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The weak bonding of A atoms with MX layers in MAX phases not only enables the selective etching of A layers for MXene preparation but brings about the chance to construct A derivatives/MXene composites via in situ conversion. Here, a facile and general gas‐solid reaction systems are elegantly devised to construct multi‐dimensional MXene based composites including AlF3 nanorods/MXene, AlF3 nanocrystals/MXene, amorphous AlF3/MXene, A filled carbon nanotubes/MXene, layered metal chalcogenides/MXene, MOF/MXene, and so on. The intrinsic effect mechanism of interlayer confinement towards crystal growth, catalytic behavior, van der Waals‐heterostructure construction and coordination reaction are rationally put forward. The tight interface combination and synergistic effect from distinct components make them promising active materials for electrochemical applications. More particularly, the AlF3 nanorods/Nb2C MXene demonstrate bi‐directional catalytic activity toward the conversion between Li2S and lithium polysulfides, which alleviates the shuttle effect in lithium‐sulfur batteries. [ABSTRACT FROM AUTHOR]

Hydrogen production through water electrolysis technology has received great attention toward the global mission of carbon neutrality. Industrial proton exchange membrane (PEM) electrolyzers stand out from other water electrolysis techniques due to their advantages such as high-current-density (HCD) operation capability, high efficiency, and more compact devices. The PEM water electrolysis efficiency largely depends on the activity and stability of the involved anodic electrocatalysts where the oxygen evolution reaction (OER) occurs. Especially for HCD water electrolysis toward large-scale hydrogen production, the operating environment of anodes is usually harsh, which accelerates the corrosion of OER catalysts particularly under such high-potential and oxygen-rich conditions. Hence, developing robust electrocatalysts for efficient OER is a longstanding challenge. Although carbon-based materials have been extensively investigated in electrocatalytic fields, the insufficient antioxidant capacity of carbonous substrates limits their practical application in the OER. Therefore, the development of carbon-free OER electrocatalysts for HCD water splitting in acidic media is highly meaningful. This contribution systematically reviews the existing problems and solutions of acidic OER, the key factors for rational design of carbon-free catalysts, and the designing strategies of supported/unsupported catalysts for industry under acidic conditions. Finally, the challenges and future research orientations in carbon-free electrocatalysts for HCD acidic OER are rationally proposed. [ABSTRACT FROM AUTHOR]

Zinc‐ion capacitors (ZICs) have great potential for energy storage applications due to high safety, environmental friendliness, low cost, and high energy density. However, challenges such as poor ion diffusion kinetics and the low conductivity of cathode materials still need to be addressed. Nano ZnV2O4/nitrogen‐doped porous carbon (ZVO/N‐PC) composites are efficiently synthesized via a simple annealing process. Highly crystalline ZVO nanoparticles are in‐situ grown on the three‐dimensional N‐PC surface by precisely tuning the ratio of the vanadium source, achieving a dual enhancement in electronic and ionic conductivities. Benefiting from the nanoengineering build‐up, the optimized ZVO‐0.6/N‐PC anode exhibits impressive rate performance (405.9/308.8 mAh g−1 at 0.2/5.0 A g−1) and cycling capability (0.0029 % capacity drop per cycle at 5.0 A g−1 after 5,800 cycles). Using nitrogen‐doped porous activated carbon (N‐PAC) as the anode and ZVO‐0.6/N‐PC as the cathode, the assembled ZICs deliver a high energy density of 27.5 Wh kg−1 at a power density of 450.0 W kg−1. After 10,000 cycles at 1.0 A g−1, the capacity retention rate remains as 72.8 %, demonstrating excellent cycling stability. This highlights the promising application of nano ZVO/N‐PC composites towards ZICs as competitive cathodes. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur batteries (LSBs) have recently gained extensive attention due to their high energy density, low cost, and environmental friendliness. However, serious shuttle effect and uncontrolled growth of lithium dendrites restrict them from further commercial applications. As "the third electrode", functional separators are of equal significance as both anodes and cathodes in LSBs. The challenges mentioned above are effectively addressed with rational design and optimization in separators, thereby enhancing their reversible capacities and cycle stability. The review discusses the status/operation mechanism of functional separators, then primarily focuses on recent research progress in versatile separators with purposeful modifications for LSBs, and summarizes the methods and characteristics of separator modification, including heterojunction engineering, single atoms, quantum dots, and defect engineering. From the perspective of the anodes, distinct methods to inhibit the growth of lithium dendrites by modifying the separator are discussed. Modifying the separators with flame retardant materials or choosing a solid electrolyte is expected to improve the safety of LSBs. Besides, in‐situ techniques and theoretical simulation calculations are proposed to advance LSBs. Finally, future challenges and prospects of separator modifications for next‐generation LSBs are highlighted. We believe that the review will be enormously essential to the practical development of advanced LSBs. [ABSTRACT FROM AUTHOR]

Nanowhisker-like Cu3(HHTP)2 composed of neat arrays grown on a copper foam is rationally designed and prepared using Cu(OH)2 nanowire arrays as a self-sacrifice template. Benefiting from the good conductivity of Cu3(HHTP)2 and an ordered array structure, the optimized Cu3(HHTP)2@CF-3 electrode exhibits high area capacity, good rate performance and cyclic stability. [ABSTRACT FROM AUTHOR]

Zinc-ion capacitors (ZICs), combining the merits of both high-energy zinc-ion batteries and high-power supercapacitors, are known as high-potential electrochemical energy storage (EES) devices. However, the research on ZICs still faces many challenges because of the lack of appropriate cathode materials with robust crystal structures and rich channels for stable and fast Zn2+ ion transport. In this study, we synthesized a robust, conductive, two-dimensional metal–organic framework (MOF) material, zinc-benzenehexathiolate (Zn-BHT), and investigated its electrochemical performance for zinc storage. Zn2+ ions could insert into/extricate from the host structure with a high diffusion rate, enabling the Zn-BHT cathode to exhibit a surface-controlled charge storage mechanism. Due to its unique structure, Zn-BHT exhibited a good reversible discharge capacity approaching 90.4 mAh g−1 at 0.1 A g−1, as well as a desirable rate capability and good cycling performance. In addition, a ZIC device was fabricated using the Zn-BHT cathode and a polyaniline-derived porous carbon (PC) anode, which depicted a high working voltage of up to 1.8 V and a high energy density of ~37.2 Wh kg−1. This work shows that conductive MOFs are high-potential electrode materials for ZICs and provide new enlightenment for the development of electrode materials for EES devices. [ABSTRACT FROM AUTHOR]

Hollow porous AuAg nanospheres (AuAg HPNSs) were obtained through a simple solvothermal synthesis, complemented by a dealloying strategy. The hollow interior, open pore voids, and integral interconnected skeleton shell in AuAg HPNSs are beneficial for providing sufficient electrolyte diffusion and contacts, abundant active sites, and efficient electron transport. This specific structure and the favorable alloy synergism contribute to the superior electrocatalytic activity toward dopamine (DA) and acetaminophen (AC). AuAg HPNSs show high sensitivity, good selectivity, excellent sensing durability, and outstanding repeatability for amperometric assays of AC and DA. In particular, the AuAg-based sensors achieve effective ultrasensitive simultaneous analyses of AC and DA, exhibiting the characteristics of the wide linear range and low detection limit. With their prominent electrocatalytic activity and simple preparation methods, AuAg HPNSs present broad application prospects for constructing a highly responsive electrochemical sensing system. [ABSTRACT FROM AUTHOR]

Recently, silicon has been considered one of the preferred materials for the anodes of next-generation high-energy-density Li-ion batteries due to its advantages of high specific capacity, low working voltage, and abundant reserves. However, the huge volume change and poor electrical conductivity of silicon anodes during the lithiation and de-lithiation process seriously affect their practical application. Herein, honeycomb porous silicon is synthesized by a modified Stöber method and magnesium thermal reduction, which avoids using toxic gases (such as silane) in the traditional preparation of commercial nano-silicon. Moreover, the honeycomb porous structure can effectively alleviate the volume expansion during the charge/discharge process and agglomeration behavior of nano-silicon. Therefore, thanks to its unique structural merits, the honeycomb porous silicon anode is endowed with a reversible specific capacity of 824.1 mA h g−1 after 100 cycles at 0.5 A g−1 and 679.2 mA h g−1 even at an ultrahigh current density of 1.0 A g−1 after an extended cycling period of 200 cycles, which is almost twice that of commercial nano-silicon. More importantly, this finding offers promising advancements in designing silicon anodes in energy storage. [ABSTRACT FROM AUTHOR]

Carbonized polymer dots (CPDs) have received much attention in recent years owing to their cost‐effective synthesis, high resistance to photobleaching, environmental friendliness, and excellent biocompatibility. However, the aggregation‐induced fluorescence quenching is a great obstacle to its applications. In this work, the highly fluorescent CPDs are prepared by a facile hydrothermal method assisted by polyethylene glycol (PEG) as the surface passivation agent, where phthalic acid and ethylenediamine are used as carbon and nitrogen source, respectively. Meanwhile, five types of PEG species are applied to prepare five CPDs to investigate PEG on optical properties of the resultant CPDs, among which the best quantum yield reaches 57.0 %. The promising applications of CPDs as fluorescent inks, sensors, light emitting diodes, and UV shielding films have been demonstrated. Overall, our contribution here develops a facile and accessible route for the synthesis of CPDs and further demonstrates its versatile applications. [ABSTRACT FROM AUTHOR]

The orthorhombic CuNb2O6 (O–CNO) is established as a competitive anode for lithium‐ion capacitors (LICs) owing to its attractive compositional/structural merits. However, the high‐temperature synthesis (>900 °C) and controversial charge‐storage mechanism always limit its applications. Herein, we develop a low‐temperature strategy to fabricate a nano‐blocks‐constructed hierarchical accordional O–CNO framework by employing multilayered Nb2CTx as the niobium source. The intrinsic stress‐induced formation/transformation mechanism of the monoclinic CuNb2O6 to O–CNO is tentatively put forward. Furthermore, the integrated phase conversion and solid solution lithium‐storage mechanism is reasonably unveiled with comprehensive in(ex) situ characterizations. Thanks to its unique structural merits and lithium‐storage process, the resulted O–CNO anode is endowed with a large capacity of 150.3 mAh g−1 at 2.0 A g−1, along with long‐duration cycling behaviors. Furthermore, the constructed O–CNO‐based LICs exhibit a high energy (138.9 Wh kg−1) and power (4.0 kW kg−1) densities with a modest cycling stability (15.8% capacity degradation after 3000 consecutive cycles). More meaningfully, the in‐depth insights into the formation and charge‐storage process here can promote the extensive development of binary metal Nb‐based oxides for advanced LICs. [ABSTRACT FROM AUTHOR]