A novel hollow CuMn-PBA@NiCo-LDH nanobox for efficient detection of glucose in food

Designing a rapid and sensitive glucose detection method is of great significance to public health. Herein, hollow CuMn-PBA@NiCo-LDH nanoboxes (CuMn-PBA@NiCo-LDH NBs) were prepared using acid etching, cation exchange, and reflux method. The modified electrode exhibited outstanding electrocatalytic performance for glucose oxidation due to the unique hollow nanostructure and synergistic effects. The CuMn-PBA@NiCo-LDH NBs electrode displayed excellent electrocatalytic oxidation activity for glucose in an alkaline solution. Under optimal conditions, the electrode achieved a wide linear range (0.0005-1 mmol L-1, and 1-7 mmol L-1) and high sensitivity (10,300 μA L/mmol cm-2 and 5310 μA L/mmol cm-2), with a limit of detection (LOD) of 19 nmol L-1. The feasibility of the sensor applied to the detection of glucose was verified in real food samples through spiked recovery experiments. This electrode material offers an alternative method for the non-enzymatic glucose sensors.

Enhancing supercapacitor electrochemical performance through acetate-ion intercalation in layered nickel-cobalt double hydroxides

Enhancing the performance of layered nickel-cobalt double hydroxides (NiCo-LDH) as electrode materials for supercapacitors represents a promising strategy for optimizing energy storage systems. However, the complexity of the preparation method for electrode materials with enhanced electrochemical performance and the inherent defects of nickel-cobalt LDH remain formidable challenges. In this study, we synthesized acetate-ion-intercalated NiCo-LDH (NCLA) through a simple one-step hydrothermal method. The physical and chemical structural properties and supercapacitor characteristics of the as-prepared NCLA were systematically characterized. The results indicated that the introduction of Ac- engendered a distinctive tetragonal crystal structure in NiCo-LDH, concomitant with a reduced interlayer spacing, thus enhancing structural stability. Electrochemical measurements revealed that NCLA-8 exhibited a specific capacitance of 1032.2 F g-1 at a current density of 1 A g-1 and a high specific capacitance of 922 F g-1 at 10 A g-1, demonstrating a rate performance of 89.3%. Furthermore, NCLA-8 was used to construct the positive electrode of an asymmetric supercapacitor, while the negative electrode was composed of activated carbon. This configuration resulted in an energy density of 67.7 Wh kg-1 at a power density of 800 W kg-1. Remarkably, the asymmetric supercapacitor retained 82.8% of its initial capacitance following 3000 charge-discharge cycles at a current density of 10 A g-1. Thus, this study demonstrates the efficacy of acetate-ion intercalation in enhancing the electrochemical performance of NiCo-LDH, establishing it as a viable electrode material for supercapacitors.

Recent progress in 1D MOFs and their applications in energy and environmental fields

Metal organic frameworks (MOFs) are porous coordination polymers with adjustable nanostructure, high porosity and large surface areas. These features make MOFs, their derivates and composites all delivered remarkable potential in energy and environmental fields, such as rechargeable batteries, supercapacitors, catalysts, water purification and desalination, gas treatment, toxic matter degradation, etc. In particular, one-dimensional (1D) MOFs have generated extensive attention due to their unique 1D nanostructures. To prepare 1D MOF nanostructures, it is necessary to explore and enhance synthesis routes. In this review, the preparation of 1D MOF materials and their recent process applied in energy and environmental fields will be discussed. The relationship between MOFs' 1D morphologies and the properties in their applications will also be analyzed. Finally, we will also summary and make perspectives about the future development of 1D MOFs in fabrication and applications in energy and environmental fields.

Salts-assistant synthesis of g-C3N4/Prussian-blue analogue/nickel foam with hierarchical structures as binder-free electrodes for supercapacitors

The exploitation of high-performance electrode materials is significant to develop supercapacitors with satisfied energy and power output properties. In this study, a g-C₃N₄/Prussian-blue analogue (PBA)/Nickel foam (NF) with hierarchical micro/nano structures was developed by a simple salts-directed self-assembly approach. In this synthetic strategy, NF acted as both 3D macroporous conductive substrate and Ni source for PBA formation. Moreover, the incidental salt in molten salt-synthesized g-C₃N₄ nanosheets could regulate the combination mode between g-C₃N₄ and PBA to generate interactive networks of g-C₃N₄ nanosheets-covered PBA nano-protuberances on NF surfaces, which further expended the electrode/electrolyte interfaces. Based on the merits from this unique hierarchical structure and the synergy effect of PBA and g-C₃N₄, the optimized g-C₃N₄/PBA/NF electrode exhibited a maximum areal capacitance of 3366 mF cm^-2 at current of 2 mA cm^-2, as well as 2118 mF cm^-2 even under large current of 20 mA cm^-2. The solid-state asymmetric supercapacitor using g-C₃N₄/PBA/NF electrode possessed an extended working potential window of 1.8 V, prominent energy density of 0.195 mWh cm^-2 and power density of 27.06 mW cm^-2. Compared to the device with pure NiFe-PBA electrode, a better cyclic stability with capacitance retention rate of 80% after 5000 cycles was also achieved due to the protective effect of g-C₃N₄ shells on the etching of PBA nano-protuberances in electrolyte. This work not only builds a promising electrode material for supercapacitors, but also provide an effective way to apply molten salt-synthesized g-C₃N₄ nanosheet without purification.

Reactant conversion-intercalation strategy toward interlayer-expanded MoS2 microflowers with superior supercapacitor performance

In order to avoid the complicated control and fussy procedure associated with foreign species and templates in conventional synthesis strategies, a simple reactant conversion-intercalation strategy is developed to synthesize interlayer-expanded MoS₂ (E-MoS₂) by employing ammonium thiocyanate converted from a thiourea reactant as intercalator. In this strategy, the thiourea plays a bifunctionality role as reactant and intercalator precursor to ensure in situ embedding into the interlayers of MoS₂ to expand the interlayer spacing. The optimal E-MoS₂ obtained presents superior supercapacitor performance with a specific capacity of 246.8 F g^-1 at 0.5 A g^-1 in 1 M Na₂SO₄ electrolyte in a three-electrode system, outperforming pristine MoS₂ prepared by a conventional hydrothermal method (42.5 F g^-1 at 0.5 A g^-1). Furthermore, a symmetric supercapacitor based on an E-MoS₂ electrode delivers a high specific capacity of 261.3 F g^-1 and energy density of 13.3 W h kg^-1 at 0.5 A g^-1, and excellent cycling life with 81.7% capacity retention after 3000 cycles at 2 A g^-1. Density functional theory calculations reveal that the NH₄⁺ and SCN^- can be effectively adsorbed on the surface to be inserted into the interlayers during the growth of MoS₂, resulting in an expanded interlayer spacing of 9.4 Å, and the favorable electrochemical performance stems from the large Na⁺ adsorption capacitance and low diffusion barrier of the E-MoS₂. This work offers a novel intercalation strategy that may be generally applicable to other layer-structured materials, shedding some light on the development of high-performance electrode materials via interface engineering for energy applications.

Ultrafast Synthesis of Metal-Layered Hydroxides in a Dozen Seconds for High-Performance Aqueous Zn (Micro-) Battery

Efficient synthesis of transition metal hydroxides on conductive substrate is essential for enhancing their merits in industrialization of energy storage field. However, most of the synthetic routes at present mainly rely on traditional bottom-up method, which involves tedious steps, time-consuming treatments, or additional alkaline media, and is unfavorable for high-efficiency production. Herein, we present a facile, ultrafast and general avenue to synthesize transition metal hydroxides on carbon substrate within 13 s by Joule-heating method. With high reaction kinetics caused by the instantaneous high temperature, seven kinds of transition metal-layered hydroxides (TM-LDHs) are formed on carbon cloth. Therein, the fastest synthesis rate reaches ~ 0.46 cm2 s-1. Density functional theory calculations further demonstrate the nucleation energy barriers and potential mechanism for the formation of metal-based hydroxides on carbon substrates. This efficient approach avoids the use of extra agents, multiple steps, and long production time and endows the LDHs@carbon cloth with outstanding flexibility and machinability, showing practical advantages in both common and micro-zinc ion-based energy storage devices. To prove its utility, as a cathode in rechargeable aqueous alkaline Zn (micro-) battery, the NiCo LDH@carbon cloth exhibits a high energy density, superior to most transition metal LDH materials reported so far.

Nanoscale electrodeposition: Dimension control and 3D conformality

Electrodeposition with a long history has been considered one of the important synthesis techniques for applying various applications. It is a feasible route for fabricating nanostructures using diverse materials due to its simplicity, cost-effectiveness, flexibility, and ease of reaction control. Herein, we mainly focus on the nanoscale electrodeposition with respect to dimension control and three-dimensional (3D) conformality. The principles of electrodeposition, dimensional design of materials, and uniform coatings on various substrates are presented. We introduce that manipulating synthesis parameters such as precursors, applied current/voltage, and additives affect the synthesis reaction, resulting in not only dimensional control of materials from three-dimensional structures to zero-dimensional atomic-level but also conformal coatings on complicated substrates. Various cases regarding morphology control of metal (hydro)oxides, metals, and metal-organic frameworks according to electrodeposition conditions are summarized. Lastly, recent studies of applications such as batteries, photoelectrodes, and electrocatalysts using electrodeposited materials are summarized. This review represents significant advances in the nanoscale design of materials through methodological approaches, which are highly attractive from both academic and commercial aspects.

The PVP-assisted construction of a Co3V2O8@NiCo LDH hierarchical structure for high-performance lithium-ion batteries

In this paper, we reported 3D hierarchical Co₃V₂O₈@NiCo LDH through the assistant of PVP. The composite exhibits outstanding lithium storage performance (1329.4 mA h g⁻¹ at 1 A g⁻¹, 893.1 mA h g⁻¹ at 5 A g⁻¹ after 950 cycles). Our work reported an effective method to prepare multi-component materials.

Enhanced electrochemical performances of ZnCo2O4@CoMoO4 core–shell structures with long cycling stabilities

Developing electrode materials with high specific capacitance and excellent stability for energy storage is necessary to solve energy shortage issues.