Electrochemical Energy Storage Applications Research Articles

Development of aryl ether-free cross-linked polymer membranes for sustainable electrochemical energy conversion and storage applications

Development of aryl ether-free cross-linked polymer membranes for sustainable electrochemical energy conversion and storage applications

Facile synthesis and first principles calculations of Li-MoS2/rGO nanocomposite for high-performance supercapacitor applications

Two-dimensional (2D) nanostructured materials such as graphene oxide nanosheets and molybdenum disulfide (MoS2) are potential candidates for electrochemical energy storage applications. The layered structure of MoS2 makes it a promising active electrode material for supercapacitors. Lithium (Li) interacted with MoS2/reduced graphene oxide (Li-MoS2/rGO) nanocomposite has been synthesized in two steps using a sonochemical dispersion method, and a one-pot hydrothermal method resulting in few-layered MoS2/rGO nanosheets of 2D heterointerfaces. The Li-MoS2/rGO nanocomposite exhibits a high specific capacitance of 173.3 F g−1 at a current density of 1 A g−1. Furthermore, an asymmetric supercapacitor device fabricated with Li-MoS2/rGO achieves a good energy density of 10.6 Wh kg−1 at a power density of 686.3 W kg−1 and outstanding cycling stability with 81.2 % capacity retention over 10,000 cycles. The dispersion of 2D-MoS2 in water is due to the strong electrostatic interface. The structural and electronic properties are theoretically calculated for pristine and Li-interacted MoS2/rGO heterostructure using density functional theory. A comparison of the density of states plots of the two heterostructures and the difference charge density plot of Li-MoS2/rGO heterostructure clearly brings out the importance of the presence of Li. A value of 64 μF cm−2 for the quantum capacitance for pristine MoS2/graphene heterostructure increases to a value 99 μF cm−2 corroborating the experimental observations and we assign this change to the transfer of charge from the Li atom to the outer S atoms in the MoS2/graphene heterostructure. This comprehensive approach, combining experimental synthesis with computational modelling, significantly advances the development and optimization of high-performance supercapacitor materials in the energy storage field. The Li-MoS2/rGO nanocomposite has excellent electrochemical specific capacitance and long-term cyclic stability and has been effectively used for supercapacitor applications with high electrochemical performance.

Solid-state preparation of in-situ grown graphene-embedded bi-metallic NiMnS hybrids for high-performance asymmetric supercapacitor

Endowed with intrinsic redox-rich features and superior electronic conductivities, mixed-metallic sulphides offer high prospects in electrochemical charge storage, especially in supercapacitors. Hence, their rational design and scalable preparation are of great scientific significance. Herein, we report the in-situ growth of nanostructured hybrids of NiMnS directly embedded into graphene sheets by a straightforward, scalable solid-state synthesis method. In this environment-friendly approach, the metal precursors, elemental sulphur, and graphene oxide (GO) are homogeneously mixed under ball-milling, followed by controlled thermal treatment. Incited from their unique synergistic contribution, the resulting NiMnS/G hybrids exhibit impressive electrochemical performance as a battery-type electrode in an aqueous electrolyte. The NiMnS/G hybrid electrode displayed a high specific capacity of 871.7C g−1 at 2 A g−1 with superior rate capability. Moreover, the asymmetric supercapacitor (ASC) device assembled based on the surface-enhanced NiMnS/G nanohybrid as the positive electrode and activated carbon (AC) as the negative electrode achieves an intriguing performance, delivering a maximum energy density of 53.4 Wh kg−1 at a power density of 500 W kg−1. The ASCs were successfully cycled over 10,000 cycles with 87 % capacitance retention and around 99 % Coulombic efficiency. This simple yet scalable strategy holds high promise and may pave the way for preparing other multimetallic sulphide-based hybrid electrode materials for electrochemical energy storage applications.

Solar-driven induced photoelectron remember effect involved in core–shell NiCo2S4@Ni3V2O8 composite electrode with superior electrochemical energy storage for asymmetric supercapacitor

Photo-assisted supercapacitor systems offer a compelling approach to effectively harnessing both solar and electrical energy. In this study, the core–shell heterostructure NiCo2S4@Ni3V2O8 (NCS@NVO) was successfully synthesized for the development of photosensitive supercapacitor electrodes. NCS@NVO demonstrated a pronounced photoelectron memory effect under illumination, attributed to the solar-driven contributions of both NCS and NVO, as photon absorption facilitated electron-hole pair separation and transport. Compared to the specific capacitance in the dark (2292F g−1 at 1 A g−1), the capacitance of the NCS@NVO composite electrode increased dramatically to 3025F g−1 when exposed to light. Moreover, the capacitance retention rate remained remarkably high at 99.83 % after 10,000 cycles at 20 A g−1. In addition, the NCS@NVO hybrid supercapacitor achieved an outstanding energy density of 63.56 W h kg−1 under illumination, alongside a power density of 789.84 W kg−1. This study thoroughly investigated the solar-induced photoelectron memory effect in the NCS@NVO composite electrode for asymmetric supercapacitors, paving the way for the design of high-performance photosensitive nano-electrodes in advanced electrochemical energy storage applications.

Redox-mediated synthesis of Cu2O/CuO/Mn3O4/C quaternary nanocomposites as an efficient electrode material for oxygen reduction reaction and supercapacitor application

Earth-abundant transition metal oxides (TMOs) hold significant promise as electroactive materials in various electrochemical energy conversion and storage applications, offering economic and environmental advantages over their less abundant counterparts. In this work, a simple and cost-effective redox-mediated reaction strategy under hydrothermal conditions has been adopted to synthesize the quaternary nanocomposites Cu2O/CuO/Mn3O4/C with variable amounts of carbon. The synthesized nanocomposites have been characterized using various analysis techniques, including powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Brunauer–Emmett–Teller (BET). The synthesized COM5 nanocomposite (Cu2O/CuO/Mn3O4/C-50), when used as an electrocatalyst for the oxygen reduction reaction (ORR), demonstrates a good limiting current density (JL), half-wave potential (E1/2), and onset potential (Eonset) of −5.50 mA/cm2, 0.75 V, and 0.95 V, respectively, as per the polarization curve. The COM5 nanocomposite exhibits a four-electron transfer mechanism, calculated using the Koutecky-Levich (K-L) equation. In an O2-saturated 0.1M KOH solution, the COM5 nanocomposite has shown a superior relative current durability of 84.46% over 14,000 s compared to the commercially available 10 wt% Pt/C, indicating its potential application in the ORR. However, for supercapacitor applications, the COM3 nanocomposite (Cu2O/CuO/Mn3O4/C-20) as active electrode material in galvanic charge-discharge (GCD) study shows superior performance (201 F/g at 1 A/g) compared to the COM2 nanocomposite (117 F/g at 1 A/g) in neutral aqueous electrolyte, possibly due to the lower charge transfer resistance (Rct) of 24.04 Ω compared to COM2 (34.63 Ω). In two-electrode studies, the COM3 nanocomposite exhibits a good energy density of 24.19 Wh/kg at 1 A/g and a 4.7 kW/kg power density at 5 A/g. Additionally, the COM3 nanocomposite shows excellent long-term durability (74% capacitance retention) at the current density of 5 A/g for 8000 cycles. The electrochemical findings indicate that the COM3 nanocomposite stands out as a superior electrode material for supercapacitors, while the COM5 nanocomposite proves to be an effective electrocatalyst for the oxygen reduction reaction.

Modification of Cu-Based Current Collectors and Their Application in High-Performance Zn Metal Anode: A Review

Zinc-based batteries (ZBBs) have proven to be tremendously plausible for large-scale electrochemical energy storage applications due to their merits of desirable safety, low-cost, and low environmental impact. Nevertheless, the zinc metal anodes in ZBBs still suffer from many issues, including dendrite growth, hydrogen evolution reactions (HERs), corrosion, passivation, and other types of undesirable side reactions, which severely hinder practical application. The modification of Cu-based current collectors (CCs) has proven to be an efficient method to regulate zinc deposition and prevent dendritic growth, thereby improving the Coulombic efficiency (CE) and lifespan of batteries (e.g., up to 99.977% of CE over 6900 cycles after modification), which is an emerging research topic in recent years. In this review, we provide a systematic overview of the modification of copper-based CCs and their application in zinc metal anodes. The relationships between their modification strategies, nano-micro-structures, and electrochemical performance are systematically reviewed. Ultimately, their promising prospects for future development are also proposed. We hope that this review could contribute to the design of copper-based CCs for zinc-based batteries and facilitate their practical application.

Novel Biochar-Modified ZIF-8 Metal–Organic Frameworks as a Potential Material for Optoelectronic and Electrochemical Energy Storage Applications

Novel Biochar-Modified ZIF-8 Metal–Organic Frameworks as a Potential Material for Optoelectronic and Electrochemical Energy Storage Applications

The versatility of iota-carrageenan biopolymer for the fabrication of non-toxic bio-based energy storage devices

The number of portable devices produced worldwide is strongly increasing, which results in an increasing need for energy storage devices. These devices are typically fabricated with scarce and toxic materials. Consequently, there is a current trend towards the substitution of these materials by biopolymers, although they are still often mixed with toxic substances to improve specific performance aspects. To address this issue, this work presents a self-standing non-toxic and potentially biodegradable polymer electrolyte membrane for electrochemical energy storage applications consisting of an abundant biopolymer, iota-carrageenan, and Deep Eutectic Solvent (DES).11List of abbreviations: DES: Deep eutectic solvent [EMIM][SCN]: 1-Ethyl-3-methyl-imidazolium thiocyanate CV: Cyclic voltammetry FTIR: Fourier transformed infrared spectroscopy EIS: Electrochemical impedance spectroscopy CPE: Constant phase element. Ionic conductivities as high as 2 mS/cm were achieved for a proportion of carrageenan and DES of 25:75. Aqueous electrically conductive inks containing carbon black and active carbon were also developed using the same polymeric matrix. The inks were successfully printed (stencil method) on different substrates and electrically characterized, achieving sheet resistances as low as 38 Ω/sq. Supercapacitors were then fabricated by printing the electrically conductive ink on both sides of the self-standing membrane, demonstrating the versatility of iota-carrageenan biopolymer in the development of sustainable energy storage devices. The measured capacitance of the supercapacitors was 3.3 mF/cm2 in cyclic voltammetry characterization and 2.7 mF/cm2 when charging-discharging at 0.05 mA/cm2. The supercapacitors were found to be stable in cyclability studies, showing a capacity retention of 99 % after 5000 charge–discharge cycles.

Electrochemical analysis of sol-gel and hydrothermal synthesized mesoporous strontium titanate spherical nanoparticles as electrode material for high-performance flexible supercapacitors

Perovskite oxides with large specific surface areas present a promising avenue for enhancing supercapacitor efficiency. This study investigates the remarkable charge storage capabilities of strontium titanate (SrTiO3, STO) synthesized via sol-gel and hydrothermal techniques for electrochemical energy storage applications. The cubic crystal structure of STO, confirmed from X-ray Diffraction analysis, synthesized at lower temperatures through both methods, provides three-dimensional diffusion channels for oxygen anion movement, which is crucial for improving charge storage capacity. X-ray photoelectron spectroscopy confirmed the elements’ oxidation states and their spin-orbit splitting. The spherical nanoparticle morphology was observed in the FESEM images, BET characterization revealed a high specific surface area contributing to more charge storage and mesoporous nature facilitates excellent mass transfer rates of electrolytic ions. Electrochemical measurements and calculations confirmed that sol-gel and hydrothermally synthesized STO electrodes exhibit maximum specific capacitances of 130 F g−1 and 156 F g−1 at 10 mV s−1, respectively. A fabricated flexible supercapacitor device in an aqueous medium maintains a constant voltage of 1.2 V, capable of powering a digital watch. Hence, this study demonstrates the potential of STO electrode-based supercapacitors for a wide range of electrochemical energy storage applications.

Biogenic synthesis of porous CuO nanoparticles: Synergistic effects in photocatalytic dye degradation and electrochemical energy storage applications

This study explores the biogenic synthesis of CuO nanoparticles functionalized with Solanum nigrum, using Acalypha indica leaf extract as a reducing agent. The biogenically synthesized CuO nanoparticles were comprehensively characterized by various analytical techniques, involves X-ray diffraction analysis (XRD), BET surface area analysis (BET), energy-dispersive X-ray spectroscopy (EDAX), X-ray photoelectron spectroscopy (XPS), UV–Visible spectral analysis (UV), Fourier transform infrared spectroscopy (FTIR), fluorescence spectroscopy, photocatalytic degradation, antimicrobial assay, cytotoxicity assay, electrochemical analysis, and linear sweep voltammetry studies. The XRD analysis revealed end centered monoclinic phase with a 10 nm average crystalline size. BET analysis showed a mesoporous structure with a surface area of 11.54 m2/g. XPS and EDAX confirmed the presence of Cu2+ and O2− ions. SEM and TEM images indicated spherical, and porous nanostructures. UV–Visible spectroscopy identified an active optical range of 508–518 nm (2.40–2.45 eV), suggesting potential photocatalytic activity. The photocatalytic degradation efficiencies of Methylene blue (98.8 %) and Rhodamine B (95 %) were achieved after 100 min of irradiation. Antimicrobial tests demonstrated effectiveness against Staph. aureus, E. coli, Shigella flexneri, and Candida tropicalis. The nanoparticles exhibited notable cytotoxicity against colorectal cancer cells with IC50 values of 58.66 μg/ml and 66.78 μg/ml. Additionally, a symmetric supercapacitor electrode using these nanoparticles achieved a specific capacitance of 375 Fg−1 at the current density of 1 Ag−1. This research underscores the versatile applications of biogenic CuO nanoparticles in photocatalysis, antimicrobial treatments, cancer therapy, and energy storage.

Advanced approach for active and durable proton exchange membrane fuel cells: Coupling synergistic effects of MNC nanocomposites

AbstractAtomically dispersed metal and nitrogen co‐doped carbon (MNC) is a promising oxygen reduction reaction (ORR) catalyst for electrochemical energy storage and conversion applications but typically suffers from low durability and activity under the acidic conditions of practical polymer electrolyte exchange membrane fuel cells (PEMFCs). Recently, the performance of MNC nanocomposites under acidic ORR conditions has been enhanced by exploiting the synergistic coupling effects of their constituents (single‐atom sites, nanoclusters, and nanoparticles). The unique geometric structures formed by the coupling of diverse sites in these nanocomposites provide optimal electronic structures and efficient reaction pathways, thus resulting in high activity and long‐term durability. This work provides an overview of MNC nanocomposites as ORR electrocatalysts under practical PEMFC conditions, focusing on activity and durability enhancement methods and highlighting the strategies used to prepare electrocatalytically efficient MNC nanocomposites containing no or low amounts of platinum group metals. Progress in the development of advanced MNC nanocomposites as acidic ORR catalysts is discussed, and the pivotal role of synergistic effects resulting from the coupling sites within the nanocomposites is explored together with the characterization methods used to elucidate these effects. Finally, the challenges and prospects of developing MNC nanocomposites as next‐generation electrocatalysts are presented.image

Microstructure modification strategies of coal-derived carbon materials for electrochemical energy storage applications

Microstructure modification strategies of coal-derived carbon materials for electrochemical energy storage applications

Upcycling linear low-density polyethylene waste to turbostratic graphene for high mass loading supercapacitors

Linear low-density polyethylene (LLDPE) waste is difficult to upcycle into more valuable carbon materials because it tends to completely decompose into small molecules during thermal processing. In this work, LLDPE is upcycled into a high quality turbostratic graphene using a pre-treatment step to oxidatively crosslink the polymer with the assistance of solid additives (KCl and K2CO3) that improve crosslinking by increasing the effective surface area of the polymer melt during processing. After this pretreatment step, the crosslinked polymer could then be carbonized and catalytically graphenized between 400–950 °C without decomposition of the polymer feedstock. The LLDPE derived graphene (LLDPE-G) obtained from this process has a Brunauer–Emmett–Teller (BET) specific surface area, up to 1800 m2 g−1 and average Raman ID/IG and I2D/IG ratios of 0.85 and 0.57, respectively, indicating high quality graphene. When used as an electrode material in symmetric supercapacitors, LLDPE-G possesses a specific capacitance up to 175 Fg−1 at a mass loading of 20 mgcm−2, which is two times the commercial requirement, yielding an areal capacitance of 3.5 Fcm−2. Moreover, LLDPE-G exhibits exceptional cycling stability with a capacitance retention of 95.8 % after 100,000 cycles at a current density of 4.0 Ag−1. Additionally, the KCl and K2CO3 solids are recycled and reused over 3 complete reaction cycles to make new LLDPE-G with the material quality and electrocapacitive performance retained and verified after each cycle. Our approach creates new opportunities for upcycling waste LLDPE and other varieties of polyethylene into a higher value graphene used for electrochemical energy storage applications.

Exploring the diverse applications of sol–gel synthesized CaO:MgAl2O4 nanocomposite: morphological, photocatalytic, and electrochemical perspectives

A nanocomposite of CaO:MgAl2O4 was synthesized through a straightforward and cost-effective sol–gel method. The investigation of the novel CaO:MgAl2O4 nanocomposite encompassed an examination of its morphological and structural alterations, as well as an exploration of its photocatalytic activities and electrochemical characteristics. XRD analysis revealed a nanocomposite size of 24.15 nm. The band gap, determined through UV studies, was found to be 3.83 eV, and scanning electron microscopy (SEM) illustrated flake-like morphological changes in the CaO:MgAl2O4 samples. TEM, HRTEM, and SAED studies of a CaO:MgAl2O4 nanocomposite would reveal important details about its morphology, crystallography, and nanostructure. Photocatalytic activity was quantified by studying the degradation of Acid Red-88 (AR-88) dye in a deionized solution, achieving a 70% dye degradation under UV irradiation in 120 min. Plant growth examinations were carried out using dye degraded water to test its suitability for agriculture. The electrochemical energy storage and sensing applications of the prepared nanocomposite were examined using CaO:MgAl2O4 modified carbon paste electrode through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In conclusion, the synthesized CaO:MgAl2O4 nanocomposite demonstrated promising morphological and structural characteristics, efficient photocatalytic activity, and potential applications in electrochemical energy storage, highlighting its versatility for various technological and environmental applications.Graphical abstract

Development of a processing route for the fabrication of thin hierarchically porous copper self-standing structure using direct ink writing and sintering for electrochemical energy storage application

Development of a processing route for the fabrication of thin hierarchically porous copper self-standing structure using direct ink writing and sintering for electrochemical energy storage application

High‐Rate Polymeric Redox in MXene‐Based Superlattice‐Like Heterostructure for Ammonium Ion Storage

AbstractAchieving both high redox activity and rapid ion transport is a critical and pervasive challenge in electrochemical energy storage applications. This challenge is significantly magnified when using large‐sized charge carriers, such as the sustainable ammonium ion (NH4+). A self‐assembled MXene/n‐type conjugated polyelectrolyte (CPE) superlattice‐like heterostructure that enables redox‐active, fast, and reversible ammonium storage is reported. The superlattice‐like structure persists as the CPE:MXene ratio increases, accompanied by a linear increase in the interlayer spacing of MXene flakes and a greater overlap of CPEs. Concurrently, the redox activity per unit of CPE unexpectedly intensifies, a phenomenon that can be explained by the enhanced de‐solvation of ammonium due to the increased volume of 3 Å‐sized pores, as indicated by molecular dynamic simulations. At the maximum CPE mass loading (MXene:CPE ratio = 2:1), the heterostructure demonstrates the strongest polymeric redox activity with a high ammonium storage capacity of 126.1 C g−1 and a superior rate capability at 10 A g−1. This work unveils an effective strategy for designing tunable superlattice‐like heterostructures to enhance redox activity and achieve rapid charge transfer for ions beyond lithium.

Bipolar Supercapacitive Performance of N-Containing Carbon Materials Derived from Covalent Triazine-Based Framework.

The search for new electrode materials for bipolar-supercapacitor performance is the intention of numerous research in the area of functional framework materials. Among various electrode materials, covalent triazine-based frameworks (CTFs) are in the spotlight drawing much attention as potential electrode material for energy storage. Herein, we present the synthesis of nitrogen-functionalized CTFs marked as CTF-Py-600 and CTF-Py-700 with high nitrogen content (18% and 14%, respectively) for supercapacitor application by applying 2,6-dicyanopyridine monomer via the polymerization reaction under ionothermal condition. The BET surface area of these materials are in the range of 940-1999 m2g-1. CTF-Py-700 demonstrates outstanding electrochemical performance in both potential windows. At the negative potential window, it exhibits a higher specific capacitance of 435 F g-1 (at 1 A g-1) compared to the positive potential window, where it shows a specific capacitance of 306 F g-1 (at 1 A g-1) owing to the synergistic existence of its large surface area (1999 m2g-1) and high nitrogen content (14%) with inherent microporosity. Remarkable cycling stability without noticeable degradation of specific capacitance after 15000 cycles was recorded for CTF-Py-700. This suggests that the nitrogen-functionalized CTFs are going to be a highly demanded electrode material for electrochemical energy storage applications.

Double transition metal MXenes for enhanced electrochemical applications: Challenges and opportunities

AbstractDouble transition metal (DTM) MXenes are a recently discovered class of two‐dimensional composite nanomaterials with excellent potential in energy storage applications. Since their emergence in 2015, DTM MXenes have expanded their composition boundary beyond traditional single‐metal carbide and nitride MXenes. DTM MXenes offer tunable structures and properties through variations in the constituent transition metals and positioning within the layered lattice. These MXenes can exist in two primary forms: ordered DTMs and solid solutions. The compositional versatility of DTM MXenes offers opportunities to enhance their performance in electrochemical energy storage applications. However, the quality, stability, and surface chemistry of DTM MXenes are influenced by several factors, including the etching process, etchant type, and synthesis route. Currently, limited literature is available on experimentally synthesized DTM MXenes, with most studies focusing on carbide‐based MXenes. Most of the articles have dedicated their efforts only to generalized synthesis strategies. Although extensive theoretical studies have explored the suitability of etchants, synthesis parameters, and methods for producing high‐quality MXene with selective terminal functional groups, their stability issues have not been thoroughly examined. This review addresses various types of DTM MXenes, their synthesis techniques, and the impact of these methods on their physicochemical properties and electrochemical performance. Additionally, it provides a critical analysis of the causes of instability in MXenes, particularly DTMs, from synthesis to application. The challenges associated with these materials are discussed, along with opportunities and prospects for enhancing synthesis, structural tuning, surface modification, and applications in electrochemical energy storage.image

Growth of Ni-Ga oxalate nanoparticles on 3D current collector as a supercapacitive electrode

Metal oxalate materials have been explored for electrochemical energy storage (EES) applications. Herein, Ni-incorporated gallium oxalate (Ni-Ga-C2O4) based binder-free electrode was fabricated through a facile process. The electrode gathers the benefit of Ni foam contributed as a conductive substrate and also acting as a Ni source with binder-free approach. The Ni-Ga-C2O4 crystalline phase formation was confirmed through X-ray diffraction spectroscopy (XRD). The morphological properties and elemnetal quantification were studied via scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and transmission electron spectroscopy (TEM). Importantly, electrochemical energy storage investigation revealed the Ni-Ga-C2O4 electrode exhibits battery behavior with capacity retention of 85.5 % and possessed the highest specific capacity of 319 C g−1 at 1 A g−1. Overall, the additional contribution of Ni during the synthesis has boosted the physicochemical properties and electrochemical energy storage performance of the Ni-Ga-C2O4 electrode.

Sulfur vacancy riched pure 2H phase VS2 for efficient electrocatalytic hydrogen evolution

Vanadium disulfide (VS2), a typical metallic layered transition metal chalcogenide (TMC), has been widely concerned for its high electrical conductivity and reactivity in electrochemical energy storage and conversion applications. The 2H phase VS2 is expected to exhibit high electrocatalytic activity and be more stable for hydrogen evolution reaction (HER) than the 1T phase structure. But at present, there still lacks a facile method to prepare pure 2H phase VS2. Herein, we successfully prepared pure 2H–VS2 through a simple one-step low-temperature hydrothermal method. We have investigated the effect of the hydrothermal reaction conditions (including the proportion of raw materials and hydrothermal reaction temperatures) on the phase composition and microstructure. Under the optimal condition of 140°C-24 h with a vanadium sulfur ratio of 1:5, a nano-flower-like 2H–VS2 material with high crystallinity and rich sulfur vacancy defects was obtained. Leveraging these structural advantages, as a demonstration, the product exhibits excellent electrocatalytic HER activity (with η10 of 181 mV, Tafel slope of 52 mV dec−1, and J0 of 67.9 × 10−3 mA cm−2) and stability (it can continuously produce hydrogen for 20 h at a current density of 50 mA cm−2 with ultra-small increased potential of less than 5 mV). This work provides a new way for constructing atomic vacancy defects in layered TMCs for efficient electrocatalysis and is also expected to promote the research of the basic properties of high phase purity TMCs.