Fabrication of transition metal selenides and their applications in energy storage

Efficient recovery of heavy metals and selenium from wastewater using granular sludge: The crucial role of glutathione (GSH)

Microbial technology offers an effective method for treating heavy metals and selenium (Se) in wastewater, yet the recovery of these valuable elements is often overlooked. This study introduces a glutathione (GSH)-enhanced granular sludge technology for the removal and recovery of heavy metals and Se from wastewater. Using the new technology, the removal rates of copper (Cu), cadmium (Cd), and Se from wastewater reached 99.4-99.99%, while the recovery rates reached 73.2-87.9%. Both long-term reactor operation and short-term stimulation experiments indicated that GSH substantially increased the residual fraction of Cu, Cd, and Se in the sludge. This residual fraction was identified as metal selenides (MSe), composed of Cu1.08Se (75.4 ± 1.8%) and CdSe (15.4 ± 1.0%). The increased abundance and significant upregulation of GSH-related genes, including gshA, gshB, and gor, as well as the indispensable roles of GSH, glutathione reductase (GorA), and NADPH in the in vitro synthesis of MSe, demonstrated that the GSH-mediated Painter-type reaction was the primary pathway for MSe synthesis in the sludge. The biosynthesized MSe was efficiently extracted and recovered from the final sludge, and the extract showed high catalytic activity in pollutant degradation. Given the widespread presence of GSH in diverse microorganisms, the GSH-mediated mechanism for MSe synthesis is likely to occur in various environments contaminated with heavy metals and Se.

Toward high-performance rechargeable magnesium batteries with a Cu2Se-CTAB nanoparticle cathode and Mg[B(HFIP)4]2/DME electrolyte

Developing advanced cathode materials effectively enhances the electrochemical performance of rechargeable magnesium batteries (RMBs). Herein, we designed a CTAB-assisted hydrothermal method to construct Cu2Se nanoparticles as the cathode and Mg[B(HFIP)4]2/DME as the electrolyte shows high specific capacity and great cycling performance in RMBs.

High-Performance Flexible and Symmetric Supercapacitors Based on Micro-Flower-Like MnSe@Ti3C2Tx Heterostructure

Flexible supercapacitors, renowned for their exceptional power density and cycling stability, are a focus in the field of energy storage. Ti3C2Tx MXene is a promising electrode material for supercapacitors owing to its excellent metallic conductivity. However, its stacking layered structure limits device performance on specific capacitance, operating voltage, and energy density. Herein, a MnSe@Ti3C2Tx heterostructure is developed to enhance the electrochemical performance of Ti3C2Tx-based electrode materials. With the solvothermal synthesis method, MnSe nanosheets are in situ grown on Ti3C2Tx surface to form micro-flower-like MnSe@Ti3C2Tx heterostructures by adjusting the ratio of ethanolamine solvent and the amount of Ti3C2Tx. The specific capacitance of the optimized heterostructure (E3/MnSe@Ti3C2Tx-45) is as high as 721.4 F g-1 at 1 A g-1, approximately ten times higher than that of pure Ti3C2Tx. The MnSe@Ti3C2Tx flexible symmetric supercapacitor (MT-FSC) based on E3/MnSe@Ti3C2Tx-45 exhibits a wide working voltage window of 1.2 V and a large energy density of 28.68 Wh kg-1 at 308.23 W kg-1. The capacitance retention rate keeps 90.77% after 4000 charge-discharge cycles. Furthermore, MT-FSC can power LEDs even under large-angle (90°) bending. This heterostructure electrode material not only improves the electrochemical performance of Ti3C2Tx-based flexible supercapacitors but also offers a robust energy supply for flexible wearable electronic devices.

Microplasma-induced in situ rapid synthesis of CoSe nanosphere@N-doped polymeric carbon dots derived from ZIF-67 for highly sensitive dopamine detection

BACKGROUND

Designing a fast and sensitive electrochemical sensing platform to achieve selective quantitative detection of dopamine (DA) is a great challenge. Combining transition metal selenides (TMSs) with a variety of conductive carbonaceous materials is one of the effective strategies to improve the electrocatalytic activity of TMSs. However, most of the reported preparation methods of TMSs/carbon-based composite nanomaterials need to be annealed at a high temperature for a long time, which does not meet the requirements of sustainable development. Therefore, it is of great significance to explore an energy-efficient and fast method to prepare these compounds.

RESULTS

In this work, CoSe nanosphere@nitrogen-doped polymeric carbon dots are rapid prepared using ZIF precursor by simple dielectric barrier discharge (DBD) microplasma-induced on carbon cloth (CoSe NSs@N-PCDs/CC) for the first time. Owing to the fact that CoSe can promote rapid proton transfer, N-CDs has a high specific surface area, rich functional groups and electrical conductivity, this electrode exhibits highly sensitive non-enzymatic electrochemical sensing performance for DA detection. The linear range and detection limit are 0.1 μM-50 μM and 40.2 nM, respectively, and it have been successfully applied to the determination of DA levels in real human serum samples. Theoretical DFT calculations show that the most efficient interaction with DA on the surface of CoSe (101) can promote electrochemical reactions and catalyze DA oxidation.

SIGNIFICANCE

Using ZIF as precursor, CoSe NSs@N-PCDs/CC electrochemical electrode was synthesized in situ by simple and energy-saving DBD microplasma. CoSe NSs can effectively prevent the aggregation of function-rich N-PCDs and significantly improve the electrocatalytic activity of the composite. The mechanism of high selectivity of CoSe NSs@N-PCDs/CC electrode to DA was studied by DFT calculation. This work provides a new idea for the fast and green synthesis of transition metal and carbon-based nanomaterials by microplasma.

Enhanced Photocatalytic Hydrogen Evolution Activity Driven by the Synergy Between Surface Vacancies and Cocatalysts: Surface Reaction Matters

The incorporation of defects and cocatalysts is known to be effective in improving photocatalytic activity, yet their coupled contribution to the photocatalytic hydrogen evolution process has not been well-explored. In this study, We demonstrate that the incorporation of S vacancies and NiSe can contribute to the improvement of charge separation efficiency via the formation of a strong electric field within the bulk ZnIn2S4 (ZIS) and on its surface. More importantly, We also demonstrate that the synergy of S vacancies and NiSe benefits the overall hydrogen evolution activity by facilitating the H2O adsorption and dissociation process. This is particularly important for hydrogen evolution taking place under alkaline conditions where the proton concentration is low, allowing ZISv-NiSe (containing abundant S vacancies) to outperform ZIS-NiSe under alkaline conditions. In contrast, under acid conditions, since there are already sufficient amounts of protons available for reaction, the hydrogen evolution activity became governed by the hydrogen adsorption/desorption process rather than the H2O dissociation process. This leads to ZIS-NiSe exhibiting higher activity than ZISv-NiSe due to its more favorable hydrogen adsorption energy. The findings thus provide insights into how defect and cocatalyst modification strategies can be tailor-made to improve hydrogen evolution activity under different pH conditions.

Hydrothermal synthesis and characterization of samarium molybdate nanosheets modified multi-walled carbon nanotubes: Real-time analysis of dimetridazole in environmental and biological samples

Dimetridazole (DMZ) is commonly used as a veterinary drug, resulting in high emissions and environmental pollution and DMZ residues are carcinogenic, genotoxic, and mutagenic to humans. Therefore, it is essential to construct a fast, sensitive and simple sensor to monitor DMZ. In this study, samarium molybdate nanosheets modified multi-walled carbon nanotube composites (SmM/MWCNT) were synthesized to modify GCE for detecting DMZ. The SmM/MWCNT material was also characterized by various analytical and spectroscopic techniques, such as FE-SEM, HRTEM, FT-IR, Raman spectroscopy, XRD, elemental mapping and XPS, to demonstrate the successful synthesis of the composite. Besides, the electrochemical behavior of SmM/MWCNT/GCE for DMZ was also investigated using CV and DPV, and the modified electrode showed good electrochemical sensing performance for DMZ with a low detection limit (0.08 μM), a wide linear range (0.1∼1000 μM), and excellent selectivity. Finally, the SmM/MWCNT/GCE was successfully applied to detect DMZ in environmental and biological samples, and satisfactory recoveries (95%∼105%) were obtained. To the best of our knowledge, the synthesis of SmM/MWCNT and its application in electrochemical sensors are reported for the first time, which demonstrates that it can provide a new route for real-time monitoring of environmental pollutants.

Boosting the Electrical Transfer by Molybdenum Doping for Robust and Flexible NiSe-Based Supercapacitor

NiSe is a promising electrode material for enhancing the energy density of supercapacitors, but it faces challenges such as sensitivity to electrolyte anions, limited specific capacity, and unstable cycling. This study employs a strategy of metal atom doping to address these issues. Through a hydrothermal reaction, Mo-doped NiSe demonstrates significant improvement in electrochemical performance, exhibiting high capacity (799.90 C g-1), splendid rate performance, and excellent cyclic stability (90% capacity retention). The introduction of Mo induces charge redistribution in NiSe, leading to a reduction in the band gap. Theoretical calculation reveals that Mo doping can effectively enhance the electrical conductivity and the adsorption energy of NiSe. A flexible printed hybrid Mo-doped NiSe-based supercapacitor is fabricated, demonstrating superior electrochemical performance (367.04 mF cm-2) and the ability to power timers, LEDs, and toy fans. This research not only deepens the understanding of the electrochemical properties of metal-doped NiSe but also highlights its application potential in high-performance supercapacitors.

Integrating anti-aggregation Ta-Se motifs into copper selenide for fast and robust sodium-ion storage

We report a novel bimetallic selenide Cu3TaSe4 anode for sodium-ion batteries synthesized via a one-step solid-state method. The integration of Ta-Se motifs into copper selenide forms a cubic grid structure that prevents copper atom aggregation and mitigates electrode failure. Cu3TaSe4 exhibits a high specific capacity of 305 mAh g-1 at 1 C, excellent rate performance of 286 mAh g-1 at 50 C, and superior cycling stability with 272 mAh g-1 after 3500 cycles at 20 C. This work demonstrates the potential of bimetallic selenides in enhancing sodium-ion battery performance.

Notable synthesis, properties and chemical gas sensing trends on molybdenum disulphides and diselenides two-dimensional nanostructures: A critical review

Evaluation of synthesis methods, notable properties, and chemical gas sensing properties of molybdenum disulphides and diselenides two-dimensional nanosheets is unfold. This is motivated by the fact that the two dichalcogenides have good sensitivity and selectivity to different harmful gases at ambient temperatures. Synthesis methods explored include exceptional top-down and bottom-up approaches, which consider physical and chemical compositional inceptions. Mechanical exfoliation in both molybdenum disulphides and diselenides nanosheets demonstrate good crystalline purity with structural alterations under varying stacking conditions. These chalcogenides exhibit low energy band gaps of ±1.80 eV for MoS2 and ±1.60 eV for MoSe2, which reduces with introduction of impurities. Thus, upon doping with other metal elements, a transformation from either n-type or p-type semiconductors is normally observed, leading to tuneable electronic properties. Thus, different gases such as methane, ethanol, toluene, ammonia, nitrogen oxide have been systematically detected using molybdenum disulphide and diselenide based thin films as sensing platforms. This review highlights structural, electronic and morphological characteristics of the two dichalcogenides which influences the sensitivity and selectivity ability for a couple of gases at ambient temperatures. The strategies for enhancing the selectivity by introducing defects, impurities and interfacing with other composites expanding the choice of these gases wider is also discussed in details. The review also provides overviews of challenges and limitations that open new research avenues to further enriching both chalcogenides as flexible, stable and cost effective state-of-the-art chemical gas sensors.

Progress on Copper-Based Anode Materials for Sodium-Ion Batteries

Fossil fuels have clearly failed to meet people's growing energy needs due to their limited reserves, potential pollution of the environment, and high costs. The development of cleaner, renewable energy sources as well as secondary batteries for energy storage is imminent, in a modern society where energy demand is soaring. Sodium-ion batteries (SIBs) have become the focus of large-scale energy storage systems as a promising alternative to lithium-ion batteries. The development of SIBs relies on the construction of high performance electrode materials. The design of low cost and high performance anode materials is a key link in this regard. Copper-based anodes are characterized by high theoretical capacity, abundant reserves, low cost and environmental friendliness. A variety of copper-based anode materials, which include cobalt oxides, sulfides, selenides and phosphides, have been synthesized and evaluated in the scientific literature for sodium storage. In detail, the preparation methods, response mechanisms, strengths and weaknesses, the relationship between morphology structure and electrochemical performance are discussed, as well as highlighting strategies to improve the electrochemical performance of copper-based anode materials. Finally, we offer our perspective on the challenges and potential for the development of copper-based anodes as a means of developing practical and high performing SIBs.

Intercalation-Induced Localized Conversion Reaction in h-CuSe for Ultrafast-Rechargeable and Long-Cycling Sodium Metal Battery

Cathode materials of sodium-based batteries with high specific capacity and fast charge-discharge mode, as well as ultralong reversible cycles at wide applied temperatures, are essential for future development of advanced energy storage system. Developing transition metal selenides with intercalation features provides a new strategy for realizing the above cathode materials. Herein, this work reports a storage mechanism of sodium ion in hexagonal CuSe (h-CuSe) based on the density functional theory (DFT) guidance. This work reveals that the two-dimensional ion intercalation triggers localized redox reaction in the h-CuSe bulk phase, termed intercalation-induced localized conversion (ILC) mechanism, to stabilize the sodium storage structure by forming localized Cu7Se4 transition phase and adjusting the near-edge coordination state of the Cu sites to achieve high reversible capacity and ultra-long cycling life, while allowing rapid charge-discharge cycling over a wide temperature range.

Transition Metal Selenide-Based Anodes for Advanced Sodium-Ion Batteries: Electronic Structure Manipulation and Heterojunction Construction Aspect

In recent years, sodium-ion batteries (SIBs) have gained a foothold in specific applications related to lithium-ion batteries, thanks to continuous breakthroughs and innovations in materials by researchers. Commercial graphite anodes suffer from small interlayer spacing (0.334 nm), limited specific capacity (200 mAh g-1), and low discharge voltage (<0.1 V), making them inefficient for high-performance operation in SIBs. Hence, the current research focus is on seeking negative electrode materials that are compatible with the operation of SIBs. Many studies have been reported on the modification of transition metal selenides as anodes in SIBs, mainly targeting the issue of poor cycling life attributed to the volume expansion of the material during sodium-ion extraction and insertion processes. However, the intrinsic electronic structure of transition metal selenides also influences electron transport and sodium-ion diffusion. Therefore, modulating their electronic structure can fundamentally improve the electron affinity of transition metal selenides, thereby enhancing their rate performance in SIBs. This work provides a comprehensive review of recent strategies focusing on the modulation of electronic structures and the construction of heterogeneous structures for transition metal selenides. These strategies effectively enhance their performance metrics as electrodes in SIBs, including fast charging, stability, and first-cycle coulombic efficiency, thereby facilitating the development of high-performance SIBs.

Recent progress in metal oxide-based electrode materials for safe and sustainable variants of supercapacitors

A significant amount of energy can be produced using renewable energy sources; however, storing massive amounts of energy poses a substantial obstacle to energy production. Economic crisis has led to rapid developments in electrochemical (EC) energy storage devices (EESDs), especially rechargeable batteries, fuel cells, and supercapacitors (SCs), which are effective for energy storage systems. Researchers have lately suggested that among the various EESDs, the SC is an effective alternate for energy storage due to the presence of the following characteristics: SCs offer high-power density (PD), improvable energy density (ED), fast charging/discharging, and good cyclic stability. This review highlighted and analyzed the concepts of supercapacitors and types of supercapacitors on the basis of electrode materials, highlighted the several feasible synthesis processes for preparation of metal oxide (MO) nanoparticles, and discussed the morphological effects of MOs on the electrochemical performance of the devices. In this review, we primarily focus on pseudo-capacitors for SCs, which mainly contain MOs and their composite materials, and also highlight their future possibilities as a useful application of MO-based materials in supercapacitors. The novelty of MO's electrode materials is primarily due to the presence of synergistic effects in the hybrid materials, rich redox activity, excellent conductivity, and chemical stability, making them excellent for SC applications.

Hybrid Membrane Composed of Nickel Diselenide Nanosheets with Carbon Nanotubes for Catalytic Conversion of Polysulfides in Lithium-Sulfur Batteries

Lithium-sulfur batteries demonstrate enormous energy density are promising forms of energy storage. Unfortunately, the slow redox kinetics and polysulfides shuttle effect are some of the factors that prevent the its development. To address these issues, the hybrid membrane with combination of nickel diselenide nanosheets modified carbon nanotubes (NSN@CNTs) and utilized Li2 S6 catholyte for lithium sulfur battery. The conductive CNTs facilitates fast electronic/ionic transport, while the polarity of NSN as a strong affinity to lithium polysulfides, effectively anchoring them, facilitating the redox conversion of polysulfide species, and effectively diminishing reaction barriers. The cell with NSN@CNTs delivers the first discharge capacity of 1123.8 mAh g-1 and maintains 786.5 mAh g-1 after 300 cycles (0.2 C) at the sulfur loading 5.4 mg. Its rate capability is commendable, enabling it to sustain a capacity of 559.8 mAh g-1 even at a high discharge rate of 2 C. In addition, its initial discharge capacity can remain 8.33 mAh even at 10.8 mg for duration of 100 cycles. This research indicates the potential application of NSN@CNTs hybrid materials in lithium-sulfur batteries.

MOF-Derived Bimetallic Selenide CoNiSe2 Nanododecahedrons Encapsulated in Porous Carbon Matrix as Advanced Anodes for Lithium-Ion Batteries

Transition metal selenides have received considerable attention as promising candidates for lithium-ion battery (LIB) anode materials due to their high theoretical capacity and safety characteristics. However, their commercial viability is hampered by insufficient conductivity and volumetric fluctuations during cycling. To address these issues, we have utilized bimetallic metal-organic frameworks to fabricate CoNiSe2/C nanodecahedral composites with a high specific surface area, abundant pore structures, and a surface-coated layer of the carbon-based matrix. The optimized material, CoNiSe2/C-700, exhibited impressive Li+ storage performance with an initial discharge specific capacity of 2125.5 mA h g-1 at 0.1 A g-1 and a Coulombic efficiency of 98% over cycles. Even after 1000 cycles at 1.0 A g-1, a reversible discharge specific capacity of 549.9 mA h g-1 was achieved. The research highlights the synergistic effect of bimetallic selenides, well-defined nanodecahedral structures, stable carbon networks, and the formation of smaller particles during initial cycling, all of which contribute to improved electronic performance, reduced volume change, increased Li+ storage active sites, and shorter Li+ diffusion paths. In addition, the pseudocapacitance behavior contributes significantly to the high energy storage of Li+. These features facilitate rapid charge transfer and help maintain a stable solid-electrolyte interphase layer, which ultimately leads to an excellent electrochemical performance. This work provides a viable approach for fabricating bimetallic selenides as anode materials for high-performance LIBs through architectural engineering and compositional tailoring.

CoFeSe2 @DMSA@FA Nanocatalyst for Amplification of Oxidative Stress to Achieve Multimodal Tumor Therapy

Nanomedicine has significantly advanced precise tumor therapy, providing essential technical blessing for active drug accumulation, targeted consignment, and mitigation of noxious side effects. To enhance anti-tumor efficacy, the integration of multiple therapeutic modalities has garnered significant attention. Here, we designed an innovative CoFeSe2 @DMSA@FA nanocatalyst with Se vacancies (abbreviated as CFSDF), which exhibits synergistic chemodynamic therapy (CDT) and photothermal therapy (PTT), leading to amplified tumor oxidative stress and enhanced photothermal effects. The multifunctional CFSDF nanocatalyst exhibits the remarkable ability to catalyze the Fenton reaction within the acidic tumor microenvironment, efficiently converting hydrogen peroxide (H2 O2 ) into highly harmful hydroxyl radicals (⋅OH). Moreover, the nanocatalyst effectively diminishes GSH levels and ameliorates intracellular oxidative stress. The incorporation of FA modification enables CFSDF to evade immune detection and selectively target tumor tissues. Numerous in vitro and in vivo investigations have consistently demonstrated that CFSDF optimizes its individual advantages and significantly enhances therapeutic efficiency through synergistic effects of multiple therapeutic modalities, offering a valuable and effective approach to cancer treatment.

SiSe2 for Superior Sulfide Solid Electrolytes and Li-Ion Batteries

Among the various existing layered compounds, silicon diselenide (SiSe2) possesses diverse chemical and physical properties, owing to its large interlayer spacing and interesting atomic arrangements. Despite the unique properties of layered SiSe2, it has not yet been used in energy applications. Herein, we introduce the synthesis of layered SiSe2 through a facile solid-state synthetic route and demonstrate its versatility as a sulfide solid electrolyte (SE) additive for all-solid-state batteries (ASSBs) and as an anode material for Li-ion batteries (LIBs). Li-argyrodites with various compositions substituted with SiSe2 are synthesized and evaluated as sulfide SEs for ASSBs. SiSe2-substituted Li-argyrodites exhibit high ionic conductivities, low activation energies, and high air stabilities. In addition, when using a sulfide SE, the ASSB full cell exhibits a high discharge/charge capacity of 202/169 mAh g-1 with a high initial Coulombic efficiency (ICE) of 83.7% and stable capacity retention at 1C after 100 cycles. Furthermore, the Li-storage properties of SiSe2 as an anode material for LIBs are evaluated, and its Li-pathway mechanism is explored by using various cutting-edge ex situ analytical tools. Moreover, the SiSe2 nanocomposite anode exhibits a high Li- insertion/extraction capacity of 950/775 mAh g-1, a high ICE of 81.6%, a fast rate capability, and stable capacity retention after 300 cycles. Accordingly, layered SiSe2 and its versatile applications as a sulfide SE additive for ASSBs and an anode material for LIBs are promising candidates in energy storage applications as well as myriad other applications.

Recent Developments in Electrodeposition of Transition Metal Chalcogenides-Based Electrode Materials for Advance Supercapacitor Applications: A Review

High-performance supercapacitive electrode materials have received significant attention from researchers worldwide, thus aiming for comparable performance similar to the extensively used rechargeable batteries. For emerging energy storage technologies like flexible supercapacitors, transition metal chalcogenides (TMCs) have been in the spotlight due to their promising electrochemical features compared to other electrode materials. Among the synthesis techniques, electrodeposition-mediated preparation of thin films of TMCs offered an affordable binder-free approach for electrode fabrication that effectively improved the supercapacitor performance. Hence, this review mainly focussed on the electrodeposition-based syntheses of single/ multinary chalcogenides and their composites for supercapacitors applications. Further, the effects of different deposition parameters were discussed for boosting the supercapacitor performance. Finally, this review outlined the existing challenges and future perspectives in this research domain, which will assist the upcoming exploration in the energy storage field.

Metal Selenides Find Plenty of Space in Architecting Advanced Sodium/Potassium Ion Batteries

The rapid evolution of smart grid system urges researchers on exploiting systems with properties of high-energy, low-cost, and eco-friendly beyond lithium-ion batteries. Under the circumstances, sodium- and potassium-ion batteries with the semblable work mechanism to commercial lithium-ion batteries, hold the merits of cost-effective and earth-abundant. As a result, it is deemed a promising candidate for large-scale energy storage devices. Exploiting appropriate active electrode materials is in the center of the spotlight for the development of batteries. Metal selenides with special structures and relatively high theoretical capacity have aroused broad interest and achieved great achievements. To push the smooth development of metal selenides and enhancement of the electrochemical performance of sodium- and potassium-ion batteries, it is vital to grasp the inherent properties and electrochemical mechanisms of these materials. Herein, the state-of-the-art development and challenges of metal selenides are summarized and discussed. Meanwhile, the corresponding electrochemical mechanism and future development directions are also highlighted.

Facile Preparation of the ZnSe/Ag2Se Binary Heterojunction for Photocatalytic Antibacterial Efficiency

In a novel approach that capitalized on the differential solubility product (Ksp) of ZnSe and Ag2Se, a unique ZnSe/Ag2Se binary heterostructure was efficiently synthesized in situ. ZnSe/Ag2Se exhibited excellent antimicrobial efficiency under visible light. Incorporating Ag2Se into ZnSe significantly enhanced the photoelectric performance of the catalyst, greatly accelerating the separation of the photogenerated electrons in the system. Active species removal experiments determined that ·O2- and H2O2 played crucial roles in photocatalytic antibacterial efficiency. Further investigation into the levels of cellular membrane peroxidation, bacterial morphology, and intracellular contents concentration revealed that during the photocatalytic antimicrobial process, reactive oxygen species initially oxidize phospholipids in the cell membrane, leading to damage to the external structure of the cell and leakage of the intracellular contents, ultimately resulting in bacteria inactivation. The photocatalytic antimicrobial process of ZnSe/Ag2Se fundamentally deviates from conventional methods, offering new insights into efficient disinfection and photocatalytic antimicrobial mechanisms.

Iron Selenide Particles for High-Performance Supercapacitors

Nowadays, iron (II) selenide (FeSe), which has been widely studied for years to unveil the high-temperature superconductivity in iron-based superconductors, is drawing increasing attention in the electrical energy storage (EES) field as a supercapacitor electrode because of its many advantages. In this study, very small FeSe particles were synthesized via a simple, low-cost, easily scalable, and reproducible solvothermal method. The FeSe particles were characterized using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) measurements, and electrochemical impedance spectroscopy (EIS), revealing enhanced electrochemical properties: a high capacitance of 280 F/g at 0.5 A/g, a rather high energy density of 39 Wh/kg and a corresponding power density of 306 W/kg at 0.5 A/g, an extremely high cycling stability (capacitance retention of 92% after 30,000 cycles at 1 A/g), and a rather low equivalent series resistance (RESR) of ~2 Ω.

Metal Selenides Anode Materials for Sodium Ion Batteries: Synthesis, Modification, and Application

The powerful and rapid development of lithium-ion batteries (LIBs) in secondary batteries field makes lithium resources in short supply, leading to rising battery costs. Under the circumstances, sodium-ion batteries (SIBs) with low cost, inexhaustible sodium reserves, and analogous work principle to LIBs, have evolved as one of the most anticipated candidates for large-scale energy storage devices. Thereinto, the applicable electrode is a core element for the smooth development of SIBs. Among various anode materials, metal selenides (MSe_x ) with relatively high theoretical capacity and unique structures have aroused extensive interest. Regrettably, MSe_x suffers from large volume expansion and unwished side reactions, which result in poor electrochemistry performance. Thus, strategies such as carbon modification, structural design, voltage control as well as electrolyte and binder optimization are adopted to alleviate these issues. In this review, the synthesis methods and main reaction mechanisms of MSe_x are systematically summarized. Meanwhile, the major challenges of MSe_x and the corresponding available strategies are proposed. Furthermore, the recent research progress on layered and nonlayered MSe_x for application in SIBs is presented and discussed in detail. Finally, the future development focuses of MSe_x in the field of rechargeable ion batteries are highlighted.

Three-Dimensional Nb Nanopillar based Electrode for Energy Storage Devices

In this study, aluminum (Al) film with high purity was coated on the Niobium (Nb) sheet by thermal evaporation under ultra-high vacuum. An Anodic Aluminum Oxide (AAO) nanotemplate was prepared on the Nb sheet. During AAO nanotemplate preparation, three-dimensional (3D) Nb nanopillars were grown on the Nb sheet. We performed a simple 3D Artificial Intelligence (AI) analysis of Nb nanopillars. According to the experimental results, the width of the prepared Nb nanopillars is in the range of 100–120 nm, and the length is approximately 150 nm. The Electron Diffraction Spectroscopy (EDS) results confirmed that the nanopillars are Nb. The prepared Nb nanopillars can be a potential candidate for energy storage applications.

MAX-phase Derived Tin Diselenide for 2D/2D Heterostructures with Ultralow Surface/Interface Transport Barriers toward Li-/Na-ions Storage

2D tin diselenide and its derived 2D heterostructures have delivered promising potentials in various applications ranging from electronics to energy storage devices. The major challenges associated with large-scale fabrication of SnSe₂ crystals, however, have hindered its engineering applications. Herein, a tin-extraction synthetic method is proposed for producing large-size SnSe₂ bulk crystals. In a typical synthesis, a Sn-containing MAX phase (V₂ SnC) and a Se source are heat-treated under a reducing atmosphere, by which Sn is extracted from the V₂ SnC phase as a rectified Sn source to form SnSe₂ crystals in the cold zone. After the following liquid exfoliation, the obtained 2D SnSe₂ nanosheets have a lateral size of a few centimeters and an atomic thickness. Furthermore, by coupling with 2D graphene to form 2D/2D SnSe₂ /graphene heterostructured electrodes, as validated by theoretical calculation and experimental studies, the superior Li-/Na-ion storage performance with ultralow surface/interface ion transport barriers are achieved for rechargeable Li-/Na-ion batteries. This innovative synthetic strategy opens a new avenue for the large-scale synthesis of selenides and offers more options into the practical application of emerging 2D/2D heterostructure for electrochemical energy storage.

Advances and challenges in metal selenides enabled by nanostructures for electrochemical energy storage applications

The development of nanomaterials and their related electrochemical energy storage (EES) devices can provide solutions for improving the performance and development of existing EES systems owing to their high electronic conductivity and ion transport and abundant embeddable sites. Recent progress has demonstrated that metal selenides are attracting increasing attention in the field of EES because of their unique structures, high theoretical capacities, rich element resources, and high conductivity. However, there are still many challenges in their application in EES, and thus the use of nanoscale metal selenide materials in commercial devices is limited. In this review, we summarize recent advances in the nanostructured design of metal selenides (e.g., zero-, one-, two-, and three-dimensional, and self-supported structures) and present their advantages in terms of EES performance. Moreover, some remarks on the potential challenges and research prospects of nanostructured metal selenides in the field of EES are presented.

Dual Glutathione Depletion Enhanced Enzyme Catalytic Activity for Hyperthermia Assisted Tumor Therapy on Semi-Metallic VSe2/Mn-CS

Semimetallic nanomaterials as photothermal agents for bioimaging and cancer therapy have attracted tremendous interest. However, the poor photothermal stability, low biocompatibility, and single component limit their therapeutic efficiency in cancer treatment. Here, manganese-doped VSe₂ semimetallic nanosheets were prepared and subsequently modified with chitosan (named VSe₂/Mn-CS NSs) for combined enzyme catalytic and photothermal therapy. VSe₂/Mn-CS NSs show high photothermal property with a photothermal conversion efficiency of 34.61% upon 808 nm near-infrared laser irradiation. In the tumor microenvironment, VSe₂/Mn-CS NSs can convert endogenous H₂O₂ into lethal hydroxyl radicals (•OH) to induce cancer cell apoptosis. The interaction between glutathione (GSH) and Se-Se bonds in VSe₂/Mn-CS NSs results in the depletion of GSH level, and the valence states transition of manganese ions is also beneficial for the GSH consumption. This dual depletion of GSH markedly enhances the peroxidase (POD) activity, leading to the high •OH production and the improved therapeutic effect. What is more, the T₁-weighted magnetic resonance and photoacoustic imaging endow VSe₂/Mn-CS NSs with the ability to guide and track the treatment process. Our study provides a research strategy for the application of semimetallic nanomaterials in cancer diagnosis and treatment.

Electrochemical performance of CoSe2 with mixed phases decorated with N-doped rGO in potassium-ion batteries

Potassium-ion batteries (PIBs) have received much attention as next-generation energy storage systems because of their abundance, low cost, and slightly lower standard redox potential than lithium-ion batteries (LIBs). Nevertheless, they still face great challenges in the design of the best electrode materials for applications. Herein, we have successfully synthesized nano-sized CoSe₂ encapsulated by N-doped reduced graphene oxide (denoted as CoSe₂@N-rGO) by a direct one-step hydrothermal method, including both orthorhombic and cubic CoSe₂ phases. The CoSe₂@N-rGO anodes exhibit a high reversible capacity of 599.3 mA h g⁻¹ at 0.05 A g⁻¹ in the initial cycle, and in particular, they also exhibit a cycling stability of 421 mA h g⁻¹ after 100 cycles at 0.2 A g⁻¹. Density functional theory (DFT) calculations show that CoSe₂ with N-doped carbon can greatly accelerate electron transfer and enhance the rate performance. In addition, the intrinsic causes of the higher electrochemical performance of orthorhombic CoSe₂ than that of cubic CoSe₂ are also discussed.

Potassium-ion batteries (PIBs) have received much attention as next-generation energy storage systems because of their abundance, low cost, and slightly lower standard redox potential than lithium-ion batteries (LIBs).

Ni-soc-MOF derived carbon hollow sphere encapsulated Ni3Se4 nanocrystals for high-rate supercapacitors

Carbon hollow sphere encapsulated Ni₃Se₄ (Ni₃Se₄@CHS) nanocrystals are prepared using the Ni-soc-MOF by pyrolysis and further selenization. Ni₃Se₄@CHS exhibits a capacitance of 1720 F g^-1 at 1 A g^-1 and a capacitance retention of 97% after 6000 cycles at 5 A g^-1. Moreover, the asymmetric supercapacitor of Ni₃Se₄@CHS//AC displays a wide potential window of 1.6 V, an energy density of 45.2 W h kg^-1 at a power density of 800 W kg^-1, and excellent cycling stability (89% capacitance retention) after 5000 cycles. Overall, this work establishes a significant step to synthesize a new carbon-based material with appreciable capacitance and long cycling durability for potential applications in energy storage and beyond.

Research progress on ZnSe and ZnTe anodes for rechargeable batteries

Transition-metal chalcogenides (TMCs) with tunable direct bandgaps and interlayer spacing are attractive for energy-related applications. Semiconducting zinc chalcogenides, especially their selenides (ZnSe) and tellurides (ZnTe), with enhanced conductivity, high theoretical capacity, low operation voltage and abundance, have appeared on the horizon and receive increasing interest in terms of electrochemical energy storage and conversion. Despite the existing typical obstruction owing to the large volume change, relatively low electrical conductivity and sluggish ion diffusion kinetics into the bulk phase, several effective strategies such as compositing, doping, nanostructuring, and electrode/cell design have exhibited promising applications. We herein provide a timely and systematic overview of recent research and significant advances regarding ZnSe, ZnTe and their hybrids/composites, covering synthesis to electrode design and to applications, especially in advanced Li/Na/K-ion batteries, as well as the reaction mechanisms thereof. It is hoped that the overview will shed new light on the development of ZnSe and ZnTe for next-generation rechargeable batteries.

The Emergence of 2D MXenes Based Zn-Ion Batteries: Recent Development and Prospects

Rechargeable zinc-ion batteries (ZIBs) with exceptional theoretical capacity have garnered significant interest in large-scale electrochemical energy storage devices due to their low cost, abundant material, inherent safety, high specific energy, and ecofriendly nature. Metal carbides/nitrides, known as MXenes, have emerged as a large family of 2D transition metal carbides or carbonitrides with excellent properties, e.g., high electrical conductivity, large surface functional groups (e.g., F, O, and OH), low energy barriers for the diffusion of electrolyte ions with wide interlayer spaces. After a decade of effort, significant development has been achieved in the synthesis, properties, and applications of MXenes. Thus, it has opened up various exciting opportunities to construct advanced MXene-based nanostructures for ZIBs with excellent specific energy and power. Herein, this review summarizes the advances across multiple synthesis routes, related properties, morphological and structural characteristics, and chemistries of MXenes for ZIBs. The recent development of MXene-based electrodes is introduced, and electrolytes for ZIBs are elucidated in detail. MXene-based rocking chair ZIBs, strategies to enhance the performance of MXene-based cathodes, suppress the dendrites in MXene-based anodes, and MXene-based flexible ZIBs are pointed out. A rational design and modification of the MXenes as well as the production of composites with metal oxides exhibits promise in solving issues and enhancing the electrochemical performance of ZIBs. Finally, the present challenges and future prospects for MXene-based ZIBs are discussed.

Quasi-aligned Cu2S/Cu(OH)2nanorod arrays anchored on Cu foam as self-supported electrode for non-enzymatic glucose detection

Self-supported Cu₂S/Cu(OH)₂composite nanorods for highly sensitive non-enzymatic glucose sensing werein situgrown on Cu foam by simple hydrothermal treatment of aligned Cu(OH)₂nanorods. The physicochemical and electrochemical properties of the as-fabricated Cu₂S/Cu(OH)₂composite nanorods were characterized by scanning electron microscopy, transmission electron microscopy, x-ray diffraction, Raman spectroscope, x-ray photoelectron spectroscope, cyclic voltammetry, electrochemical impedance spectroscopy, amperometrici-tmeasurements. The mechanism of the composite nanorods produced on conductive substrates was also explored. The electrode exhibits a sensitivity of 9626.88μA mM^-1cm^-2towards glucose with good anti-interference ability, indicating it a promising electrode material for the enhanced non-enzymatic glucose detection.

Gold-selenide quantum dots supported onto cesium ferrite nanocomposites for the efficient degradation of rhodamine B

In this work, different weight percentage of gold-selenide quantum dots (AuSe QDs) (1.0, 2.5, 5.0 and 7.0 wt.%) were successfully synthesized and decorated on cesium ferrite nanocomposite (Cs2Fe2O4 NC). The as-prepared pure AuSe QDs, pure Cs2Fe2O4 NC, and x wt.% AuSe QDs/Cs2Fe2O4 NC photocatalysts were investigated using different characterization techniques such as nitrogen adsorption desorption isotherms (BET), X-ray diffraction patterns (XRD), transmission electron microscopy (TEM), and UV-vis absorption spectroscopy. The results show that AuSe QDs were uniformly distributed on Cs2Fe2O4NCs surface as spherical dots with an average size of 1.0-8.0 nm. While the Cs2Fe2O4 NCs possess an average size between 10 to 35 nm. The photocatalytic performance of x wt. % AuSe QDs/Cs2Fe2O4NCs were measured through the photodegradation of rhodamine B (RhB) dye as a model water pollutant, under a150 W-Mercury lamp with a filter (JB400) as a simulated source of visible light. The results revealed that the % degradation of RhB increased from 50.0 %, 59.1 %, 76.4 %, and to 99.15 % within 150 min for the pure Cs2Fe2O4, 1.0, 2.5 and 5.0 wt.% AuSe QDs/Cs2Fe2O4 NC photocatalysts, respectively. The 5.0 wt.% AuSe/Cs2Fe2O4 NC sample showed highest photocatalytic activity. The effect of recycling also studied. High photocatalytic performance and superior stability confirmed that the prepared nanocomposites act as good photocatalysts.

All Transition Metal Selenide Composed High-Energy Solid-State Hybrid Supercapacitor

Transition metal selenides (TMSs) have enthused snowballing research and industrial attention due to their exclusive conductivity and redox activity features, holding them as great candidates for emerging electrochemical devices. However, the real-life utility of TMSs remains challenging owing to their convoluted synthesis process. Herein, a versatile in situ approach to design nanostructured TMSs for high-energy solid-state hybrid supercapacitors (HSCs) is demonstrated. Initially, the rose-nanopetal-like NiSe@Cu₂ Se (NiCuSe) positive electrode and FeSe nanoparticles negative electrode are directly anchored on Cu foam via in situ conversion reactions. The complementary potential windows of NiCuSe and FeSe electrodes in aqueous electrolytes associated with the excellent electrical conductivity results in superior electrochemical features. The solid-state HSCs cell manages to work in a high voltage range of 0-1.6 V, delivers a high specific energy density of 87.6 Wh kg^-1 at a specific power density of 914.3 W kg^-1 and excellent cycle lifetime (91.3% over 10 000 cycles). The innovative insights and electrode design for high conductivity holds great pledge in inspiring material synthesis strategies. This work offers a feasible route to develop high-energy battery-type electrodes for next-generation hybrid energy storage systems.

Porous Microspheres Comprising CoSe2 Nanorods Coated with N-Doped Graphitic C and Polydopamine-Derived C as Anodes for Long-Lived Na-Ion Batteries

Metal-organic framework-templated nitrogen-doped graphitic carbon (NGC) and polydopamine-derived carbon (PDA-derived C)-double coated one-dimensional CoSe₂ nanorods supported highly porous three-dimensional microspheres are introduced as anodes for excellent Na-ion batteries, particularly with long-lived cycle under carbonate-based electrolyte system. The microspheres uniformly composed of ZIF-67 polyhedrons and polystyrene nanobeads (ϕ = 40 nm) are synthesized using the facile spray pyrolysis technique, followed by the selenization process (P-CoSe₂@NGC NR). Further, the PDA-derived C-coated microspheres are obtained using a solution-based coating approach and the subsequent carbonization process (P-CoSe₂@PDA-C NR). The rational synthesis approach benefited from the synergistic effects of dual carbon coating, resulting in a highly conductive and porous nanostructure that could facilitate rapid diffusion of charge species along with efficient electrolyte infiltration and effectively channelize the volume stress. Consequently, the prepared nanostructure exhibits extraordinary electrochemical performance, particularly the ultra-long cycle life stability. For instance, the advanced anode has a discharge capacity of 291 (1000th cycle, average capacity decay of 0.017%) and 142 mAh g^-1 (5000th cycle, average capacity decay of 0.011%) at a current density of 0.5 and 2.0 A g^-1, respectively.

Building core-shell FeSe2@C anode electrode for delivering superior potassium-ion batteries

Inferior electrical conductivity and large volume variation are two disadvantages of metal selenides. In this work, we have designed a core-shell structure of FeSe₂@C composite with low cost using facile hydrothermal method. The FeSe₂particles as the 'core' and the carbon layer as the 'shell' displayed good synergistic effect that attributed to alleviate volume expansion of electrode and improving the electrical conductivity, which achieved the fast potassium storage. The core-shell structural FeSe₂@C electrode achieved 286 mA h g^-1at 1 A g^-1over 1000 cycles with 99.8% coulombic efficiency and delivered excellent rate capacity with 273 mA h g^-1at 2 A g^-1, which was ascribed to dispersed FeSe₂particles and the strong carbon shell coating. This work will provide the basis for the further development of the application of metal selenides in the field of flexible electrodes.

Surface Selenization Strategy for V2CTx MXene toward Superior Zn-Ion Storage

MXenes are promising cathode materials for aqueous zinc-ion batteries (AZIBs) owing to their layered structure, metallic conductivity, and hydrophilicity. However, they suffer from low capacities unless they are subjected to electrochemically induced second phase formation, which is tedious, time-consuming, and uncontrollable. Here we propose a facile one-step surface selenization strategy for realizing advanced MXene-based nanohybrids. Through the selenization process, the surface metal atoms of MXenes are converted to transition metal selenides (TMSes) exhibiting high capacity and excellent structural stability, whereas the inner layers of MXenes are purposely retained. This strategy is applicable to various MXenes, as demonstrated by the successful construction of VSe₂@V₂CT_x, TiSe₂@Ti₃C₂T_x, and NbSe₂@Nb₂CT_x. Typically, VSe₂@V₂CT_x delivers high-rate capability (132.7 mA h g^-1 at 2.0 A g^-1), long-term cyclability (93.1% capacity retention after 600 cycles at 2.0 A g^-1), and high capacitive contribution (85.7% at 2.0 mV s^-1). Detailed experimental and simulation results reveal that the superior Zn-ion storage is attributed to the engaging integration of V₂CT_x and VSe₂, which not only significantly improves the Zn-ion diffusion coefficient from 4.3 × 10^-15 to 3.7 × 10^-13 cm² s^-1 but also provides sufficient structural stability for long-term cycling. This study offers a facile approach for the development of high-performance MXene-based materials for advanced aqueous metal-ion batteries.

Recent progress on transition metal diselenides from formation and modification to applications

The development of graphene promotes the research of similar two-dimensional (2D) materials, especially 2D transition metal dichalcogenides (TMDCs) with semiconductor properties. Monolayer or few-layer TMDCs have several advantages, such as direct band gap, weak interlayer van der Waals force, large interlayer spacing, and abundant marginal active sites, which make them widely used in catalysis, optoelectronics, as well as energy conversion and storage devices. In addition, transition metal diselenides (TMDSs) also possess many intriguing characteristics. For instance, transition metal diselenides (e.g., MoSe₂) have a more stable 1T phase, larger interlayer spacing, smaller band gap, and more obvious metallic property of Se than TMDCs (e.g., MoS₂). Thus, it has become one of the most attractive research topics branching out from TMDCs. Herein, this review unveils the structures, synthesis, properties, modifications, applications, and perspectives for TMDSs.

Structural engineering of bimetallic selenides for high-energy density sodium-ion half/full batteries

The bimetallic selenide ZnSe/MoSe2@NC fabricated by in situ selenation of a Zn/Mo MOF shows potential for application in high-energy density sodium ion batteries.

Confining MoSe2 Nanosheets into N-Doped Hollow Porous Carbon Microspheres for Fast-Charged and Long-Life Potassium-Ion Storage

The potassium-ion battery (PIB) is the most promising alternative to a lithium-ion battery (LIB). Exploitation of a suitable electrode material is crucial to promote the development of PIBs. The MoSe₂ material has attracted much attention due to its high theoretical capacity, unique layered structure, and good conductivity. However, the potassium storage property of MoSe₂ has been suffering from structural fragmentation and sluggish reaction kinetic caused by large potassium ions upon insertion/extraction, which needs to be further improved. Herein, the MoSe₂ nanosheets are confined into N-doped hollow porous carbon microspheres (MoSe₂@N-HCS) by spray drying and high-temperature selenization. It delivers a superior rate performance of 113.7 mAh g^-1 at 10 A g^-1 and remains at a high capacity of 158.3 mAh g^-1 at 2 A g^-1 even after 16 700 cycles for PIBs. The excellent electrochemical performance can be attributed to unique structure, N-doping, and robust chemical bonds. The storage mechanism of MoSe₂ for potassium ions was explored. The outstanding properties of MoSe₂@N-HCS make it a promising anode material for PIBs.

Facile Hydrothermal Synthesis and Supercapacitor Performance of Mesoporous Necklace-Type ZnCo2O4 Nanowires

In this work, mesoporous ZnCo2O4 electrode material with necklace-type nanowires was synthesized by a simple hydrothermal method using water/ethylene glycol mixed solvent and subsequent calcination treatment. The ZnCo2O4 nanowires were assembled by several tiny building blocks of nanoparticles which led to the growth of necklace-type nanowires. The as-synthesized ZnCo2O4 nanowires had porous structures with a high surface area of 25.33 m2 g−1 and with an average mesopore of 23.13 nm. Due to the higher surface area and mesopores, the as-prepared necklace-type ZnCo2O4 nanowires delivered a high specific capacity of 439.6 C g−1 (1099 F g−1) at a current density of 1 A g−1, decent rate performance (47.31% retention at 20 A g−1), and good cyclic stability (84.82 % capacity retention after 5000 cycles). Moreover, a hybrid supercapacitor was fabricated with ZnCo2O4 nanowires as a positive electrode and activated carbon (AC) as a negative electrode (ZnCo2O4 nanowires//AC), which delivered an energy density of 41.87 Wh kg−1 at a power density of 800 W kg−1. The high electrochemical performance and excellent stability of the necklace-type ZnCo2O4 nanowires relate to their unique architecture, high surface area, mesoporous nature, and the synergistic effect between Zn and Co metals.

Constructing electronic interconnected bimetallic selenide-filled porous carbon nanosheets for stable and highly efficient sodium-ion half/full batteries

Owing to their large theoretical capacity and relatively high electronic conductivity, transition metal selenides have been investigated as potential anodes for energy storage applications. On the other hand, the quick capacity decline induced by volume expansion during cycling and unconnected conducting network of the transition metal selenide-based electrode severely limit their employment in sodium-ion batteries (SIBs). Herein, a simple solvent ultrasonic technique and pyrolysis selenation process were used to make a porous N-doped carbon nanosheet-supported FeSe₂/CoSe₂ electrode. The electrochemical kinetics could be improved, and the stress generated by volume expansion could be efficiently adjusted by exquisitely constructed boundary of the FeSe₂/CoSe₂-CN electrode. As expected, the FeSe₂/CoSe₂-CN porous nanosheets exhibited a high Na⁺ storage capacity of 350 mA h g^-1 (10 A g^-1, 1000 cycles). Kinetic studies were conducted to explore the Na⁺ storage mechanism of FeSe₂/CoSe₂-CN. The as-constructed full sodium-ion batteries, when combined with Na₃V₂(PO₄)₂O₂F, have a phenomenal energy density (109 W h kg^-1), encouraging the exploration of energy-related components with the high-energy density properties.