Abstract Aqueous potassium-ion batteries (AKIBs) have emerged as highly attractive candidates for grid-scale energy storage due to their intrinsic safety, low cost, and fast ion transport kinetics. However, their practical deployment is severely impeded by insufficient energy density, typically falling below 80 Wh kg-1, which is largely attributed to the narrow electrochemical stability window of conventional dilute electrolytes and subsequent electrode degradation. To address this critical bottleneck, this article provides a systematic overview dedicated to boosting the energy density of AKIBs. We comprehensively evaluate recent advances from two key dimensions: phase-transition mitigation and structural hydration engineering through water-in-salt electrolytes and hydrogen-bond regulation. Specifically, the evolution of electrolyte design from super-concentrated formulations to cost-effective fluorine-free alternatives and less salt hybrid concepts are elucidated. Finally, we outline persisting challenges and offer strategic outlooks regarding interfacial chemistry and realistic full-cell metrics to facilitate the practical development and commercialization of high-energy-density AKIBs.
Abstract Seawater electrolysis offers a promising route to low‑cost, large‑scale green hydrogen production without competing for precious freshwater resources. However, seawater electrolysis faces two major challenges: the chlorine evolution reaction (CER) on the anode side and the precipitation of Mg2+/Ca2+ ions on the cathode side. To this end, this work constructs a pH-asymmetric seawater electrolyzer based on a bipolar membrane (BPM), in which acidified seawater is fed to the cathode and alkaline freshwater to the anode. Acidification avoids precipitation of Mg²⁺/Ca²⁺ ions on the cathode side, while the BPM blocks chloride ions, preventing the CER on the anode side. Isotope labeling experiments confirm that the water molecules dissociated in BPM mainly come from the cathodic seawater. The electrolyzer operates stably even when the cathode is fed with saturated seawater. By optimizing the electrolyte concentration and electrode types, this seawater electrolyzer achieves continuous and stable operation for 500 hours at a current density of 100 mA cm-2, with a voltage rise rate of only 1.76 mV h-1, no scaling on the cathode, and no chlorine evolution on the anode. This work provides meaningful exploration for the development of seawater electrolysis for hydrogen production.
CO2 activation and transformation processes are essential for sustainable energy development and environmental remediation. In this review, we describe our advances in the use of gas-phase ions to mediate these processes, which have provided unique molecular-level mechanistic insights by combining mass spectrometry and density functional theory calculations. This review is structured around three fundamental CO2 transformation reactions: reduction to CO through O-atom transfer to a suitable oxygen acceptor, Bu2013C bond formation via reactions with metal borides, and Cu2013N bond formation via coupling with NH3 or N2. The fundamental knowledge uncovered in these gas-phase studies establishes a foundational framework for future research and the rational design of novel catalytic systems for CO2 conversion.
Electrochemical reduction of CO2/CO (eCO(2)R) powered by renewable electricity to produce value-added chemicals offers a promising pathway toward sustainable fuel production. Although advances in catalyst design and system engineering have enabled CO2/CO electroreduction to achieve high current densities for generating hydrocarbons and oxygenates, the products remain largely limited to small carbon molecules (C1u2013C3). Recently, significant progress has been made in cascading eCO(2)R with downstream reactions to expand the product spectrum toward polymeric or higher-value carbon products. However, comprehensive summaries and perspectives on these cascade systems remain scarce in the eCO(2)R literature. This review systematically summarizes recent developments in cascade eCO(2)R and downstream conversion. The advantages of integrating eCO(2)R with additional reaction steps are analyzed, followed by a discussion of representative systems that couple eCO(2)R with thermo-catalytic, biological, and electrochemical processes. Finally, the key challenges facing this emerging field are highlighted, along with perspectives on future research directions.
Composites of TiO2 with graphene and other carbon-based nanomaterials are widely used as photocatalysts, since they improve the efficiency of TiO2 photocatalysts by reducing charge recombination and extending TiO2 light-harvesting to the visible range. However, the exact nature of binding at TiO2/graphene interfaces is still unclear. Experimental studies show that Tiu2013C and Tiu2013Ou2013C covalent bonds are often present in TiO2/graphene heterostructures. In this study, we used density functional theory to investigate the nature of binding at the interfaces of graphene with the anatase polymorph of TiO2. We investigated graphene binding with both the most stable (101) surface of anatase and the less stable but more photocatalytically active (100) and (001) surfaces, and analysed the electronic properties of these interfaces. We found that pristine graphene binds to anatase surfaces by physisorption, while graphene with carbon vacancies can form covalent bonds to TiO2. The presence of these covalent bonds alters the electronic structure of TiO2/graphene composites, creating hybridised states that may facilitate charge transfer and hinder electronu2013hole recombination. This study highlights the important role of defects, such as vacancies, in creating interfacial covalent bonds that may be responsible for the high photocatalytic activity of TiO2/graphene heterostructures.
Photoelectrochemical (PEC) water splitting is a promising strategy for providing clean, sustainable fuel. However, its efficiency is limited by the high overpotential and sluggish kinetics of the oxygen evolution reaction. To improve oxidation kinetics and produce a higher-value product, it is possible to oxidize organic molecules instead. One such molecule is 5-hydroxymethylfurfural (HMF), which can be converted into the high-value platform chemical 2,5-furandicarboxylic acid (FDCA). In this study, we used porous tungsten oxide (WO3) photoanodes to oxidize HMF photoelectrochemically. Our work focuses on electrolyte selection for this conversion reaction, and we therefore conducted a detailed reproducible study. Furthermore, we carried out a mechanistic investigation and studied the capability of oxidizing the reaction intermediates to support our electrolyte choice. Using the most suitable electrolytes in a self-designed flow-cell setup enabled us to produce FDCA (0.02 mM) for the first time using WO3 photoanodes under AM 1.5 G illumination. Due to the identification of the side products maleic acid and formic acid, this work also provides knowledge for further optimization of PEC HMF oxidation.
Hard carbon is the most commercially viable anode for sodium-ion batteries, with low operating potential, high reversible capacity, abundant raw materials and low manufacturing cost. However, its intrinsic structural disorder, characterized by randomly stacked turbostratic graphene layers, nanopores and amorphous regions, has sparked long-standing debates on fundamental sodium storage mechanisms, significantly impeding rational electrode design and industrial translation. This review overviews sodium storage processes in hard carbon, analyzes synergistic contributions of intercalation, pore filling and surface adsorption, and establishes microstructural-electrochemical performance correlations. It focuses on four mainstream modification strategies: Precursor engineering, pore structure regulation, heteroatom doping and interface engineering, elucidating their enhancement mechanisms and discussing inherent limitations and trade-offs. Finally, it outlines key challenges and future directions, providing critical theoretical and technical guidance for next-generation hard carbon anodes and practical sodium-ion battery deployment.
Electrochemical methods for carbon capture potentially have the advantage of low cost and low energy consumption. The practical applicability of pH-swing carbon capture processes driven by proton-coupled redox-active molecules has been limited by the sensitivity of reduced molecules to oxidation by O2. In those CO2 capture processes, the molecules are reduced, basifying the electrolyte; the electrolyte containing the reduced molecules is exposed to air or flue gas containing CO2 but also containing enough O2 to oxidize the molecules. O2 sensitivity would not be problematic if the electrolyte that captures CO2 contains the oxidized form of the molecule instead; this can be accomplished by switching from an electron-driven system to an ion-driven system. We report the development and performance of a two-chamber flow cell incorporating a reverse-bias bipolar membrane (BPM) and non-proton-coupled redox-active molecules for ion-driven pH-swing. When using ferri/ferrocyanide electrolytes in this cell with a BPM, the cell pH can be spatially swung with the oxidized side basified for CO2 capture and the reduced side acidified for release. Buffering agents and cell rebalancing mediators improved the efficiency and stability of the system. This work points out an alternative way of employing redox couples for electrochemically-powered pH swings.
Unregulated interfacial electric fields critically undermine the stability of lithium-metal batteries (LMBs) by driving heterogeneous Li+ flux and dendritic deposition. Here, we report a dielectric-mediated electrolyte design that actively modulates the local electric field to enable uniform Li+ transport and Li0 deposition. By integrating fluorinated diluents with varying dielectric constants into localized high-concentration electrolytes (LHCE), a stable dielectric environment was constructed at the Liu2013electrolyte interface. Specifically, the high-dielectric diluent 1,1,1,3,3-pentafluorobutane facilitates electrolyte to realize uniform and flat lithium deposition under high current density of 3 mAu00B7cmu22122 by suppressing the electrostatic tip effect that typically triggers dendrite formation. The optimized electrolyte achieves high Coulombic efficiency (u0026gt; 99.5%), negligible growth in interfacial impedance, and stable cycling in thin Li-based cells. Moreover, Li (30 u03BCm)||LiCoO2 (3.6 mAhu00B7cmu22122) full cells retain 80% of their initial capacity after 250 cycles within a voltage window of 3u20134.5 V, outperforming the reference cells (u0026lt; 50 cycles) using high-concentration electrolyte and LHCE with low-dielectric-constant diluent. The strategy of dielectric-mediated interface homogenizes electric field distribution and stabilizes ion transport beyond conventional interphase-focused approaches. This work establishes dielectric modulation as a viable paradigm for interfacial regulation, advancing the design of high-energy-density LMBs.
The conversion of carbonaceous waste into value-added chemicals represents a sustainable waste management paradigm with the potential to alleviate mounting global carbon emission pressures and environmental crises. The inherent chemical inertness of carbonaceous wastes, such as CO2 and plastics, necessitates harsh recycling conditions, making it challenging to achieve both high conversion and high selectivity, which severely limits the process efficiency. Conversely, enzyme-driven biotransformations operate under ambient conditions with exceptional selectivity, but are hindered by narrow substrate scope and slow kinetics. By synergistically integrating the high efficiency of chemical catalysis with the precision of biosynthetic pathways, chemo-bio catalytic integrated strategies offer a promising alternative. These approaches enable continuous energy input for enzymatic upgrading of carbon waste through chemical energy-transduction mechanisms, while converting complex carbonaceous materials into small molecule intermediates that are readily assimilated by microbes, thus overcoming limitations in both substrate scope and energy supply. This perspective systematically summarizes recent advances and evolving trends in chemo-bio integrated strategies for the valorization of carbonaceous waste. We provide a comprehensive analysis from the perspectives of spatially coupled and spatially decoupled systems, and further examine persistent challenges related to efficiency enhancement, system robustness, energy utilization, and scalable integration.
Over the past three decades, substantial efforts have been dedicated to developing high-performance photocatalysts for solar fuel production and scaling up their applications, particularly through the fabrication of photocatalytic thin films. These efforts have led to significant advancements moving towards practical applications. In this review, various techniques have been introduced to achieve thin films over time, including vapor deposition, solution-phase growth, and in-situ polymerization, each tailored to different materials and their applications. Ultimately, the choice of method should be based on a comprehensive evaluation of factors such as efficiency, stability, process complexity, and cost in the context of solar fuel production. This review seeks to address the critical question of how to guide photoredox catalysis toward practical implementation, contributing to sustainable solutions for global energy, environmental, and other challenges.
Lignin, the most abundant aromatic biopolymer on Earth, serves as a sustainable but underutilized precursor for advanced carbon materials. Herein, we introduce a green hydrothermal reorganization strategy designed to direct the transformation of lignin into porous carbons with an ultrahigh specific surface area for advanced supercapacitors. The hydrothermal treatment effectively removes hydroxylated functional groups while preserving and enriching aromatized lignin units, resulting in a structurally optimized precursor for subsequent reorganization into porous carbon. The optimized carbon material (HEHLC-800) demonstrates an exceptionally high specific surface area of approximately 3598 m2u00B7gu22121, accompanied by a well-balanced distribution of micropores and mesopores. In symmetric supercapacitor configurations, HEHLC-800 delivers significantly superior energy-power characteristics compared to commercial activated carbon (YP-80). Specifically, it achieves a high energy density of 91.9 Whu00B7kgu22121 at a power density of 427.5 Wu00B7kgu22121 and retains 70.2 Whu00B7kgu22121 even at a high power density of 43.7 kWu00B7kgu22121 under a 3.5 V ionic liquid electrolyte. This work offers a sustainable and scalable route for producing biomass-derived carbons that exceed commercial benchmarks in high-energy supercapacitors.
The direct conversion of abundant methane into valuable products represents a promising strategy for constructing new chemical synthesis networks. However, conventional thermocatalysis often suffers from moderate selectivity and stability due to the harsh reaction conditions required for methane activation, while photocatalysis typically exhibits low conversion rates owing to intrinsic limitations such as charge recombination and poor mass transfer. Photo-thermo synergistic catalysis has emerged as a next-generation approach that integrates photo and thermal energy inputs, leveraging photons to overcome activation barriers and phonons to accelerate bulk/surface kinetics, thereby addressing the limitations of single-energy systems. In this review, we clarify the advantages and limitations of dual-energy versus single-energy approaches, explain four distinct synergistic modes between photo and thermo, and summarise recent strategies for methane valorisation into a range of valuable products. We also discuss the roles of photon and phonon in modulating reaction kinetics and product selectivity. Finally, we propose insights into current challenges and potential solutions, including scientific performance evaluation, expansion of product scope, development of dual-energy in-situ characterisation techniques, photo-thermo reactor design, and AI-driven catalyst discovery.
Methane plasma pyrolysis represents a promising clean technology for solid carbon production, enabling simultaneous hydrogen generation without direct CO2 emissions. Current research primarily focuses on single-feed methane processes, yet the strategic utilization of byproduct acetylene to enhance reaction efficiency and product value remains underexplored. This study systematically optimized key parametersu2014including plasma power, methane flow rate, and nozzle designu2014achieving a methane conversion rate of 91.3% and a solid carbon selectivity of 21.9%. Furthermore, an innovative cyclic feeding strategy combining methane and in-situ-generated acetylene was proposed. This approach significantly boosted solid carbon selectivity to 36.9%, outperforming conventional pure methane feeding. Mechanistic analysis revealed that acetylene not only redirects reaction pathways toward solid carbon formation but also acts as an efficient carbon source and template, promoting the synthesis of highly graphitized solid carbon with a graphitization degree of 89.2%. These findings provide critical insights into plasma-driven carbon material synthesis and establish a foundation for sustainable manufacturing through byproduct valorization.
