Interconnected Nanosheet Arrays Research Articles

Multi-interface and rich-defects 1T phase MoS2 combine with FeS anchored on reduced graphene oxide for efficient alkaline hydrogen evolution

Exploring and fabricating noble-metal-free and cost-effective electrocatalysts to minimise the excessive potential required is of great significance for alkaline hydrogen evolution reaction (HER). Herein, we report FeS/1T-MP MoS2@rGO heterostructure with 1T and 2H mixed phase MoS2 (1T-MP MoS2) combining with FeS anchored on reduced graphene oxide (rGO) matrix, which is synthetized by utilizing Anderson polyoxometalate as Fe–Mo precursor by a facile hydrothermal method. The FeS/1T-MP MoS2@rGO heterostructure in the form of interconnected nanosheet arrays with multiple interfaces and rich-defects, which is in favor of the immersion of the electrolyte and exposing more active sites. Benefiting from the synergistic advantages of 1T-MoS2, FeS and rGO, FeS/1T-MP MoS2@rGO heterostructure delivers enhanced conductivity, enlarged electrochemical active surface area, and eventually promote the HER kinetics. As expected, FeS/1T-MP MoS2@rGO heterostructure emerges prominent HER activity with low overpotentials of 102 and 256 mV to achieve current density of 10 and 100 mA cm−2, outperforming vast majority of the advanced 1T MoS2-based alkaline HER electrocatalysts.

In situ self-assembled macroporous interconnected nanosheet arrays of Ni-1,3,5-benzenetricarboxylate metal − organic framework on Ti mesh as high-performance oxygen evolution electrodes

Highly efficient metal–organic framework (MOF)-based oxygen evolution reaction (OER) catalysts are desirable for water splitting, but their development remains challenging due to poor accessibility of coordinatively unsaturated metal (cum) sites and low intrinsic activity. A large-area three-dimensional (3-D) macroporous interconnected nanosheet array of Ni-1,3,5-benzenetricarboxylate has been in situ self-assembled on Ti mesh (TM) by using ethanol as the solvent and high-affinity oxide layer on TM to promote in situ nucleation. The obtained nanoarchitecture exhibits much superior catalytic activity compared to most reported catalysts including MOF-based catalysts, other precious-metal-free ones, and Ir/Ru-based ones. Additionally, this electrode undergoes no current decay after 300 cyclic voltammetry (CV) cycles and can maintain at 250 mA cm−2 for over 266 h. The excellent catalytic performance is mainly due to the 3-D macroporous and interconnected nanosheet array structure improving cum site exposure and charge transport and in situ activated cum cations enhancing OH− adsorption. This work not only develops a facile and economical approach to synthesize 3-D macroporous interconnected MOF nanosheet arrays to simultaneously increase the number, exposure, and intrinsic activity of active sites and facilitate charge transport for high-performance eletrocatalysis, but provides scientific insights into the mechanisms for self-assembly of this unique nanoarchitecture and for the high OER performance.

High-Performance Ternary NiCoMo Electrocatalyst with Three-Dimensional Nanosheets Array Structure.

Oxygen evolution reaction is a key process in hydrogen production from water splitting. The development of non-noble metal electrode materials with high efficiency and low cost has become the key factor for large-scale hydrogen production. Binary NiCo-layered double hydroxide (LDH) has been used as a non-noble metal electrocatalyst for OER, but its overpotential is still large. The microstructure of the catalyst is tuned by doping Mo ions into the NiCo-LDH/NF nanowires to form ternary NiCoMo-LDH/NF nanosheet catalysts for the purpose of enhancing the active sites and reducing the initial overpotential. Only 1.5 V (vs. reversible hydrogen electrode (RHE), ≈270 mV overpotential) is required to achieve a catalytic current density of 10 mA cm-2 and a small Tafel slope of 81.46 mV dec-1 in 1 M KOH solution, which manifests the best performance of NiCo-based catalysts reported up to now. Electrochemical analysis and micro-morphology show that the high catalytic activity of NiCoMo-LDH/NF is attributable to the change of the microstructure. The interconnected nanosheet arrays have the obvious advantages of electrolyte diffusion and ion migration. Thus, the active sites of catalysts are significantly increased, which facilitates the adsorption and desorption of intermediates. We conclude that NiCoMo-LDH/NF is a promising electrode material for its low cost and excellent electrocatalytic properties.

Facile synthesis of hierarchical flower-like NiMoO4-CoMoO4 nanosheet arrays on nickel foam as an efficient electrode for high rate hybrid supercapacitors

• Flower-like NiMoO 4 CoMoO 4 nanosheet arrays (NSAs) are grown on Ni foam using facile chemical bath deposition route. • NiMoO 4 CoMoO 4 NSAs used as a battery-type material for supercapacitor applications. • Unique NiMoO 4 CoMoO 4 NSAs are favourable for rapid ion and electron transfer. • NiMoO 4 CoMoO 4 NSAs electrode exhibit the superior electrochemical properties than bare NiMoO 4 and CoMoO 4 . • Hybrid supercapacitor (NiMoO 4 CoMoO 4 NSAs//G-ink) delivers the high specific energy, specific power and long-term cycling stability. Binder-free hierarchical flower-like NiMoO 4 CoMoO 4 nanosheet arrays (NSAs) have been successfully grown on nickel (Ni) foam surface via a facile one-step chemical bath deposition method followed by calcination treatment. The as-prepared NiMoO 4 CoMoO 4 NSAs electrode material has been effectively used as a battery-type material for supercapacitor applications. Surface morphological and structural studies reveal that the as-fabricated NiMoO 4 CoMoO 4 electrode exhibits a flower-like heterostructures constructed with interconnected nanosheet arrays. In a three-electrode system, the potential plateaus from the cyclic voltammetry and galvanostatic charge–discharge measurements indicate that the obtained NiMoO 4 CoMoO 4 NSAs electrode exhibits Faradic battery-type redox behaviour, which is different form the profiles of carbon-based materials. As a battery-type material, NiMoO 4 CoMoO 4 NSAs electrode delivers a remarkable specific capacity of (~236.86 mA h g −1 at 2 A g −1 ), excellent rate capability (~92.44% retains even at 10 A g −1 ), and superior cycling stability (~97.19% at 6 A g −1 over 5000 cycles), which are much higher than those of the bare NiMoO 4 and CoMoO 4 electrodes. The superior electrochemical properties of the NiMoO 4 CoMoO 4 composite material are due to the synergetic effect from CoMoO 4 and NiMoO 4 and to the fact that the hierarchical nanosheet arrays provide abundant electroactive sites for rapid redox reactions. Additionally, hybrid supercapacitor (HSC) has been assembled using NiMoO 4 CoMoO 4 NSAs/Ni foam as the positive electrode and graphene-ink/Ni foam as the negative electrode. It is found to exhibit a good cycling stability and a high specific energy of 27.58 Wh kg −1 at a specific power of 636.05 W kg −1 . Thereby, these electrochemical performances suggest that the as-fabricated NiMoO 4 CoMoO 4 NSAs are promising candidates for electrodes in high-performance supercapacitors.

Construction of FeNiP@CoNi-layered double hydroxide hybrid nanosheets on carbon cloth for high energy asymmetric supercapacitors

The rational design and fabrication of flexible pseudocapacitive materials with high energy density and superior cycling stability is desirable to high-performance supercapacitors. A hybrid FeNiP@CoNi-LDH assembled from FeNiP nanosheets and CoNi-LDH nanosheets have been vertically grown on carbon cloth via a sequential hydrothermal reaction, phosphorization treatment and electrodeposition strategy. The as-prepared FeNiP@CoNi-LDH possesses a large surface area, 3D interconnected nanosheet arrays architecture, hierarchical pore structure, and abundant active sites with multiple valances, which provides rapid electron and mass transfer channels within its conducive network. Impressively, as a binder-free electrode for supercapacitors, the FeNiP@CoNi-LDH electrode exhibits a high specific capacitance of 2280.6 F g−1 at a current density of 1 A g−1, outstanding rate capability (1222.2 F g−1 at 20 A g−1), and significantly improved cyclic stability (70.4% capacitance retention after 5000 cycles) compared to pure FeNiP and CoNi-LDH nanosheets, owing to its well-designed nanostructure and synergetic effect between two well-matched pseudocapacitive materials. Besides, an aqueous asymmetric supercapacitor device based on FeNiP@CoNi-LDH and porous carbon delivers a maximum energy density of 87.3 Wh kg−1 at a power density of 408.8 W kg−1, and an excellent cycling stability with a capacitance retention of 73.9% after 20,000 cycles.

고성능 슈퍼 커패시터용 전극재료의 결합재가 없는 배터리 타입 나노시트로 정렬된 CuSe 나노구조의 합성

Hierarchical CuSe interconnected nanosheet arrays (NSAs)-like structures are grown on nickel foam via a facile and low-cost chemical bath deposition technique. These CuSe electrodes are used as an efficient electrode material for supercapacitor without using any binders or conducting polymer additives. The structural, composition and morphological behaviors of the CuSe electrodes are characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy methods. The CuSe NSAs provide the abundant active sites, high conductivity and rapid charge transport, which resulting the low-charge transfer resistance at the interface of electrode-electrolyte. Cyclic voltammetry and galvanostatic charge-discharge plateaus from the CuSe electrode exhibit the Faradic battery-type redox behavior, which is distinct form the profiles of carbon based materials. As a battery-type electrode, the NSAs-like CuSe nanoarchitectures exhibits the outstanding electrochemical performances with a high specific capacity (∼192.93 mA h g-1at2Ag-1) and excellent cycling life(∼95.23% at 6Ag-1over3000cycles), respectively. Therefore, with the above findings, CuSe material has remarkable application potential in supercapacitors and could be effectively applied in other energy storage technologies.

Hierarchical Mo-doped CoP3 interconnected nanosheet arrays on carbon cloth as an efficient bifunctional electrocatalyst for water splitting in an alkaline electrolyte.

Design and fabrication of highly efficient and robust noble-metal-free bifunctional electrocatalysts for overall water splitting in alkaline media is challenging. Herein, we report a unique bifunctional electrocatalyst consisting of three-dimensional (3D) hierarchical Mo-doped CoP3 nanosheet arrays on carbon cloth (Mo-CoP3 NAs@CC) fabricated by a facile electrodeposition process and the subsequent PH3 plasma-assisted phosphorization. Benefiting from the hierarchical nanostructure and doping effect of Mo, the optimal Mo-CoP3-2@CC electrode demonstrates excellent HER and OER catalytic activity with an overpotential of 62 and 300 mV at 10 mA cm-2, respectively, and reasonable stability up to 20 h in 1.0 M KOH. Impressively, when Mo-CoP3-2@CC is used as both HER and OER electrodes in an alkaline electrolyzer, a current density of 10 mA cm-2 is achieved at a cell voltage of only 1.65 V, and the stable water-splitting current is maintained for 25 h, showing great promise for practical applications.

Electrodeposition of Ni-Co-S nanosheet arrays on N-doped porous carbon nanofibers for flexible asymmetric supercapacitors

In this work, a novel flexible electrode material for supercapacitor is prepared by electrodeposition of Ni-Co-S interconnected nanosheet arrays on N-doped hierarchical porous carbon nanofibers (Ni-Co-S@N-pCNFs). The electrode exhibits a remarkable specific capacitance of 520.2 F g-1 at the current density of 0.2 A g−1 and 670 F g-1 at 2 mV s−1. The activated charcoal (AC) loaded N-doped porous carbon nanofibers (AC@N-pCNFs) as electrode is also prepared which exhibits a specific capacitance of 257.2 F g-1 at 0.2 A g−1, as well as excellent cycling stability with a capacitance retention of 92.6% after 5000 cycles. Furthermore, the Ni-Co-S@N-pCNFs as the positive electrode, active carbon loaded N-doped hierarchical porous carbon nanofibers (AC@N-pCNFs) as negative electrode, and KOH/NKK hybrids as both the electrolyte and separator are assembled into flexible asymmetric supercapacitor. The assembled supercapacitor device without using any current collectors or binders shows a high energy density of 21.6 Wh·kg−1 at a power density of 134.9 W kg−1 and robust long-term cycling stability retaining over 90.0% after 3000 cycles at 1.0 A g−1. The as-assembled asymmetric supercapacitors (ASCs) have an outstanding mechanical flexibility and electrochemical stability and no significant attenuation occurred during cycling under different bending states.

Halloysite nanotubes favored facile deposition of nickel disulfide on NiMn oxides nanosheets for high-performance energy storage

The exploitation of electrode materials is extremely important for electrochemical energy storage systems with high energy and power densities as well as long lifespan. Herein, a facile halloysite nanotubes (HNTs) assisting deposition method is developed to prepare nickel disulfide interconnected nanosheet arrays on nickel manganese oxides (Ni-Mn-O) as electrodes for battery-type supercapacitors, resulting in exceptional energy storage performance. Taking advantage of the unique tubular architecture of hollow HNTs, gradient deposition of NiS2 and Ni-Mn-O nanosheets on HNTs are realized with two-step in-situ hydrothermal reaction and sulfidation. HNTs not only favor the formation of NiS2 during sulfidation but also offer good porosity for electrochemical energy storage. In solution state, the hybrid electrode exhibits a high capacity (1144.7C g−1 at 1 A g−1 and 597.5C g−1 at 20 A g−1) with excellent cyclic stability (92.6% after 2000 cycles). Solid-state symmetric supercapacitors fabricated with NiS2@Ni-Mn-O/HNT hybrid demonstrate outstanding electrochemical performance for portable energy storage application. Our symmetric supercapacitors show a highest energy density of 164.2 Wh kg−1 at a power density of 1.3 kW kg−1. The energy density remains as high as 28 Wh kg−1 even at the highest power density of 15.1 kW kg−1 with good long-term cycling stability (90.5% after 2000 cycles).

Microwave synthesis of three-dimensional nickel cobalt sulfide nanosheets grown on nickel foam for high-performance asymmetric supercapacitors

A facile and cost-effective microwave method is developed to prepare ternary nickel cobalt sulfide (NiCo2S4) interconnected nanosheet arrays on nickel foam (NF). When acting as an electrochemical supercapacitor electrode material, the as-prepared NiCo2S4/NF shows a high specific capacitance of 1502 F g−1 at a current density of 1 A g−1, and outstanding cycling stability of 91% capacitance retention after 8000 cycles. In addition, a asymmetric supercapacitor (ASC) is composed of NiCo2S4/NF as positive electrode and activated carbon as negative electrode, which exhibits a high energy density of 34.7 W h kg−1 at a power density of 750 W kg−1 and long-term cyclic stability (83.7% capacity retention after 8000 cycles). Even at a high power density of 15 kW kg−1, it still remains an energy density of 17.9 W h kg−1, which is able to light up a light-emitting diode. These findings provide a new and facile approach to fabricate high-performance electrode for supercapacitors.

Interconnected α-Fe2O3 nanosheet arrays as high-performance anode materials for lithium-ion batteries

The electrode materials with structure stability and binder-free are urgently required for improving the electrochemical performance of lithium-ion batteries. In this work, interconnected α-Fe2O3 nanosheet arrays directly grown on Ti foil were fabricated via a facile galvanostatic electrodeposition method followed by thermal treatment. The as-prepared α-Fe2O3 has an open network structure constituted of interconnected nanosheets and can be directly used as integrated electrodes for lithium-ion batteries. The α-Fe2O3 nanosheet arrays exhibit a high reversible capacity of 986.3mAhg−1 at a current density of 100mAg−1. Moreover, a reversible capacity of ca. 425.9mAhg−1 is achieved even at a superhigh current density of 10Ag−1, which is higher than the theoretical capacity of commercially used graphite. The excellent performance could be attributed to the efficient electron transport, the large electrode/electrolyte interfaces and the good accommodations for volume expansion from the interconnected nanosheet arrays structure.

One-Step Electrodeposited Nickel Cobalt Sulfide Nanosheet Arrays for High-Performance Asymmetric Supercapacitors

A facile one-step electrodeposition method is developed to prepare ternary nickel cobalt sulfide interconnected nanosheet arrays on conductive carbon substrates as electrodes for supercapacitors, resulting in exceptional energy storage performance. Taking advantages of the highly conductive, mesoporous nature of the nanosheets and open framework of the three-dimensional nanoarchitectures, the ternary sulfide electrodes exhibit high specific capacitance (1418 F g(-1) at 5 A g(-1) and 1285 F g(-1) at 100 A g(-1)) with excellent rate capability. An asymmetric supercapacitor fabricated by the ternary sulfide nanosheet arrays as positive electrode and porous graphene film as negative electrode demonstrates outstanding electrochemical performance for practical energy storage applications. Our asymmetric supercapacitors show a high energy density of 60 Wh kg(-1) at a power density of 1.8 kW kg(-1). Even when charging the cell within 4.5 s, the energy density is still as high as 33 Wh kg(-1) at an outstanding power density of 28.8 kW kg(-1) with robust long-term cycling stability up to 50,000 cycles.

Enhanced Rate Performance of Mesoporous Co3O4Nanosheet Supercapacitor Electrodes by Hydrous RuO2Nanoparticle Decoration

Mesoporous cobalt oxide (Co3O4) nanosheet electrode arrays are directly grown over flexible carbon paper substrates using an economical and scalable two-step process for supercapacitor applications. The interconnected nanosheet arrays form a three-dimensional network with exceptional supercapacitor performance in standard two electrode configuration. Dramatic improvement in the rate capacity of the Co3O4 nanosheets is achieved by electrodeposition of nanocrystalline, hydrous RuO2 nanoparticles dispersed on the Co3O4 nanosheets. An optimum RuO2 electrodeposition time is found to result in the best supercapacitor performance, where the controlled morphology of the electrode provides a balance between good conductivity and efficient electrolyte access to the RuO2 nanoparticles. An excellent specific capacitance of 905 F/g at 1 A/g is obtained, and a nearly constant rate performance of 78% is achieved at current density ranging from 1 to 40 A/g. The sample could retain more than 96% of its maximum capacitance even after 5000 continuous charge-discharge cycles at a constant high current density of 10 A/g. Thicker RuO2 coating, while maintaining good conductivity, results in agglomeration, decreasing electrolyte access to active material and hence the capacitive performance.