Three-Dimensional Hierarchical Porous Structures Constructed by Two-Stage MXene-Wrapped Si Nanoparticles for Li-Ion Batteries

Enhancing Interfacial Interactions Through Microwave-Irradiated Reduction for the Recycling of Photovoltaic Silicon Waste for Lithium Storage

The application of micro-nano size photovoltaic waste silicon (wSi) as an anode material for lithium-ion battery holds significant practical potential; However, it faces a series of challenges related to the volume expansion of Si during cycling. In this study, a simple, efficient, and eco-friendly microwave method is proposed for the rapid preparation of graphene-coated silicon materials (wSi@rGO) in just a few seconds, in which graphene as the stable interface mitigates structural failure caused by significant volume expansion, enhances electron and ion conductivity, inhibits undesirable side reactions between silicon and electrolyte, and promotes the stability of solid electrolyte interface (SEI). Importantly, the instantaneous high temperature generated by microwaves facilitates the formation of interfacial SiC chemical bonds, which strengthen the interaction between Si and graphene, thereby reducing Si delamination. The wSi@rGO anode exhibits remarkable cycling stability, maintaining a specific capacity of 1100 mA h g-1 over 250 cycles. Furthermore, the assembled wSi@rGO//LiFePO4 full battery demonstrates robust performance, retaining a stable capacity of 150 mA h g-1 after 80 cycles at 0.5 C. This research not only demonstrates a straightforward and efficient microwave technique for synthesizing wSi@rGO anode materials, but also offers an environmentally friendly and economical pathway for recycling photovoltaic waste silicon, contributing positively to carbon peaking and carbon neutrality.

A novel four-modal nano-sensor based on two-dimensional Mxenes and fully connected artificial neural networks for the highly sensitive and rapid detection of ochratoxin A

Timely and accurate on-site detection of ochratoxin A (OTA) is extremely important for global public health. In this study, a fluorescence/colorimetric biosensor based on Ti3C2 nano-materials (Ti3C2-NMS) and a machine-learning (ML) based fluorescence/colorimetric intelligent learning system for detection of OTA concentration (COTA) were developed. The sensor was fabricated by functionalizing Ti3C2-NMS prepared by physical-exfoliation assisted metal-ion-induction using ssDNA. The Ti3C2-NMS exhibited good fluorescence quenching characteristics (FQC) and peroxidase-like activity (PLA). More surprisingly, the functionalization of Ti3C2-NMS by ssDNA further enhanced the FQC and PLA of the material, which could be used for dual-mode detection of OTA. When different COTA existed, ssDNA competitively bound to OTA, resulting in regular changes in fluorescence and colorimetric signals of the sensor, which realized the accurate and sensitive biosensing detection of OTA in two modalities. Based on a series of fluorescent/colorimetric RGB datasets collected by a self-developed application, a dual-channel ML model had been developed. This model can be integrated into mobile phones, clouds, and PCs to achieve intelligent sensing detection of OTA with the assistance of fully connected artificial neural networks. The method constructed had high specificity, low cost, and fast responsiveness, with a LOD as low as 1.58 pg mL-1, indicating excellent potential for application and promotion.

Boosted Efficiency of Fe2O3 for Photocatalytic CO2 Reduction via Engineering Fe-O-Ti Bonding

Visible light-driven photocatalytic CO2 reduction (CO2RR) offers a sustainable and promising solution to environmental and energy challenges. However, the design of efficient photocatalysts is hindered by poor interface interactions in heterojunctions and a limited understanding of reaction kinetics. A modified Fe2O3 photocatalyst, M-Fe2O3@MXene, is introduced featuring KH-550-modified M-Fe2O3 hollow nanocubes coated with MXene, constructed via an electrostatic and Fe-O-Ti bonding self-assembly method. This design achieves an unprecedented CO production rate of 240 µmol g⁻¹ h⁻¹ among non-noble metal catalysts (8.6 folds vs Fe2O3). The Fe-O-Ti sites enhance *COOH intermediate formation and CO production through higher electron deficiency of Fe3+ and rapid charge transfer. This study offers new insights on the use of functional metal oxides and high-quality Mxene layers to design efficient metal oxide-based photocatalysts.

Synergistic effects of hierarchical micro/nanostructures and PDMS/lubricant composites for superior tribological and wetting performance on aluminum

In this study, we propose a method to enhance the friction and wetting properties of aluminum surfaces with micro-/nanostructures by coating them with a PDMS/lubricant composite. Hierarchical micro/nanostructures were formed on the aluminum surface through an etching process, and coating solutions were prepared by mixing xylene and the PDMS/lubricant composites in various ratios. The surface morphology, roughness, and wettability of the coated specimens were analyzed, and their friction and wear characteristics were evaluated under dry and lubricated conditions. The results showed that the PDMS/lubricant composite coating significantly reduced friction and wear under both dry and lubricated conditions owing to the formation of a stable lubricating film. Additionally, the hierarchical micro/nanostructures formed by the etching process improved hydrophobicity and self-cleaning ability. The coated surface exhibited selective wettability towards water and oil, offering various advantages such as prevention of contamination, prevention of wear and performance degradation caused by lubricant oxidation, and enhanced corrosion resistance. The findings of this study are expected to contribute to the development of lightweight mechanical-component technologies with improved durability and wear resistance.

Recent progress in Si/Ti3C2Tx MXene anode materials for lithium-ion batteries

Cardiovascular diseases (CVDs) are a major global health issue, causing significant morbidity and mortality worldwide. Early diagnosis and continuous monitoring of physiological signals are crucial for managing cardiovascular diseases, necessitating the development of lightweight and cost-effective wearable devices. These devices should incorporate portable energy storage systems, such as lithium-ion batteries (LIBs). To enhance the durability and consistency of the monitoring systems, there is a need to develop LIBs with high energy density. Silicon-based materials hold great promise for future LIBs anodes due to their high theoretical capacity and cost-efficiency. Despite their potential, silicon-based materials encounter challenges like substantial volume fluctuations and sluggish kinetics. Transition metal carbide, MXene, features a two-dimensional structure, offering advantages in silicon-based anode materials. This review initially presents the potential of silicon-based anodes and then addresses their challenges. Subsequently, the advantages of MXene are systematically reviewed, including unique structure, abundant surface functional groups, excellent electrical conductivity, and excellent ion transport performance. Next, the detailed discussion covers recent advancements in Si/Ti3C2Tx MXene anode materials for LIBs, with a focus on their synthesis methods. Finally, the challenges and future perspectives of synthesizing Si/Ti3C2Tx nanocomposites are examined, aiming to provide a foundational resource for designing advanced materials for high-energy LIBs.

Diatom-Based Artificial Anode-Uniform Coating of Intrinsic Carbon to Enhance Lithium Storage

Pursuing improved electrode materials is essential for addressing the challenges associated with large-scale Li-ion battery applications. Specifically, silicon oxide (SiOx) has emerged as a promising alternative to graphite anodes, despite issues related to volume expansion and rapid capacity degradation. In this study, we synthesized carbon-coated SiOx using diatom biomass derived from artificially cultured diatoms. However, the inherent carbon content from diatoms poses a significant challenge for the electrochemical performance of diatom-based anodes in large-scale applications. Subsequently, we conducted further research and demonstrated excellent performance with a carbon content of 33 wt.% as anodes. Additionally, real-time characterization of the carbonization process was achieved using thermogravimetry coupled with infrared spectroscopy and gas chromatography mass spectrometry (TG-FTIR-GCMS), revealing the emission of CO and C3O2 during carbonization. Furthermore, electrochemical tests of the processed diatom and carbon (PD@C) anode exhibited outstanding rate capability (~500 mAh g-1 at 2 A g-1), high initial Coulomb efficiency (76.95%), and a DLi+ diffusion rate of 1.03 × 10-12 cm2 s-1. Moreover, structural characterization techniques such as HRTEM-SAED were employed, along with DFT calculations, to demonstrate that the lithium storage process involves not only reversible transport in Li2Si2O5 and Li22Si5, but also physical adsorption between the PD and C layers. Exploring the integration of diatom frustules with the intrinsic carbon content in the fabrication of battery anodes may contribute to a deeper understanding of the mechanisms behind their successful application.

Beyond graphene: exploring the potential of MXene anodes for enhanced lithium-sulfur battery performance

The high theoretical energy density of Li-S batteries makes them a viable option for energy storage systems in the near future. Considering the challenges associated with sulfur's dielectric properties and the synthesis of soluble polysulfides during Li-S battery cycling, the exceptional ability of MXene materials to overcome these challenges has led to a recent surge in the usage of these materials as anodes in Li-S batteries. The methods for enhancing anode performance in Li-S batteries via the use of MXene interfaces are thoroughly investigated in this study. This study covers a wide range of techniques such as surface functionalization, heteroatom doping, and composite structure design for enhancing MXene interfaces. Examining challenges and potential downsides of MXene-based anodes offers a thorough overview of the current state of the field. This review encompasses recent findings and provides a thorough analysis of advantages and disadvantages of adding MXene interfaces to improve anode performance to assist researchers and practitioners working in this field. This review contributes significantly to ongoing efforts for the development of reliable and effective energy storage solutions for the future.

A Uniform Self-Reinforced Organic/Inorganic Hybrid SEI Chelation Strategy on Microscale Silicon Surfaces for Stable-Cycling Anodes in Lithium-Ion Batteries

A promising anode material for Li-ion batteries, silicon (Si) suffers from volume expansion-induced pulverization and solid electrolyte interface (SEI) instability. Microscale Si with high tap density and high initial Coulombic efficiency (ICE) has become a more anticipated choice, but it will exacerbate the above issues. In this work, the polymer polyhedral oligomeric silsesquioxane-lithium bis (allylmalonato) borate (PSLB) is constructed by in situ chelation on microscale Si surfaces via click chemistry. This polymerized nanolayer has an "organic/inorganic hybrid flexible cross-linking" structure that can accommodate the volume change of Si. Under the stable framework formed by PSLB, a large number of oxide anions on the chain segment preferentially adsorb LiPF6 and further induce the integration of inorganic-rich, dense SEI, which improves the mechanical stability of SEI and provides accelerated kinetics for Li+ transfer. Therefore, the Si4@PSLB anode exhibits significantly enhanced long-cycle performance. After 300 cycles at 1 A g-1 , it can still provide a specific capacity of 1083 mAh g-1 . Cathode-coupled with LiNi0.9 Co0.05 Mn0.05 O2 (NCM90) in the full cell retains 80.8% of its capacity after 150 cycles at 0.5 C.

MOF-Derived ZnS Nanodots/Ti3C2Tx MXene Hybrids Boosting Superior Lithium Storage Performance

ZnS has great potentials as an anode for lithium storage because of its high theoretical capacity and resource abundance; however, the large volume expansion accompanied with structural collapse and low conductivity of ZnS cause severe capacity fading and inferior rate capability during lithium storage. Herein, 0D-2D ZnS nanodots/Ti₃C₂T_x MXene hybrids are prepared by anchoring ZnS nanodots on Ti₃C₂T_x MXene nanosheets through coordination modulation between MXene and MOF precursor (ZIF-8) followed with sulfidation. The MXene substrate coupled with the ZnS nanodots can synergistically accommodate volume variation of ZnS over charge-discharge to realize stable cyclability. As revealed by XPS characterizations and DFT calculations, the strong interfacial interaction between ZnS nanodots and MXene nanosheets can boost fast electron/lithium-ion transfer to achieve excellent electrochemical activity and kinetics for lithium storage. Thereby, the as-prepared ZnS nanodots/MXene hybrid exhibits a high capacity of 726.8 mAh g^-1 at 30 mA g^-1, superior cyclic stability (462.8 mAh g^-1 after 1000 cycles at 0.5 A g^-1), and excellent rate performance. The present results provide new insights into the understanding of the lithium storage mechanism of ZnS and the revealing of the effects of interfacial interaction on lithium storage performance enhancement.

Unraveling the New Role of Metal-Organic Frameworks in Designing Silicon Hollow Nanocages for High-Energy Lithium-Ion Batteries

Metal-organic framework (MOF)-derived materials are attracting considerable attention because of the moldability in compositions and structures, enabling greater performances in diverse applications. However, the nanostructural control of multicomponent MOF-based complexes remains challenging due to the complexity of reaction mechanisms. Herein, we present a surface-induced self-nucleation-growth mechanism for the zeolitic imidazolate framework (ZIF) to prepare a new type of ZIF-8@SiO₂ polyhedral nanoparticles. We discover that the Zn hydroxide moieties (Zn-OH) within ZIF-8 can trigger the hydrolysis of tetraethyl orthosilicate effectively on the ZIF-8 surface precisely, avoiding the formation of free orthosilicic acid (Si(OH)₄) successfully. This is a pioneering work to elucidate the importance of MOF surface properties for preparing multicomponent materials. Then, a novel well-dispersed silicon hollow nanocage (H-Si@C) modified by the carbon was prepared after removal of the ZIF-8 and magnesiothermic reduction. The as-prepared H-Si@C demonstrates an overwhelmingly high lithium storage capability and extraordinary stability in lithium-ion batteries (LIBs), particularly the impressive performances when it was matched with the LiNi_0.6Co_0.2Mn_0.2O₂ cathode in a full cell. The MOF surface-induced self-nucleation-growth strategy is useful for preparing more multifunctional materials, while the study of lithium storage performances of the H-Si@C material is practical for LIB applications.

Microbe-Assisted Assembly of Ti3C2Tx MXene on Fungi-Derived Nanoribbon Heterostructures for Ultrastable Sodium and Potassium Ion Storage

As a typical family of two-dimensional (2D) materials, MXenes present physiochemical properties and potential for use in energy storage applications. However, MXenes suffer some of the inherent disadvantages of 2D materials, such as severe restacking during processing and service and low capacity of energy storage. Herein, a MXene@N-doped carbonaceous nanofiber structure is designed as the anode for high-performance sodium- and potassium-ion batteries through an in situ bioadsorption strategy; that is, Ti₃C₂T_x nanosheets are assembled onto Aspergillus niger biofungal nanoribbons and converted into a 2D/1D heterostructure. This microorganism-derived 2D MXene-1D N-doped carbonaceous nanofiber structure with fully opened pores and transport channels delivers high reversible capacity and long-term stability to store both Na⁺ (349.2 mAh g^-1 at 0.1A g^-1 for 1000 cycles) and K⁺ (201.5 mAh g^-1 at 1.0 A g^-1 for 1000 cycles). Ion-diffusion kinetics analysis and density functional theory calculations reveal that this porous hybrid structure promotes the conduction and transport of Na and K ions and fully utilizes the inherent advantages of the 2D material. Therefore, this work expands the potential of MXene materials and provides a good strategy to address the challenges of 2D energy storage materials.