CoS2 Nanoparticles Research Articles

Highly stable lamellar array composed of CoSe2 nanoparticles for supercapacitors

Two-dimensional hierarchical structures of transition metal selenides with more active sites and shorter electrolyte diffusion channels hold great potential for application in supercapacitors. A lamellar array electrode composed of well-patterned CoSe2 nanoparticles, using leaf-like ZIF-67 as a precursor, is successfully fabricated by a two-step calcination method. Primarily, the cobalt selenide particles were anchored to the carbon skeleton, as to obtain lammellar array and keep stable in electrochemical measurements. The novel CoSe2/carbon (CoSe2/C) electrode shows excellent electrochemical performance, with a specific capacitance of 462 F g−1 at a current density of 5 A g−1, and a 100% capacitance retention at 10 A g−1 after 10,000 cycles. Meanwhile, an asymmetric supercapacitor is assembled and it exhibits an energy density of 20.6 Wh kg−1 with a power density of 698.8 W kg−1 and an outstanding cycling stability. Concisely, benefiting from the effective method of controllable morphology, we construct the lamellar array composed of CoSe2 particles, and confirm it is of great potential in application for stable supercapacitors.

Fabrication and photocatalytic degradation activity of core/shell ZIF-67@CoWO4@CoS heterostructure photocatalysts under visible light

In this work, high photocatalytic degradation activity towered organic pollutants (methylene blue (MB) dye) has been achieved under visible light using new core/shell ZIF-67@CoWO4@CoS heterostructures. The optical, structural and morphological properties were studied using XRD, FE-SEM, EDX, UV-DRS, VSM, and BET surface area characterization methods. Noticeably, the photocatalytic degradation efficiency of the ZIF-67@CoWO4@CoS photocatalyst was higher to that of its individual-component complements (about 100% after 10 min of irradiation time). Furthermore, ZIF-67@CoWO4@CoS photocatalyst showed higher activity than ZIF-67@CoWO4 and ZIF-67@CoS nanocomposites. This enhanced photocatalytic degradation efficiency of ZIF-67@CoWO4@CoS can be attributed to the synergistic effects of ZIF-67, CoWO4 and CoS nanoparticles, and the narrow band gap energy of the synthesized core/shell ZIF-67@CoWO4@CoS heterostructure. The photocatalytic degradation of MB followed a pseudo-first-order kinetic model (K1 = 0.105 min−1). Moreover, the recyclability study exhibited that the ZIF-67@CoWO4@CoS photocatalyst was extremely stable and can be used eight times without considerable loss in its photocatalytic degradation activity. The results of this work underline the use of effective, low-cost and easily available ZIF-67@CoWO4@CoS photocatalyst for the decomposition of wide range of organic pollutants in wastewater under visible light irradiation.

Enhanced properties of CoS2/Cu2S embedded N/S co-doped mesh-like carbonaceous composites for electromagnetic wave absorption

CoS2/Cu2S embedded N/S co-doped mesh-like carbonaceous composites with enhanced electromagnetic wave absorbing performance was successfully prepared using carboxymethyl cellulose hydrogel spheres as starting materials by freeze-drying and high-temperature carbonization, in which thiourea as a source of N/S was favorably achieved. This newly designed three-dimensional mesh-like structures embedded with CoS2 and Cu2S nanoparticles was confirmed by various techniques, while the N/S co-doped carbonaceous matrix, would contribute to the enhancement of electron transport, interfacial polarization, dipole polarization, ferromagnetic resonance, and magnetic coupling. This unique three-dimensional mesh structure facilitates multiple reflections and scattering of electromagnetic waves within the single matrix. By adjusting the dosage ratio between components and the filling amount of filler, the composite material exhibited a good impedance matching, which promotes the synergy between conductive loss, dielectric loss, and magnetic loss, and improves the electromagnetic wave loss. When the composite is filled with 25 wt%, there is a minimum reflection loss value of −51.68 dB at 5.20 GHz, and when the coating thickness is 4.5 mm, the effective absorption bandwidth is 3.84 GHz when the coating thickness reaches 2.0 mm. The experimental results illustrated that the synthesized composites might be alternative materials for low-frequency band electromagnetic wave absorption.

ZIF-67-derived Mn doped Co9S8 supported on N-Enriched porous carbon polyhedron as an efficient electrocatalyst for oxygen evolution reaction

Rational design of efficient oxygen evolution reaction (OER) electrocatalysts plays a significant role in various applications like water splitting and metal-air batteries. Simultaneous modulation of geometric and electronic structure is a promising strategy for boosting the electrocatalytic active of OER catalysts. Herein, a novel type of Mn doped Co9S8 supported on N-enriched porous carbon polyhedron composite material (Mn–Co9S8/NC) is constructed via absorption-pyrolysis-sulfurization treatment of Zeolitic-imidazolate frameworks (ZIF-67). ZIF-67 derived N-enriched porous carbon polyhedron serves as the porous skeleton for anchoring numerous Co9S8 nanoparticles. The results confirm that the incorporation of Mn in Co9S8/NC can improve the degree of graphitization compared with Co9S8/NC, implying the enhancement of the conductivity. Meanwhile, the incorporation of Mn can lead to electronic modulation of Co species to bump up the intrinsic activity of active site in Mn–Co9S8/NC. Due to the synergistic effect of Mn, Co9S8 and porous carbon structure, the specific surface area and electronic structure are optimized, endowing the maximum utilization of active sites. The Mn–Co9S8/NC electrocatalyst exhibits superior OER activity with the overpotential of 286 mV at current density of 10 mA cm−2 in 1.0 M KOH electrolyte. This work provides prospective insights into the synergistic coupling of geometric and electronic structure of Metal-Organic Frameworks (MOFs) material for efficient electrocatalysts.

Graphene-reinforced metal-organic frameworks derived cobalt sulfide/carbon nanocomposites as efficient multifunctional electrocatalysts

Developing cost-effective electrocatalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is vital in energy conversion and storage applications. Herein, we report a simple method for the synthesis of graphene-reinforced CoS/C nanocomposites and the evaluation of their electrocatalytic performance for typical electrocatalytic reactions. Nanocomposites of CoS embedded in N, S co-doped porous carbon and graphene (CoS@C/Graphene) were generated via simultaneous sulfurization and carbonization of one-pot synthesized graphite oxide-ZIF-67 precursors. The obtained CoS@C/Graphene nanocomposites were characterized by X-ray diffraction, Raman spectroscopy, thermogravimetric analysis-mass spectroscopy, scanning electronic microscopy, transmission electronic microscopy, X-ray photoelectron spectroscopy and gas sorption. It is found that CoS nanoparticles homogenously dispersed in the in situ formed N, S co-doped porous carbon/graphene matrix. The CoS@C/10Graphene composite not only shows excellent electrocatalytic activity toward ORR with high onset potential of 0.89 V, four-electron pathway and superior durability of maintaining 98% of current after continuously running for around 5 h, but also exhibits good performance for OER and HER, due to the improved electrical conductivity, increased catalytic active sites and connectivity between the electrocatalytic active CoS and the carbon matrix. This work offers a new approach for the development of novel multifunctional nanocomposites for the next generation of energy conversion and storage applications.

Near-infrared light-triggered synergistic antitumor therapy based on hollow ZIF-67-derived Co3S4-indocyanine green nanocomplex as a superior reactive oxygen species generator

Reactive oxygen species (ROS) with strong oxidability have been considered as effective agents for antitumor therapy through oxidative damage to lipids, proteins, DNA and RNA. In this work, a multifunctional hollow cobaltosic sulfide (Co3S4)/photosensitizer indocyanine green (ICG) nanocomplex (Co3S4-ICG) has been synthesized by efficiently loading ICG into the hollow Co3S4 to realize synergistic antitumor therapy via chemodynamic therapy (CDT), photodynamic therapy (PDT) and photothermal therapy (PTT) under near-infrared (808 nm) laser irradiation. Co3S4 nanoparticles would be degraded in tumor acidic microenvironment into Co2+, which locally triggers a Fenton-like reaction to produce cytotoxic hydroxyl radicals (OH) for CDT. Co3S4-ICG could also produce singlet oxygen (1O2) through a multi-step photochemical process for PDT under 808 nm laser irradiation. The slow release of ICG in the tumor region was achieved due to hollow-structured Co3S4 working as nanocarriers, and which has been proved an effective approach for combined CDT/PDT. In addition, Co3S4-ICG showed high photothermal conversion efficiency (40.5%) for PTT, and excellent OH generation capability via photothermal-improved Fenton reaction, leading to the synergistically improved antitumor efficacy. In vitro and in vivo experimental results confirm that the combined PTT/PDT/photothermal-enhanced CDT therapy can effectively ablate tumors with a negligible systemic toxicity. This work provides a valuable strategy for designing and constructing of a multifunctional nanoplatform for synergistic antitumor therapy of solid tumors.

N, S Dual Doped Mesoporous Carbon Supported Co9S8 Nanoparticles as Efficient Hydrogen Evolving Electrocatalysts in a Wide pH Range

AbstractA series of Co9S8 nanoparticles (NPs) embedded, N, S co‐doped mesoporous carbons were synthesized by the combination of evaporation induced self‐assembly (EISA) method and simple pyrolysis method. Melamine formaldehyde (MF) resin was used as carbon and nitrogen precursor. CoCl2 and thiourea were utilized as cobalt and sulfur precursors, respectively. The as‐obtained samples possessed mesoporous structure. The optimized sample of MF4.0T6.0 exhibited excellent electrochemical performance towards hydrogen evolution reaction (HER) in wide pH range, which achieved a current density of 10 mA cm‐2 at 163 mV (pH 0), 149 mV (pH 14), and 325 mV (pH 7).

Multidimensional synergistic architecture of Ti3C2 MXene/CoS2@N-doped carbon for sodium-ion batteries with ultralong cycle lifespan

Sodium-ion batteries (SIBs) based on conversion-type anode materials exhibit great prospect in the field of large-scale energy storage because of their superior sodiation capacities and low costs. However, poor charge transfer kinetics and short cycle life induced by huge volume change remain two great challenges. Herein, a multidimensional synergistic structure of few-layered Ti3C2 MXene/CoS2@N-doped porous carbon (f-Ti3C2/CoS2@NPC) is rationally designed as SIBs anodes, where N-doped porous carbon matrix-encapsulated ultrafine CoS2 nanoparticles are anchored on few-layered Ti3C2 MXene via TiOC bonds. The synergistic effects among each component greatly inhibit the aggregation of CoS2 nanoparticles (CoS2 NPs), readily build a long-range electron/Na+ conductive network and effectively provide a dual protection effect on CoS2 NPs during sodiation/desodiation process. Consequently, the f-Ti3C2/CoS2@NPC anode delivers a high-rate performance (282.6 mAh g−1 at 10 A g−1) and superior cyclability (200.6 mAh g−1 at 2 A g−1 after 1500 cycles). Furthermore, Na3V2(PO4)3//f-Ti3C2/CoS2@NPC full cells can release a high reversible capacity and good cyclability (325.8 mAh g−1 at 200 mA g−1 after 50 cycles), demonstrating great potential in practical application. This work further broadens the scope of multidimensional synergistic architectures and may inspires more research on MXene-based multidimensional structure for high-performance SIBs.

CoS2 Nanoparticles Embedded in Covalent Organic Polymers as Efficient Electrocatalyst for Oxygen Evolution Reaction with Ultralow Overpotential.

Cobalt disulfide (CoS2 ) has been explored as attractive electrocatalyst for oxygen evolution reaction (OER). However, bulk CoS2 sheets have limited catalytic activity due to low exposure of active sites. Herein, through an in-situ vulcanization approach, CoS2 nanoparticles are embedded into bipyridine-containing covalent organic polymer (BP-COP). The as-prepared nanocomposite CoS2 @BP-COP exhibits high catalytic activity toward OER with an ultra-low overpotential of 270 mV (vs. RHE) at a current density of 10 mA cm-2 , a small Tafel slope of 36 mV dec-1 , and an excellent durability for 24 h without decay. The surface of CoS2 is partially converted into CoOOH to form CoS2 /CoOOH as active sites under OER conditions. CoS2 @BP-COP displays superior OER catalytic activity to CoS2 nanosheets and commercially available RuO2 under the same conditions. The outstanding OER performance activity of CoS2 @BP-COP could be attributed to the uniform and small particle sizes of CoS2 /CoOOH distributed in BP-COP.

Bimetallic MOF-derived CoSe2 embedded within N-doped carbon with enhanced lithium storage properties

Transition metal selenides are considered to be a potential anode material for lithium-ion batteries (LIBs) owing to their excellent electronic conductivity and high theoretical capacity. However, the application of transition metal selenides electrodes is still limited by their large volume expansion and sluggish kinetics during cycling. Herein, CoSe2 nanoparticles embedded in N-doped carbon nanotubes (CNTs) and carbon layer (CoSe2@NC) were constructed by pyrolysis of CoZn-based zeolitic imidazolate framework (CoZn-ZIFs) and melamine mixtures followed by selenization. During the pyrolytic process, the volatilization of zinc derived from CoZn-ZIFs, the retardation of the complete decomposition of g-C3N4 derived from melamine by Zn species played important roles in the formation of enriched N-doped carbon nanotubes (CNTs) and amorphous carbon layer. As a result, CoSe2@NC could show a large reversible lithium-ion storage capacity of 395 mAh g−1 at 0.5 A g−1 over 200 cycles, good rate capabilities of 367 mAh g−1 even at 2 A g−1, which outperformed CoSe2@NC-1 and CoSe2@NC-2 derived from carbonization of Co-Zn-ZIFs and Co-ZIF/melamine precursors followed by selenization, respectively. The enhanced lithium storage performance of CoSe2@NC could owe to the unique structure, where the N-doped CNTs and amorphous carbon layer can provide a rapid electron transfer channel and enable surface-dominated pseudocapacitive lithium storage, and the robust interface between CoSe2 and carbon can also effectively alleviate the volume expansion and enhance the integrity during the charge-discharge process.

Cobalt Selenide Hollow Polyhedron Encapsulated in Graphene for High-Performance Lithium/Sodium Storage.

Owing to the high specific capacities, high electrochemical activity, and various electronic properties, transition metal selenides are considered as promising anodes for lithium- and sodium-ion storage. However, poor electronic conductivity and huge volume expansion during cycling are still responsible for their restricted electrochemical performance. Herein, CoSe hollow polyhedron anchoring onto graphene (CoSe/G) is synthesized by self-assembly and subsequent selenization. In CoSe/G composites, the CoSe nanoparticles, obtained by in situ selenization of metal-organic frameworks (MOFs) in high temperature, are distributed among graphene sheets, realizing N element doping, developing robust heterostructures with a chemical bond. The unique architecture ensures the cohesion of the structure and endorses the reaction kinetics for metal ions, identified by in situ and ex situ testing techniques, and kinetics analysis. Thus, the CoSe/G anodes achieve excellent cycling performance (1259 mAh g-1 at 0.1 A g-1 after 300 cycles for lithium storage; 214 mAh g-1 at 2 A g-1 after 600 cycles for sodium storage) and rate capability (732 mAh g-1 at 5 A g-1 for lithium storage; 290 mAh g-1 at 5 A g-1 for sodium storage). The improved electrochemical performance for alkali-ion storage provides new insights for the construction of MOFs derivatives toward high-performance storage devices.

In situ synthesis of Ti3C2Tx MXene/CoS nanocomposite as high performance counter electrode materials for quantum dot-sensitized solar cells

Low electrocatalytic activity and/or high charge transfer resistance of counter electrodes (CEs) in quantum-dot-sensitized solar cells (QDSSCs) are the main reasons for the low photovoltaic performance. Herein, the CoS nanoparticles are anchored on the MXene (Ti3C2Tx) via a simple in-situ hydrothermal reaction process. It is the first attempt to use the MXene/CoS as a highly electrocatalytic CE for QDSSCs. The QDSSCs with a MXene/CoS CE shows a significant enhancement in cell performances and yields a promising power conversion efficiency (PCE) of 8.09% compared with that of the QDSSCs with bare CoS (5.77%) and bare MXene (4.25%) CEs. The significant enhancement of PCE value is mainly attributed to the synergistic effects of the unique layered morphology of conductive MXene nanosheets and its cocatalysis with CoS nanoparticles. The coupling of layered MXene with small CoS nanoparticles (~15 nm) provides abundant catalytic active sites. The improved mesoporous morphology contributes a high specific surface area and fast electron transfer channels for Sx2− reduction. Consequently, the MXene/CoS nanocomposite can be utilized as an effective agent to boost up the photovoltaic performance of QDSSCs.

Rational design of a cobalt sulfide nanoparticle-embedded flexible carbon nanofiber membrane electrocatalyst for advanced lithium–sulfur batteries

Both the sluggish redox kinetics and severe polysulfide shuttling behavior hinders the commercialization of lithium–sulfur (Li–S) battery. To solve these obstacles, we design a cobalt sulfide nanoparticle-embedded flexible carbon nanofiber membrane (denoted as CoS2@NCF) as sulfiphilic functional interlayer materials. The hierarchically porous structure of carbon nanofiber is conducive to immobilizing sulfur species and facilitating lithium-ion penetration. Moreover, electrocatalytic CoS2 nanoparticles can significantly enhance the catalytic effect, achieving favorable adsorption-diffusion-conversion interface of polysulfide. Combined with these synergistic features, the assembled Li–S cell with CoS2@NCF interlayer exhibited a great discharge capacity of 950.9 mAh g−1 with prolonged cycle lifespan at 1 C (maintained 648.1 mAh g−1 over 500 cycles). This multifunctional interlayer material used in this contribution provides an advanced route for developing high-energy-density Li–S battery.

P-doped Co9S8 nanoparticles embedded on 3D spongy carbon-sheets as electrochemical catalyst for lithium-sulfur batteries

Co9S8 can catalyze polysulfides conversion in Lithium sulfur batteries (LSBs) owing to its metallic nature and rich catalytic sites. However, its catalytic activity and chemical adsorption is not strong enough to suppress the shuttle effect of Lithium polysulfides (LiPS) under high sulfur loading. Herein, Phosphorous (P)-doped Co9S8 nanoparticle was synthesized and embedded into 3D Spongy carbon (SC) sheets as electrochemical catalyst for LSBs. Our Density functional theory (DFT) calculations and experimental results revealed that moderate P doping can modulate the electronic structure of Co9S8 and simultaneously improve its interaction with LiPS and promote LiPS conversion. When P-doped Co9S8 nanoparticles are in situ formed and homogeneously distributed on 3D spongy carbon sheet matrix, the resulting P-Co9S8@SC can ensure good exposure of their adsorption and catalytic sites. As a result, the LSB based on an optimized P-Co9S8@SC modified polypropylene separator exhibited excellent cycling stability (capacity decay of 0.05% per cycle over 900 cycles at 1 C) and high areal capacity (4.38 mAh cm−2 at 5.6 mg cm−2 sulfur loading at 0.1 C). Our work demonstrates that moderate heteroatom doping is a promising strategy to develop effective polysulfides catalysis.

In situ N-doped CoS2 anchored on MXene toward an efficient bifunctional catalyst for enhanced lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries with high theoretical energy and power density offer a potential alternative for the development of electric vehicles and other applications. However, it suffers from the shuttle effect of lithium polysulfides (LiPSs) and sluggish chemistry reaction kinetics. Herein, a novel N-doped MXene-CoS2 (denote as N-MX-CoS2) nanohybrid is developed by a one-step in situ sulfidation strategy. Owing to the synergistic chemisorption of dopant nitrogen sites and polar CoS2 nanoparticles, such nanohybrid ensures a high ability to adsorb LiPSs. The highly electrical conductivity of MXene substrate with an extended layered structure facilitates fast sulfur electrochemistry redox reaction. We provide a strategy for rational design and fully explore its synergy as an efficient bifunctional heterostructure, which achieves the “all-in-one” results. Consequently, the deliberately designed bifunctional nanohybrid achieves effective LiPSs immobilization and conversion, which address the deficiencies for Li-S batteries. The cell with N-doped MXene-CoS2 modified separator exhibits high initial specific capacity (1031 mAh g−1 at 1 C), outstanding rate performance, and cycle stability (with a low decay rate of 0.052% per cycle at 1 C).

Three-dimensional CoSe2 nanoparticles/PANI films composite via co-electrodeposition as a binder-free and a non-noble metal catalyst alternative for methanol oxidation application

Herein, we report a novel binder-free polyaniline coated 3D crumpled CoSe2 nanoparticles on Ni foam (CoSe2/PANI/NF) electrode developed by a simple co-electrodeposition process for methanol oxidation application. The as-electrodeposited 3D CoSe2 with PANI films on Ni foam morphology was confirmed through in-depth material characterizations. As a non-noble electro-catalyst for methanol oxidation, the CoSe2/PANI/NF electrode showed high current density of 139 mA cm−2, low onset potential and no decay in the current response over 3000 s at 0.5 V. The high electrochemical performance of the electrode is due to the synergistic effect between PANI and CoSe2 nanostructures, high electrical conductivity, and hydrophilic functional groups of PANI contributing to the low internal resistance and effective diffusion of ions. These results demonstrate that the CoSe2/PANI/NF with its unique 3D morphology has great potential in energy storage and catalytic applications.

Construction of CoS2 nanoparticles embedded in well-structured carbon nanocubes for high-performance potassium-ion half/full batteries

Construction of CoS2 nanoparticles embedded in well-structured carbon nanocubes for high-performance potassium-ion half/full batteries

Binder-free polyaniline sheathed crumpled cobalt diselenide nanoparticles as an advanced electrode for high specific energy asymmetric supercapacitor

Herein, we report for the first time a novel and binder-free polyaniline sheathed 3D crumpled CoSe2 nanoparticles on Ni foam (PANI/CoSe2/NF) electrode was developed by a simple co-electrodeposition method for supercapacitor application. The as-electrodeposited 3D CoSe2 with PANI sheets on Ni foam morphology was confirmed through in-depth material characterizations. The PANI/CoSe2/NF as supercapacitor electrode delivered a superior specific capacitance of 1980 F g−1 or 3825 F g−1 (with the integral area) and a specific capacity of 792 C g−1 at 2 A g−1 in a three-electrode cell configuration. The assembled PANI/CoSe2/NF//sulfonated activated carbon from oak nutshell (AC) hybrid supercapacitor cell delivered excellent specific energy of 118 Wh kg−1 and good cyclic stability by retaining 82% of initial capacitance after 10,000 charge-discharge cycles. The high electrochemical performance of the electrode is due to the synergistic effect between PANI and CoSe2 nanostructures, high electrical conductivity, and hydrophilic functional groups of PANI contributing to the low internal resistance and effective diffusion of ions. These results demonstrate that the PANI/CoSe2/NF, with its unique 3D morphology, has great potential in energy applications.

Uniformly growing Co9S8 nanoparticles on flexible carbon foam as a free-standing anode for lithium-ion storage devices

Lithium-ion capacitor (LIC) possesses multiple merits of Faradaic and capacitive behaviors and shows excellent energy and power densities. Herein, Co9S8 nanoparticles embedded on melamine foam derived three-dimensional (3D) carbon foam (M-Co9S8@NCF) was successfully constructed by an in-situ anchoring and annealing method. When the composite was used as a free-standing anode electrode of lithium-ion battery, volume expansion effect is relieved and reaction kinetic is significantly improved benefitting from the synergistic effect of unique 3D carbon network and ultrafine nanoparticles. Therefore, the M-Co9S8@NCF free-standing electrode delivers superior rate performance (1024 mAh g−1 at 0.1 A g−1 and 468 mAh g−1 at 2 A g−1) and stable cycling performance (617 mAh g−1 at 1 A g−1 for 500 cycles). Moreover, porous nitrogen-doped carbon foam (PNCF) was synthesized as the cathode of LIC. M-Co9S8@NCF//PNCF LIC device was then fabricated to combine the advantages of battery-type anode and supercapacitor-type cathode, which achieves a high energy density (166 Wh kg−1 at 182 W kg−1), high power density (83 Wh kg−1 at 7674 W kg−1) as well as satisfactory capacitance retention (83.5% at 5 A g−1 after 5000 cycles). This work offers a convenient method to construct metal sulfide-based free-standing electrode for the advanced lithium-ion storage devices.

High-performance heterojunction Ti3C2/CoSe2 with both intercalation and conversion storage mechanisms for magnesium batteries

Searching for high-performance cathode materials has become the key to the development of rechargeable magnesium batteries (RMBs). Herein, we successfully constructed a novel heterostructure Ti3C2/CoSe2 by in-situ selenization of Ti3C2/ZIF-67 composite as a cathode for RMBs. In the heterostructure, the unique MXene structure plays a role in maintain the stability of the material skeleton during the charge/discharge process, and the CoSe2 nanoparticles can fully deliver the advantage of high capacity. As a result, the Ti3C2/CoSe2 heterojunction has great obvious improvement in electrochemical performance, leading to a high-rate performance (75.7 mA h g−1 at 1000 m A g−1) and long cycling life with ~79% capacity retention after 500 cycles. Moreover, the Mg storage mechanism and Mg-migration kinetics of Ti3C2/CoSe2 are analyzed and discussed by ex-situ X-ray diffraction and X-ray photoelectron spectroscopy. In particular, the Ti3C2/CoSe2 heterostructures display impressive Mg storage performance (67.3 mA h g−1 after 70 cycles at 55 °C) in quasi-solid-state magnesium batteries. Importantly, the selenization strategy has inspired the exploration of the preparation of other novel MXene-based selenide electrodes for high-performance energy storage devices.