NiCo-layered Double Hydroxide Research Articles

A low-cost and efficient route for large-scale synthesis of NiCoSx nanosheets with abundant sulfur vacancies towards quasi-industrial electrocatalytic oxygen evolution

Transition-metal sulfides (TMS) have piqued a great deal of interest due to their unprecious nature and high intrinsic catalytic activity for water splitting. In this work, a low-cost and efficient route was developed, which included electrodeposition to prepare Ni-Co layered double hydroxide (NiCo-LDH) followed by ion exchange to form nickel cobalt sulfide (NiCoSx). Electrochemical reduction was used to modulate sulfur vacancies in order to produce sulfur vacancies-rich NiCoSx with nanosheet arrays on -three-dimensional nickel foam (NiCoSx-0.4/NF) with a large area of more than 250 cm2. Combining data from experiments and density functional theoretical (DFT) calculations reveals that engineered sulfur vacancies change the electronic structure, electron transfer property, and surface electron density of NiCoSx, significantly improving the free energy of water adsorption and boosting electrocatalytic activity. The developed NiCoSx-0.4/NF has long-term stability of more than 300 h at 500 mA cm−2 in 1 M KOH at ambient temperature and only needs a 289 mV overpotential at 100 mA cm−2. Remarkably, the synthesized electrocatalyst rich in sulfur vacancies, exhibits exceptional performance with a high current density of up to 1.9 A cm−2 and 1 A cm−2 in 6 M KOH and leads to overpotentials of 286 mV at 80 °C and 358 mV at 60 °C, respectively. The catalyst's practicability under quasi-industrial conditions (60 °C, 6 M KOH) is further demonstrated by its long-term stability for 220 h with only a 3.9 % potential increase at 500 mA cm−2.

The Guest Doping Effects of Fe on Bimetallic NiCo Layered Double Hydroxide for Enhanced Electrochemical Oxygen Evolution Reaction: Theoretical Screening and Experimental Verification

AbstractExploring efficient transition‐metal‐based electrocatalysts for oxygen evolution reaction (OER) is imperative but remain challenging for sustainable energy storage and conversion systems. Foreign species doping is a significant regulation strategy to enhance the intrinsic activity of host matrix. However, the potential relationship of structure‐activity caused by guest doping elements is seldom tracked systematically. In this case, both theoretical screening and experimental verification are complementarily employed to investigate the guest doping effects of ten first‐row transition metals (Sc∼Zn) on bimetallic NiCo layered double hydroxide (NiCo‐LDH). As a result, the optimized Fe‐doped NiCo‐LDH is identified as the most promising candidate toward alkaline electrocatalytic OER, which exhibits the quasi‐industrial current density of 1000 mA cm−2 at overpotential of 400 mV. Meanwhile, it also shows impressively long‐term stability of 500 h at 500 mA cm−2 with a negligible activity loss. Moreover, in situ electrochemical Raman spectroscopy unveils the dynamic structure evolution from pre‐catalytic state (Fe‐NiCo‐LDH) to metal oxyhydroxide (Fe‐(NiCo)OOH) during the oxidation reaction, and ab‐initio molecular dynamics simulations are further performed to confirm the thermodynamic stability of activated Fe‐(NiCo)OOH phase. This work provides a promising platform for exploring the critical role of transition metal guest doping on host matrix in developing industrially required OER electrocatalysts.

Glucose pillared Ni-Co layered double hydroxide clay materials toward durable cathodes for alkaline zinc batteries

Alkaline Ni-Zn batteries are gaining more and more attention because of their safety, environmental friendliness, low cost and excellent performance. However, the volume and structure of the cathode changes during the charging and discharging process, resulting in particle flaking and structural rupture during the cyclic charging and discharging process, thus reducing their cyclic stability and limiting wide application. Herein, NiCo Layered double hydroxides (LDHs)clay materials with a low crystallinity multilayer nanosheet structure are prepared by glucose intercalation as cathode materials for alkaline Ni-Zn batteries. Expanded NiCo LDH layer spacing through glucose intercalation reduces interlayer peeling and collapse, accelerates interlayer diffusion of ions, and thus improves electron transport performance. NiCo LDH-G1.5 electrode material provides a specific capacity of 224 mAh g-1 and a capacity retention rate of 76% at a current density of 40 A g-1, 2000 cycles to maintain 86% of maximum capacity. Alkaline NiCo LDH-G1.5//Zn battery, a specific capacity of 180 mAh g-1 can be achieved at a high current density of 20 A g-1 and still maintain 76% of their maximum capacity after 2000 cycles, a maximum energy density of 364 Wh kg-1 and a maximum power density of 54 kW kg-1. This work provides a viable cathode for the development of high specific capacity and stable alkaline Ni-Zn batteries.

Fabrication of NiCo Layered Double Hydroxide on Carbon Fiber Paper as High Performance Binder-free Electrode for Supercapacitors

Design of binder-free electrode with high performance exhibits great glamour for energy storage devices recently. Herein, nickel cobalt layered double hydroxide (NiCo LDH) has been directly grown on carbon fiber paper (CFP) by an electrodeposition method. Thanks to the porous nanosheet-like morphology of the deposits, the high conductivity of carbon fibers, as well as the strong connection between the deposits and the substrate, the optimized electrode, labeled as NiCo LDH-2/CFP can deliver a discharge specific capacitance of 878.4 F g−1 at 1 A g−1, which can increase to 1080.0 F g−1 at 20 A g−1, exhibiting excellent rate performance. Moreover, after cycled at 5 A g−1 for 5000 cycles, the capacitance of the electrode can retain 96.1%, manifesting unique cyclic stability. This work provides a new strategy for preparing high performance binder-fee electrodes for supercapacitors, lithium batteries and catalytes.

Fabrication of NiCo@Ni3S2/Nickel foam electrocatalyst with ultrathin NiCo layered double hydroxide film wrapping Ni3S2 nanoarrays for efficient oxygen evolution reaction

Developing efficient and durable electrocatalysts for faster anodic oxygen evolution reaction (OER) in water electrolysis is significant to hydrogen production. In this study, an electrocatalyst NiCo@Ni3S2/NF for OER was prepared using a two-step method. Ni3S2 nanoarray was initially grown on a nickel foam (NF) substrate, followed by the deposition of an ultrathin NiCo layered double hydroxides (LDH) film that wrapped around the surface of Ni3S2/NF to form a hill-shaped morphology. Characterization results of SEM, TEM, and XPS confirmed the presence of a heterogeneous interface with an enlarged contact area between NiCo LDH and Ni3S2 in this unique structure. This leads to more active species such as Ni3+ and Co3+, resulting in enhanced intrinsic catalytic activity. This hill-shaped topography also demonstrated to be conducive to the release of oxygen bubbles generated during OER process. The prepared electrocatalyst NiCo@Ni3S2/NF exhibits a rapid charge transfer rate and a Tafel slope as low as 63 mV·dec−1. It therefore demonstrates excellent OER performance with a low overpotential of 245 mV at current density of 10 mA cm−2, and long-term stability under both currents of 10 and 50 mA cm−2.

Hierarchical 3D architecture NiCo–layered double hydroxide decorated functionalized halloysite nanotubes composite. An efficient electrocatalyst for ractopamine detection

As a nutrient partitioning agent and a growth stimulator, ractopamine (RCT) enhances the feed efficiency in animal-based food products and further it is employed clinically in certain pharmaceuticals. Subsequently, metabolites of RCT have long shelf life in animals associated with deleterious repercussions in humans. It is thus, vital to develop an effective design for screening method towards RCT detection to ensure human health, food and environmental safety. Thus, we present an integrate electrocatalyst hydrothermally designed by employing NiCo–LDH (NiCo- Layered Double Hydroxides) and F-HNT (functionalized- Halloysite nanotubes) and further utilized in the electrochemical sensing of RCT. The novelty of the present work shed light upon the unique assembly of the two individual NiCo–LDH and F-HNT components with superior structural features that resulted in a hybrid matrix. The outcomes of CV and i-t analysis under optimum conditions demonstrate outstanding electrochemical performance of the NiCo–LDH/F-HNT modified GCE sensor with a wide linear range 0.003–631 μM and low detection limit 1.1 nM, enhanced selectivity towards the detection of RCT. The uniquely engineered electrode material has therefore been applied to quantitate RCT levels in real-world samples in terms of practical applications.

Simple construction of NiCo-LDH@FeOOH nanoflower heterostructure by chemical etching strategy for efficient oxygen evolution reaction

The large overpotential and slow kinetics of the oxygen evolution reaction (OER) on an anode seriously reduces the water splitting efficiency. Herein, the FeOOH decorated NiCo-layered double hydroxides (NiCo-LDH@FeOOH) nanoflower heterostructure electrocatalyst is synthesized using a simple one-step ZIF-67 derivation and chemical etching strategy. Owing to the unique 3D heterogeneous nanoflowers structure formed by etching, the strong interface interaction regulates the electronic structure, and combined with the synergistic effect between the three metals, the electrochemical activity of the catalyst is significantly increased. NiCo-LDH@FeOOH exhibits superior OER activity with a low overpotential of 255 mV at a current density of 50 mA cm–2 under alkaline conditions and provides long-term durability (73 h). Moreover, experiments and density functional theory calculations reveal that the Co-site synergistically promote the OER activity of the Fe site. This study sheds new light on constructing LDH-based heterogeneous composite electrocatalysts.

Ultrafine Bimetallic Nickel–Cobalt Alloy from a Layered Hydroxide for Oxygen Evolution Reaction and Capacitors

NiCo bimetallic alloys on layer double hydroxide-derived nitrogen-doped carbon support (NiCo@LDH-NC) were derived from bimetallic NiCo-layered double hydroxides (NiCo@LDH). With the structural and compositional advantages, NiCo@LDH-NC exhibits an XRD pattern of NiCo alloy particles supported by X-ray absorption spectroscopy (XAS) analysis, high-resolution transmission electronic microscopy (HR-TEM) imaging, and HR-TEM lattice spacing analysis, which confirms the NiCo alloy particle with coherent substitution of Co strongly aligned with the (111) plane of Ni particles. This resulted in a strained lattice of the NiCo alloy (fcc) with strong interaction between pure Ni and Co metals. The relation of the host Ni (fcc) lattice with dopant Co in NiCo@LDH-NC exhibits a free atom-like electronic structure as compared to host Ni. In the oxygen evolution reaction (OER) of water electrolysis, the monolayer electrode of NiCo@LDH-NC exhibits minimum overpotentials of 330 and 346 mV at 10 and 20 mA cm–2, respectively, with an improved electrokinetics-driven 36.4 mV dec–1 Tafel slope obtained from the Tafel plot. The charge transfer resistance (Rct) value obtained for NiCo@LDH-NC was 2.48 Ω, confirming a faster charge transfer kinetics throughout the electrode-electrolyte interface that influenced the OER activity. This investigation on the NiCo alloy and associated electronics is promising for upgrading the features of the bimetallic alloy nanoarchitecture and their potential for advanced electrochemical processes.

Ni-Co layered double-hydroxide arrays on stainless steel substrate: Interfacial hydroxide layer enhanced electrocatalyst with high stability for oxygen evolution reaction in alkaline media

High-efficiency electrocatalysts for oxygen evolution reaction (OER) are highly desired during large-scale water electrolysis in hydrogen production. In this work, a commercial stainless steel (SS) mesh substrate is activated through an alternate acid etching/alkali-hydrothermal treatment to form an interfacial hydroxide layer. Subsequently, a seamless integrated electrode including Ni-Co layered double hydroxide (NiCo-LDH) nanoarrays and SS substrate is successfully synthesized. The pre-formed interfacial layer guides the growth of NiCo-LDH nanoarrays, and firmly connect NiCo-LDH nanoarray and stainless steel substrate, wherein a durable catalyst with high activity and low resistance nature for OER is constructed. The as-prepared integrated electrode delivers the low OER overpotential of 243 and 292 mV for 10 and 250 mA cm−2 current densities respectively, and excellent long-term durability over 100 h in 1 M KOH solution. Electrocatalysis studies reveal the role of the interfacial hydroxide layer on the growth and catalytic activity of NiCo-LDH nanoarrays, and structural stability in durability test.

Facile design and synthesis of nickel foam@Mxene@NiCo layered hydroxides core-sheath nanostructure for high mass-loading of supercapacitors

NiCo layered double hydroxides (NiCo-LDH) represent widespread application in supercapacitor owing to the unique two-dimensional layer structure. However, improving its electrochemical energy storage and cycle stability with high mass-loading remains a huge challenge. By introducing self-assembled Ti3C2Tx (Mxene) on the surface of nickel foam (NF) and then electrodepositing NiCo-LDH, a hierarchical nickel foam@Ti3C2Tx@NiCo layered hydroxides (NF@Mxene@NiCo-LDH) ternary core-sheath nanostructure with high mass-loading is created in this article. The synergistic effect of Mxene and NiCo-LDH greatly improves the cycling stability of the composites. When NF was immersed in Ti3C2Tx solution three times and then electrodeposited for 1000s, the obtained composite electrode NF@Mxene@NiCo-LDH (denoted as M3-NC (1000)) owns a high mass loading up to 14 mg cm−2. The M3-NC (1000) has an areal capacitance of 22.6 F cm−2 at a current density of 5 mA cm−2 and a mass-specific capacitance of 224 mAh g−1 at 0.375 A g−1. The asymmetric supercapacitor with M3-NC (1000) as the positive electrode and AC as the negative electrode achieves an energy density of 3.79 mWh cm−2 at a power density of 3.74 mW cm−2, which is significantly better than the previously reported work of NiCo-LDH. The device also exhibits excellent cycling stability with capacitance retention of 87% after 10,000 cycles at a current density of 200 mA cm−2. This work highlights the design approach of electrode material with high mass-loading for advanced energy applications.

Sheet-like NiCo-layered double hydroxide anchored on NiTi alloy wire for extraordinary shape memory and high-performance supercapacitors

Sheet-like NiCo-layered double hydroxide anchored on NiTi alloy wire for extraordinary shape memory and high-performance supercapacitors

A robust perovskite photosensitizer for efficient visible-light-driven CO2 reduction

Efficient conversion of CO2 to valuable fuels via artificial photosynthesis under visible-light irradiation is of great significance. However, traditional photocatalytic systems based on homogeneous photosensitizers (PSs) usually suffer from high costs and poor stability. Herein, we report all-inorganic perovskite CsPbBr3 quantum dots (QDs) as a robust PS for efficient visible-light-driven CO2 photoreduction. This perovskite PS-based photocatalytic system, using NiCo-layered double hydroxide (LDH) as a catalyst, offers 204.4 μmol g−1 h−1 of CO evolution rate and 100% selectivity under visible-light irradiation over 35 h. The efficient electron transfer from CsPbBr3 QDs to the catalyst is demonstrated by ultrafast transient absorption analysis. The key role of oleylamine on CsPbBr3 QDs as a sacrificial electron donor in improving the photostability of the photocatalytic system is verified via systematic control experiments. This work sheds light on the rational design of efficient CO2 photocatalytic systems with low cost and long-term photostability.

A composite structural supercapacitor based on Ni–Co-layered double hydroxide–coated carbon cloth electrodes

Composite structural supercapacitors (CSSs) are valuable for their use in structural optimization because they can provide energy storage capacity while bearing mechanical loads, thereby enabling weight and volume reduction. Herein, flexible energy storage devices are embedded into carbon fiber reinforced polymer (CFRP) to form a CSS. In the flexible device, a positive electrode (carbon cloth coated with Ni–Co-layered hydroxide, NiCo-LDH@CC), a negative electrode (activated carbon–coated carbon cloth, AC@CC), and a separator (glass fabric) are bonded together by PVA-KOH gel electrolyte. The CSS (5:5 NiCo-LDH-CSS) provides competitive electrochemical properties (specific capacitance of 610 mF g−1, energy density of 191 mWh kg−1, and power density of 1,508 mW kg−1) and good mechanical properties (flexural strength of 495 MPa and flexural modulus of 125 GPa). The study conducts a systematic analysis of capacity decay during the electrochemical cycling process of 5:5 NiCo-LDH-CSS. In-situ mechano-electrochemical tests are also performed to verify the stable electrochemical behavior under external dynamic and static loads, which is a rarely studied aspect in other reports. This investigation provides assurance for the safety and reliability of future CSS applications. The study findings suggest that the 5:5 NiCo-LDH-CSS possesses good multifunctionality, and can provide a new idea for further development in CSSs.

Hydrangea-like NiCo-layered double hydroxide core-shell structure growing on licorice porous carbon for high-performance supercapacitors

Hydrangea-like NiCo-layered double hydroxide core-shell structure growing on licorice porous carbon for high-performance supercapacitors

Atomically Dispersed Silver Atoms Embedded in NiCo Layer Double Hydroxide Boost Oxygen Evolution Reaction.

Bimetallic layered double hydroxides (LDHs) are promising catalysts for anodic oxygen evolution reaction (OER) in alkaline media. Despite good stability, NiCo LDH displays an unsatisfactory OER activity relative to the most robust NiFe LDH and CoFe LDH. Herein, a novel NiCo LDH electrocatalyst modified with single-atom silver grown on carbon cloth (AgSA -NiCo LDH/CC) that exhibits exceptional OER activity and stability in 1.0m KOH is reported. The AgSA -NiCo LDH/CC catalyst only requires a low overpotential of 192mV to reach a current density of 10mA cm-2 , obviously boosting the OER activity of NiCo LDH/CC (410 mV@10mA cm-2 ). Inspiringly, AgSA -NiCo LDH/CC can maintain its high activity for up to 500h at a large current density of 100mA cm-2 , exceeding most single-atom OER catalysts. In situ Raman spectroscopy studies uncover that the in situ formed NiCoOOH during OER is the real active species. Hard X-ray absorption spectrum (XAS) and density functional theory (DFT) calculations validate that single-atom Ag occupying Ni site increases the chemical valence of Ni elements, and then weakens the adsorption of oxygen-contained intermediates on Ni sites, fundamentally accounting for the enhanced OER performance.

High electrochemical performance of MnCo2O4.5 nanoneedles/NiCo LDH nanosheets as advanced electrodes of supercapacitor

MnCo2O4.5@NiCo layered double hydroxides (LDHs) are synthesized on nickel foam (NF) using the hydrothermal-calcination-hydrothermal method. It retains MnCo2O4.5 nanoneedles and NiCo LDH nanosheets structures, improving its electrochemical performance. The composite has an excellent specific capacity (1266 C g−1 when current density is 2 A g−1) and deliver an outstanding initial capacity retention (96.8% when current density is 20 A g−1). Moreover, the self-assembled MnCo2O4.5@NiCo LDH/NF//AC (actived carbon) asymmetric supercapacitor (ASC) provides the highest energy density of 33.3 W h kg−1 when the power density is 798 W kg−1 and has a long cycle life of 81% at 5 A g−1 after 7000 cycles. The above results provide a useful strategy for new-generation energy storage devices with excellent properties.

Multi‐layer Architecture of Novel Sea Urchin‐like Co‐Hopeite to Boosting Overall Alkaline Water Splitting

AbstractElectrochemical water splitting coupled with renewable energy offers a promising avenue for energy conversion and storage, but it is also extremely suppressed by the sluggish kinetics of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, a multi‐layer architecture strategy was utilized by the in situ growth for cobalt phosphate of Hopeite‐like phase (Co‐H) on NiCo‐layered double hydroxide (NiCo‐LDH) to prepare a self‐supported electrode (Co‐H/NiCo@NF). The Co‐H formed over the NiCo‐LDH shows a unique sea urchin‐like morphology. The Co‐H/NiCo@NF displays excellent HER and OER activity, requiring only overpotentials of 180 mV and 350 mV to deliver 100 mA cm−2, consequently, be capable to generate an appealing cell potential of 1.76 V for overall water splitting at the corresponding current density. In addition, the prepared Co‐H/NiCo@NF has long‐term stability against 500 mA cm−2 and exhibits a trend of increased activity, which may associate with the structural reconstructions to form new phases and the strong bonding between layers. These findings demonstrate that the multi‐layer architecture with fine‐component modulation is a promising strategy for the development of robust and efficient cobalt phosphate electrocatalysts, and the role of multi‐layer in the evolution of structural reconstructions deserves further investigation.

Optimized Fabrication of Bimetallic ZnCo Metal-Organic Framework at NiCo-Layered Double Hydroxides for Multiple Storage and Capability Synergy All-Solid-State Supercapacitors.

Rational design and structural regulation of hybrid nanomaterials with superior electrochemical performance are crucial for developing sustainable energy storage platforms. Among these materials, NiCo-layered double hydroxides (NiCo-LDHs) demonstrate an exceptional charge storage capabilities owing to their tunable 2D lamellar structure, large interlayer spacing, and rich redox electrochemically active sites. However, NiCo-LDHs still suffer from sever agglomeration of their particles with limited charge transfer rates, resulting in an inadequate rate capability. In this study, bimetallic ZnCo-metal organic framework (MOF) tripods were grown on the surface of NiCo-LDH nanowires, which significantly reduced the self-agglomeration and stacking of the NiCo-LDH nanowire arrays, offering more accessible active sites for charge transfer and shortening the path for ion diffusion. The fabricated hybrid ZnCo-MOF@NiCo-LDH and its individual counterparts were tested as supercapacitor electrodes. The ZnCo-MOF@NiCo-LDH electrode demonstrated a remarkable specific capacitance of 1611 F g-1 at 2 A g-1 with an enhanced rate capability of 66% from 2 to 20 A g-1. Moreover, an asymmetric all solid-state supercapacitor device was constructed using ZnCo-MOF@NiCo-LDH and palm tree-derived activated carbon (P-AC) as positive and negative poles, respectively. The constructed device can store a high specific energy of 44.5 Wh Kg-1 and deliver a specific power of 876.7 W Kg-1 with outstanding Columbic efficiency over 10,000 charging/discharging cycles at 15 A g-1.

Raw sugarcane juice assisted hybrid electrolysis for formic acid and hydrogen production based on reversible redox cycle of CoNi LDH

The major bottleneck in self-powered water splitting devices by renewable energy lies in the kinetically sluggish oxygen evolution reaction (OER), which only produces low-value oxygen. Herein, we explore sucrose electrooxidation as an alternative anodic reaction for production of valuable chemicals at a reduced electricity consumption. By developing a reversible redox cycle of Ni2+/Ni3+ and Co2+/Co3+ in the CoNi layered double hydroxide (LDH), the required voltage of sucrose oxidation for 100 mA cm−2 is reduced by 240 mV compared to oxygen evolution. The sucrose electrooxidation by CoNi LDH is a two-step reaction including the electrooxidation of Ni2+/Co2+ to Ni3+/Co3+ and the spontaneous reaction between Ni3+/Co3+ and sucrose. By feeding with natural sugarcane juice, a solar-driven electrolyser is assembled for the co-production of value-added formic acid and hydrogen. Our work demonstrates a sustainable route for integrating hydrogen production and biomass electrooxidation for energy applications.

Anisotropic Strain Boosted Hydrogen Evolution Reaction Activity of F-NiCoMo LDH for Overall Water Splitting

Layered double hydroxide (LDH) catalysts provide promising OER activity which can be employed in overall water splitting for hydrogen production. However, their weak surface hydrogen adsorption (Had) and high water dissociation energy can result in the inferior hydrogen evolution reactions (HER) activity. In this paper, a highly efficient HER catalyst of F-doped NiCoMo LDH is successfully designed and synthesized through in situ growing on nickel foam (F-NiCoMo LDH/NF) for overall water splitting. DFT calculations demonstrate that the introduction of Mo and F atoms in NiCo LDH can induce the generation of anisotropic lattice strain, resulting in the generation of high-energy active interface and shifting the d-band centers. Therefore, the adsorption energy of Had is optimized and the water dissociation energy barrier is decreased. As a result, this F-NiCoMo LDH/NF catalyst electrode displays a low overpotential of 107.5 mV at 10 mA cm−2 and a small Tafel slope of 67.2 mV dec−1 for HER. The assembled electrolyzer by employing this catalyst electrode requires only 1.83 V to deliver 300 mA cm−2 and operates stably for 100 h.