Efficient Ion Transport Research Articles

Nanomaterials in Solid-State Batteries: Enhancing Safety and Performance

Solid-state batteries (SSBs), utilizing solid electrolytes instead of liquid ones, represent a promising advancement in energy storage technology due to their higher energy density and enhanced safety. Despite their potential, SSBs face significant challenges such as high interfacial resistance, low ionic conductivity, and high production costs. Recent advancements in nanomaterial technology have offered innovative solutions to these issues. Nanomaterials with high specific surface areas and controllable morphologies optimize interfacial contact, reduce resistance, and enhance ionic conductivity through efficient ion transport channels. Additionally, surface modifications and doping improve the chemical and thermal stability of SSB components, extending battery life and preventing adverse reactions. Although initial preparation costs are high, advancements in production technology and large-scale manufacturing are expected to lower these costs, facilitating commercialization. Future research should focus on new nanostructure designs, nanocomposites, and interfacial engineering to further enhance battery performance and safety. Understanding the influence of nanomaterials on safety performance and improving thermal and mechanical shock resistance are crucial for the reliable implementation of solid-state batteries in practical applications.

Hybrid Particle Size Template Method for Controllable Synthesis of Nitrogen-doped Multilevel Porous Carbon as High-rate Zn-ion Hybrid Supercapacitor Cathode Materials.

Achieving high rate performance without compromising energy density has always been a critical objective for zinc-ion hybrid supercapacitors (ZHSCs). The pore structure and surface properties of carbon cathode materials play a crucial role. We propose utilizing a hybrid particle size (20 and 40 nm) magnesium oxide templates to regulate the pore structure of nitrogen-doped porous carbon derived from the soybean isolate. The multilevel pore structure enhanced ion transport efficiency while also improving the utilization of micropores. Nitrogen doping and oxygen-containing functional groups enhanced the wettability of carbon materials with aqueous electrolytes and facilitated the chemisorption of Zn2+ on the carbon material surface. The nitrogen-doped multilevel porous carbon material (HT-NMPC-1/1) prepared with a 1:1 mass ratio of the two templates exhibited a specific capacity of 146.65 mAh g-1 at 0.2 A g-1. Moreover, the Swagelok cells assembled with HT-NMPC-1/1 and Zn foil achieved a high energy density of 121.5 W h kg-1, high power output of 166 W kg-1, and 93.09% capacity retention after 8000 cycles at 2 A g-1. Therefore, HT-NMPC-1/1 is a highly promising candidate for ZHSCs cathode materials. Furthermore, the novel pore regulation strategy and straightforward preparation method offer valuable reference points for other porous carbon-based functional materials.

Nanoarchitecture via Synchronic Stacking of Metallic and Nonmetallic Two-Dimensional Nanosheets for Optimal Light-Driven Ion Transport.

The exceptional selectivity and responsive ion transport in biological channels inspire technology breakthrough in energy, environmental, and resource sectors. However, existing nanofluidic systems with a high photothermal conversion efficiency often exhibit excessive thermal conductivity, which impedes the creation of effective temperature gradients and results in a low ion transport efficiency. In this study, a strategy based on the synchronic stacking of metallic and nonmetallic two-dimensional (2D) nanosheets was presented to construct heterogeneous nanofluidic channels. This specific nanoconfined architecture sustained high temperatures in the illuminated area while maintaining low temperatures in the nonilluminated area, thus obtaining a robust driving force from sunlight for directional ion transport. As a result, our light-responsive ion transport system demonstrated significant potential in solar energy conversion and osmotic energy harvesting, surpassing those of all previously reported nanofluidic systems. Additionally, although it is still at the proof-of-concept stage, it shows great promise in light signal monitoring. This work provides an effective strategy for developing advanced light-responsive ion transport systems and their important applications.

In-Situ CO2 Release from Captured Solution and Subsequent Electrolysis: Advancements in Integrated CO2 Capture and Conversion Systems

The electrochemical reduction of carbon dioxide (CO2ER) offers a compelling strategy for sustainable energy and carbon management by transforming CO2 into valuable chemicals and fuels. This approach is particularly attractive when powered by surplus renewable energy, aiding in the closure of the carbon cycle. However, the significant energy requirements for CO2 isolation, pressurization, and purification from capture media pose challenges for industrial-scale implementation. To overcome these obstacles, recently innovative electrolyzers have developed that directly convert reactive carbon solutions, such as bicarbonate-rich effluents from carbon capture units, into higher-value products. This electrolyzers produces CO2 in situ by reacting (bi)carbonate with acid generated within the electrolyzer, facilitating efficient CO2ER at the cathode surface and eliminating the need for costly CO2 recovery and compression steps. This study details recent efforts in advancing this type of electrolyzer, focusing on CO2 sources for capturing step, technical aspect consideration of integrated systems, electrolyzer design consideration and membrane designs for integrated systems. Herein, we emphasize the need for a permeable cathode that allows efficient (bi)carbonate ion transport while maintaining a high catalytic surface area. Additionally, we discuss the critical role of electrolytes, including the impact of (bi)carbonate concentration, their effect on CO2 utilizations and CO2ER selectivity. We also demonstrate the state-of-the-art performance metrics for electrolyzers that utilize CO2-captured solutions, such as Faradaic efficiency, experimental validation of CO2 sources, current density, and CO2 utilization efficiency, a guideline for future studies. Collectively, we believe that this analysis will contribute to the development of industrial-scale electrochemical reactors for CO2 conversion, advancing towards a sustainable and closed-loop carbon cycle.

Efficient sodium ion transport enhanced by anionophilic sites in polymer-supported plastic crystal electrolyte for high performance sodium metal anode

The design of sodium metal batteries (SMBs) is seen as an excellent solution to solve the request of next-generation energy storage technologies with high energy density, high safety, low cost, and environmental friendliness. However, the direct use of sodium metal as an anode produces the dendritic sodium, which harms the normal operation of battery. Inspired by solid-state lithium metal batteries, solid-state electrolyte (SSE) designed for SMBs effectively solves this shortcoming. Herein, a novel SSE with mask-based polymer membrane supporting plastic crystal electrolyte with ZIF-67 (MPPZ) is designed. The experimental results and density functional theory (DFT) calculations indicate that the addition of ZIF-67 in MPPZ electrolyte availably fixes TFSI− and achieves high Na+ transference number. Additionally, a protective layer of NaF is formed in situ on the surface of sodium metal to avoid side reactions between Na and MPPZ electrolyte while further guide the uniform deposition of Na. Accordingly, Na||Na symmetric battery with NaF-coated Na metal anode and MPPZ electrolyte has a stable deposition and stripping of Na for 3000 h. The assembled room temperature solid-state sodium-sulfur battery (RTSSSSB) exhibits a good cycle stability. This study provides an innovative thinking for the construction of high performance dendrite-free SMBs.

Impact of ultrasonic treatment duration on the microstructure and electrochemical performance of NiZnCo2O4 electrode materials for supercapacitors

This work investigates the impact of different ultrasonic treatment durations on the synthesis and electrochemical performance of NiZnCo2O4 (NZC) supercapacitor electrodes. Optimizing treatment to 20 min resulted in a uniform, compact NiZnCo2O4 layer with improved nanostructures, which increased the surface area and active sites for electrochemical reactions. X-ray diffraction (XRD) confirmed successful NiZnCo2O4 synthesis, revealing distinct crystalline phases of NiO, ZnCo2O4, and Co3O4, with improved crystallinity. Electrochemical tests, conducted using a 1.0 M KOH electrolyte, demonstrated that the NZC-2 electrode treated for 20 min achieved the highest 5.678 F/cm3 volumetric capacitance at 0.5 mA/cm2 current density along with 70.5 Wh/kg an energy density at 260 W/kg power density. The galvanostatic charge-discharge and cyclic voltammetry tests revealed that NZC-2 maintained superior charge-discharge efficiency, showing the longest discharge time at 1 mA/cm². Electrochemical impedance spectroscopy (EIS) measurements demonstrated that NZC-2 exhibited the lowest total impedance, thereby enhancing ion transport efficiency. The NZC-2/AC asymmetric supercapacitor showed excellent long-term stability, retaining 64.2% of its capacity after 20,000 charge-discharge cycles. It successfully powered a 1.2 V small fan, demonstrating its practical applicability. The results highlight the crucial importance of ultrasonic treatment in greatly improving the structural and electrochemical characteristics of NiZnCo2O4 electrodes, which opens up possibilities for the advancement of high-performance supercapacitors.

Microbial Surface Confined Growth Strategy for the Synthesis of Highly Loaded NiCoP Nanoparticles with Hollow Derived Carbon Shells for Sodium Ion Capture.

NiCoP is considered to be a very promising material for sodium ion (Na+) capturing, however, the volume expansion and poor cyclic stability of NiCoP during the storage limit its application. In response to these limitations, Finite element simulations are used to help in the rational design of the NiCoP structure. A novel microbial surface confined growth strategy is employed to synthesize highly loaded NiCoP nanoparticles (NiCoP NPs) supported on hollow derived carbon shells (NPC), constructing a stable composite structure known as NiCoP@NPC. The highly loaded and uniformly dispersed NiCoP NPs are anchored in-situ and fully exposed, enabling enhanced electron and ion transport efficiency and thereby boosting pseudocapacitance. The NPC from yeast played a crucial role in mitigating the volume expansion of NiCoP NPs, thereby enhancing the structural stability of the electrode. Consequently, NiCoP@NPC demonstrated a high Na+ storage capacity of 59.70 ± 1.51 mg g-1 at 1.6 V and maintained good cycling stability, retaining over 73.3% of its capacity after 80 cycles at 1.6 V. Scanning transmission X-ray microscopy (STXM) analysis confirmed the reversible conversion reaction mechanism and the robust structure of NiCoP@NPC before and after the reaction; Density function theory (DFT) and electrochemical quartz crystal microbalance (EQCM-D) further confirmed that the structural design of NiCoP@NPC promoted electron transport, Na+ adsorption as well as improved cycling stability. This study is intended to provide a new idea for the in-situ confined synthesis of metal phosphides electrodes with stable performance and structure.

Bifunctional Ion Rectification Layer Separators Toward Superior Reversible Dendrite‐Free Zinc Metal Anodes

AbstractThe slow transport dynamics and poor dendritic growth significantly hinder the performance of zinc metal batteries. Here, a unique difunctional ion rectification strategy is developed using vacuum evaporation technology to design a coated separator for efficient ion transport. The highly conductive Cu‐coated separator acts as an ion redistributor, ensuring homogenized electric field distribution. The excellent znophilicity of the copper coating acts as an ion accelerator, promoting ion transport and facilitating face‐to‐face zinc deposition on the separator. Consequently, this synergy enables stable battery operation at high current densities (cumulative capacity up to 10 800 mAh cm−2 at 8 mA cm−2) and high depth of discharge (over 200 h at 94% DOD). The Cu‐coated separator exhibits a reversible plating/stripping life of over 2400 h with an average coulombic efficiency of 99.88%. Notably, the Cu‐coated separator significantly enhances the rate performance and cycle capacity of Zn||V6O13 and Zn||MnO2 full cells. This functional separator with a difunctional ion rectification strategy presents a promising solution to the challenge of zinc metal anodes.

Regulation of transmembrane current through modulation of biomimetic lipid membrane composition.

Ion transport through biological channels is influenced not only by the structural properties of the channels themselves but also by the composition of the phospholipid membrane, which acts as a scaffold for these nanochannels. Drawing inspiration from how lipid membrane composition modulates ion currents, as seen in the activation of the K+ channel in Streptomyces A (KcsA) by anionic lipids, we propose a biomimetic nanochannel system that integrates DNA nanotechnology with two-dimensional graphene oxide (GO) nanosheets. By modifying the length of the multibranched DNA nanowires generated through the hybridization chain reaction (HCR) and varying the concentration of the linker strands that integrate these DNA nanowire structures with the GO membrane, the composition of the membrane can be effectively adjusted, consequently impacting ion transport. This method provides a strategy for developing devices with highly efficient and tunable ion transport, suitable for applications in mass transport, environmental protection, biomimetic channels, and biosensors.

Enhancing the Filler Utilization of Composite Gel Electrolytes via In Situ Solution-Processable Method for Sustainable Sodium-Ion Batteries.

The composite gel electrolyte (CGE), which combines the advantages of inorganic solid-state electrolytes and solid polymer electrolytes, is regarded as the ultimate candidate for constructing batteries with high safety and superior electrode-electrolyte interface contact. However, the ubiquitous agglomeration of nanofillers results in low filler utilization, which seriously reduces structural uniformity and ion transport efficiency, thus restricting the development of consistent and durable batteries. Herein, a solution-processable method to in situ construct CGE with high filler utilization is introduced. The homogeneous metal-organic framework fillers contribute to uniform ionic and electronic filed distribution, realizing a stable electrode-electrolyte interface. Consequently, the CGE with high filler utilization achieves an ultra-long lifespan of 10000 cycles with a capacity retention of 80.2%. This work provides guidance for constructing high-performance CGEs in electrochemical energy-storage devices.

Facile synthesis of monoclinic (NH4)2V4O9 nanosheets for zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) are increasingly popular due to their low cost and high safety. However, the quest for cathode materials with robust internal structures and efficient ion transport pathways remains critical. In this study, we introduce a simple hydrothermal method to synthesize monoclinic (NH4)2V4O9 nanosheets, serving as a advanced cathode for ZIBs. This material demonstrates outstanding electrochemical properties, with a high specific capacity of 389 mAh g−1 at 0.1 A g−1, and retains 78.9 % capacity after 3000 cycles at 1 A g−1 and 77.3 % after 15,000 cycles at 5 A g−1. Additionally, it achieves an energy density of 325 Wh kg−1 at 101 W kg−1. In-depth electrochemical analysis reveals the structural stability during reversible Zn2+ ion intercalation/de-intercalation, underscoring the potential of (NH4)2V4O9 as a high-performance material for ZIBs.

Horizontal Transport in Ti3C2Tx MXene for Highly Efficient Osmotic Energy Conversion from Saline‐Alkali Environments

AbstractOsmotic energy from the ocean has been thoroughly studied, but that from saline‐alkali lakes is constrained by the ion‐exchange membranes due to the trade‐off between permeability and selectivity, stemming from the unfavorable structure of nanoconfined channels, pH tolerance, and chemical stability of the membranes. Inspired by the rapid water transport in xylem conduit structures, we propose a horizontal transport MXene (H‐MXene) with ionic sequential transport nanochannels, designed to endure extreme saline‐alkali conditions while enhancing ion selectivity and permeability. The H‐MXene demonstrates superior ion conductivity of 20.67 S m−1 in 1 M NaCl solution and a diffusion current density of 308 A m−2 at a 10‐fold salinity gradient of NaCl solution, significantly outperforming the conventional vertical transport MXene (V‐MXene). Both experimental and simulation studies have confirmed that H‐MXene represents a novel approach to circumventing the permeability‐selectivity trade‐off. Moreover, it exhibits efficient ion transport capabilities, addressing the gap in saline‐alkali osmotic power generation.

Horizontal Transport in Ti3C2Tx MXene for Highly Efficient Osmotic Energy Conversion from Saline-Alkali Environments.

Osmotic energy from the ocean has been thoroughly studied, but that from saline-alkali lakes is constrained by the ion-exchange membranes due to the trade-off between permeability and selectivity, stemming from the unfavorable structure of nanoconfined channels, pH tolerance, and chemical stability of the membranes. Inspired by the rapid water transport in xylem conduit structures, we propose a horizontal transport MXene (H-MXene) with ionic sequential transport nanochannels, designed to endure extreme saline-alkali conditions while enhancing ion selectivity and permeability. The H-MXene demonstrates superior ion conductivity of 20.67 S m-1 in 1 M NaCl solution and a diffusion current density of 308 A m-2 at a 10-fold salinity gradient of NaCl solution, significantly outperforming the conventional vertical transport MXene (V-MXene). Both experimental and simulation studies have confirmed that H-MXene represents a novel approach to circumventing the permeability-selectivity trade-off. Moreover, it exhibits efficient ion transport capabilities, addressing the gap in saline-alkali osmotic power generation.

Nanowires for Solid‐State Lithium Batteries

AbstractA vital approach to accessing high‐safety and high‐energy‐density lithium batteries is to develop solid‐state electrolytes (SSEs) instead of liquid electrolytes. However, lithium‐ion transport and interface stability issues puzzle the construction of solid‐state lithium batteries (SSLBs). Thus, developing fast‐ionic conductors with high electrochemical performances and chemical stability is crucial to SSLBs. Nanowires (NWs) possess high aspect ratios for maintaining carrier transport along the radial direction, thus being extensively employed in SSLBs for the enhancement of ion transport efficiency, mechanical properties, thermostability, flame retardancy, and interface stability between electrodes and electrolytes, consequently boosting the cycle stability and safety of SSLBs. In this work, the advances in NWs for SSLBs, from rational design and synthesis strategies to applications in composite cathodes, anode materials, and SSEs of SSLBs, are systematically reviewed. The key role of NWs in electrodes and the enhancement mechanism of SSE performance by introducing NWs are concluded in detail. Finally, the existing challenges and anticipated prospects for the future development of advanced nanowire‐based SSLBs are summarized and demonstrated. This review aims to provide a comprehensive understanding to facilitate the application of NWs in SSLBs.

High Entropy Induced Local Charge Enhancement Promotes Frank–Van der Merwe Growth for Dendrite‐Free Potassium Metal Batteries

AbstractPotassium metal batteries (PMBs) are promising for next‐generation energy storage. However, the high reactivity of the anode causes instability in the solid electrolyte interface (SEI), resulting in Volmer‐Weber (V‐W) type deposition. To achieve uniform Frank‐van der Merwe (F‐M) type deposition, high entropy alloy nanoparticles are designed (HEA NPs) with equimolar ratios of Mn, Fe, Co, Cu, and Ni to enhance the substrate‐K metal interface. HEA NPs enhance the K affinity of the N‐doped nanocarbon fiber substrate (N‐PCNF) and maximize ion and electron transport efficiency. The dendrite‐free horizontal growth of K metal confirmed through Operando X‐ray diffraction (XRD) and optical microscopy (OM). Consequently, the asymmetric cell exhibits ultra‐long cycling stability of 2350 hours at a high current density of 8 mA cm−2. The full cell composed of molten K diffusion into HEA NPs decorated N‐PCNF anode with perylene‐3,4,9,10‐tetracarboxylic dianhydride cathode (HEA‐N‐PCNF‐K||PTCDA) delivers an energy density of 331 W h kg−1 and remains stable over 2000 cycles. This study offers a promising pathway for innovative PMBs designs with broad application prospects.

Efficient Isolation of Cellulose Nanocrystals from Seaweed Waste via a Radiation Process and Their Conversion to Porous Nanocarbon for Energy Storage System.

This article presents an efficient method for isolating cellulose nanocrystals (CNcs) from seaweed waste using a combination of electron beam (E-beam) irradiation and acid hydrolysis. This approach not only reduces the chemical consumption and processing time, but also improves the crystallinity and yield of the CNcs. The isolated CNcs were then thermally annealed at 800 and 1000 °C to produce porous nanocarbon materials, which were characterized using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy to assess their structural and chemical properties. Electrochemical testing of electrical double-layer capacitors demonstrated that nanocarbon materials derived from seaweed waste-derived CNcs annealed at 1000 exhibited superior capacitance and stability. This performance is attributed to the formation of a highly ordered graphitic structure with a mesoporous architecture, which facilitates efficient ion transport and enhanced electrolyte accessibility. These findings underscore the potential of seaweed waste-derived nanocarbon as a sustainable and high-performance material for energy storage applications, offering a promising alternative to conventional carbon sources.

Reinforced Magnetic-Responsive Electro-Ionic Artificial Muscles by 3D Laser-Induced Graphene Nano-Heterostructures.

Efficient ion transport and enriched responsive modals via modulating electrochemical properties of conductivity and capacitance are essential for soft electro-ionic actuators. However, cost-effective and straightforward approaches to achieve expedited fabrication of active electrode materials capable of multimodal-responsiveness remain limited. Herein, this work reports the one-step ultrafast laser direct patterning method, to readily synthesize electro- and magneto-active electrode material, derived from the unique cobalt-phosphorus co-doped core-shell heterostructures within 3D graphene frameworks, for fulfilling the dual-mode responsive electro-ionic actuators. The designed nanofiber-structured heterointerfaces across electrodes and electrolytes further promote highly efficient electron/ion transfer. The developed soft actuator exhibits superior actuation performance of peak-to-peak displacement to 13.08mm under an ultra-low ±0.5V, with doubled direct current deflection under 200 mT at 1V, an ultrafast response of 1.38 s and long-term stability (>90% retention for ≈106000 cycles), even detectable bending to ≈280µm under exceptional ±10mV. The promising demonstration of promoting differentiation and proliferation of stem cells under mechanical strain and electrical stimuli, sheds more light as well on the possibility of facilitating biomedical soft robotics with ultrahigh actuation performance.

Enhanced dynamics of Al3+/H+ ions in aqueous aluminum ion batteries: Construction of metastable structures in vanadium pentoxide upon oxygen vacancies

In recent years, aqueous aluminum ion batteries have been widely studied owing to their abundant energy storage and high theoretical capacity. An in-depth study of vanadium oxide materials is necessary to address the precipitation of insoluble products covered cathode surface and the slow reaction kinetics. Therefore, a method using a simple one-step hydrothermal preparation and oxalic acid to regulate oxygen vacancies has been reported. A high starting capacity (400 mAh g−1) can be achieved by Ov-V2O5, and it is capable of undergoing 200 cycles at 0.4 A g−1, with a termination discharge capacity of 103 mAh g−1. Mechanism analysis demonstrated that metastable structures (AlxV2O5 and HxV2O5) were constructed through the insertion of Al3+/H+ during discharging, which existed in the lattice intercalation with V2O5. The incorporation of oxygen vacancies lowers the reaction energy barrier while improving the ion transport efficiency. In addition, the metastable structure allows the electrostatic interaction between Al3+ and the main backbone to establish protection and optimize the transport channel. In parallel, this work exploits ex-situ characterization and DFT to obtain a profound insight into the instrumental effect of oxygen vacancies in the construction of metastable structures during in-situ electrochemical activation, with a view to better understanding the mechanism of the synergistic participation of Al3+ and H+ in the reaction. This work not only reports a method for cathode materials to modulate oxygen vacancies, but also lays the foundation for a deeper understanding of the metastable structure of vanadium oxides.

Development of a Superior Anion Exchange Membrane with Hyperbranched Polymer for Anion Exchange Membrane Water Electrolysis

The production of hydrogen using membrane-based electrolyzersposes significant advantages and benefits compared to traditionalelectrolysis methods. Among the electrolyzers, anion exchangemembrane water electrolysis (AEMWE) has emerged as one of thepromising technologies owing to its unique advantages. However,the development of efficient AEMs for water electrolysis presentssignificant challenges, particularly in achieving enhanceddimensional stability and conductivity. In this study, ahyperbranched polyesteramide (HPEA) was synthesized andblended with poly(ether sulfone) (PES) to address the challenges.The resulting QPES-HPEA blend membrane exhibited a lowswelling ratio and high water uptake, which are critical formaintaining dimensional stability and enhancing the hydroxide iontransport efficiency of AEM. The enhanced physical properties andoptimized structure of the membrane make it a promising candidatefor next-generation AEMs in water electrolysis systems.

Boosting the electrocatalytic performance of CuCo2S4 via surface-state engineering for ampere current water electrolysis applications

For the efficient production of green H2 on an industrial scale, developing durable, cost-effective electrocatalysts using earth-abundant transition-metals is crucial. Herein, we report a robust, bifunctional sulfurized CuCo2O4 (CCS/Ov) catalyst with engineered oxygen-vacancies, in which the metal catalyst is tunes to high valence state, significantly altering the intrinsic reaction kinetics and generating better catalytic activity for efficient ion transport in various electrolytes (neutral, seawater, alkaline simulated-seawater (ASW), and KOH). The optimized dual-strategy synthesized CCS/Ov catalysts with hierarchical morphology exhibits modest overpotential of 383 and 355 mV at 1000 mA cm−2 for OER and HER, respectively, in 1 M KOH. Impressively, an electrolyzer cell (CCS/Ov||CCS/Ov) demonstrates low cell-voltage of 1.487 V (6 M KOH), with excellent robustness in an ASW (1 and 2 M) environment against corrosive chlorine. The bifunctional CCS/Ov||CCS/Ov catalyst outperforms a state-of-the-art paired Pt/C||RuO2 catalyst and maintains the lowest potential response at up to 2000 mA cm−2, while demonstrating remarkably stable simultaneous O2 and H2 generation over 10 days at various current rates. Additionally, DFT calculations confirmed that CCS/Ov catalysts demonstrate significantly enhanced HER and OER activities due to reduced H2O dissociation energy and strong intermediate binding energy, which is attributed to the anionic vacancy near Co3+. The excellent bifunctional performance of the hierarchical CCS/Ov highlights its potential as non-precious catalyst with facile fabrication approach.