Conductive Ni Foam Research Articles

In-situ constructed NiCoZnS composite on nickel foam with hierarchical structures as bifunctional electrocatalysts for oxygen evolution reaction (OER) and supercapacitors

Transition metal sulfides have shown promise as candidates for energy storage and conversion devices, but the limited electroactive sites may greatly hinder further improvement. The novel nanostructured morphologies enhance active sites and surface area, thereby increasing overall electrochemical performance. Herein, we successfully synthesized various morphologies such as ZnS spheres, CoS star anise spice-like structures, and NiS flakes-like structures, which were directly grown on Ni foam using a single-step hydrothermal method. Additionally, the novel nanostructured morphologies were combined as a heterojunction NiCoZnS electrode to further utilize electronic and junction properties, thereby enhancing performance. This combination of morphologies—spheres, star anise spice, and flakes-like structures with ultrathin thickness and large surface areas—effectively increases the number of active sites, resulting in enhanced supercapacitor and oxygen evolution reaction (OER) performance. Moreover, directly growing nanostructures on conductive Ni foam endows the electrode materials with higher conductivity and richer active sites. In terms of supercapacitor performance, the NiCoZnS electrode exhibits a specific capacity of 1171.3 C g−1 at 0.5 A g−1 and remarkable rate performance. Furthermore, NiCoZnS maintains a capacitance retention of 94.9 % after 5000 cycles. As an electrocatalyst, NiCoZnS undergoes a rapid self-reconstruction process during the oxygen evolution reaction (OER), producing rich oxygen vacancies and thus demonstrating remarkable long-term stability. The NiCoZnS nanocomposites exhibit small overpotential (157 mV at 100 mA cm−2) and a Tafel slope of 128 mV dec−1. NiCoZnS's unique hierarchical nanostructures, doping-optimized electronic structural configuration, and specific surface lead to high catalytic performance. These remarkable performances of mixed morphologies like NiCoZnS hold great promise for energy storage and conversion devices.

Enhancement of urea oxidation reaction in alkaline condition via heterointerface engineering

Water electrolysis involving low energy barrier anodic urea oxidation reaction (UOR) is a promising way for hydrogen production. In this study, we present a superior heterostructured UOR electrocatalyst of (NiFeCo)Sx/FeOOH/NiFeCo(OH)x supported on conductive Ni foam prepared using a simple, ultrafast, energy-saving single-step corrosion engineering method. Leveraging the high conductivity of the (NiFeCo)Sx, plentiful Fe3+ in the amorphous FeOOH, high catalytic activity of the NiFeCo(OH)x, and abundant heterointerfaces, the resulting (NiFeCo)Sx/FeOOH/NiFeCo(OH)x electrode exhibits remarkable electrocatalytic performance toward UOR under alkaline condition. The electrocatalyst shows an ultra-low potential of 1.36 V at 100 mA cm−2, a small Tafel slope of 24.8 mV dec–1, and excellent stability. Density functional theory calculation shows that the multiple heterointerfaces provide synergistic effect of shifting the d-band center to optimize the intermediate chemisorption energy, thus boosting the catalytic kinetics for catalyzing UOR.

In situ growth of iron incorporated Ni3S2 nanosheet on nickel foam in mediating electron transfer to peroxymonosulfate for pollutant abatement

Catalytic oxidation of organic pollutants is a well-known and effective technique for pollutant abatement. Unfortunately, this method is significantly hindered in practical applications by the low efficiency and difficult recovery of the catalysts in a powdery form. Herein, a three-dimensional (3D) framework of Fe-incorporated Ni3S2 nanosheets in-situ grown on Ni foam (Fe-Ni3S2@NF) was fabricated by a facile two-step hydrothermal process and applied to trigger peroxymonosulfate (PMS) oxidation of organic compounds in water. A homogeneous growth environment enabled the uniform and scalable growth of Fe-Ni3S2 nanosheets on the Ni foam. Fe-Ni3S2@NF possessed outstanding activity and durability in activating PMS, as it effectively facilitated electron transfer from organic pollutants to PMS. Fe-Ni3S2@NF initially supplied electrons to PMS, causing the catalyst to undergo oxidation, and subsequently accepted electrons from organic compounds, returning to its initial state. The introduction of Fe into the Ni3S2 lattice enhanced electrical conductivity, promoting mediated electron transfer between PMS and organic compounds. The 3D conductive Ni foam provided an ideal platform for the nucleation and growth of Fe-Ni3S2, accelerating pollutant abatement due to its porous structure and high conductivity. Furthermore, its monolithic nature simplified the catalyst recycling process. A continuous flow packed-bed reactor by encapsulating Fe-Ni3S2@NF catalyst achieved complete pollutant abatement with continuous operation for 240 h, highlighting its immense potential for practical environmental remediation. This study presents a facile synthesis method for creating a novel type of monolithic catalyst with high activity and durability for decontamination through Fenton-like processes.

Interfacial Electronic Modulation of Mo5N6/Ni3S2 Heterojunction Array Boosts Electrocatalytic Alkaline Overall Water Splitting.

Bifunctional electrocatalysts with excellent activity and durability are highly desirable for alkaline overall water splitting, yet remain a significant challenge. In this contribution, palm-like Mo5N6/Ni3S2 heterojunction arrays anchored in conductive Ni foam (denoted as Mo5N6-Ni3S2 HNPs/NF) are developed. Benefiting from the optimized electronic structure configuration, hierarchical branched structure and abundant heterogeneous interfaces, the as-synthesized Mo5N6-Ni3S2 HNPs/NF electrode exhibits remarkably stable bifunctional electrocatalytic activity in 1m KOH solution. It only requires ultralow overpotentials of 59 and 190mV to deliver a current density of 10mAcm-2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1m KOH solution, respectively. Importantly, the overall water splitting electrolyzer assembled by Mo5N6-Ni3S2 HNPs/NF exhibits an exceptionally low cell voltage (1.48V@10mAcm-2) and outstanding durability, surpassing most of the reported Ni-based bifunctional materials. Density functional theory (DFT) further confirms the heterostructure can optimize the Gibbs free energies of H and O-containing intermediates (OH, O, OOH) during HER and OER processes, thereby accelerating the catalytic kinetics of electrochemical water splitting. The findings provide a new design strategy toward low-cost and excellent catalysts for overall water splitting.

Maximizing urea-/hydrazine-assisted electrolytic hydrogen production by defective nickel copper selenide nanostructures

Replacing the formidable oxygen evolution reaction (OER) with other oxidizable species is an appealing approach to attain highly efficient hydrogen (H2) generation with a lower potential. Accordingly, the kinetically favorable electrooxidation reaction of urea or hydrazine molecule can increase the return on energy profiteering and prevent pollutant emission. Thus, opening up an innovative direction to replace the sluggish OER and generate high-purity H2 gas via an energy-saving approach. Thus, constructing highly efficient and stable bifunctional electrodes/electrocatalysts is a key to realize economical and sustainable H2 production. In this work, we developed defect-enriched two-dimensional (2D) heterogeneous nickel copper selenide (D/Ni-Cu-Se) on a conductive Ni foam (NF) scaffold as an integrated bifunctional electrocatalytic electrode for energy-saving for H2 production. The self-supported D/Ni-Cu-Se/NF electrode with a regulated interfacial property and abundant metal defects is fabricated through a hydrothermal approach and a metal-defect engineering route. The thus-prepared electrode exhibits a high electrocatalytic performance for both hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) in a 1.0 M KOH electrolyte, achieving the catalytic current density of 10 mA cm−2 at a potential of 87.7 mV and 1.335 V vs. RHE, respectively. In relation, the two-electrode urea-water electrolyzer and hydrazine-water electrolyzer utilizing the bifunctional D/Ni-Cu-Se/NF as both the cathode and anode electrodes reveal a cell voltage of ∼ 1.395 V and 0.268 V at 10 mA cm−2 in 1.0 M KOH/0.33 M urea and 1.0 M KOH/0.25 M hydrazine, respectively, which is much less than that of conventional water electrolysis (1.572 V). The implemented electrolyzer systems consequently endow high long-term durability over 48 h of continuous electrolysis, indicating that the defect-rich D/Ni-Cu-Se/NF can serve as a potential bifunctional electrocatalyst with an outstanding electrolysis performance and excellent stability for H2 generation. Indeed, such a novel bifunctional electrode configuration and corresponding electrolysis performances are much desired for energy-saving electrolytic H2 production and pave the way for exploring highly efficient and robust electrodes.

Optimum iron-pyrophosphate electronic coupling to improve electrochemical water splitting and charge storage

Tuning the electronic properties of transition metals using pyrophosphate (P2O7) ligand moieties can be a promising approach to improving the electrochemical performance of water electrolyzers and supercapacitors, although such a material’s configuration is rarely exposed. Herein, we grow NiP2O7, CoP2O7, and FeP2O7 nanoparticles on conductive Ni-foam using a hydrothermal procedure. The results indicated that, among all the prepared samples, FeP2O7 exhibited outstanding oxygen evolution reaction and hydrogen evolution reaction with the least overpotential of 220 and 241 mV to draw a current density of 10 mA/cm2. Theoretical studies indicate that the optimal electronic coupling of the Fe site with pyrophosphate enhances the overall electronic properties of FeP2O7, thereby enhancing its electrochemical performance in water splitting. Further investigation of these materials found that NiP2O7 had the highest specific capacitance and remarkable cycle stability due to its high crystallinity as compared to FeP2O7, having a higher percentage composition of Ni on the Ni-foam, which allows more Ni to convert into its oxidation states and come back to its original oxidation state during supercapacitor testing. This work shows how to use pyrophosphate moieties to fabricate non-noble metal-based electrode materials to achieve good performance in electrocatalytic splitting water and supercapacitors.

Bifunctional Ni Foam Supported TiO2 @Ni3 S2 core@shell Nanorod Arrays for Boosting Electrocatalytic Biomass Upgrading and H2 Production Reactions.

Replacing traditional oxygen evoltion reaction(OER) with biomass oxidation reaction (BOR) is an advantageous alternative choice to obtain green hydrogen energy from electrocatalytic water splitting. Herein, a novel of extremely homogeneous Ni3 S2 nanosheets covered TiO2 nanorod arrays are in situ growth on conductive Ni foam (Ni/TiO2 @Ni3 S2 ). The Ni/TiO2 @Ni3 S2 electrode exhibits excellent electrocatalytic activity and long-term stability for both BOR and hydrogen evolution reaction (HER). Especially, taking glucose as a typical biomass, the average hydrogen production rate of the HER-glucose oxidation reaction (GOR) two-electrode system reached 984.74µmol h-1 , about 2.7 times higher than that of in a common HER//OER two-electrode water splitting system (365.50µmol h-1 ). The calculated power energy saving efficiency of the GOR//HER system is about 13% less than that of the OER//HER system. Meanwhile, the corresponding selectivity of the value-added formic acid produced by GORreaches about 80%. Moreover, the Ni/TiO2 @Ni3 S2 electrode also exhibits excellent electrocatalytic activity on a diverse range of typical biomass intermediates, such as urea, sucrose, fructose, furfuryl alcohol (FFA), 5-hydroxymethylfurfural (HMF), and alcohol (EtOH). These results show that Ni/TiO2 @Ni3 S2 has great potential in electrocatalysis, especially in replacing OER reaction with BOR reaction and promoting the sustainable development of hydrogen production.

Banyan wood-derived activated carbon and binder-free Co9S8/NF@PPy hierarchical flower-like electrodes: Na+ and K+ electrolytes based solid-state asymmetric supercapacitor

Supercapacitors require immediate electrode materials with outstanding performance. Here, a heterostructure Co9S8@PPy supported on conductive Ni foam (Co9S8/NF@PPy) is created utilizing hydrothermal and chemical polymerization techniques. The Co9S8/NF@PPy electrode exhibits an exceptional specific capacitance of 1485C g−1 and 1936C g−1 at a current density of 2 A g−1, respectively, using various Na2So4 and KOH electrolytes. The improved electrochemical efficiency could be attributed to the superior structural properties, the numerous active sites, the abundance of redox reactions, the strong synergistic effect in the heterogeneous conducting polymer composition, and the good conductivity resulting from the NF and the Co9S8/NF@Ppy. An asymmetric supercapacitors (HSCs) device is made utilizing activated carbon made from banyan wood (BWAC) as the negative electrode and Co9S8/NF@Ppy as the positive electrode to further assess the effectiveness of the Co9S8/NF@Ppy electrode in practical applications. The prepared BWAC material exhibits a high surface area of 1038 m3/g and a tiny pore size of 4 nm. The BWAC electrode exhibits high specific capacitance and volumetric capacitance of 156 Fg−1 and 89 Fcm−2 at a low current density of 2 A g−1. The different electrolyte-based assembled Asymmetric Solid-State Supercapacitor (ASSN and ASSK) constructed of Co9S8/NF@PPy and BWAC also exhibits power densities (4284, 2053Wkg−1) and energy densities (47.6, 73.5 Whkg−1) at a low current density of 2 A g−1. This study provides a framework for the optimal material preparation and logical electrode material design, including the enhancement of the characteristics of Ni foam-based materials for use in supercapacitors.

In-situ reconstruction of self-supported amorphous Ni-Mo electrode for stable hydrogen evolution at large and intermittent current density

Solar power drived water splitting for hydrogen production is pivotal for sustainable energy conversion. Yet, it is challenging to develop earth abundant, high active, and durable electrodes to catalyzing hydrogen evolution reaction (HER) under fluctuating solar electricity. Herein we report self-supprted NiMo phosphate (NiMo-Pi) electrodes, where amorphous NiMo-Pi with nanosheets-like structure grow directly on conductive Ni foam by a facile one-step hydrothermal treatment. The electronic structures of Ni and Mo are tuned by O and P in NiMo-Pi electrodes, resulting the down-shift of their d-band centers. NiMo-Pi electrodes offer high activity and stability for HER, delivering -100 and -500 mA cm−2 mgcat−1 with overpotentials of 343 and 461 mV, repectively. They also sustain long-term electrolysis at a constant industrial-level current density of 500 mA cm−2 and at dynamic current densities ranging from -10 to -1 000 mA cm−2. Their HER activity become higher after stability tests, benefitting from in-situ surface reconstruction. This reconstruction makes the surface rich in active higher-lying d-band centers. This work suggests that tuning the electronic structure of electrodes is an efficient way to design efficient and stable electrodes for HER under harsh conditions.

Phase-Controlled Synthesis of Nickel-Cobalt-Iron Sulfides By Electrodeposition for Efficient Oxygen Evolution Reaction

Water electrolysis is an appealing and sustainable technology to produce clean hydrogen fuels to resolve the energy and environmental crisis. The development of highly efficient, stable, and cost-effective electrocatalysts for oxygen evolution reaction (OER) is crucial for future sustainable energy systems. In this work, the synthesis of nickel-cobalt-iron sulfides deposited on Ni foam (NiCoFeS@NF) was successfully realized via a facile electrodeposition method. It was found that the deposition potentials could affect the phase and nanostructures of nickel-cobalt-iron sulfides. The electrocatalyst NiCoFeS@NF was obtained by applying a deposition potential of -1.2 V (vs. Ag/AgCl), which exhibits superior OER activity in alkaline media with overpotentials of 309 mV and 370 mV to reach the current densities of 20 mA cm-2 and 50 mA cm-2, respectively. The high OER activity of NiCoFeS@NF is mainly attributed to the collaborative advantages of trimetallic sulfides and the porous conductive Ni foam as substrate. The introduce of iron to nickel-cobalt sulfides could generate more active sites for OER, and Ni foam can provide large area for active sites and facilitate the mass transport during the electrochemical process. This study highlights the importance of the construction of trimetallic sulfides with heterostructures, providing insights into the OER performance.

Synthesis of nickel cobalt sulfide on Ni foam for improved electrochemical energy storage: Effect of binder-free reverse pulse potentiostatic electrodeposition and redox additive

Nickel cobalt sulfide (Ni-Co-S) was grown on 3D conductive Ni foam (NF) using binder-free electrochemical deposition to serve as a positive electrode (NCS@NF) for electrochemical energy storage application. Multiple cycles of reverse pulse potentiostatic electrochemical deposition (RPP-ED) were systematically applied to study their influence on the physico-chemical properties of NCS@NF. During the 300 optimized RPP-ED cycles uniform mesoporous interconnected nanoflakes of Ni-Co-S were formed on NF. The NCS@NF electrode demonstrated remarkable electrochemical storage performance, achieving a maximum areal capacity of 0.590 C cm−2 (590 C g−1) in 2 M KOH electrolyte. This remarkable property of NCS@NF can be associated with the improved ionic diffusion at the interconnected nanoflake structure and improved redox transitions at the active sites of nanoflakes. Moreover, the addition of K4(CN)6 as a redox additive improved the areal capacity of NCS@NF to 2.56 C cm−2 (2560 C g−1). Furthermore, an aqueous hybrid supercapacitor was assembled by integrating activated carbon on NF as the negative electrode, while employing NCS@NF as the positive electrode. The aqueous hybrid supercapacitor exhibited an enhanced charge-discharge potential of 1.5 V and demonstrated remarkable stability, maintaining 89% of its performance over 10,000 cycles. Notably, it achieved maximum energy and power densities, 33 μWh cm−2 and 6019 μW cm−2, respectively. These results establish its suitability for hybrid supercapacitor applications.

Prussian Blue Analogue-Assisted Formation of Iron–Nickel Selenide Porous Nanosheets for Enhanced Oxygen Evolution

The development of active and stable electrocatalysts made from earth-abundant elements to accelerate the oxygen evolution reaction (OER) kinetics is of great significance for improving the efficiency of overall water splitting. Herein, a Prussian blue analogue (PBA)-assisted strategy to synthesize FeSe–NiSe nanosheets is reported. With this approach, porous FeSe–NiSe nanosheets supported on conductive Ni foam (NF) are fabricated via controlled chemical etching of Ni(OH)2/NF with Fe(CN)63– and subsequent selenylation treatment. The as-derived FeSe–NiSe/NF electrode with unique interpenetrated porous three-dimensional (3D) network architecture successfully combines the desired merits including high conductivity and a large specific surface area. As a result, it exhibits enhanced electrocatalytic OER performance in alkaline media, which requires overpotentials of only 234 and 268 mV to deliver current densities of 10 and 100 mA cm–2, respectively, outclassing its counterpart NiSe/NF. Furthermore, the catalyst possesses a very low Tafel slope (22 mV dec–1) and excellent durability.

A comparative study on the oxygen evolution reaction of cobalt and nickel based hydroxide electrodes in alkaline electrolyte

• Co and Ni-based hydroxide nanostructures are prepared by electrodeposition. • Systematic comparison of five discrete electrocatalysts for OER. • Co(OH) 2 @Ni shows a favorable performance on water oxidation with better durability. Oxygen evolution reaction (OER) plays the key role in determining the kinetics of the electrochemical water splitting reaction. The natural abundancy and unique redox properties of transition metal-based (oxy)hydroxides with layered structure make them one of the most preferred OER electrocatalysts in alkaline medium. Herein, we fabricated a set of Co– and Ni-based hydroxide nanoflakes/nanowalls on conductive Ni foam substrate via a simple and quick electrochemical deposition method. OER experiments were systematically conducted on Co(OH) 2 @Ni, Ni(OH) 2 @Ni, NiCo LDH@Ni, Co(OH) 2 /Ni(OH) 2 @Ni, Ni(OH) 2 /Co(OH) 2 @Ni electrocatalysts. The results from the OER experiments reveal that Co(OH) 2 @Ni nanostructures are the best electrocatalyst with the lowest overpotential and have preserved their morphology after 24 h of chronopotentiometric test. It is believed that the current work will provide an idea of how Co– and Ni-based hydroxide or their combination can influence OER.

Dandelion‐like Nanospheres Synthesized by CoO@CuO Nanowire Arrays for High‐Performance Asymmetric Supercapacitors

AbstractRecently, three‐dimensional‐structure materials have attracted enormous attention in energy‐storage fields on account of their excellent electrochemical performance. In this study, hierarchical nanospheres consisting of mesoporous CoO@CuO nanowires on a three‐dimensional conductive Ni foam are prepared by a one‐step hydrothermal method combined with a subsequent annealing process. Compared to CoO or CuO alone, the as‐obtained CoO@CuO/Ni hybrid nanowires show good electronic conductivity owning to the abundant existence of O vacancies in them. In a three‐electrode system, the area capacitance of the prepared CoO@CuO/Ni electrode reaches 2.94 F cm−2 (1.32 C cm−2) at 1 mA cm−2, and the CoO@CuO/Ni electrode presents an outstanding cycle performance. Moreover, a CoO@CuO/Ni//AC ASC asymmetric supercapacitor is fabricated and found to display a high energy density of 20.22 Wh kg−1 at 800 W kg−1. Hence, this novel CoO@CuO/Ni hybrid nanowires with excellent electrochemical properties shows outstanding potential in the practical application of high‐energy storage devices.

Starfruit-like vanadium oxide with Co2+ pre-intercalation and amorphous carbon confinement as a superior cathode for supercapacitors

The vanadium dioxide (VO2(D)), with ultra-high theoretical capacitance, has been considered as a boon for electrode materials of advanced supercapacitors (SCs). However, the VO2 has a series of shortcomings such as poor electrical conductivity, severe structural damage, and rapid capacity fading during cycles, resulting in unsatisfactory electrochemical performance. Herein, the Co2+ pre-intercalation and amorphous carbon confined vanadium dioxide (CoxVO2@C) with starfruit-like nanostructure is synthesized on a conductive Ni foam substrate via a versatile and cost-effective method. As a cathode for SCs, the obtained CoxVO2@C not only enables a small amount of Co2+ pre-intercalation layer to offer faster ion diffusion kinetics for VO2, but also utilizes a high-conductivity amorphous carbon to protect VO2 from dissolution in an alkaline electrolyte, thereby exhibiting the ultrahigh specific capacitance up to 4440.0 mF cm−2 at 5 mA cm−2 (525.2 F g−1 at 2 A g−1) and the prominent long-term stability performance of the electrode. Benefited from these excellent characteristics, a high-performance CoxVO2@C//V2O3 hybrid supercapacitor (HSC) device with an operating voltage of 1.7 V is further assembled. The HSC device delivers a superior energy density of 102.3 W h kg−1 at a power density of 6.1 kW kg−1, manifesting its practical feasibility.

3D hierarchical flower-like CuCo2S4 as high energy density faradaic electrode

A direct one-step solvothermal approach was developed towards the preparation of flower-like CuCo2S4 (CCS) directly on the conductive Ni foam substrate. The morphological and structural studies of the synthesized materials were performed using XRD, HR-SEM and TEM studies, proves that the cubic spinel structured CCS flowers were decorated over the Ni foam substrate homogenously. The electrochemical performance of CCS was evaluated by cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD). Benefiting from the synergistic effect between the two metal ions and special microstrual effect, resulted in an admirably high specific capacity value of 966.45C g−1 (1607.93F g−1) at 5 A g−1 current density, excellent rate capability at various applied current density (ranging from 5 A g−1 to 30 A g−1) and cycling stability upto 5000 cycles at very high current density of 5 A g−1 with 66.12% capacity retention. Hence, the binder free spinel CCS flowers demonstrated its penitential aspect as high-performance faradic electrode material for supercapacitors.

Accelerating pH-universal hydrogen-evolving activity of a hierarchical hybrid of cobalt and dinickel phosphides by interfacial chemical bonds

A big challenge for hydrogen generation from electrocatalytic water splitting is the development of highly active and stable hydrogen-evolving electrocatalysts from noble-metal-free materials with excellent pH universality, since various water sources such as seawater, industrial wastewater and residential water can be employed as ideal ingredients. However, most of the available inexpensive electrocatalysts cannot exhibit superb catalytic activities in acidic, neutral and alkaline electrolytes with different pH values. Here we report an active and durable hybrid electrocatalyst based on metal phosphides in-situ synthesized on conductive Ni foam, which is demonstrated to exhibit Pt-like activity over a wide pH range. It requires as low as 36, 54 and 57 mV to achieve 10 mA cm−2 in acidic, neutral and basic environments, respectively, outperforming most of the pH-universal hydrogen-evolving electrocatalysts made of earth-abundant and non-noble elements. In particular, this CoP/Ni2P hybrid exhibits exceptional large-current durability for hydrogen evolution in different pH electrolytes, indicating its potential application for large-scale H2 production. Density functional theory studies confirm that the outstanding catalytic activity of this hybrid is attributed to the strong synergistic effects between the CoP(101) and Ni2P (001) planes, which lead to low Gibbs free energy for hydrogen adsorption. This work provides a simple and straightforward strategy toward the design and development of inexpensive and efficient all-pH electrocatalysts for hydrogen evolution reaction.

Manganese-doped tungsten disulfide microcones as binder-free electrode for high performance asymmetric supercapacitor

Manganese-doped tungstate sulfide (Mn-WS2) microcones were developed with varying levels of Mn, grown directly on electrically conductive Ni foam, and used as binder-free electrode material for supercapacitors. The experimental research indicates that Mn-WS2 microcones has significantly improved electrochemical activity and cyclic stability compared with pure WS2 due to additional ion diffusion channels. A strong synergy between the transitional metal ions in Mn-WS2 remarkably improved the redox activity, rate capability, and cycling stability. The Mn-WS2 microcones had a high specific capacitance of 107.79 mA h g−1 at 1 A g−1, a high rate capability of 75.18% at 20 A g−1, and 96.1% capacitance retention after 10,000 charge–discharge cycles. The effect of Mn ions on the electrochemical performance of WS2 microcones was also studied in detail. The enhanced electrochemical performance of the electrode can be attributed to the unique structural features of WS2 microcones arrays grown in Ni foam, which allow the surface of WS2 to be highly accessible to electrolyte ions. Furthermore, an all solid state asymmetric supercapacitor (ASCs) assembled with Mn-WS2 microcones as anode and GO/Fe3O4 cathode (Mn-WS2//PVA-KOH// GO/Fe3O4) delivered high specific energy of 70.65 W h kg−1 at 997.41 W kg−1. These results confirm that Mn-WS2 with outstanding electrochemical properties could be a promising electrode material for practical application in electrochemical energy storage field.

Embellishing hierarchical 3D core-shell nanosheet arrays of ZnFe2O4@NiMoO4 onto rGO-Ni foam as a binder-free electrode for asymmetric supercapacitors with excellent electrochemical performance

Tailoring hierarchical hybrid core-shell electrodes with impartial microstructural features and excellent electroactive constituents is crucial for the design of high-performance supercapacitors (SCs). Herein, for the first time, we fabricate uniformly aligned porous ZnFe2O4 (ZFO) nanosheet arrays onto reduced graphene oxide-garnished conductive Ni foam (rGO-NF) substrates and subsequently embellish the first layer of ZFO nanosheets with morphology-controlled secondary NiMoO4 nanosheets to achieve a hierarchical 3D core-shell structure of ZnFe2O4@NiMoO4 nanosheet arrays (NSAs) onto rGO-NF for SC applications. Improving the synergistic effect of the core-shell nanoarchitecture with a conductive rGO-NF substrate, the hierarchical 3D ZFO@NMO NSAs tend to have superb electronic conductivity, tailoribility, effective nanoporous channels, and appropriate roadways for rapid ion/electron transfer, which are required for rapid reversible redox reactions, thus reflecting the excellent electrochemical features, including the excellent specific capacitance, good rate performance, and prolonged cyclic performance of the three electrode assemblies for SCs. An asymmetric supercapacitor (ASC) device composed of ZFO@NMO NSAs@rGO-NF as the cathode and MOF-derived hollow porous carbon (MDHPC) as the anode exhibits a high energy density of 58.6 Wh kg-1 at a power density of 799 W kg-1 with prolonged cyclic durability (89.6 % after 7000 cycles), thus indicating its potential applicability towards advanced hybrid SCs.

In Situ Electrochemical Activation Derived Lix MoOy Nanorods as the Multifunctional Interlayer for Fast Kinetics Li-S batteries.

Li-S batteries (LSBs) have attracted worldwide attention owing to their characteristics of high theoretical energy density and low cost. However, the commercial promotion of LSBs is hindered by the irreversible capacity decay and short cycling life caused by the shuttle effect of lithium-polysulfides (LiPSs). Herein, a hybrid interlayer consisting of MoO3 , conductive Ni foam, and Super P is prepared to prevent the shuttle effect and catalyze the LiPSs conversion. MoO3 with a reversible lithiation/delithiation behavior between Li0.042 MoO3 and Li2 MoO4 within 1.7-2.8V versus Li/Li+ combines the Li+ insertion and LiPSs immobilization and efficiently improve the LSBs redox kinetics. Benefiting from the reversible Li+ insertion/extraction in lithium molybdate (Lix MoOy ) and the highly conductive Ni foam substrate, the sulfur cathode coupled with such electrochemical activation derived catalytic interlayer exhibits a high initial discharge capacity of 1100.1 mAh g-1 at a current density of 1 C with a low decay rate of 0.09% cycle-1 . Good capacity retention can still be obtained even the areal sulfur loading is increased to 13.28mg cm-2 .