Electro-enhanced adsorption and desorption (electrosorption) is emerging as a versatile route to remove and concentrate trace organic contaminants, including PFAS and pharmaceuticals, by coupling conductive adsorbents with electrical control. Many systems borrow process concepts from capacitive deionization (CDI), yet at environmentally relevant influent levels, they operate in a low-loading regime where affinity, competition, and transport dominate rather than charge-storage-limited salt/ion uptake. The electrical step also enables controlled release (electrodesorption) for regeneration, recovery, and enrichment, supporting capture-concentrate operation. This Making Waves article proposes a mechanism-consistent vocabulary and a compact reporting framework that links treatment goals to key metrics: affinity- and process-relevant descriptors (adsorption coefficient, selectivity, breakthrough/retardation, recovery, and enrichment) when electrosorption of trace organic compounds is the goal. Clear terminology and reporting will improve comparability across studies and accelerate rational design of electrosorption technologies tailored to trace organic pollutants.

A phase-resolved multi-reaction model bridges atomistic energetics and electrode behavior, accurately capturing hysteresis and relaxation in Si anodes.

Commercialization of lithium-sulfur batteries (Li-S) remains complex due to limited cycling stability related to the solubility of polysulfide intermediates, specifically higher-order polysulfides (Li2S4 to Li2S8). Some studies have utilized microporous carbons with pore sizes <= 0.7 nm, which can accommodate only short-chain polysulfides (Li2S2-4) to resolve the challenge of polysulfide shuttling. However, the discharge products of long-chain polysulfides, Li2S8 and Li2S6 molecules with diameters of 0.84 nm and 0.76 nm, are not entirely confined in the micropores due to the poor affinity of the carbon host and polysulfides. In this study, we created microporous carbon (AC900) with a pore size of 1.2 nm that can accommodate both long and short-chain polysulfides and infiltrated it with sulfur (AC900S). To mitigate capacity fading, we further modified the carbon using urea (AC900NS) and nickel sulfate (AC900S-Ni) treatments. The latter did not result in detectable Ni incorporation but induced partial changes in carbon hybridization and surface structure. The synthesis-driven structural adjustment in AC900S-Ni influenced solid-state conversion and improved electrochemical stability compared to AC900S and AC900NS. The AC900S-Ni cathode demonstrated a capacity retention of 72% with a capacity of 773 mAh gS-1 after 100 cycles and 1000 mAh gS-1 in the first cycle at C/20, higher than those of AC900S and AC900NS. An improvement in capacity retention to 96% was noted at C/10, with a discharge capacity of 722 mAh gS-1 after 100 cycles, compared to 805 mAh gS-1 in the first cycle. The results identify the factor contributing to capacity fading in unmodified AC900S and demonstrate that chemical/structural modification of microporous carbon combined with a carbonate electrolyte provides a promising pathway for Li-S systems. This study offers a facile approach to tune carbon hosts and expand their applicability in Li-S batteries.

MXenes are a rapidly expanding family of two-dimensional transition metal carbides and nitrides whose exceptional compositional, structural, and surface-chemical tunability has driven rapid growth across materials science, chemistry, physics, and engineering. This roadmap consolidates the current state of MXene research, spanning synthesis, processing, fundamental properties, computation, electrochemical energy storage, biomedical applications, electronics, optoelectronics, membranes, sensing, tribology, and extreme-environment technologies. By identifying key advances, persistent challenges, and emerging opportunities, the roadmap provides a forward-looking outlook for guiding MXenes from laboratory discovery toward transformative applications.

Transition metal oxalates have been proven to be a promising electrode material for lithium-ion batteries. Here, we have designed a series of multi-phase transition metal oxalates with different structures and compositions by simply adjusting the proportions of five transition metal elements. Among them, the multi-phase mixture (MC2O4 & centerdot;2H2O - CuC2O4 - MC2O4 & centerdot;2H2O, M = Mn, Fe, Co, Ni, Cu) provides a more stable framework for the material during lithiation and delithiation, effectively alleviating the structural collapse during the cycling process. In addition, the electron transport and fast charge compensation processes of multiple electrochemically active metal pairs also contribute to the improvement of performance. Therefore, the multi-phase transition metal oxalate TMOx-2 electrode with an additional CuC2O4 phase exhibits high reversible capacity and long-term cycling stability. After 400 cycles at 100 and 500 mA/g, the specific discharge capacities are 827 mAh/g and 498 mAh/g, respectively. Constructing multi-metal, multi-phase systems by combining different transition metals enables control over potential, reaction pathways, and stability of high-performance electrodes.

Electrical double-layer capacitors offer high power density and long cycle life but are limited by moderate energy density. We investigate a strategy to improve their performance using quaternary electrolytes containing two distinct cations and two distinct anions. Our theoretical analysis shows that such electrolytes outperform pure ionic liquids and conventional mixtures sharing a common ion. We validate this approach experimentally using [EMIM][BF4] mixed with lithium salts, characterizing their local structure and electrochemical behavior via NMR, Raman spectroscopy, conductivity measurements, and electrochemical testing. We further demonstrate that the enhancement depends sensitively on electrode microporosity, underscoring the interplay between electrolyte composition and pore structure.

The performance of novel electrode materials and the influence of cell geometry or flow rate on capacitive water deionization (CDI) are usually described by global metrics from the analysis of the effluent electrolyte together with the electrochemical response of the system. However, these approaches cannot provide information on local variations of ion concentration and related local efficiency within an operating device. Here, a novel approach of position-resolved operando synchrotron-based X-ray transmission is introduced to determine local ion concentration changes along the flow channel from the inlet (feedwater) to the outlet (effluent water) of a working CDI cell. A specific cell design allows the independent quantification of concentration changes within the bulk electrolyte in the flow channel as well as the two oppositely charged nanoporous electrodes. Results from a 15 mM CsCl feed solution using three flow rates and two carbon materials with hierarchical porosity reveal a complex spatial-and temporal ion distribution in the system. A distinct dependence of local concentration on the flow rate is observed, with generally decreasing local desalination capacity towards the outlet of the cell, particularly for slow flow rates. It is also found that a significantly better overall performance for one of the two materials can be related to dominant counter-ion adsorption within ultramicropores, which ions cannot access in their hydrated state at no applied potential (ionophobicity). Overall, the results demonstrate the unique potential of position-resolved operando X-ray techniques to get mechanistic insight into local ion redistribution in CDI systems, allowing ultimately guiding performance optimization.

There is a need for new electrochemical energy storage materials that can handle high cycling rates (high power) for rapid charging without compromising high energy density, such as high-power Li-ion batteries (LIBs) and Li-ion capacitors (LICs). Electrically conductive and redox-active two-dimensional (2D) materials, such as transition metal carbides and borides, are promising candidates for these applications. Tailoring in-plane chemically ordered MAB phases (i-MAB) has facilitated the synthesis of their 2D derivatives (i-MBenes), which possess ordered vacancies at the metal sites. The first reported i-MBene paper is Mo4/3B2Tx, which is derived from the parent i-MAB phase (Mo2/3Y1/3)2AlB2 by the selective etching of Al and Y. In this study, we report on the synthesis of 2D Mo4/3B2Tx aerogel and its electrochemical performance as an electrode material for LIBs. Our aerogel exhibits remarkable stability during life-cycling testing at high applied specific currents, maintaining a specific capacity of 260 mAh g-1 even after completing 500 cycles under a high specific current of 2 A g-1. At a moderate specific current of 100 mA g-1, it delivers an energy density of 363 Wh kg-1, while at a high specific current of 2 A g-1, it achieves a specific power of 1300 W kg-1. Complementary density functional theory calculations further reveal that Li preferentially occupies hexagonal Mo sites in Mo4/3B2Tx, supporting the observed stable lithiation behavior and excellent high-rate capability. These results suggest that 2D Mo4/3B2Tx aerogel is a promising candidate for high-power LIBs and LICs.

MXenes, an emerging class of two-dimensional van der Waals materials, have become the focus of research, demonstrating exceptional potential in electrochemical, biochemical and electronic applications. This chapter provides a brief overview of MXenes, covering their fundamental characteristics, synthesis methods and current challenges, with particular attention on synthesis methods.

Electrochemical nitrate reduction (eNO3RR) mitigates environmental nitrate pollution while offering a sustainable approach for green NH3 synthesis, but is plagued by limited electrocatalytic activity and unsatisfactory stability. Accordingly, we adopted an exfoliation-induced in situ electrochemical deep reconstruction strategy to construct an amorphous/crystalline heterostructure using a multilayer CuCoAl layered double hydroxide (LDH) as a precursor. The characterization results illustrate that the few-layer CuCoAl LDH underwent a deep reconstruction process to transform into a structure with co-existing metallic Cu, crystalline Co(OH)2, and amorphous CoOOH. Among these, CoOOH can firmly anchor the Cu cluster to promote the transformation of NO3 - to NO2 -, while Co(OH)2 mainly facilitates the subsequent hydrogenation steps. These three species act cooperatively to endow the reconstructed few-layer LDH with extraordinary eNO3RR activity (99.5% Faradaic efficiency, 95.7% NH3 selectivity, and 1.92 mol h-1 g-1 yield rate at -0.57 V vs. RHE in 0.1 m nitrate) and stability. The Zn-NO3 - battery assembled with FA2-CuCoAl LDH simultaneously achieved environmental remediation, energy storage, and sustainable ammonia synthesis. Thus, this study reveals the reconstruction behavior of CuCoAl LDH, demonstrates the positive effect of the exfoliation step, and provides a novel strategy for designing efficient and stable eNO3RR catalysts based on amorphous/crystalline heterostructure engineering.

Porous and functional cellulose-based materials play a key role in the field of novel sensors and membrane technologies, yet their full potential remains unexplored. This article elaborates on a procedure for creating porous coatings with reactive chemical groups on their surfaces by covering a cellulose membrane with hybrid core-shell particles. The silica cores of these particles, synthesized via the Stöber procedure, could easily be etched with hydrofluoric acid. The cross-linked polymer shell of the particles was synthesized via emulsion polymerization. These particles were analyzed via dynamic light scattering and transmission electron microscopy. After coating the cellulose and an etching process, the former core particles formed pores within the matrix of the shell polymer, as observed via scanning electron microscopy and atomic force microscopy. The coated area also featured chemical functionalities via appropriate polymers used in the shell of the particles, enabling further cellulose modification. In particular, hydroxy groups were incorporated into a copolymer containing 2-hydroxyethyl methacrylate, and epoxy groups were incorporated using glycidyl methacrylate. These functionalities can be combined to yield a wide range of specific properties. For this reason, this work paves the way for advanced smart and stimuli-responsive porous filtration systems, paper-based sensors, and adsorbers.

We report a hybrid layered metal-phosphonate framework, [Ni(2,2'-bpy)3]2+[(VO(H2O))2(VO)4(μ-O)2(C6H5PO3)6]2-·2H2O, in which redox-active [(Ni(2,2'-bpy)3)]2+ cations are embedded between anionic vanadium phosphonate layers [(VO(H2O))2(VO)4(μ-O)2(C6H5PO3)6]2- (with 2,2'-bpy = 2,2'-bipyridine). X-ray photoelectron spectroscopy reveals coexisting Ni2+, V2+, V3+, and V4+/V5+ species on the surface of the crystals, indicating a highly dynamic redox system. The material exhibits a main photoluminescence peak at 2.25 eV and strong short-range antiferromagnetic coupling between the V4+ centers. Electrochemical characterization in aqueous media yields capacitances of 79 F/g in Na2SO4 (pH 7) and 43 F/g in H3PO4 (pH 4) at 1 A/g. In Na2SO4 (pH 7), the material reaches about 300 F/g at a scan rate of 1 mV/s and retains capacity over more than 10,000 cycles. The crystals remain chemically stable between pH 2 and pH 10 for at least 1 week. Combined sustainable synthesis, robust redox activity, high capacitance, long cycle stability, and broad pH tolerance make these hybrid metal-phosphonate crystals promising candidates for next-generation aqueous energy-storage applications.

Herein, we report the charge storage and plastic properties of the redox-active, bimetallic metal phosphonate framework of [Cu(2,2 '-bpy)VO(O3PC6H5)2]. The flexible crystals of [Cu(2,2 '-bpy)VO(O3PC6H5)2] combine high energy storage with mechanical flexibility on the same platform, which is an unusual and significant property that is not observed in traditional rigid layered electrode materials. In contrast to RuO2, graphene, or MXenes, which prefer concentrated acidic or basic electrolytes to operate effectively as electrodes, [Cu(2,2 '-bpy)VO(O3PC6H5)2] operates between pH values of 4 and 10 while reaching a specific capacitance of about 140 F/g in H3PO4 at pH 4 and in NaOH at pH 10 at 1 mV/s. It also demonstrates high chemical and electrochemical stability between pH 2 and 12 and in lithium hexafluorophosphate for extended periods. The use of [Cu(2,2 '-bpy)VO(O3PC6H5)2] as electrodes eliminates the need for harsh chemical environments, generating more sustainable and environmentally friendly energy storage solutions, and [Cu(2,2 '-bpy)VO(O3PC6H5)2] can be synthesized in water at mild temperatures. The combination of chemical stability, mechanical flexibility of [Cu(2,2 '-bpy)VO(O3PC6H5)2], and compatibility with mild electrolytes makes [Cu(2,2 '-bpy)VO(O3PC6H5)2] a more sustainable alternative to conventional metal oxides, MXenes, and carbon-based electrodes in next-generation supercapacitors and battery technologies.

Electrochemical desalination is a promising technology for the selective recovery of Lithium-ions or other rare ions from spent electronics, contributing to a circular economy. Due to its high-energy efficiency and selective Lithium-ion recovery, this method offers a low environmental impact, making it a promising tool for recovering Lithium-ions from spent batteries. Few studies have examined electrochemical desalination as a tool to recover Lithium-ions from real spent battery solutions. In this work, solutions obtained from real shredding of Lithium-iron-phosphate (LFP) batteries inside a cooling water reservoir were used as a Lithium-rich source to obtain a high-purity Lithium-ion recovery solution. A 96%-pure Lithium-ion recovery solution was obtained while only requiring an energy input of 1.10 kWh/kg.

The formation of a stable cathode-electrolyte interphase (CEI) is critical for the performance of lithium-sulfur (Li-S) batteries with carbonate-based electrolytes, as it suppresses parasitic polysulfide reactions and enables solid-state sulfur conversion. In nanoporous carbon hosts, the CEI together with nanopore confinement plays a key role in capacity retention and long-term cycling. Yet, its spatial formation, stability, and contribution to electrochemical performance remain poorly understood, partly due to challenges in characterization caused by beam and air sensitivity. Here, we employ cryogenic transmission electron microscopy (cryo-TEM) with electron energy loss spectroscopy and energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and electrochemical testing together with galvanostatic intermittent titration technique measurements to elucidate how carbon particle size affects CEI formation and electrochemical performance. We find that the CEI is not a uniform surface film but extends heterogeneously into the particle bulk. Mass transport during the first discharge dictates CEI development, and larger particles suffer from inactive regions due to the preferential CEI formation only in the outer regions of the particles. During extended cycling, charge transfer resistance at confined CEI/active material/carbon interfaces emerges as the dominant performance-limiting factor. These findings show that particle size controls CEI formation during initial discharge, offering guidance for designing carbon hosts from nano- to micrometer length scales in Li-S battery cathodes.

The development of efficient carbon-based materials is crucial for overcoming the performance limitations of traditional electrodes in capacitive deionization (CDI). However, the practical performance of heteroatom-doped carbon electrodes for desalination in complex multi-ion water matrices remains largely unexplored. In this work, we studied the ion selectivity toward Li+ and the removal efficiency of nitrogen-sulfur co-doped and boron-doped carbon electrodes in brackish water, using multi-salt cation solutions containing monovalent (Li+, Na+, K+) and divalent (Ca2+, Mg2+) ions. These modifications enhanced charge distribution, wettability, and ion diffusion within the electrodes. As a result, the N,S-AC electrode exhibited pronounced lithium selectivity in brackish water, while the B-AC electrode delivered higher adsorption capacity. The B-AC electrode achieved both high capacity and enhanced lithium selectivity even under strong competition from Na+, Mg2+, and Ca2+. These findings demonstrate the distinct and complementary roles of N,S-co-doping and B-doping, offering valuable insights into how heteroatom engineering can advance CDI performance.

We report a hybrid layered metal-phosphonate framework, [Ni(2,2'-bpy)3]2+[(VO(H2O))2(VO)4(mu-O)2(C6H5PO3)6]2-& centerdot;2H2O, in which redox-active [(Ni(2,2'-bpy)3)]2+ cations are embedded between anionic vanadium phosphonate layers [(VO(H2O))2(VO)4(mu-O)2(C6H5PO3)6]2- (with 2,2'-bpy = 2,2'-bipyridine). X-ray photoelectron spectroscopy reveals coexisting Ni2+, V2+, V3+, and V4+/V5+ species on the surface of the crystals, indicating a highly dynamic redox system. The material exhibits a main photoluminescence peak at 2.25 eV and strong short-range antiferromagnetic coupling between the V4+ centers. Electrochemical characterization in aqueous media yields capacitances of 79 F/g in Na2SO4 (pH 7) and 43 F/g in H3PO4 (pH 4) at 1 A/g. In Na2SO4 (pH 7), the material reaches about 300 F/g at a scan rate of 1 mV/s and retains capacity over more than 10,000 cycles. The crystals remain chemically stable between pH 2 and pH 10 for at least 1 week. Combined sustainable synthesis, robust redox activity, high capacitance, long cycle stability, and broad pH tolerance make these hybrid metal-phosphonate crystals promising candidates for next-generation aqueous energy-storage applications.

The increasing demand for sustainable energy storage drives the development of advanced lithium-ion battery (LIB) materials that combine high performance, cost efficiency, and environmental sustainability. Carbon spherogels, characterized by high surface area, interconnected porosity, and high conductivity, are promising electrode candidates; however, they suffer from low specific capacities when used alone. This study presents iron-loaded carbon spherogels as next-generation LIB electrodes, leveraging iron's high theoretical capacity, abundance, and eco-friendliness. A scalable and tailorable synthesis method enabled the integration of tunable iron contents (15-40 mass %) into the carbon framework, forming robust porous networks with uniformly distributed iron nanoparticles. Electrochemical characterization revealed high specific capacities (up to 1190 mAh g-1) and high cycling stability (>99% Coulombic efficiency over 300 cycles). Post-mortem analysis highlighted the synergistic interaction between iron redox activity and carbon matrix stability. The medium (27 mass %) iron-loaded carbon spherogel sample achieved the best balance between capacity and durability. These findings position iron-loaded carbon spherogels as sustainable, high-performance LIB electrodes, offering a cobalt-free and nickel-free alternative that addresses key challenges of conversion-type materials, such as volume expansion and capacity fading.

A multi-scale model is crucial for combining experiments and simulations to reveal the energy storage mechanism. As novel electrode materials, conductive metal-organic frameworks (c-MOFs) provide an ideal platform for understanding the energy storage process in supercapacitors. However, the prevailing circuit models lack consideration of the distinctive transmission path of c-MOFs, which hinders accurate descriptions of c-MOF supercapacitors. By proposing a concept for representing the c-MOF electrode as a crystal-matrix electrode according to the crystallinity, we developed a universal multi-scale circuit model considering crystal shape and porosity to describe the impedance and capacitance of c-MOF electrodes. For supercapacitors with c-MOF electrodes and ionic liquid electrolytes, results predicted from the new multi-scale circuit model, based on microscale parameters obtained from molecular dynamics simulations, demonstrate quantitative agreement with experimental data for electrodes with different crystallinities.