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[Display omitted] • Electrochemically active Oxygen doped carbon (O-PCNs) was fabricated by superbase templated method. • The template basicity on the functionalities and the supercapacitor performances of the derived O-PCNs were disclosed. • The O-PCN-20 is rich in porosity, large in surface area (930 m2/g) and high in active oxygen content (11.4 atom%). • · The O-PCN-20 electrode exhibits large capacitance of 375 F/g@1.0 A/g and energy density of 25.7 Wh/kg@900 W/kg. Templating techniques have been widely adopted for the synthesis of porous carbons, such as oxygen-doped porous carbon nanosheets (O-PCNs), but the effect of the surface characteristics of templates on the surface functionality and performance of a derived carbon has not been well studied. Herein, a series of laboratory-made superbases of K/Mg(OH) 2 with different K/Mg ratios were employed as template to fabricate nanocarbon materials. The aim is to find out how the strength of template basicity could influence the surface functionalities and the supercapacitor performances of the derived O-PCNs. The resulting materials are rich in conjugated hydroxyl and carbonyl groups that are electrochemically active owing to the protection of the conjugated hydroxyl group by KOH and the dehydrogenation step catalyzed by magnesium oxide. Systematic investigations revealed that with the increase of basic strength, the content of the derived electrochemically active oxygen species in the forms of conjugated carbonyl (C O) and hydroxyl (C OH) first increases from 8.4 atom% to 11.4 atom% then decreases to 9.25 atom%. Moreover, the microporosity of the O-PCNs stepwise increases with the rise of KOH loading, ascribable to the effect of KOH etching on the carbon skeleton. The O-PCN-20 templated by 20 % K/Mg(OH) 2 is rich in porosity, large in surface area (930 m2/g) and high in active oxygen content (11.4 atom%). With high active surface area and extra Faradaic capacitance, O-PCN-20 exhibited superior supercapacitor performances including large specific capacitance of 375 F/g@1.0 A/g, high rate capability of 81.1 % (from 1.0 A/g to 20 A/g), energy density of 25.7 Wh/kg@900 W/kg and excellent cycling stability with near 100 % capacitance retentions after 10 000 cycles and more than 86.2 % capacitance retention over 20 000 cycles at large current density of 10 A/g, indicating O-PCN-20 has potential to be used as electrode material for energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heterostructure integrated with Fe 0.4 Co 0.6 Se 2 nanobelts and NiCo-P nanosheets is synthesized via a simple two-step electrodeposition. • This core–shell hybrid material has hierarchical porous architecture. • Synergy of two components results in boosted specific capacity and cycling stability. • Hybrid supercapacitor illustrates an energy density of 64.4 Wh kg−1. Exploring novel heterostructure with multiscale nanoarchitectures and modulated electronic structure is crucial to improve the electrochemical properties of electrode materials for supercapacitors (SCs). In this study, a two-step electrodeposition approach which involves suitable efficient procedures, is leading to in-situ preparation of iron cobalt selenide (Fe 0.4 Co 0.6 Se 2) @ nickel cobalt phosphate (NiCo(HPO 4) 2 ·3H 2 O, denoted as NiCo-P) hybrid nanostructure on carbon cloth (CC) substrate. Particularly, depositing two-dimensional (2D) NiCo-P nanosheets on the surface of Fe 0.4 Co 0.6 Se 2 nanobelts results in formation of well-organized Fe 0.4 Co 0.6 Se 2 @NiCo-P nanocomposite with large surface area, hierarchical porous nanoarchitecture as well as numerous electroactive sites, leading to enhanced electroactivity and accelerated mass/electron transfer. Benefiting from its unique nanoarchitecture and synergistic effect of two components, the obtained free-standing Fe 0.4 Co 0.6 Se 2 @NiCo-P electrode demonstrates gravimetric capacity (C m)/volumetric capacity (C d) of 202.3 mAh/g/319.6 mAh cm−3 at 1 A g−1 and good cyclic stability (83.9% capacity retention over 5000 cycles), which are superior to those of pure Fe 0.4 Co 0.6 Se 2 and NiCo-P electrodes. Impressively, it was established that an aqueous hybrid supercapacitor (HSC) based on Fe 0.4 Co 0.6 Se 2 @NiCo-P and rape pollen derived hierarchical porous carbon (RPHPC) achieves gravimetric energy density (E m)/volumetric energy density (E d) of 64.4 Wh kg−1/10.7 mWh cm−3 and a long cycle life with 90.3% capacity retention over 10,000 cycles. This report offers a perspective to design selenide/phosphate heterostructure on conducting substrate for electrochemical energy storage applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanoporous NiAlP@Co-NiCH nanosheet arrays were fabricated. • This hybrid had modified electronic structure and synergistic effect. • The specific capacity and cycling performance were greatly enhanced. • Asymmetric supercapacitor showed an energy density of 82.3 Wh kg−1. Transitional metal phosphides with high electrical conductivity and superb physicochemical features have been recognized as ideal battery-type electrode materials for outstanding performance supercapacitors. However, their specific capacities and structural stability are needed to be enhanced for large-scale practical applications. To overcome these shortcomings, we fabricated heterostructured NiAlP@cobalt substituted nickel carbonate hydroxide (Co-NiCH) nanosheet arrays by sequential a hydrothermal reaction, a phosphorization treatment, and a second hydrothermal reaction. Profiting from its core–shell porous nanostructure and synergistic effect of NiAlP with high electrical conductivity and Co-NiCH with high redox reactivity, the resultant NiAlP@Co-NiCH electrode delivers a large specific capacity of 825.7C g−1 at 1 A g−1, excellent rate capability with 78.9% capacity retention and long lifespan, superior to those of pure NiAlP and Co-NiCH electrodes. Additionally, an aqueous asymmetric supercapacitor device is constructed by NiAlP@Co-NiCH and lotus pollen-derived hierarchical porous carbon, which demonstrates a large energy density of 82.3 Wh kg−1 at a power density of 739.8 W kg−1, and wonderful cycle stability with 88.2% capacity retention after 10,000 cycles. This work proposes a feasible strategy on construction of transitional metal phosphide-based heterojunctions for advanced asymmetric supercapacitor devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • CoFeP@NiV-LDH hybrid nanosheet arrays are synthesized. • 2D/2D porous heterostructure with high mass loading provides accessible ion/electron transport paths. • The synergy between the two components boosts the energy storage performance. • A hybrid supercapacitor delivers an energy of 77.9 Wh kg−1/0.98 Wh cm−2. Designing multidimensional heterostructures on flexible substrates is an efficient approach to resolve the low energy density of supercapacitors. Herein, a three-dimensional (3D) porous cobalt iron phosphide (CoFeP)@nickel vanadium-layered double hydroxide (NiV-LDH) heterostructure has been prepared anchored on carbon cloth (CC) substrate. In this nanoarchitecture, NiV-LDH nanosheets are densely wrapped on the surface of CoFeP nanosheets, which forms a hierarchically porous framework with an enlarged surface area and accessible pore channels. Benefiting from the strong interaction and synergistic effect between CoFeP and NiV-LDH, the well-defined heterostructure can realize simultaneously rich redox active sites, rapid reaction dynamics, and good structural stability. Thus, the binder-free CoFeP@NiV-LDH electrode with a high mass loading of 6.47 mg cm−2 displays a significantly increased specific capacity of 903.1C g−1 (2.35C cm−2) at 1 A g−1 and enhanced rate capability when compared to pristine CoFeP and NiV-LDH. Additionally, the assembled hybrid supercapacitor (HSC) yields an energy density of 77.9 Wh kg−1/0.98 Wh cm−2 and excellent long-term stability. This research proposes a rational route for designing heterogeneous micro-/nanoarchitectures with commercial-level mass loading for the practical application of high-energy-density supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] Herein, we report the rational fabrication of unique core–shell nanoclusters composed of cobalt carbonate hydroxide (Co-CH) @ nickel aluminum layered double hydroxide (NiAl-LDH) on a carbon cloth (CC) substrate using a two-step hydrothermal strategy. The one-dimensional (1D) Co-CH nanowires core–shell functions as a framework for the growth of two-dimensional (2D) NiAl-LDH nanosheets, leading to the formation of a hierarchically porous core–shell heterostructure. The presence of abundant heterointerfaces enhances electrical conductivity, reduces charge transfer resistance, and facilitates ion/electron transfer. Taking full advantage of its unique nanostructure and synergistic effect of two components, the as-prepared Co-CH@NiAl-LDH hybrid material illustrates a specific capacity of 1029.4 C/g (2058.9 mC cm−2) at 1 A g−1 and good rate capability with a capacity retention of 68.5% at 20 A g−1. Additionally, the assembled Co-CH@NiAl-LDH//pine pollen-derived porous carbon (PPC) hybrid supercapacitor (HSC) delivers impressive energy and power densities of 66.2 Wh kg−1 (0.27 Wh cm−2) and 17529.7 Wh kg−1 (0.11 Wh cm−2), respectively. This device also achieves a superior capacity retention of 80.3% over 20,000 cycles. These findings prove the importance of engineering heterointerfaces in heterostructure for the promotion of energy storage performance. [ABSTRACT FROM AUTHOR]

A simple two-step electrodeposition strategy is firstly developed for the construction of Co 0.85 Se@Ni 3 S 2 hybrid nanosheet arrays, illustrating remarkable electrochemical properties in supercapacitors. [Display omitted] Rational design of porous heterostructured electrode materials for high-performance supercapacitors remains a big challenge. Herein, we report the in situ synthesis of Co 0.85 Se@Ni 3 S 2 hybrid nanosheet arrays supported on carbon cloth (CC) substrate though an efficient two-step electrodeposition method. Compared with pure Co 0.85 Se and Ni 3 S 2 , the well-defined Co 0.85 Se@Ni 3 S 2 heterojunction possesses enriched active sites, improved electrical conductivity, and reduced ion diffusion resistance. Benefiting from its hierarchically porous nanostructure and the synergistic effect of Co 0.85 Se and Ni 3 S 2 , the as-synthesized Co 0.85 Se@Ni 3 S 2 electrode delivers a gravimetric capacitance (C g)/volumetric capacitance (C v) of 1644.1F g−1/3161.7F cm−3 at 1 A g−1, outstanding rate capability of 60.7% capacitance retention at 20 A g−1, as well as good cycling performance of 87.8% capacitance retention after 5000 cycles. Additionally, a hybrid supercapacitor (HSC) device presents a maximum energy density (E) of 65.7 Wh kg−1 at 696.2 W kg−1 with 93.3% cyclic durability after 15,000 cycles. Thus, this work proposes a simple and effective strategy to fabricate porous heterojunctions as high-performance electrode materials for energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] Designing a heterostructure with unique morphology and nanoarchitecture is regarded as an efficient strategy to achieve high-energy-density supercapacitors (SCs). Herein, a rational nickel sulfide @ nickel boride (Ni 9 S 8 @Ni 2 B) heterostructure is in situ synthesized on carbon cloth (CC) substrate via a simple electrodepositon strategy followed by a chemical reduction method. The three-dimensional hierarchically porous Ni 9 S 8 @Ni 2 B nanosheet arrays, consisting of crystalline Ni 9 S 8 nanosheets and amorphous Ni 2 B nanosheets, can expose ample electroactive centers, shorten ion diffusion distance, and buffer volume changes during charging/discharging process. More importantly, the generation of crystalline/amorphous interfaces in the Ni 9 S 8 @Ni 2 B composite modulates its electrical structure and improves electrical conductivity. Owing to the synergy of Ni 9 S 8 and Ni 2 B, the as-synthesized Ni 9 S 8 @Ni 2 B electrode acquires a specific capacity of 901.2C g−1 at 1 A g−1, a sound rate capability (68.3% at 20 A g−1), along with good cycling performance (79.7% capacity retention over 5000 cycles). Additionally, the assembled Ni 9 S 8 @Ni 2 B//porous carbon asymmetric supercapacitor (ASC) exhibits a cell voltage of 1.6 V and a maximum energy density of 59.7 Wh kg−1 at 805.2 W kg−1. These findings might offer a simple and innovative approach to fabricate advanced electrode materials for high-performance energy storage systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mg-Co-Ni LDH were homogenously grown on the surface of reduced graphene (Mg-Co-Ni LDH/rG- x). • The Mg-Co-Ni LDH/rG- x was fabricated by a novel ball milling combined ion-exchange method. • The present ball milling combined ion-exchange method is versatile and does not needs extra alkali sources or auxiliary assembly reagents. • The Mg-Co-Ni LDH/rG- x based asymmetric supercapacitor achieve high energy density and superlong cycling stability. As an electrode for energy storage, the inherently poor conductivity of metal hydroxides (MHs) can be improved by in situ growth of MHs on conductive carbon based substrates so that their performances on energy storage could be enhanced to a high level. However, the incompatibility of hydrophilic component (metal hydroxides) and hydrophobic counterpart (carbon based materials) makes it difficult to be accomplished. Herein, we presented a scalable and easy-operated strategy by ball-milling combined with ion-exchange technique to grow Mg-Co-Ni LDH (layered double hydroxides) on reduced graphene, in which ball-milling was utilized to disperse the staring material of magnesium acetate on graphene oxide (GO) to obtain the composite of Mg(Ac) 2 /GO. The composite can be in situ transformed to MgO/reduced grapheme (rG) by following heat treatment. While, the ion-exchange reaction could enables the in situ growth of Mg-Co-Ni LDHs on the reduced graphene. The derived products (denoted as Mg-Co-Ni LDH/rG- x) owns nanosheet morphology, surface area of 59–115 m2/g, homogenous elements distribution. As electrode for supercapacitor, the maximum capacitance of 1204F/g@1.0 A/g was achieved and the corresponding asymmetric supercapacitor device shows a large energy density of 44.3 Wh/kg@800 W/kg. Particularly, a superlong cycling stability with 90.5% capacitance retention of the first cycle was attained after continuous charge/discharge for 20 000 cycles at current density of 5.0 A/g, promising great potential for practical energy storage application. The present strategy is simple and scalable that can be widely applied to the synthesis of various hydroxides/oxides or multi-component hydroxides/oxides on carbon substrates forming a composite structure, thus offers a great potential for broad application areas including catalysis, adsorption, energy storage, etc. [ABSTRACT FROM AUTHOR]

[Display omitted] Although transition metal metaphosphates (TMPOs) display special physical/chemical features and high theoretical capacities, their applications for supercapacitors (SCs) are still restricted by their low energy densities and inferior cycling stability. Herein, a novel strategy has been proposed to address these issues through in situ construction of cobalt nickle metaphosphate (Co 0.2 Ni 0.8 (PO 3) 2)@nickel diselenide (NiSe 2) core–shell heterostructure on carbon paper (CP) as a self-supporting flexible electrode for SCs. Particularly, this unique mushroom-like porous nanoarchitecture assembled by one-dimensional (1D) Co 0.2 Ni 0.8 (PO 3) 2 nanorods and zero-dimensional (0D) NiSe 2 nanospheres can expose abundant active sites and afford multi-dimensional channels, which favors rapid electron ions/electron transfer, accelerates the reaction kinetics, and alleviates volume changes during charging/discharging processes. Profiting from its well-aligned 1D/0D nanostructure and strong synergistic effect between Co 0.2 Ni 0.8 (PO 3) 2 and NiSe 2 , the Co 0.2 Ni 0.8 (PO 3) 2 @NiSe 2 /CP electrode delivers a specific capacity of 219.4 mAh/g/0.414 mAh cm−2 at 1 A/g and good cycling stability with capacity retention of 90.7% after 5000 cycles, outperforming many previously reported TMPO-based electrodes in literature. Impressively, an asymmetric supercapacitor (ASC) device assembled with Co 0.2 Ni 0.8 (PO 3) 2 @NiSe 2 as cathode and porous carbon as anode achieves an energy density of 69.2 Wh kg−1 at 736.0 W kg−1 and maintains a capacity retention of 97.6% after 20,000 charge–discharge cycles. This work provides an efficient approach to design multi-dimensional hybrid nanomaterials for high-performance SCs. [ABSTRACT FROM AUTHOR]

1D-on-1D cobalt iron selenide @ cobalt nickel carbonate hydroxide nanowire arrays as novel battery-type electrode materials were in-situ assembled on carbon cloth, illustrating outstanding energy storage behavior in hybrid supecapacitors. [Display omitted] • 1D-on-1D CoFe 2 Se 4 @CoNi-CH hybrid nanowires are synthesized. • The heterojunction has accelerated mass transfer and altered electronic structure. • Imitate interaction of two components boosts the mechanical stability. • Hybrid supercapacitor device shows an energy density of 67.3 Wh kg−1. Sluggish kinetics and poor structural stability are two main obstacles hampering the exploration of transition metal selenides (TMSs) for supercapacitor. Developing a reasonable core–shell heterostructure with unique morphology is an effective approach to resolve these issues. Herein, a core–shell cobalt iron selenide (CoFe 2 Se 4) @ cobalt nickel carbonate hydroxide (CoNi-CH) heterostructure is directly fabricated on carbon cloth via an electrodeposition method followed by a hydrothermal reaction. In this well-defined heterostructure, one-dimensional (1D) CoFe 2 Se 4 nanowires function as the cores and CoNi-CH nanowires as the shells, which combines the merits of highly conductive CoFe 2 Se 4 for rapid electron transfer and highly electroactive CoNi-CH for multiple redox reactions. Further, the intimate interaction between CoNi-CH and CoFe 2 Se 4 realizes large surface area with hierarchical network and generates rich heterointerfaces with modified the electronic structure. By virtue of its facile 1D-on-1D nanoarchitecture and synergistic effect, the CoFe 2 Se 4 @CoNi-CH electrode delivers a increased specific capacity of 218.6 mAh g−1 at 1 A-1 and enhanced rate capability (65.5% at 20 A g−1) compared with pure CoFe 2 Se 4 and CoNi-CH. Besides, a hybrid supercapacitor is established by coupling CoFe 2 Se 4 @CoNi-CH cathode and porous carbon anode, which enjoys a maximum energy density of 67.3 Wh kg−1 at 765.9 W kg−1 and prominent durability with 85.4% of capacity retention over 20,000 cycles. [ABSTRACT FROM AUTHOR]

Hierarchical core–shell FeNiSe 2 @Ni 4.5 Co 4.5 S 8 nanosheet arrays as a rational self-supported electrode material for hybrid supercapacitors were constructed on carbon cloth substrate, which displays superior electrochemical performance. [Display omitted] • Core-shell structured FeNiSe 2 @Ni 4.5 Co 4.5 S 8 is decorated on carbon cloth. • This heterostructure owns rich active sites and rapid ion/mass transfer. • Synergetic effect of dual units enhances the electrochemical behavior. • Hybrid supercapacitor provides an energy density of 69.0 Wh kg−1. Tailoring the electronic structure of nanomaterials by constructing core–shell heterostruture is a compelling strategy to design novel electrode materials with modified physiochemical properties for supercapacitors with improved performance. Herein, for the first time, we in situ fabricate iron nickel selenide (FeNiSe 2)@nickel cobalt sulfide (Ni 4.5 Co 4.5 S 8) core–shell nanosheet arrays on carbon cloth by an electrodeposition approach and a selenization treatment. This three-dimensional hierarchcial porous framework formed by plentiful interconnected nanosheets can expose numerous redox active sites with varied oxidation states and provide a conductive and porous skeleton for rapid ion/electrolyte ions transport. Benefiting from its modulated electronic structure and synergetic effect of metal-like FeNiSe 2 and Ni 4.5 Co 4.5 S 8 , the as-synthesized FeNiSe 2 @Ni 4.5 Co 4.5 S 8 electrode displays a large specific capacity of 236.9 mAh g−1 at 1 A g−1, remarkable rate capability with 80.6% capacity retention at 20 A g−1, and stable cyclic performance, which are superior to those of pure FeNiSe 2 and Ni 4.5 Co 4.5 S 8 electrodes. Besides, the assembled FeNiSe 2 @Ni 4.5 Co 4.5 S 8 //porous carbon hybrid supercapacitor device offers an energy density of 69.0 Wh kg−1 at 799.2 W kg−1, and exceptional cycling stability with 91.2% capacity retention after 10,000 cycles. This work offers a synthetic strategy to explore core–shell electrode materials with tunable architecture and morphology for high-performance energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] The investigation of high-efficiency electrodes is essential for the energy conversion/storage devices. In this work, mesoporous two-dimensional Ni-Co hydroxide nanosheets stabilized by BO 2 - (denoted as (Ni x Co y)(OH) 2 /Co(BO 2) 2) are prepared via a facile and cost-effective procedure to circumvent the shortage of nickel hydroxide, viz. poor conductivity and fast phase transition. The (Ni x Co y)(OH) 2 /Co(BO 2) 2 materials have high specific surface area and plenty of exposed active sites. As electrode, the optimized (Ni 0.5 Co 0.5)(OH) 2 /Co(BO 2) 2 delivers a remarkable specific capacity of 2257 F g−1 at 1 A g−1 with superior rate capability (2071 F g−1 at 20 A g−1). Moreover, the asymmetric supercapacitors assembled by (Ni 0.5 Co 0.5)(OH) 2 /Co(BO 2) 2 and active carbon provides high energy density (56.5 Wh kg−1 at 0.8 kW kg−1) and excellent cyclic stability (maintaining 98% of initial capacity over 10 000 cycles), demonstrating the promising potential of (Ni 0.5 Co 0.5)(OH) 2 /Co(BO 2) 2 in practical applications. [ABSTRACT FROM AUTHOR]

A facile nonthermal strategy to in-situ imprisoning sulfur into Co/ N -codoped hollow carbon spheres has been designed and the obtained hollow structured S@NC-Co sulfur cathode is evaluated for Li-S batteries. Owing to the Co/N co-doping effect which results in boosted physical confinement and catalytic conversion activity toward lithium polysulfides, the S@NC-Co cathode achieves excellent performance both in rate capability and long cycle durability. [Display omitted] Lithium-sulfur (Li-S) batteries have hitherto attracted dramatic research interests as an optional high-energy output candidate to replace the traditional lithium-ion batteries on account of its high energy density and low cost. Nonetheless, their kinetics arrearage and detrimental "shuttling effect" caused by the migration of soluble lithium polysulfide (LiPS) intermediates severely limit its practical application. Here, by a nonthermal route sulfur is in-situ imprisoned into Co/ N -codoped hollow carbon sphere (NC-Co) to construct an integrated S/C-Co-N hollow cathode (S@NC-Co) and directly applied in Li-S batteries, which effectively avoids complex template removal and sulfur infiltration process. The hollow NC-Co sphere not only restricts polysulfides migration via physical confinement but also enhances polysulfides conversion through redox-active electro-catalysis. Moreover, the hollow structure has large cavity offering sufficient space to accommodate volume expansion and excellent conductivity promising efficient electron/charge transfer. As a result, the batteries assembled by the S@NC-Co cathode achieve low polarization and high-rate capability (551 mAh g−1 at 4C). Remarkably, the batteries also present an outstanding long-term durability over 800 cycles at 1C, in which the capacity attenuation is merely 0.06 % per cycle. This work demonstrates a novel strategy in designing hierarchical structures or nanoreactors for electrochemical reactions and energy storage systems. [ABSTRACT FROM AUTHOR]

[Display omitted] Transition metal phosphides hold great promise for high performance battery-type electrode materials due to their superb electrical conductivity and high theoretical capacity. Unfortunately, the electrochemical properties of single metal or bimetallic phosphides are unsatisfactory owing to their low energy density and poor cyclic stability, and one feasible approach is to introduce heteroatoms to form trimetallic phosphides. Here, novel Fe–Co–Ni–P nanosheet arrays are in situ synthesized on a flexible carbon cloth substrate via an electrodeposition method followed by a phosphorization treatment. Due to the presence of abundant redox active sites, large specific surface area with mesoporous channels, desirable electrical conductivity, modified electronic structure, and synergistic effect of Fe, Co, and Ni ions, the as-prepared Fe–Co–Ni–P electrode displays significantly enhanced electrochemical performance when compared to bimetallic phosphides Fe–Co–P and Fe–Ni–P. Remarkably, the Fe–Co–Ni–P electrode exhibits a large specific capacity of 593.0 C g−1 at 1 A g−1, exceptional rate performance (80.3% capacity retention at 20 A g−1), and good cycling stability (84.2% capacity retention after 5000cycles). Besides, an asymmetric supercapacitor device with Fe–Co–Ni–P electrode as a positive electrode and a hierarchical porous carbon as a negative electrode shows a high energy density of 57.1 Wh kg−1 at a power density of 768.5 W kg−1 as well as excellent cyclability with 88.4% of initial capacity after 10,000cycles. This work manifests that the construction of trimetallic phosphides is an effective strategy to solve the shortcomings of single or bimetallic phosphides for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

In this work, Ag 3 PO 4 /PANI/Cr:SrTiO 3 photocatalysts were designed to effectively eliminate organic pollutants including Rhodamine B and phenol from high salinity wastewater under visible light. The phase composition, optical properties, and morphology of powders were studied, and the effects of inorganic salts on removal performance of the as-prepared particles were also tested. Results showed that the photocatalytic activities of Ag 3 PO 4 /PANI/Cr:SrTiO 3 composites for Rhodamine B and phenol reached 100% within 10 min and 18 min, respectively. The reaction rate of pure Ag 3 PO 4 was 7 times less than that of the ternary composite with the adding of PANI and Cr:SrTiO 3. The activity of Ag 3 PO 4 /PANI/Cr:SrTiO 3 remained at 92.25% after five cycles, so the photocatalytic and recyclable performance of ternary composite was greatly improved. In addition, when there was SO 4 2− with a content of ranging from 1% to 21%, the degradation activity of the ternary catalyst under visible light was not changed for Rhodamine B, which indicated that the ternary catalyst exhibited the excellent sulfate resistance ability. Results from ESR and radical trapping experiments showed that O 2 − and h+ made an important contribution to visible-light photocatalytic activities. [ABSTRACT FROM AUTHOR]

Electrochemical water-splitting is an ideal strategy to produce the promising substitutable energy source, hydrogen (H 2). However, the sluggish kinetics of electrochemical oxygen evolution reaction (OER) and the prohibitive cost, low reserves and easy oxidation of noble metal-based electrocatalysts force researchers to explore efficient and low-cost electrocatalysts. Bimetal nanostructred materials are proved to have enhanced OER catalytic performances. In this study, a series of bimetallic metal-organic frameworks (Fe/Ni-MOFs) are prepared by a solvothermal method. The prepared MOFs present abundant unsaturated metal active sites for OER. The optimized Fe/Ni bimetal-MOF has low overpotentials of 236 mV at 10 mA cm−2 and 284 mV at 100 mA cm−2 for OER. In addition, in comparison with most of the previously reported OER electrocatalysts, the present MOF shows a lower Tafel slope of 49 mV dec−1. Besides, the MOF catalyst exhibits high electrochemical stability and the OER activity shows a negligible change after stability test for 15 h and 10,000 voltammetric cycles. Meanwhile, the Fe-doped Ni-MOFs show faster catalytic kinetics and higher conductivity than the monometallic Ni-MOF. This work paves a way to exploit bi- or multi-metallic MOFs with high conductivities and electrocatalytic performances for electrochemical energy conversion. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Nonprecious-metal electrocatalysts have been intensively investigated, but how to keep a balance between their sustainability and competitive performance for the oxygen reduction reaction (ORR) is still a big challenge for energy applications. In this work, a type of bimetal- and nitrogen-codoped mesoporous carbon electrocatalyst (FeCo-N/C-800) was successfully synthesized via a simple hydrothermal method, followed by a calcination process at 800 °C in nitrogen atmosphere and an acid-etching process. The obtained FeCo-N/C-800 can act as a high-performance ORR catalyst with high onset and half-wave potentials (0.94 and 0.85 V), a large limiting current density (5.94 mA cm−2) and a four-electron reaction process in 0.1 M KOH solution, which can be comparable with commercial Pt/C catalyst. Additionally, the FeCo-N/C-800 exhibited superior long-term durability and high methanol tolerance. The excellent electrocatalytic performance of the FeCo-N/C-800 can be ascribed to the mesoporous structure (bimodal pores system), the synergetic interaction of the multiple ORR active sites, suitable N-doping level and the highly conductive carbon matrix. These structural features can promote efficiently the mass and electron transfer, provide abundant active sites for the adsorption and reaction of oxygen molecules, and thus improve the reaction kinetics. The present study not only provides a strategy for the synthesis of carbon-based electrocatalyst with high ORR catalytic activity and stability, but also demonstrates that the bimetal- and nitrogen-codoped carbon materials could be a class of competitive candidate for non-noble metal-based electrocatalysts. [ABSTRACT FROM AUTHOR]