58 Wh kg−1 at 745.62 W kg−1 as well as the outstanding long-term stability of 91.3% capacitance retention after 10,000 cycles. These results provide insights into the rational design of transition metal compound composite materials to construct integrated electrodes for high performance supercapacitors. [ABSTRACT FROM AUTHOR]

A novel composite porous NiCo 2 O 4 /ZnCo 2 O 4 /Co 3 O 4 hollow polyhedral nanocage is prepared by etching and the coprecipitation mechanism using the zeolitic imidazolate framework-67 as template. The use of the organic ligand in the template can prevent the agglomeration of the metal caused by high temperature calcination, which is beneficial to obtain the metal oxide nanocages composites with uniform particle size. The unique hollow nanocage structure of the composite material has a complex shell and shows a porous network-like structure which can provide more active sites, and promote the redox reaction of electrode material. At the current density of 1 A g −1 and 10 A g −1 , the nanocage exhibits the specific capacitance of 1892.5 F·g −1 and 1135 F·g −1 , respectively. After the 2000 cycles, the nanocage shows 66% of the capacitance retention rate and good cycle stability. Moreover the assembled NiCo 2 O 4 /ZnCo 2 O 4 /Co 3 O 4 //AC hybrid device can be reversibly cycled in a large potential range of 0–1.6 V and can deliver high energy density of 83.11 Wh kg −1 as well as the maximum power density of 8006.67 W kg −1 . This study provides insight into the synthesis of other composites and more possibilities for constructing more desirable electrode materials. [ABSTRACT FROM AUTHOR]

In this paper, hybrid CuO/ZnO nanocomposites are synthesized by a simple and cost-effective solid-state grinding method for multifunctional applications as supercapacitor electrodes and photocatalysts for the degradation of dye pollutants. In the synthesis process, ZnCO 3 -SLS used as a reactant that not only provides Zn source but also serves as a template to induce the nanoparticles to arrange orderly. The resultant CuO/ZnO (ZnCO 3 -SLS, 1.00 g) nanocomposites exhibit a maximum degradation efficiency of 91.5% for Rhodamine B and 74.3% for Congo Red under visible light irradiation for 240 min, respectively. Besides, it also demonstrates high specific capacitance of 579.5 F g −1 and excellent cyclic performance with nearly 83.0% capacity retention after 2000 cycles at a current density of 5 A g −1 , seemed to be superior to other nanocomposites. The excellent electrochemical performance can be attributed to a rational combination of two electrochemical active materials. The hybrid nanocomposites design opens up new opportunities to use in wastewater treatment and energy storage applications. [ABSTRACT FROM AUTHOR]

Bi 2 MoO 6 /Polyaniline (PANI) hybrid nanocomposite with enhanced specific capacity and rate performance was synthesized by compositing Bi 2 MoO 6 with the PANI layer using sodium lignosulphonate (SLS) as a dopant through a simple chemical polymerization. The Bi 2 MoO 6 /PANI (BMP) nanocomposite affords a large reaction surface area, an excellent structural stability, a large number of active sites, good strain accommodation, and fast electron and ion transportation compared with pure Bi 2 MoO 6 , which all are beneficial for improving the electrochemical performance. Hence, the Bi 2 MoO 6 /PANI electrode with 0.15 g Bi 2 MoO 6 (BMP-2) shows a high specific capacitance of 826 F g −1 at a current density of 1 A g −1 and capacitance retention of 75.5% after 3000 cycles at a current density of 5 A g −1 , which is higher than pristine Bi 2 MoO 6 and other electrodes. In addition, an all-solid-state asymmetric supercapacitor (ASC) fabricated by the BMP-2 electrode and activated carbon (AC) displays a high specific capacitance of 90.0 F g −1 and a high energy density of 31.9 Wh kg −1 . Moreover, the BMP-2//AC ASC device exhibits high cycle stability, and 86.5% of its initial capacitance is retained after continuous 6000 cycles. Therefore, these results will promote a promising potential application of the Bi 2 MoO 6 /PANI nanocomposite for use as an effective electrode material in supercapacitors. [ABSTRACT FROM AUTHOR]

• Ni(Co)MoO 4 hybrid electrode with a mixed structure was synthesized on nickel foam. • The hybrid electrode exhibits a remarkable cycling performance due to the mixed morphology. • The asymmetric supercapacitor shows a high energy density of 55.71 Wh kg−1 at the power density of 375 W kg−1. [Display omitted] In this work, the Ni(Co)MoO 4 (NMO-Co) hybrid materials with nanoneedle and nanosheet structure were prepared on nickel foam (NF) by the hydrothermal method for high-stability supercapacitors. The effect of Co presence on the structure and electrochemical properties of NMO-Co was investigated. As the molar of Cobalt increased, more nanoneedles grew on the surface of NiMoO 4 /NF. The combination of the Ni-doped CoMoO 4 nanoneedles and Co-doped NiMoO 4 nanosheets was irregularly arranged on the surface of NF, which emerged an improvement of the cycling performance. When the molar ratio of Co: Ni: Mo was 0.5: 1: 1, the capacitance retention of the hybrid electrode was 80.1% after 10,000 cycles at 10 A g−1, while the pure NiMoO 4 electrode was 53.1%. Moreover, an asymmetric supercapacitor device displayed high energy density and power density. The maximum energy density and power density could reach 55.71 Wh kg−1 and 14,999 W kg−1, respectively. The hybrid electrode's good electrochemical performance is due to the combination of mutual doping of Ni and Co with a mixed morphology. [ABSTRACT FROM AUTHOR]

Ultrafine CuS nanoparticles anchored on nitrogen-sulfur co-doped graphene nanosheets are synthesized by a simple-green solvothermal method, the composite has excellent electrochemical performance for CO 2 reduction. [Display omitted] • The CuS/N, S-rGO was synthesized via a facile and environmentally friendly method. • The co-doping of N and S on graphene can promote the activation and conversion of CO 2. • CuS/N, S-rGO exhibits outstanding formate selectivity for CO 2 RR. Electrochemical conversion of CO 2 into hydrocarbons can effectively alleviate the energy crisis and promote carbon cycle. Herein, we report that small-size CuS nanoparticles are confined in nitrogen and sulfur co-doped reduced graphene oxide (CuS/N,S-rGO) for electrochemically reducing CO 2 to formate. Specifically, the CuS/N,S-rGO electrode achieves maximum Faradaic efficiency of 82% for formate formation at −0.63 V versus the reversible hydrogen electrode (RHE). Moreover, this catalyst exhibits a stable performance during 20 h-electrolysis. Experiments demonstrate that the doping of nitrogen and sulfur can create an abundance of active sites on the graphene nanosheets to accelerate the CO 2 reduction reaction (CO 2 RR). The CuS/N,S-rGO electrode exhibits excellent performance for CO 2 RR is attributed to the synergistic effect between N,S-rGO and CuS, and graphene can improve stability of composite. This work provides an efficient electrocatalyst for CO 2 RR and offers a facile and environmental friendly approach to synthesize small-size Cu-based composites. [ABSTRACT FROM AUTHOR]

Construction of NiCo 2 O 4 /N-rGO composite and its application in all solid state asymmetric supercapacitor. • NiCo 2 O 4 /N-rGO composites can be prepared by using solvothermal method and hydrothermal method. • Hexamethylene tetramine can provide nitrogen source and used as precipitant and reducing agent. • The NiCo 2 O 4 /N-rGO composite material exhibited excellent electrochemical performance. • The NiCo 2 O 4 /N-rGO//AC exhibited an excellent cycling stability and a high specific capacitance. Herein, NiCo 2 O 4 /N-rGO nanocomposites were prepared by using solvothermal method and hydrothermal method. The specific surface area of the composite material reaches 99.38 m2 g−1, and NiCo 2 O 4 /N-rGO shows a high specific capacitance of 2090 F g−1 at a current density of 1 A g−1. When the current density reaches 10 A g−1, the electrode material still maintains the specific capacitance of 1257.5 F g−1 and the capacitance retention rate is 96.19% after 5000 cycles, which demonstrates that NiCo 2 O 4 /N-rGO nanocomposites have high activity, large specific capacitance and good rate performance as electrode materials for supercapacitors. Furthermore, solid-state asymmetric supercapacitor (ASC) is assembled in sealing form with NiCo 2 O 4 /N-rGO as positive electrode, active carbon (AC) as negative electrode and polyving akohol (PVA)-KOH as gel electrolyte. The relevant electrochemical test data show that the specific capacitance retention of the supercapacitor device is still 95.67% after 10,000 cycles, and the maximum energy density is 20.10 Wh kg−1 at a power density of 720.71 W kg−1, indicating that the device has excellent rate capability and cycle stability. [ABSTRACT FROM AUTHOR]