Heterostructure Electrode Research Articles

Photoelectrocatalytic degradation of organic contaminants by spray coated Z-scheme TiO2/Bi2WO6 heterostructure electrode under solar light

This study demonstrates that spray deposited layered TiO2/Bi2WO6 heterostructure photoelectrodes exhibit strong interfacial interactions, leading to significant enhancements in photoelectrochemical performance. Time-resolved photoluminescence (TRPL) spectra indicated a prolonged lifetime of photoinduced carriers. The red shift in the absorption edge of TiO2/Bi2WO6 improved the visible light harvesting capability of Bi2WO6. Nyquist plots showed effective charge separation, and the TiO2 layer at the bottom significantly influenced the flat band potential compared to pristine Bi2WO6, as evidenced by Mott-Schottky analysis. This configuration improved the separation of photogenerated charge carriers via a Z-scheme charge transfer mechanism. The TiO2/Bi2WO6 electrode demonstrated a higher efficiency of 94% for methylene blue degradation within 160 min, compared to pure Bi2WO6. Quenching experiments confirmed the Z-scheme charge transfer mechanism in the coupled TiO2/Bi2WO6 heterojunction during degradation reactions. This study highlights the benefits of semiconductor coupling with different band potentials, promoting large-scale applications of solar-driven TiO2/Bi2WO6 photoelectrodes for environmental remediation.

Two-step cathodic microwave electrodeposition for construction of Co9S3(OH)5@Ni(OH)2 hetero-structure as supercapacitor electrode materials

The preparation of two-phase electrode materials of Co9S8@Ni(OH)2 typically involves a laborious three-step process. In this study, a two-step cathode microwave electrochemical method was proposed for the fabrication of Co9S8@Ni(OH)2 electrode materials for supercapacitors, eliminating the need for precursor synthesis. This approach not only simplified the preparation process and saved time but also successfully produced a p-n heterostructure electrode material consisting of Co9S8@Ni(OH)2 phases, where the Co9S8 phase has a chemical formula of Co9S3(OH)5. This unique structure is capable of inducing an internal electrical field by facilitating the transfer of charge carriers from Co9S3(OH)5 to Ni(OH)2, thereby enhancing charge transfer kinetics. As a result, the electrode exhibited remarkable supercapacitive performance, achieving a high specific capacitance of 255.4 mAh g-1 (7.56 F cm-2) at 1 A g-1. Even at a 20-fold increase in charge/discharge current density, the specific capacitance remained high at 218.9 mAh g-1 (6.48 F cm-1), retaining 85.8 % of the initial capacity. Furthermore, the Co9S3(OH)6@Ni(OH)2 electrode materials demonstrated excellent durability, enduring 10000 cycles with a capacitance retention of 92.9 % of the initial value. An asymmetric supercapacitor constructed with Co9S3(OH)5@Ni(OH)2 as the anode and a commercial active carbon film as the cathode was able to power a red light diode continuously emitting light for up to 42 min.

Electron-Spin Regulation Driving Heterointerface Electron Distribution and Phase Transition toward Ultrafast and Durable Sodium Storage.

Phase engineering is an effective strategy for modulating the electronic structure and electron transfer mobility of cobalt selenide (CoSe2) with remarkable sodium storage. Nevertheless, it remains challenging to improve fast-charging and cycling performance. Herein, a heterointerface coupling induces phase transformation from cubic CoSe2 to orthorhombic CoSe2 accompanied by the formation of MoSe2 to construct a CoSe2/MoSe2 heterostructure decorated with N-doped carbon layer on a 3D graphene foam (CoSe2/MoSe2@NC/GF). The incorporated Mo cations in the bridged o-CoSe2/MoSe2 not only act an electron donor to regulate charge-spin configurations with more active electronic states but also trigger the upshift of d/p band centers and a decreased ∆d-p band center gap, which greatly enhances ion adsorption capability and lowers the ion diffusion barrier. As expected, the CoSe2/MoSe2@NC/GF anode demonstrates a high-rate capability of 447 mAh g-1 at 2 A g-1 and an excellent cyclability of 298 mAh g-1 at 1 A g-1 over 1000 cycles. The work deepens the understanding of the elaborate construction of heterostructured electrodes for high-performance SIBs.

Interface engineering of La0.6Sr0.4Co0.2Fe0.8O3−δ/Gd0.1Ce0.9O1.95 heterostructure oxygen electrode for solid oxide electrolysis cells with enhanced CO2 electrolysis performance

For CO2 electrolysis in solid oxide electrolysis cells (SOECs), oxygen evolution reaction in the oxygen electrode limits the electrolysis process due to its slower reaction kinetics. Composite oxygen electrodes with good uniformity and interfacial connectivity are expected to promote the charge carriers' transport effectively and thus increase the electrocatalytic performance of the cell. In this work, interface engineering is applied to promote the conventional La0.6Sr0.4Co0.2Fe0.8O3−δ-Gd0.1Ce0.9O1.95 (LSCF-GDC) composite oxygen electrode to form a heterostructure via co-synthesis method. The results prove that LSCF co-synthesized with 40 wt%GDC (LSCF/40GDC) exhibits higher conductivity and faster oxygen exchange kinetics and bulk diffusion processes. The nickel/yttria stabilized zirconia (Ni-YSZ) supported cell with LSCF/40GDC oxygen electrode could approach an impressive CO2 electrolysis current density of 2.6 A·cm−2 at 1.6 V and 800 °C. Meanwhile the cell can operate at 1.5 V and 750 °C with electrolysis current density of 1.3 A·cm−2 for more than 100 h without apparent degradation. This heterostructure enhances the interfacial bonding strength between LSCF and GDC phases, thereby providing a continuous network structure for electron and ion transport. Such an interface engineering via co-synthesis method offers a straightforward and convenient modification for oxygen electrodes, providing an alternative route for advanced materials development of CO2 electrolysis.

MoS2@Ti3C2Tx Heterostructure: A new negative electrode material for Li-Ion hybrid supercapacitors

Lithium-ion hybrid supercapacitors (LHSCs) demonstrate promising electrochemical performance, including long cyclic stability and a high-power density. However, their limited energy density has restricted the development towards commercialization. In this work, a novel heterostructure (HS) has been introduced based on molybdenum disulfide (MoS2) nanosheets (NSs) anchored on the surface of exfoliated layers of titanium carbide (Ti3C2Tx) MXenes. The prepared negative electrode material named as MoS2@Ti3C2Tx–HS holds substantial promise for advancing LHSCs to enhance energy density. The MoS2@Ti3C2Tx–HS demonstrates outstanding pseudocapacitive performance in a three-electrode system by achieving a capacitance of 1022.7 F g−1 at 1 A g−1. It exhibited a stable cyclic life (5,000 cycles) and retained 97.02 % of its initial capacitance. Theoretical calculations based on density functional theory (DFT) show impressive results to support the experimental work. The calculated density of states (DOS), band structures, adsorption energies (Eads), and diffusion energy demonstrate that MoS2@Ti3C2Tx–HS possesses excellent electronic and adsorption properties. The fabricated MoS2@Ti3C2Tx–HS//CP–LHSCs device shows a high capacitance of 153.75 F g−1 at 2 A g−1, with stable cyclic life (94.5 %) over 10,000 cycles. Furthermore, it shows a notable high energy density of 54.7 Wh kg−1 at a power density of 1,601.3 W kg−1. The prepared MoS2@Ti3C2Tx–HS electrode, with its synergistic combination, stands out as an auspicious material, showing remarkable electrochemical performance and paving the way for LHSCs.

CoNi layered double hydroxides grown on Ag nanowires for high-efficient nitrate-to-ammonia conversion

Electrocatalytic reduction of nitrate to ammonia is a promising technology. The sluggish rate of the nitrate-to-nitrite reduction is the core issue. By reducing the energy barrier of this step, the reactivity can be greatly promoted. Here, we have documented Co2Ni1 layered double hydroxide (LDH) on Ag nanowire (NW) that demonstrates efficient catalytic activity in electro-reducing nitrate to ammonia under a diverse set of application conditions. It achieves a high ammonia yield (2.50 mmol h−l cm−2) and Faradaic efficiency (99.6 %) at −0.7 V versus a reversible hydrogen electrode (VRHE). Through comparative experiments, it has been proven that the selective reduction of nitrate to nitrite on Ag NW is the key. This series of Ag NW heterostructure electrodes provides new insights into the design principles of high-performance and high-durability nitrate reduction electrodes under environmentally relevant wastewater conditions.

Strength in Unity: Designing of hybrid heterostructure (NiSe2/rGO/PANI) electrode towards high Performance, Flexible, asymmetric supercapacitor device for renewable energy storage

Heterostructure creation has been an effective strategy to synthesise hybrid supercapacitor electrodes by combining materials of various charge storage mechanisms, leveraging the advantages, and minimising the drawbacks of individual materials as separate entities. Herein, a hybrid supercapacitor electrode has been fabricated producing ternary NiSe2/rGO/PANI heterostructure, through simple hydrothermal followed by in-situ polymerisation techniques. Owing to the synergy between the materials, the electrode decorated on a flexible carbonaceous template exhibits a remarkable capacity of 657.36C g−1@1 A g−1 offering excellent stability over 12,000 cycles. Subsequently, a hybrid asymmetric supercapacitor (HASC) constructed using NiSe2/rGO/PANI as a positive electrode and AC as a negative electrode possesses a high energy density of 98.82 Wh kg−1 at a power density of 750.05 W kg−1 with a capacitive retention of 95.04 %. Encasing the complete device with Polydimethylsiloxane (PDMS) mould acting as an energy storage band demonstrates an unaltered device performance at various bending angles of 0° to 135°, which refers to its compatibility in flexible electronics. Further, the practical usefulness of the as-designed prototype has been exhibited by powering several devices such as; Light Emitting Diodes (LEDs) of various colours, homemade windmill, Arduino board, and LCD monitor via charging through a commercial silicon solar panel paving the way to bloom renewable energy conversion and storage.

Controllable Metal–Organic Framework‐Derived NiCo‐Layered Double Hydroxide Nanosheets on Vertical Graphene as Mott–Schottky Heterostructure for High‐Performance Hybrid Supercapacitor

Layered double hydroxide (LDH) is considered a highly promising electrode material for supercapacitors (SCs) due to its high theoretical specific capacitance. However, LDH powders often suffer from poor electrical conductivity, structure pulverization, slow charge transport, and insufficient active sites. Herein, a self‐supporting electrode with a Mott–Schottky heterostructure has been designed for high‐performance SCs. The electrode consists of low crystallinity NiCo‐LDH nanosheets and vertical graphene (VG) directly grown on carbon cloth. The LDH was converted from a metal–organic framework (MOF) by the sol–gel method. This self‐supporting electrode provides fast charge transfer, reducing the pulverization effect and energy barrier. The Mott–Schottky heterostructure of LDH@VG regulates electron density and enhances electron transfer, as confirmed by density functional theory calculation. The optimized LDH@VG heterostructure electrode exhibits an excellent areal capacitance of 5513.8 mF cm−2 and rate capability of 82.1%. Furthermore, the fabricated hybrid SC demonstrates excellent energy density of 404.8 μWh cm−2 at 1.6 mW cm−2 and a remarkable cycling life, with a capacitance of 92.0% after 10 000 cycles. This work not only provides a simple dip‐coating and MOF conversion method to synthesize heterojunction‐based electrodes, but also broadens the horizon for designing advanced electrode materials for SCs.

Giant tunnel magnetoresistance in in-plane magnetic tunnel junctions based on the heterointerface-induced half-metallic 2H-VS[formula omitted]

Magnetic tunnel junctions (MTJs) constructed from atomically thin two-dimensional (2D) magnetic materials have attracted great attention in recent years because it meets the requirements of miniaturization and high tunability of next-generation spintronic devices. In this work, we demonstrate that the ferromagnetic semiconductor VS2 is transformed into a half-metal in VS2/MoSSe vdW heterostructure. Based on the heterostructure, we design an in-plane MTJs that comprise a monolayer VS2 barrier sandwiched between two VS2/MoSSe heterostructure electrodes. Through density functional calculations combined with a nonequilibrium Green’s function technique, it is found that the tunnel magnetoresistance (TMR) ratio as high as 4.35 × 109% can be achieved. Moreover, the TMR ratio can be tuned by the barrier length, and the maximum value exceeds 1015%. These results not only provide a novel route for designing MTJs using 2D ferromagnetic semiconductor material, but also demonstrate the great importance of vdW heterostructures in the design of spintronic devices.

Flower-like B-FeNiCoP/NF prepared by NaBH4 treatment for water splitting

This paper presents the preparation of a flower-like heterostructure self-supporting working electrode for the purpose of designing an electrolytic water catalyst with high stability and catalytic activity. The study investigates the impact of different ratios of nickel, cobalt, and iron on the microstructure and catalytic performance of the electrode. It was found that a Fe:Ni:Co ratio of 1:1:1 resulted in fluffy nanowires dispersed on nanosheets of flower-like nanoflowers, leading to an increase in specific surface area. Additionally, the heterogeneous structure of NiCoP and Fe2P significantly enhanced the catalytic performance of the electrode. The exceptional electrocatalytic performance of B-FeNiCoP/NF can be attributed to the synergistic interface effect and the presence of numerous exposed active sites. In the electrochemical evaluation of the hydrogen evolution reaction (HER), an overpotential of 185.5 mV at a current density of 100 mA cm−2 has been identified as sufficient, with a difference of 35.9 mV compared to Pt-C and a Tafel slope of 58.3 mV/dec. In the assessment of the oxygen evolution reaction (OER), an overpotential of 301.8 mV at a current density of 100 mA cm−2 was found necessary, with a discrepancy of 18.2 mV compared to RuO2 and a Tafel slope of 69.5 mV/dec. The stability assessment of the HER and OER at a current density of 100 mA cm−2 over a duration of 48 hours demonstrated exceptional stability. This study introduces a hydrothermal pretreatment method for sodium borohydride, which has the potential to enhance the phosphorylation of catalytic application systems.

ZnS/MXene/CdS heterostructure modified electrode for ultrasensitive miRNA-21 assay with signal amplified photoelectrochemical strategy

The early-stage detection of microRNA (miRNA) holds significant value for clinical diagnosis of tumor. In this study, a highly sensitive miRNA detection platform is developed using a photoelectrochemical sensing system based on layer-by-layer (LBL) assembled ZnS/MXene/CdS (ZMC) heterostructure electrode. By incorporating ultrathin and highly conductive MXene, the ZMC electrode exhibits robust photocurrent signals upon exposure to light. The electrode is further modified HS-H1 DNA via disulfide bonds.With the help of auxiliary H2 DNA, a target miRNA-21 triggered catalytic hairpin assembly (CHA) amplification reaction is realized on the electrode surface through complementary base pairing. Then, manganese porphyrin (MnPP) is introduced to the formed double-stranded DNA after CHA reaction to catalyze the conversion of 4-chloro-1-naphthol (4-CN) to benzo-4-chloro-hexanedione (4-CD) precipitate in the presence of hydrogen peroxide, which leads to a significant decrease in photocurrent signals. As a result, the sensor demonstrates a reliable linear correlation in miRNA-21 detection with detection limits as low as 0.36 fM. The recoveries of miRNA-21 in human serum samples ranged from 98.27 % to 101.35 % with RSD values below 3.67 % suggest the reliability and practicality of this method. Therefore it shows great potential for the construction and application of highly sensitive photoelectrochemical biosensors in clinical sample detection.

Electrodeposition of CoSx-graphene nanoplatelets on Ni(OH)2 nanosheets for improving the pseudocapacitance performance

In the present work, binder-free CoSx–graphene nanoplatelets porous structures were coated on Ni(OH)2 nanosheets using a one-step electrodeposition process. The graphene was produced from the electroreduction of CO2∗ intermediates during the electrodeposition of CoSx. The surface morphology and interfacial bonding states of CoSx–graphene@Ni(OH)2 were sensitive to the deposition time and Co–to–thiourea molar ratio (Mr). The interface reconstruction between CoSx–graphene NCs and Ni(OH)2 nanosheets improved the pseudocapacitance performance, which was investigated at different Mr and varying deposition times. Raman spectra verified the presence of graphene and CoSx mixed phases in all heterostructure electrodes, where CoS2 was dominant at Mr = 0.2. An XPS analysis indicated the evolution of various interfacial bonding states (CO, CO, CoONi, and SO) between Ni(OH)2 nanosheets and CoSx-graphene nanoplatelets, revealing the improvement in the interfacial synergy and concentration of electroactive sites. The hybrid CoSx-graphene@Ni(OH)2 NCs at Mr = 0.2 exhibited the highest capacitance of 2116 F∙g−1 at 2 mV∙s−1 and 1618 F∙g−1 at 1 A∙g−1 compared with bare Ni(OH)2, which achieved 1212 F∙g−1 at 2 mV∙s−1 and 882.88 F∙g−1 at 1 A∙g−1, and other NCs. Bare Ni(OH)2 nanosheets retained only capacitance retention of 25 % after 2000 cycles, which improved to 70 % in all CoSx-graphene@Ni(OH)2 nanoplatelets.

Atomic layer deposition of SnO2 enables fast-dynamics in electrochromic vanadium oxide/polyaniline films

Heterostructure materials hold great promise for electrochromism, but the complexity in coupling the optical and electronic properties of multiple materials remains a challenge. Herein, SnO2 film with excellent transparency and electronic properties is deposited on electro-deposited inorganic-organic vanadium oxide-polyaniline composite films by atomic layer deopisiton (ALD). As a result, the heterostructure strategy stimulated the reaction dynamics, significantly reducing the response time (from 30 s to 5 s). In addition, the thickness of the SnO2 films is found to have a crucial influecne on the electrochromic performance of heterostructure electrodes. Our work highlights the potential of semiconductor films in improving the electrochoromic materials.

Tuning built-in potential of NiP/NiFe LDH p-n junction towards efficient electrocatalytic water and urea oxidation

Oxygen evolution reaction (OER) and urea oxidation reaction (UOR) are critical half-reactions to realize sustainable hydrogen production. However, the sluggish dynamics derived from the multi-electron pathways necessitate the exploration for efficient catalysts. Herein, a p-n junction nanorod array composed of Mo doped NiP nanorod and ultrathin NiFe LDH nanosheets (NiMoP/NiFe LDH) is proposed to regulate charge distribution of interface for triggering decomposition of water and urea. The p-n junction with a powerful built-in potential (EBI) of 1.2 V at the interface facilitates the adsorption and fracture of chemical group in water and urea molecules. Consequently, the heterostructured electrode demonstrates exceptional electrochemical performance with ultralow potentials of 1.43 and 1.33 V (vs. RHE) at 10 mA cm−2 for OER and UOR, respectively. The overall urea electrolysis driven by NiMoP/NiFe LDH needs only 1.51 V to deliver 100 mA cm−2. This work demonstrates a promising strategy to regulate the EBI of semiconductor heterostructure for energy conversion and sewage treatment.

Approaching Theoretical Capacity: 0D/2D Amorphous/Crystalline Bi‐Based Heterostructures Anode for Aqueous Alkaline Rechargeable Batteries

AbstractAlthough various bismuth (Bi) electrode materials are reported to assemble aqueous alkaline rechargeable batteries (AARBs) owing to desirable potential window and high theoretical capacity, the Bi‐based electrode materials are still confronted with by their “death space” and poor stability. Herein, a zero‐dimensional/two‐dimensional (0D/2D) amorphous/crystalline BiOx‐Bi heterostructure is successfully synthesized by a one‐step reduction method for achieving nearly theoretical capacity. Under proper NaBHNaBH4 content, the Bi33+ is reduced to form ultra‐thin 2D metallic bismuth nanoflakes (Bi‐nf), and incompletely reduced amorphous 0D BiOx nanodots are embedded in Bi‐nf to form the target BiOx/Bi‐nf heterostructure. The embedded 0D nanodots inhibit the aggregation of 2D Bi‐nf, accelerate the mass transport rate with more oxygen vacancies and pores at heterogeneous interface, and the active centers of amorphous nanodots and ultrathin nanoflakes are recognized as completely accessible which is benefit for up to theoretical capacity. Accordingly, the optimized 0D/2D amorphous/crystalline BiOx‐Bi‐nf heterostructure electrode presents an admirable capacity of 350 mAh g−1 at 1 A g−1 and outstanding capacity retention of 79.9% at 20 A g‐1. Moreover, the assembled BCNP (basic cobalt/nickel phosphate)//BiOx/Bi‐nf battery exhibits exceptional energy density of 191.64 Wh kg‐1 at 1.28 kW kg‐1 power density and durable stability (80% after 14000 cycles).

Photoelectrocatalysis degradation of P-aminophenol using PbO2-TiO2 heterojunction electrode: Catalytic, theoretical calculating and mechanism

To lengthen the lifetime and extend the potential commercial applications of lead dioxide electrode. Herein, PbO2–TiO2 heterostructured electrodes were fabricated via direct current electrodeposition and the surface of the electrode was characterized by electron microscopy (EDS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The PbO2–TiO2 heterostructure electrode could produce an obvious photocurrent under UV irradiation, indicating a photoelectrocatalytic reaction. The PbO2–TiO2 heterostructured electrode was examined using density functional theory calculations(DFT). Work function(WF) confirmed that the applied electric field is conducive to the movement of photoelectrons, which promotes the photoelectrocatalysis effect. The nudged elastic band(NEB) results showed that the PbO2–TiO2 heterostructure electrode can promote the formation of •OH by reducing the activation barrier. The PbO2–TiO2 electrode was used as an anode to treat P-aminophenol (PAP) wastewater simulated wastewater and real PAP wastewater via photoelectrocatalytic degradation. The PbO2–TiO2 electrode effectively removes chemical oxygen demand (COD) from actual wastewater was 54.93 %,The after-treated Pb2+ concentration (0.037 mg·L−1) was lower than China’s wastewater discharge standard (1 mg·L−1). Finally, the degradation pathway of PAP was determined based on the intermediates detected using gas chromatography–mass spectrometry and the reactive sites of PAP were predicted using the Fukui function.These results suggest that the photoelectrocatalysis degradation of PAP using electrodes is feasible.

Compositionally Tunable Mn-V-Fe Phosphoselenide Nanorods with Minimal Ion-Diffusion Barrier as High Energy Density Battery Electrode Materials.

The design and synthesis of novel heterostructured electrode materials are crucial to enable the fabrication of efficient supercapacitor devices. In this regard, transition metal phosphochalcogenides (S, Se) are promising candidates owing to their exotic electronic properties. Herein, a facile two-step hydrothermal protocol was used to synthesize binary and ternary metal phospho-selenide electrodes (Mn-Fe-P-Se, V-Fe-P-Se, Mn-V-P-Se, and Mn-Fe-V-P-Se). The chemical composition, morphology, and structure of the as-fabricated materials were fully investigated. The three-electrode electrochemical evaluation at 1.0 A g-1 demonstrated that the ternary metal electrode (MFVP-Se) exhibits a high capacity of 1968.63 C g-1. To assess the practical value of the rationally designed Mn-Fe-V-P-Se electrode material, Mn-Fe-V-P-Se was used as a positive electrode coupled with activated carbon (AC) as a negative electrode to assemble a hybrid supercapacitor device. This Mn-Fe-V-P-Se//AC device delivers a power density of 1999.96 W kg-1 with a high energy density of 149.88 Wh kg-1 coupled with no capacity loss after 5000 charging/discharging cycles. Additionally, density functional theory calculations revealed that our electrode exhibits suitable adsorption energy for OH- ions with a minimal diffusion barrier for ions.

The (In)Stability of Heterostructures During the Oxygen Evolution Reaction

AbstractThe urgent need for efficient oxygen evolution reaction (OER) catalysts has led to the development and publication of many heterostructured catalysts. The application of such catalysts with multiple phases tremendously increases the material design dimensions, and numerous interface‐related effects can tune the OER performance. In this regard, multiple of these heterostructured electrodes show remarkable OER activities. However, it is not clear if these carefully designed interfaces remain under prolonged OER conditions. Herein, a molecular approach is used to synthesize four different nickel‐iron phosphide (heterostructured) materials and deposit them on fluorine‐doped tin oxide and nickel foam electrodes. The OER performance of the eight electrodes and the reconstruction of the four materials is investigated by in‐situ spectroscopy after one day of operation, enabled by a freeze‐quench approach. The most active electrode is also applied under industrial OER conditions and for the value‐added oxidation of alcohols to ketones. Before catalysis, this electrode comprises crystalline 4 nm nickel phosphide particles on an amorphous iron phosphide matrix. However, after 24 h, a homogenous nickel‐iron oxyhydroxide phase has formed. This work questions to which extent the design of heterostructures is a suitable strategy for non‐noble metal OER catalysis.

Design and Fabrication of Island‐Like CoNi2S4@NiCo‐LDH/Biomass Carbon Heterostructure as Advanced Electrodes for High‐Performance Hybrid Supercapacitors

AbstractThe utilization of heterostructured electrodes offers an effective approach to boost the energy density of supercapacitors without sacrificing their power density. However, the adoption of such materials is frequently impeded by sluggish reaction kinetics. Herein, an island‐like CoNi2S4@NiCo‐layered double hydroxide/biomass carbon (CoNi2S4@NiCo‐LDH/BC) heterostructure is synthesized by embedding CoNi2S4 in the interlayer of NiCo‐LDH nanosheets on BC through a partial in situ sulfidation process. Theoretical and experimental analyses indicate that this unique structural configuration lowers transport barriers and enhances ion adsorption capacity, leading to a significant improvement in ion/electron reaction kinetics. In addition, the embedded structural design effectively alleviates the significant volume expansion during charge–discharge process, while the robust BC framework prevents electrode degradation, thereby enhancing stability. These advantages enable the developed electrode material to achieve a high specific capacity (1655.75 C g−1 at 1 A g−1) and an extended cycle life (86.82% capacity retention after 10 000 cycles). Significantly, the assembled hybrid supercapacitor CoNi2S4@NiCo‐LDH/BC// activated carbon demonstrates a remarkable energy density of 95.57 Wh kg−1 at 866.61 W kg−1 and exceptional cycling stability, maintaining 95.16% capacity after 10 000 cycles. This research offers an effective strategy to promote ion/charge transfer and adsorption capacity of heterostructure and provides a new approach to the development of advanced supercapacitor electrodes.

Nitrogen-Doped Graphene-Like Carbon Intercalated MXene Heterostructure Electrodes for Enhanced Sodium- and Lithium-Ion Storage.

MXene is investigated as an electrode material for different energy storage systems due to layered structures and metal-like electrical conductivity. Experimental results show MXenes possess excellent cycling performance as anode materials, especially at large current densities. However, the reversible capacity is relatively low, which is a significant barrier to meeting the demands of industrial applications. This work synthesizes N-doped graphene-like carbon (NGC) intercalated Ti3C2Tx (NGC-Ti3C2Tx) van der Waals heterostructure by an in situ method. The as-prepared NGC-Ti3C2Tx van der Waals heterostructure is employed as sodium-ion and lithium-ion battery electrodes. For sodium-ion batteries, a reversible specific capacity of 305mAhg-1 is achieved at a specific current of 20mAg-1, 2.3 times higher than that of Ti3C2Tx. For lithium-ion batteries, a reversible capacity of 400mAhg-1 at a specific current of 20mAg-1 is 1.5 times higher than that of Ti3C2Tx. Both sodium-ion and lithium-ion batteries made from NGC-Ti3C2Tx shows high cycling stability. The theoretical calculations also verify the remarkable improvement in battery capacity within the NGC-Ti3C2O2 system, attributed to the additional adsorption of working ions at the edge states of NGC. This work offers an innovative way to synthesize a new van der Waals heterostructure and provides a new route to improve the electrochemical performance significantly.