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Laminated and scale-like Ni/Zn-MOF/ZnO@CC hybrid materials with high orientation are synthesized and exhibit promising electrochemical properties. [Display omitted] Metal-organic frameworks (MOFs) are attracting tremendous research interest because of their rich redox sites and high specific area which are beneficial for the energy storage applications. Nevertheless, the poor conductivity, low mechanical strength and unsatisfactory capacity severely hinder their wide application. Hence, it is of practical significance to design highly efficient and facile strategy to solve these issues. Herein, vertically oriented ZnO nanorod arrays are applied as precursor to synthesize laminated scale-like and highly-oriented Ni/Zn-MOF/ZnO nanocomposite. Owing to the desirable conductivity resulting from the doping nickel ions and the interaction between ZnO and its relative MOF, the fabricated 0.3Ni/Zn-MOF/ZnO@CC electrode exhibits an electrochemical capacitance of 1693 mF cm−2 at 1 mA cm−2. Moreover, the electrochemical capacitance retention of 80.7 % after 2500 cycling numbers is obtained under the constant current density of 10 mA cm−2 and the low internal resistance R s of 0.89 Ω is observed. For practical application, the as-synthesized laminated scale-like Ni/Zn-MOF/ZnO@CC nanocomposite is served as positive electrode to fabricate solid-state asymmetric supercapacitor device. Moreover, a 2.5 V indicator could be powered for 8 min when the prepared supercapacitor units are connected. This work demonstrates the promising potential of the synthesized scale-like Ni/Zn-MOF composites for electrochemical energy storage applications. [ABSTRACT FROM AUTHOR]

DFT calculation is used to study the electrochemical capacity enhancement mechanism of the fabricated flexible 3D porous rOHNM-AGs electrodes based on open-hollow Ni-MOF microspheres with high mechanical strength and superior electrochemical properties. [Display omitted] • 3D rOHNM-AGs are achieved by embedding open-hollow Ni-MOF microspheres into graphene nanosheets. • DFT calculation reveals charge-transfer interaction between the rOHNM-AGs and OH– ions. • The rOHNM-AGs/KOH/PVA film can be twisted with different angles, which can lift 500 g plastic bottle. • The fabricated rOHNM-AGs electrode exhibit superb specific capacitance of 1644F·g−1 at 1 A·g−1. • A portable multifunctional instrument can be powered by all-solid-state supercapacitor device for 15 mins. Metal-organic frameworks (MOFs) are extensively used for electrode materials of supercapacitors under their unique characteristics like customizable pore size, plentiful active sites and tunable structure. However, the MOFs lack adequate electrical conductivity and satisfactory stability, when directly applied to supercapacitor electrode materials, limiting the further improvement of their electrochemical properties. Accordingly, three-dimensional porous aerogels (rOHNM-AGs) have been achieved by embedding open-hollow nickel-based metal–organic framework microspheres between graphene layers. Under the controllable and highly ordered metal nodes as well as organic linkers, the prepared rOHNM-AGs still reserve the preponderance of MOF materials with multifarious exceptional constituent and configurational benefits. Furthermore, the remarkable electrical conductivity from graphene leads to a significant increase in electron/ion transport rate. In addition, charge-transfer interaction between the acceptor of OH– ions and the donor of rOHNM-AGs has been exposed by the density functional theory calculations. Moreover, a pliable and high tensile rOHNM-AGs/PVA/KOH film electrode has been fabricated by the PVA/KOH gel-electrolyte, which is capable of curving at multifarious angles. For actual utilizations, the manufactured supercapacitor apparatus can run a multi-purpose display for over 15 mins. Therefore, this groundbreaking research furnishes a new inspiration for preparing composite electrodes based on MOFs and graphene for flexible asymmetric supercapacitors. [ABSTRACT FROM AUTHOR]

The development of cost-effective non-precious metal bifunctional electrocatalysts with performance comparable to that of precious metal-based catalysts is an important factor in achieving industrial hydrogen production from electrolytic water. In order to prepare electrocatalysts with highly exposed active sites and high intrinsic activity, unique heterostructure and element doped 2D Co–NiS 2 /CeO 2 nanosheets grown on foamed nickel (Co–NiS 2 /CeO 2 /NF) are prepared by hydrothermal reaction and annealing. The Co–NiS 2 /CeO 2 /NF catalyst demonstrates excellent performance and stability in alkaline solutions. In 1.0 M KOH solution, the overpotentials for the HER and OER were found to be as low as 88 mV and 240 mV, respectively. Moreover, when utilized as both the anode and cathode in a standard two-electrode water electrolyzer, Co–NiS 2 /CeO 2 /NF delivers 50 mA cm−2 at a relatively low voltage of 1.82 V and was able to maintain its high performance levels without any degradation even after 48 h of CP test. The combination of doping and interfacial effects greatly increases the number of active sites and the activity of the catalyst. This study provides a new pathway for the design of cost-effective, high-performance catalytic materials for overall water splitting. Co-doped and CeO 2 heterostructure modified NiS 2 grown on foamed nickel electrocatalyst is successfully constructed through a simple hydrothermal process followed by further vulcanization treatment and exhibits excellent electrocatalytic performance and stability towards overall water splitting. In 1.0 M KOH solution, the current densities of the HER and OER can reach 10 mA cm−2 with minimum overpotentials of 88 mV and 240 mV, respectively. Additionally, when a standard two-electrode water electrolyzer is fabricated by employing Co–NiS 2 /CeO 2 /NF as both the cathode and anode, it can generate 10 mA cm−2 at 1.38 V and operate steadily without performance degradation after 48 h. [Display omitted] • The combination of doping and interfacial effects greatly increases the activity of the catalyst. • Co–NiS 2 /CeO 2 /NF exhibits excellent activity towards overall water splitting. • Co–NiS 2 /CeO 2 /NF shows a remarkably stability with a nearly unchanged potential after a longer stability test. [ABSTRACT FROM AUTHOR]

A honeycomb-like structure nanocomposite composed of Ag nanoparticles doped NiMn-LDHs nanosheets shell and uniformly arranged Co 2 (OH) 2 CO 3 nanoneedles core shows promising electrochemical storage properties. [Display omitted] • Honeycomb-like CC@Co 2 CH/NM-LDH-Ag nanosheet arrays are synthesized on carbon cloth. • The hybrid of various active components provides abundant active sites and fast ion diffusion. • CC@Co 2 CH/NM-LDH-Ag is used to prepare binder-free electrodes and exhibits excellent electrochemical properties. • The assembled all-solid-state asymmetric supercapacitor shows high energy density and power density. Layered double hydroxides are considered promising electrode materials for the preparation of high-energy–density supercapacitors owing to their suitable microstructure and significant electrochemical properties. In this study, honeycomb-like NiMn-layered double-hydroxide (NiMn-LDH) nanosheet arrays with numerous electron/ion channels, a large number of active sites, considerable redox reversibility, and significant electrical conductivity were synthesized by combining Co 2 (OH) 2 CO 3 nanoneedle arrays with NiMn-LDH nanosheet arrays and Ag nanoparticles on a carbon cloth (CC) substrate through a hydrothermal strategy (CC@Co 2 CH/NM-LDH-Ag). The fabricated CC@Co 2 CH/NM-LDH-Ag binder-free electrode exhibited a high specific capacitance of 10,976 mF cm−2 (3092F/g, 1391.4C g−1) at 2 mA cm−2 (1 A/g), and a high capacitance retention of 93.2 % after 10,000 cycles at a current density of 20 mA cm−2. In addition, a solid-state asymmetric supercapacitor (ASC) device assembled using CC@Co 2 CH/NM-LDH-Ag as the cathode possessed an ultrahigh energy density of 68.85 Wh kg−1 at a power density of 722.6 W kg−1, and two fabricated ASC units in series were able to power a multifunctional display for more than 30 min. Therefore, this study provides a new approach for the design and synthesis of high-performance flexible electrodes. [ABSTRACT FROM AUTHOR]

Zn metal as a promising anode of aqueous batteries faces severe challenges from dendrite growth and side reactions. Here, tetraphenylporphyrin tetrasulfonic acid (TPPS) is explored as an electrolyte additive for advanced Zn anodes. It is interesting to note that TPPS spontaneously assembles into unique aggregates. As they adsorb on the Zn anode, the aggregates enhance the resistance to electrolyte percolation and dendrite growth compared to single molecules. Meanwhile, TPPS facilitates anion association in the solvation sheath of Zn2+, and boosts the transference number of Zn2+ up to 0.95. Therefore, anion‐related side reactions and anion‐induced electrode overpotentials are reduced accordingly. In this context, the electrolyte containing TPPS exhibits excellent electrochemical performance. Even under a high loading of MnO2 (25 mg cm−2), a limited Zn supply (N/P ratio=1.7), and a lean electrolyte (15 μL mAh−1), the full cells still represent a higher cumulative capacity compared to the reported data. The advantages of this electrolyte are also adapted to other cathode materials. The pouch cells of Zn||NaV3O8 ⋅ 1.5H2O realize a capacity of ~0.35 Ah at 0.4 C under harsh conditions. [ABSTRACT FROM AUTHOR]

Zn metal as a promising anode of aqueous batteries faces severe challenges from dendrite growth and side reactions. Here, tetraphenylporphyrin tetrasulfonic acid (TPPS) is explored as an electrolyte additive for advanced Zn anodes. It is interesting to note that TPPS spontaneously assembles into unique aggregates. As they adsorb on the Zn anode, the aggregates enhance the resistance to electrolyte percolation and dendrite growth compared to single molecules. Meanwhile, TPPS facilitates anion association in the solvation sheath of Zn2+, and boosts the transference number of Zn2+ up to 0.95. Therefore, anion‐related side reactions and anion‐induced electrode overpotentials are reduced accordingly. In this context, the electrolyte containing TPPS exhibits excellent electrochemical performance. Even under a high loading of MnO2 (25 mg cm−2), a limited Zn supply (N/P ratio=1.7), and a lean electrolyte (15 μL mAh−1), the full cells still represent a higher cumulative capacity compared to the reported data. The advantages of this electrolyte are also adapted to other cathode materials. The pouch cells of Zn||NaV3O8 ⋅ 1.5H2O realize a capacity of ~0.35 Ah at 0.4 C under harsh conditions. [ABSTRACT FROM AUTHOR]

Hierarchical CoSe 2 @NiMn-LDH@Cu 1.8 Se/CF nanosheet arrays with core-shell structure are synthesized via phase pseudomorphic transformation process achieved by selective selenization for Cu and Co elements for green chemistry energy storage. [Display omitted] As an emerging energy storage device, the practical application of supercapacitors (SCs) is currently constrained by their low energy density. Enhancing the capacitance of supercapacitors by leveraging the synergistic effect of multiple components in composite electrodes with well-designed structures can effectively increase their energy density. Here, a wire-sheet-particle hierarchical heterostructured CoSe 2 @NiMn-layered double hydroxide (NiMn-LDH) @Cu 1.8 Se/Copper foam (CF) electrode is synthesized via phase pseudomorphic transformation process achieved by selective selenization for Cu and Co elements. Benefiting from the stable support structure of CuBr 2 , the large specific surface area of NiMn-LDH, and the excellent conductivity of CoSe 2 , the prepared binder-free electrode shows excellent electrochemical properties. The CoSe 2 @NiMn-LDH@Cu 1.8 Se hybrid electrode exhibits a superior specific areal capacitance of 7064 mF cm−2 at 2 mA cm−2 and a stable cyclic performance with 80.11 % capacitance retention after 10,000 cycles. Furthermore, the assembled CoSe 2 @NiMn-LDH@Cu 1.8 Se/CF//AC (activated carbon) asymmetric supercapacitor (ASC) achieves an energy density of 36.6 Wh kg−1 when the power density is 760.6 W Kg−1 and retains 87.35 % of the initial capacitance after 5000 cycles. Overall, this pioneering research provided new insight for preparing supercapacitor electrode materials by selective selenization and ration design of the structures. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • LiFe 5 O 8 @PPy nanocomposite were synthesized through a etching/regrowing method. • The 3D-porous architecture provides a pathway for electrolyte diffusion. • LiFe 5 O 8 @PPy nanocomposite show much enhanced electrochemical performances. Abstract In this work, a core-shell hierarchical LiFe 5 O 8 @PPy nanocomposite has been successfully fabricated through a simple etching/regrowing method. The core buffer of highly conductive PPy nanotubes is introduced to enhance the electrochemical performance of LiFe 5 O 8. Owing to improved electron transfer capability, charge transfer resistances of the core-shell nanostructured composites are decreased and the electrochemical properties are enhanced. The representative LiFe 5 O 8 @PPy nanocomposite exhibits a high specific capacitance of 292 F g−1 at a scan rate of 5 mV s−1, and an excellent cycling stability (82.99% after 10,000 cycles) because of the synergistic effect of LiFe 5 O 8 nanosheets and PPy nanotubes. This study confirms that the as-prepared LiFe 5 O 8 @PPy nanocomposites are promising candidates for supercapacitor electrode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Ortho-hexagonal and highly-oriented NiMnCo-LDH/ZnO@CC self-supporting electrode derived from ZIF-67 covered ZnO nanorod-arrays is fabricated and employed for portable asymmetric solid-state supercapacitor. • Novel ortho -hexagonal NiMnCo-LDH has been synthesized. • ZIF-67 covered ZnO nanorod-arrays as self-supporting electrode is synthesized. • The fabricated electrodes exhibit superior electrochemical properties. • A multifunctional instrument can be powered for more than 30 mins. • The device can be carried outdoors to monitor time, temperature and air humidity. Metal-organic frameworks have attracted much attention due to their abundant redox sites and tunable characteristics, which are advantageous for energy storage applications. However, the low electrical conductivity, poor physical strength and undesirable capacity seriously hinder their applications. Therefore, designing effective and convenient strategies to build composites with unique structures will be of practical significance. Herein, we successfully generate NMC-LDH/ZnO@CC nanocomposites by growing ortho -hexagonal nickel–cobalt layered double hydroxide (NMC-LDH) nanosheets in-situ on ZIF-67 precursor covering vertical arrays of ZnO nanorods. As a result of the unqiue ortho -hexagonal structure, highly ordered arrangement of active substances and multi-dimensional spaces of the prepared NMC-LDH/ZnO@CC binder-free electrode, its capacitance is as high as 9258 mF cm−2 at a current density of 2 mA cm−2 and the capacitance retention is maintained at 87.5 % after 5000 cycles. Furthermore, in order to explore the practical value of the prepared binder-free electrode, the NMC-LDH/ZnO@CC//AC solid-state asymmetric supercapacitor device is assembled. The energy density of the assembled supercapacitor is 24.6 W h kg−1 at a power density of 170 W kg−1 and 1020 W kg−1 at an energy density of 11.8 W h kg−1. In addition, a versatile instrument for monitoring air humidity, time and ambient temperature in portable environments can be powered by a single ultracapacitor unit for more than 30 min. Overall, this study provides a unique strategy for synthesizing ZIF derivatives with novel morphologies for electrochemical energy storage applications. [ABSTRACT FROM AUTHOR]

Carbon nanotube-decorated nitrogen-doped carbon-coated nickel (CNT/Ni@N-C) microspheres have been fabricated by pyrolyzing the mixture of nickel-based metal organic framework (Ni-MOF) and melamine. The resultant composite is assembled from CNTs and spherical Ni@N-C composite. Besides, the CNT/Ni@N-C composite contains abundant nitrogen (N) dopants that contribute to defect dipole polarization. The melamine content is important for controlling the amount of N element and N dopant state in the composite. The optimized CNT/Ni@N-C composite with high content of pyridinic N exhibits strong absorption of −55.1 dB at 10.56 GHz with the thickness of 2.5 mm, and the effective absorbing bandwidth (reflection loss < −10 dB) is 11.2 GHz (6.0–17.2 GHz) with the thickness range of 1.5–4.0 mm. These results indicate that the N content and N dopant state have a great influence on electromagnetic wave absorption properties. This strategy will contribute to fabricate the carbon hybrid network consisting of metal organic frameworks derived metal/carbon hybrid and CNTs for electromagnetic wave absorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous NCS nanosheets are prepared by a one-step method. • CS@NCS/CC core–shell hetero-nanostructure with abundant mesopores is constructed. • Flexible CS@NCS/CC electrode can be bent and twisted at multiple angles. • CS@NCS/CC electrode exhibits excellent electrochemical performance. • CS@NCS/CC//AC/CC device continuously lights up a small bulb for 12 min. Flexible portable supercapacitor devices have gained increasing attention in the field of energy storage in recent years. However, challenges remain in the selection of applicable flexible materials and/or the preparation of materials. Through our research, we have effectively constructed a flexible CS@NCS/CC core–shell hetero-nanostructured cathode material by anchoring Co 9 S 8 (CS) nanopins on a flexible carbon cloth (CC) substrate firstly, and then wrapping NiCo 2 S 4 (NCS) nanosheets on the outer surface of CS nanopins. In this process, we have improved the traditional two-step method of preparing NCS nanosheets into a one-step method, which has greatly improved the efficiency of the material preparation. The prepared CS@NCS/CC material has abundant mesopores, stable core–shell heterostructures and multiple valence states of metal ions, which enable the CS@NCS/CC electrode material to have strong electrochemical reaction kinetics and excellent cycling stability. Additionally, the CC as the flexible substrate improves the charge transfer capability of the transition metal composite. Benefiting from the synergistic effect of these favorable factors, the electrode material exhibits a high C s value of 2020.6F g−1, which maintains 89.8% after 10,000 constant current charges and discharges. It is worth noting that the CS@NCS/CC can be folded and twisted at multiple angles, which proves that it can be used in wearable applications. The flexible hybrid supercapacitor CS@NCS/CC//AC/CC displays terrific energy density (58 Wh kg−1, at 800 W kg−1) with the synergistic effect of pseudocapacitance and electrical double-layer capacitance, and a capacitance retention rate of 92.9% after 10,000 cycles of constant current charging and discharging. Therefore, using CC as the flexible substrate and transition metal sulphides as the active material is an effective strategy for constructing high-performance flexible supercapacitors. [ABSTRACT FROM AUTHOR]

CeCoS x -SA/GF porous aerogels are fabricated based on sodium alginate with "egg-box" model and exhibited superior electrochemical properties as well as high mechanical strength. [Display omitted] • CeCoS x -SA/GF aerogels with "egg-box" structure is synthesized. • The CeCoS x -SA/GF electrode exhibits great electrochemical properties. • A portable multifunctional instrument can be powered for 28 mins. • Flexible CeCoS x -SA/GF/KOH/PVA film can be bent and twisted. • The CeCoS x -SA/GF/KOH/PVA film can lift 1 kg plastic bottle. Practical applications of flexible electrochemical energy storage devices are still limited by the lack of robust mechanical structures and high capacitive storage capabilities. Herein, the 3D CeCoS x -SA/GF porous aerogels are designed and prepared based on sodium alginate, which possess a special structure that can be explained by the so-called "egg-box" model. Each metal ion can be paired with the carboxyl and hydroxyl groups of the G monomer on two adjacent sodium alginate molecular chains. Melamine foam is used as carrier for graphene/sodium alginate impregnation and plays an important role on significantly limiting the agglomeration of graphene nanosheets due to their strong π-π stacking. The fabricated electrode based on CeCoS x -SA/GF shows an excellent electrochemical capacitance of 873.3F/g at the current density of 1A/g. In addition, the capacitance retention rate can still remain 87.1 % after 5000 cycles at a high current density of 8 A/g. Moreover, the fabricated all-solid state asymmetric supercapacitor device assembled with CoCeS x -SA/GF and active carbon shows an energy density of 29.58 Wh kg−1 at a power density of 801 W kg−1. For practical applications, the fabricated supercapacitor device can power a multifunctional display for 28 mins and illuminate a small light bulb for 3 mins. Moreover, the KOH/polyvinyl alcohol gel-electrolyte was used to fabricate high-strength and flexible CeCoS x -SA/GF/PVA/KOH composite film electrode, which can be bent at various angles (0°-180°) and can be twisted into various shapes. Notably, the CeCoS x -SA/GF/PVA/KOH composite film can lift plastic bottles containing 500 mL (500 g) and 1000 mL (1 kg) water, respectively, indicating that it has great application potential for wearable and portable electronic devices. [ABSTRACT FROM AUTHOR]

The use of molecular imprinting technology (MIT) to achieve specific recognition of target analytes is burgeoning research in the field of sensing. Herein, a UV self-initiated polymerized platform based on Au and TiO 2 co-functionalized fluorescent lanthanum metal-organic framework (La-MOF) has been first fabricated for the specific recognition and elimination of caffeic acid (CA). Impressively, the synthesis of the molecularly imprinted polymers (MIPs) needs no foreign initiator because the polymerization is initiated by hydroxyl radicals (•OH) photogenerated by TiO 2 under UV light, which is more environmentally friendly and more efficient than traditional MIT. More importantly, La-MOF can emit fluorescence to assist photocatalysis of TiO 2 under UV light while Au NPs can decompose the hydrogen peroxide photogenerated by TiO 2 to produce •OH to initiate the polymerization. As a result, with the aid of unique MIPs, the pre-fabricated sensor is utilized for the specific determination of CA by ultraviolet and visible spectrophotometry with the detecting range of 1–150 μM and a low limit of detection of 0.15 μM. Meanwhile, the determinations for CA in real environmental water samples have also been performed with good recoveries, revealing the auspicious application potential in environmental monitoring. A UV self-initiated polymerized platform is fabricated without any foreign initiators by molecular imprinting technology to simultaneously achieve the specific recognition and elimination of caffeic acid in solution under UV light. [Display omitted] • A UV self-initiated polymerized platform is fabricated to synthesize MIPs under UV light. • The synthesis of MIPs needs no foreign initiators and produces no environmental pollution. • The sensing probe based on the TiO 2 @La-MOF@Au is about 10.32 times that of TiO 2. • La-MOF can produce fluorescence to assist the photolysis of water under UV light. • Au is used as the peroxidase enzyme to decompose H 2 O 2 to produce •OH. [ABSTRACT FROM AUTHOR]

The specific detection of resorcin from its isomers is a current research hotspot. Thus in our work, a ternary hierarchical porous nanoprobe has been constructed based on the combination of cuttlefish ink and bimetallic Au@Ag nanoclusters for the specific sensing of resorcin. Briefly, through electrostatic interaction, Au@Ag core-shell nanoclusters are immobilized on the surface of polydopamine extracted from cuttlefish, which is turned into nitrogen-doped porous carbon functionalized by bimetallic Au@Ag by topological transformation subsequently. Afterward, an electrochemical sensor is fabricated based on the nanoprobes for specifically determining resorcin in solution by differential pulse voltammetry, and the linear detection ranges of the sensor are 1–100 μM and 1.2–4 mM while the detection limit reaches 0.06 μM. Meanwhile, the sensing mechanism of resorcin by the pre-fabricated sensor is detailedly studied by density functional theory to obtain a clear electrochemical process. Besides, the selectivity, stability, plus reproducibility of the pre-fabricated sensor have been also tested, and the determinations for resorcin in real environmental water samples have also been performed with good recoveries, revealing the auspicious application potential in the environmental monitoring. A ternary hierarchical porous nanoprobe composed of Au@Ag bimetallic core-shell nanoclusters and biological templates of cuttlefish ink has been fabricated through the topological transformation for the specific determination of resorcin. [Display omitted] • Ternary hierarchical porous nanoprobes with enormous surface area are fabricated. • The sensor can specifically recognize resorcin from three dihydroxybenzene isomers. • The specific sensing of resorcin with a detection limit of 0.06 μM has been achieved. • The recovery of real sample detection is 98–104%, revealing satisfactory feasibility. [ABSTRACT FROM AUTHOR]