Ion-solvaing membranes(ISMs)have received extensive attention in recent years as a key component in electrochemical energy conversion and storage devices.This article provides an overview of structural composition,performance advan-tages,research progress,ion conduction mechanism and existing issues of ISMs,primarily classifying them according to the matrix structure.A detailed analysis of performance enhancement methods,key performance indicators of ISMs and performance influencing factors is also presented.The article contributes to further optimizing the design and application of ion-solvation membranes,providing theoretical support for the development of fields such as hydrogen production through electrolysis of water and electrochemical energy in the future.
The redox active species in all-vanadium redox flow batteries(VRFBs)reside in the electrolyte,while the heterogeneous reactions occur on the electrode surface;the electrode is therefore the decisive platform for dynamic adsorption,electron transfer,and ion conversion,especially for the VO2+/VO2+and V2+/V3+couples.One of the major challenges for VRFBs is the slow charge transfer in VO2+/VO2+and V2+/V3+reactions,mainly caused by poor catalytic performance of electrodes and weak adhesion of catalysts to electrodes.This review focuses on the key challenges and recent advancements in VRFBs.It begins with an overview of VRFBs,including their history,working principles,applications,and the advantages and limita-tions associated with their use.One persistent,under-addressed trade-off is that strategies that boost apparent activity(e.g.,high defect density or surface area)can degrade adhesion and cycling durability under flow shear;activity should therefore be co-reported with adhesion and durability descriptors.Addressing this trade-off is critical to improving overall efficiency and stability in VRFBs systems.A comprehensive discussion of various electrode materials is presented,categorized by their properties and preparation methods.Special emphasis is placed on the synthesis and application of carbon-based electrode materials,highlighting their potential in addressing these challenges.Finally,we map materials-level gains to stack-and system-level metrics,and outline strategies,with a focus on bifunctional and in-situ grown catalysts,for achiev-ing high-efficiency,high-stability VRFBs.
Exploring cost-effective and efficient catalysts for oxygen reduction reaction(ORR)poses a significant challenge,espe-cially in the pursuit of alternatives to precious metals like platinum.Significant advancements have driven electrochem-ists to develop efficient ORR catalysts using abundant materials,particularly iron(Fe)-based,known for their exceptional performance in ORR.While the crucial function of Fe in boosting ORR catalytic activity is recognized,the connection between material attributes and catalytic performance remains enigmatic.Understanding the dynamic processes involved in oxygen electrocatalysis is paramount for designing precious-metals-free ORR electrocatalysts.Mössbauer spectroscopy stands out as a powerful technique for deciphering the structural characteristics of Fe species in catalysis,facilitating the identification of active sites and the clarification of catalytic mechanisms.By showcasing noteworthy case studies within this review,we demonstrate the application of in-situ/operando 57Fe Mössbauer spectroscopy across diverse Fe-involved materials in ORR catalysis.This sheds light on various aspects of ORR catalysis,such as identifying active sites,assessing stability,and understanding the reaction mechanism.Our inquiry drives towards the opportunities and hurdles associ-ated with Mössbauer spectroscopy,unveiling potential breakthroughs and avenues for enhancement within this pivotal research realm.
Molecular catalysts serve as ideal platforms for studying electrocatalytic reaction mechanisms. While current research mainly focuses on modulating central metals or surrounding ligands, the influence of molecular spatial configuration remains largely unexplored. Herein, we synthesized two cobalt complexes with similar ligand environments but distinct spatial geometries, a planar cobalt hexaazamacrocyclic complex (CoHAM) and a non-planar acyclic Co(phen)2Cl2, and evaluated their performance in CO2 reduction reaction (CO2RR). The planar CoHAM exhibited dramatically superior CO2RR performance compared to the non-planar Co(phen)2Cl2. Through a series of combined analyses using in-situ UV-vis spectroscopy, high-resolution mass spectrometry (HRMS), and Raman spectroscopy, we elucidated the origins of this performance gap by identifying key intermediates and reaction pathways. These findings underscore the critical role of the spatial configuration of molecular catalysts in governing electrocatalytic performance and provide a strategic direction for the rational design of efficient CO2RR catalysts.
Aqueous sodium-ion batteries (ASIBs) have attracted great attention in aqueous batteries due to their merit of high safety. However, the constrained work potential and insufficient chemical stability of anode materials in aqueous electrolytes hinder the large-scale application of ASIBs. Sodium titanium phosphate, NaTi2(PO4)3 (NTP), is considered one of the most promising anode materials for ASIBs due to its excellent electrochemical performance and tunable structure. Recently, great achievements have been made in the development of NTP, however, a comprehensive review of existing studies is still lacking. This article firstly introduces the basic properties of NTP and analyzes the existing challenges. Subsequently, it will provide a comprehensive overview of the key strategies related to the design and modification of NTP materials with optimized electrochemical performance. Finally, based on the current research status and practical needs, suggestions, and future perspectives for advancing NTP in practical applications of ASIBs are presented. This review aims to guide the future research trajectory from basic material innovation to industrial applications, thus promoting the large-scale commercialization of ASIBs.
Hybrid ion conductors that transport multiple ionic conductive species provide a useful platform for understanding how mixed-ion transport governs ionic conductivity within a single phase. However, the controlled introduction of multiple mobile ions into solid-state electrolytes and a mechanistic understanding of their migration within the framework remain challenging. Herein, a skeleton-retained Li+<-> Na+ cationic exchange was used to simultaneously induce Li+ and Na+ cations into the NASICON-type framework of Li3-xNaxZr2Si2PO12 (0 < x < 3). We show that the interpenetration of NaO6 and NaO8 coordination polyhedra significantly influences the ionic conductivity of hybrid ion conductors. Computational analysis indicates that Na+ transfer from octahedral NaO6 sites to octa-coordinated NaO8 sites is thermodynamically favorable, accompanied by Li+ relocation from NaO(8 )to tetrahedral LiO4 environments at former NaO6 sites, thereby promoting Li+/Na+ site segregation. The increased occupation of Na+ at NaO8 sites not only suppresses Na+ mobility due to bottleneck limitations but also hinders the formation of a continuous Li+ migration network, thereby reducing the room-temperature ionic conductivity from 1.78 to 0.50 mS & centerdot;cm(-1). Upon re-exchange, Na+ in the NaO8 sites is replaced by Li+ in penta-coordinated LiO5, which re-establish percolating ion-transport pathways for Li+ and enable reversible recovery of the overall conductivity. These results reveal a fast dual-ion conduction mechanism enabled by the interpenetrating occupation of Li+ and Na+ across the available sites. This work opens a new avenue for the development of hybrid ion conductors.
Carboxymethyl cellulose (CMC) is a water-processable binder widely used for graphite anodes. However, a microscopic understanding of why the identity of CMC counterions (Li+/Na+/K+) strongly affects electrode performance remains limited. Here, molecular dynamics (MD) simulations are used to track Li+ transport accessibility across electrolyte/CMC/ graphite three-phase interfaces, comparing pure CMC-Li, CMC-Na, CMC-K, and mixed-counterion CMC binders. We find that CMC-Li sustains a continuous Li+ transport pathway from the electrolyte through the binder phase toward graphite. In contrast, in CMC-Na and CMC-K, Na+/K+ ions preferentially enrich at the graphite/binder interface, forming a cation-enriched interfacial layer which reduces Li+ accessibility to graphite. Partial replacement of Na+/K+ in CMC-Na and CMC-K with Li+ weakens this interfacial blocking effect and increases Li+ accessibility. Furthermore, a stage-resolved kinetic analysis visualizes the progressive suppression of Li+ crossing the binder phase upon the barrier layer formation. These results provide a microscopic rationale for the experimentally observed performance advantage of CMC-Li over CMC-Na and CMC-K binders.
The increasing demand for cost-effective and efficient renewable energy solutions presents significant optimization challenges in hybrid energy systems. This paper addresses these challenges by conducting a comparative analysis of three advanced optimization algorithms-L & eacute;vy Flight Optimization (LFO), Archimedean Optimization (AO), and Quantum Gorilla Optimization (QGO)-to minimize the Total Net Present Cost (TNPC) and Levelized Cost of Energy (LCOE) in hybrid renewable energy systems. The study integrates critical cost parameters such as Capital Expenditure (CAPEX), Operational Expenditure (OPEX), replacement costs, and salvage values into an advanced optimization framework. Three system configurations are evaluated: Wind Turbines and Fuel Cells (WT/FC), Photovoltaic Systems and Fuel Cells (PV/FC), and a combined system (PV/WT/FC), under varying availability levels (100%, 96%, and 92%). The results demonstrate that LFO consistently outperforms the other algorithms, achieving the lowest TNPC of $0.051 for the WT/FC system at 96% availability, compared to $0.719 using QGO. These findings underscore the importance of selecting tailored optimization strategies to balance cost, performance, and system reliability. This research provides valuable insights into designing efficient and economically viable renewable energy systems, particularly, for applications requiring consistent high energy output, such as monocrystalline and polycrystalline PV-based configurations.
High-entropy oxides (HEOs) present significant scientific challenges in both design and synthesis due to their multielement and high-entropy nature, which involves complex combinations of multiple metal cations and oxygen anions, typically arranged in equimolar ratios to achieve structural stability. Herein, one-dimensional (Co,Ni,Mn,Cu,Zn)O high-entropy oxide nanotubes (HEO-NTs) are fabricated by means of a gradient electrospinning strategy with a tailored polyvinyl alcohol (PVA) molecular weight distribution and controlled pyrolysis. Benefiting from the HEO features and the synergistic effect of multicomponent sites, the as-synthesized (Co,Ni,Mn,Cu,Zn)O HEO-NTs exhibit exceptional bifunctional electrocatalytic activity for the oxygen evolution and hydrazine oxidation reactions (OER/HzOR). This study offers new insight into the design of HEO-NTs and unveiling the multicomponent synergy on HEOs for enhanced electrocatalytic activities of OER and HzOR.
High-voltage n-type organic cathode materials are critical for constructing zinc-organic batteries (ZOBs) with high energy density and long cycle life. However, the intrinsically unfavorable electronic structures and relatively high LUMO energy levels of most n-type materials often lead to sluggish kinetics, high solubility, and suboptimal discharge voltages (< 0.8 V). Here, we design a small molecule, quinoxalino[2',3':5,6]pyrazino[2,3-f][1,10]phenanthroline (DPQP), as a ZOB cathode by introducing locally electron-deficient motifs into the conjugated backbone of aromatic compounds. The linearly fused pyrazine units extending the pyrazine-benzene framework effectively optimize the electronic structure, thereby significantly enhancing the discharge voltage. Meanwhile, the expanded pi-conjugated plane suppresses dissolution and accelerates charge-transfer kinetics. Benefiting from these features, the DPQP electrode exhibits an exceptional increase in average operating voltage from 0.61 V to 1.07 V (vs. Zn-2(+)/Zn) at 0.1 A & centerdot;g(-1), with an overpotential of only 140 mV. Notably, no discernible voltage decay occurs as the current density increases, indicating rapid and highly reversible redox kinetics. Furthermore, the DPQP cathode delivers outstanding cycling stability, maintaining over 2000 h of continuous operation at 0.1 A & centerdot;g(-1) and retaining 82.5% of its capacity after more than 10,000 cycles at 10 A & centerdot;g(-1). Remarkably, the DPQP electrode also demonstrates excellent tolerance to extreme temperatures, achieving stable electrochemical performance across a wide temperature range from -20 degrees C to 60 degrees C. In addition, a series of spectroscopic and microscopic characterizations confirm the highly reversible redox behavior and Zn2+ storage mechanism of the DPQP cathode.
Economical Fe-N-C catalysts are considered as promising alternatives to platinum group metal catalysts for proton exchange membrane fuel cells (PEMFCs). Despite exhibiting robust activity on rotating disk electrodes, their performance within membrane electrode assemblies often experiences limitations, such as decreased O2 diffusion, high H2O2 formation, low proton conduction, and a lower electron transfer number. In this study, key factors, including proton transport, electron conduction, and gas diffusion within air-breathing PEMFCs, have been investigated by adjusting cathode catalyst layer (CCL) compositions. From the experimental results, the optimal peak power density was obtained when the loading of Fe-N-C catalyst was 1 mg center dot cm-2 and Nafion content was 0.15 mg center dot cm-2 within CCLs. The addition of polytetrafluoroethylene to enhance hydrophobicity was found to have a negative impact on PEMFC performance. Furthermore, the incorporation of diverse carbon nanotubes into CCLs resulted in a significant increase of over 30% in peak power density, attributed to enhancements in the gas diffusion and proton conductivity. The critical roles of gas transport and proton conductivity within Fe-N-C-based CCLs have been highlighted by this study. These findings contribute to the advancement of rational design principles for economical PEMFCs, offering valuable insights to drive the development of efficient and cost-effective technology in future.
Flow-cell architectures have emerged as a powerful platform for continuous and stable lithium-mediated nitrogen reduction (Li-NRR), enabling ambient-condition electrochemical ammonia synthesis and offering a promising alternative to Haber-Bosch processes. However, Li-NRR is exceptionally sensitive to trace water, and even minor variations in water content can profoundly alter interfacial chemistry. Here, we systematically investigate how initial water concentration affects Li-NRR performance in a continuous-flow cell. Excess water drives the formation of a thick solid electrolyte interphase (SEI) layer, which may impede nitrogen access to metallic lithium and hinder lithium-ion transport. As a result, the ammonia Faradaic efficiency collapses from ~61% to ~3%. These findings reveal the decisive, previously underappreciated role of water in governing SEI evolution and highlight the necessity of precise water control for achieving stable, high-efficiency continuous-flow Li-NRR.
Homogeneous electrocatalytic nitrogen reduction reaction (NRR) provides a powerful framework to interrogate molecular nitrogen-fixation pathways under mild conditions. By tuning the metal center, ligand architecture, and reaction medium, these systems enable capturing key intermediates and delivering mechanistic insight at the molecular-level resolution. Nevertheless, advances remain constrained by highly reduced operating potentials, intense competition from the hydrogen evolution reaction (HER), limited durability in turnover, and inadequate long-term stability. In this review, we take electron delivery to the molecular active site as the guiding principle for organizing homogeneous electrochemical N2 activation and transformation. We classify reported systems into direct electron transfer (DET), in which the electrode reduces the molecular catalyst directly, and mediated electron transfer (MET), in which the electrode reduces a redox mediator, and the reduced mediator subsequently transfers electrons to the molecular catalyst to access the active states that drive N2 conversion. Mediated systems are further divided into electron-transfer (ET) mediators, which shuttle electrons only, and proton-coupled electron transfer (PCET) mediators, which deliver coupled proton-electron equivalents. For DET systems, we chart progress from early low-valent Ti and W species to widely studied Mo, Fe, and Re complexes, highlighting structurally defined intermediates identified along the reaction pathway. Mechanistically, DET reactivity commonly falls into two routes: a cleavage-first pathway that splits N equivalent to N to form isolable, characterizable metal nitride (M equivalent to N), and a PCET-first pathway that preserves the N-N bond, with stepwise hydrogenation generating NxHy intermediates before NH3 release. This perspective clarifies how ligand electronics, secondary-sphere design, multimetal cooperativity, and solvent/electrolyte microenvironments together control activity and selectivity in NRR. In mediated electrocatalysis, ET mediators can partly shift the burden of extreme reducing conditions away from the catalyst, shielding it from over-reduction and deactivation. PCET mediators, enabled by tunable redox potentials and mediator-H bond strengths, offer a more controlled route for coupled proton/electron transfer, thereby accelerating intermediate hydrogenation, and improving effective activity and turnover of electrocatalytic NRR. Finally, we emphasize that homogeneous NRR still demands stringent contamination control and quantitative product identification, and we highlight the need for more rational molecular-and system-level design strategies to enhance stability and durability under extended operation. Looking ahead, integrating mediator strategies, molecular catalyst design, and electrolyzer engineering could help move homogeneous platforms from mechanistic models toward scalable electrochemical ammonia devices.
Entropy is a basic thermodynamic property of the electrical double layer(EDL)at metal/solution interfaces,yet,its defi-nition,measurement,and theoretical treatment are dispersed in the literature,and,in some cases,ambiguous.In this paper,we revisit the thermodynamic theory of EDL,from which two variants of entropy,excess entropy and formation entropy,are obtained and compared.In terms of the formation entropy,two calculation routes are validated in the context of a primitive EDL model,namely,the Gouy-Chapman(GC)model.After clarifying the concepts and calculation routes,we investigate interfacial water effects on the EDL entropy,using a refined Gouy-Chapman-Stern(GCS)model accounting for chemical potential difference between oxygen-and hydrogen-down water molecules,denoted δµ.The model-derived differential capacitance and entropy are compared with experimental data for the EDL at Au(111)in an aqueous electrolyte solution.The model reveals that the charge of maximum entropy(CME)is negative when water molecules have higher tendency to take oxygen-down configuration at the uncharged surface.Moreover,the formation entropy profile becomes asymmetric around the CME,when δµ is potential-dependent.However,the model fails to simultaneously reproduce capacitance and entropy measurements on the same system taken from two separate studies,indicating deficiencies of the model or experimental errors.Nevertheless,this work stresses the importance of measuring both capacitance and entropy of EDLs at the same time.
Anodic aluminium oxide (AAO) porous films with an interpore distance of several hundred nanometers are of great interest due to their unique interaction with visible and near-infrared light, and high thermal stability up to 1500 degrees C. These porous films are prepared by aluminium anodizing at high voltages in weak acids, leading to a slow kinetics of initial stages of porous structure formation. Here, we propose an approach to accelerate AAO formation in electrolytes based on weak acids such as phosphoric acid. Aluminium foils, pre-patterned using first anodizing under different conditions and subsequent selective dissolution of a sacrificial AAO layer, were utilized as substrates. The morphology of the aluminium surface, including surface roughness and height of pyramidal spikes, plays a crucial role in the pore nucleation and rearrangement process during the second anodizing. In particular, by first anodizing in strong acid electrolytes at low voltages (such as 0.3 mol & centerdot;L-1 sulfuric acid at 25 V), it is possible to double the rate of pore nucleation and subsequent reach of the steady-state regime during second anodizing in phosphoric acid. As a result, about 2 hours can be saved during the two-step anodizing process in phosphoric acid if a strong acid electrolyte is used for the first anodizing to pre-pattern aluminium surface.
Redistribution Layer (RDL), composed of layered dielectrics and electroplated copper materials, is a basic structure to rearrange numerous I/O pads on the chip surface in wafer-level advanced packaging. As the key chemicals in electrolyte baths, electroplating additives have undergone continuous development to meet the industrial needs for high-speed and fine-line/fine-pitch applications. Meanwhile, the intricate relationships between additive chemical structures and electroplated copper properties are yet to be well understood. In this work, a pair of triphenylmethane-based dye molecules, i.e., gentian violet (GV) and methyl green (MG), was comparatively investigated as levelers for high-speed RDL copper electroplating. Compared to GV, significantly stronger electrochemical polarization and tunable deposit morphology can be achieved by MG with just one extra quaternized amine terminal. Combining quantum chemical computations, in situ spectroelectrochemical analyses, and microstructural characterization, it is found that MG possesses enhanced electrostatic adsorption, surface coverage and multi-additive synergies, enabling tailored copper trace morphology. This study elaborates the adsorption mechanism and screening criteria of triphenylmethane-derived levelers, and presents a candidate additive structure for high-speed copper electroplating.
Electrochemiluminescence (ECL) of luminol has been studied on a screen-printed gold electrode for a simple and sensitive detection of arsenic ions (As(III)). Cyclic voltammetry (CV) was applied as the proposed technique to study luminol's electrochemical behavior and to evaluate the arsenic's effect in the ECL system, while hydrogen peroxide (H2O2) served as a co-reactant to enhance luminol's light emission under alkaline conditions. To achieve optimal electrode performance, key parameters including pH, scan rate, and the concentrations of H2O2 and luminol were carefully optimized. The presence of As(III) induced a quenching effect on the luminol/H2O2 ECL system, leading to a linear decrease in ECL signal across the wide concentration range of 1 nmol & centerdot;L-1 to 150 & micro;mol & centerdot;L-1. The system demonstrated a low detection limit of 1.21 nmol & centerdot;L-1 and exhibited excellent repeatability with a relative standard deviation of 2.27%, highlighting its sensitivity and reliability for As(III) detection. A key advantage of this study was the successful use of commercial bare electrodes, which were readily available and required no modifications, proving their effectiveness for ECL-based arsenic sensing. The optimized buffer solution pH of 10 played a critical role in enhancing arsenic detection selectivity, as it facilitated the optimal deprotonation of luminol and ensured arsenic remained in its dissolved state, whereas other potential metal ion interferences were more likely to form solid metal (hydro)oxides. Furthermore, the developed sensor was successfully applied for As(III) detection in a seawater matrix, demonstrating its potential as a robust and effective ECL-based arsenic sensor for environmental applications.
Thermal safety associated with lithium-ion cells as power sources remains a critical industry concern. A comprehensive understanding of how internal exothermic side reactions contribute to temperature rise is fundamental for accurately analyzing thermal runaway processes and predicting the thermal safety of lithium-ion cells. While various side-reactions, such as decomposition of solid electrolyte interphase layer, reaction between anode materials and electrolyte, reaction between cathode materials and electrolyte, and electrolyte decomposition, have been identified as heat generation sources in previous studies, the quantification of these reactions remains insufficiently standardized. Particularly, the impact of heat generation from binder decomposition (most commonly polyvinylidene difluoride) at elevated temperatures on the thermal runaway process of lithium-ion cells has not been fully elucidated. Therefore, in this study, an electro-thermal coupled numerical model was developed for 18650-type lithium-ion cells to systematically investigate the synergistic effects of these five major side-reactions under high-temperature conditions leading to thermal runaway. Special emphasis was placed on precisely quantifying the contribution from binder decomposition heat during the thermal runaway process. The results demonstrate that once the ambient temperature exceeds the threshold required to initiate cascading exothermic side reactions, the inclusion or exclusion of the binder reaction in the model does not affect the overall assessment results of thermal runaway for lithium-ion cells. However, under these conditions, the heat contribution from binder decomposition to the total heat release increases significantly and therefore becomes one of the dominant heat sources for temperature rise during the thermal runaway propagation. Conversely, when ambient temperatures do not reach the threshold, the heat contribution from binder decomposition is negligible. Additionally, the improved electro-thermal coupling model serves as an effective simulation tool for designing battery systems with enhanced safety, selecting appropriate binder materials to mitigate the adverse effects of thermal runaway, and optimizing thermal management during battery development. This approach significantly reduces the research and development cycle. These findings establish appropriate heat source selection criteria for electro-thermal models under varying precision requirements and provide a theoretical foundation for both model simplification and high-fidelity optimization in lithium-ion battery design.
Proton exchange membrane fuel cells (PEMFCs) are considered as a promising renewable power source. However, the massive commercial application of PEMFCs has been greatly hindered by their high expense and less-satisfied performance mainly due to the sluggish oxygen reduction reaction (ORR) kinetics even on state-of-the-art Pt catalyst. Octahedral PtNi nanoparticles (oct-PtNi NPs) with excellent ORR activity in a half-cell have been widely studied, while their performance in membrane electrode assembly (MEA) has much less reported. Herein, we investigated the MEA performance using the carbon supported oct-PtNi NPs (oct-PtNi/C) as the cathode catalyst. Under the mild acid washing condition, the surface Ni atoms of oct-PtNi/C were largely removed, and the performance of the MEA using the acid-leaching oct-PtNi/C (PNC-A) as the cathode catalyst was greatly improved. The maximum power density of the MEA reached 1.0 W & centerdot;cm-2 with the cathode Pt loading of 0.2 mg & centerdot;cm-2, which is 15% higher than that using Pt/C as the catalyst. After 30k cycles in the accelerated degradation test (ADT), the MEA using PNC-A as the catalyst showed a performance retention of 82%, higher than that of Pt/C (74%). The results reported here verify the possibility of using PNC-A as an advanced cathode catalyst in PEMFCs, thus enhancing the performance of PEMFCs while lowering the amount of expensive Pt.
Fe-N-C catalysts have long suffered from kinetically sluggish oxygen reduction reaction (ORR) due to excessive adsorption strength toward oxygen intermediates and low site utilization. Heteroatom doping effectively accelerates ORR reaction kinetics through electronic structure modulation of metal sites for optimal intermediate adsorption, while chemical vapor deposition (CVD) enhances the turnover frequency (TOF) of active sites. Herein, we developed an FeSNC catalyst featuring abundant FeS1N4 sites via a dual-precursor CVD strategy. Experimental and theoretical analyses revealed that S incorporation disrupts the symmetric coordination of active sites, which optimizes OH* adsorption energies from 0.212 eV to 1.194 eV. Moreover, the TOF increased from 1.98 e–1·site–1·s–1 to 6.32 e–1·site–1·s–1, significantly enhancing the intrinsic activity of the catalyst. More notably, the hydrophilic character of S-containing species substantially improved hydrophilicity in the S-doped catalyst, thereby promoting mass transport of oxygen and proton delivery. As a result, the FeSNC catalyst exhibited an extremely high half-wave potential of 0.863 V in 0.1 mol·L–1 HClO4 and achieved a peak power density of 1.2 W·cm–2 in H2-O2 PEMFCs. This work highlights the critical role of coordination engineering.
