A Highly Efficient Electrochemical Biosensing Platform by Employing Conductive Nanocomposite Entrapping Magnetic Nanoparticles and Oxidase in Mesoporous Carbon Foam

A conductive multi‐catalyst system consisting of Fe₃O₄ magnetic nanoparticles (MNPs) and oxidative enzymes co‐entrapped in the pores of mesoporous carbon is developed as an efficient and robust electrochemical biosensing platform. The construction of the nanocomposite begins with the incorporation of MNPs by impregnating Fe(NO₃)₃ on a wall of mesoporous carbon followed by heat treatment under an Ar/H₂ atmosphere, which results in the formation of magnetic mesoporous carbon (MMC). Glucose oxidase (GOx) is subsequently immobilized in the remaining pore spaces of the MMC by using glutaraldehyde crosslinking to prevent enzyme leaching from the matrix. H₂O₂ generated by the catalytic action of GOx in proportion to the amount of target glucose is subsequently reduced into H₂O by the peroxidase mimetic activity of MNPs generating cathodic current, which can be detected through the conductive carbon matrix. To develop a robust and easy‐to‐use electrocatalytic biosensing platform, a carbon paste electrode is prepared by mechanically mixing the nanocomposite or MMCs and mineral oil. Using this strategy, H₂O₂ and several phenolic compounds are amperometrically determined employing MMCs as peroxidase mimetics, and target glucose was successfully detected over a wide range of 0.5 × 10^?3 to 10 × 10^?3 M , which covers the actual range of glucose concentration in human blood, with excellent storage stability of over two months at room temperature. Sensitivities of the biosensor (19 to 36 nA mM ^?1) are about 7–14 times higher than that of the biosensor using immobilized GOx in mesoporous carbon without MNPs under optimized condition. The biosensor is of considerable interest because of its potential for expansion to any oxidases, which will be beneficial for use in practical applications by replacing unstable organic peroxidase with immobilized MNPs in a conductive carbon matrix.     

Bio‐Inspired Preparation of Fibrin‐Boned Bionanocomposites of Biomacromolecules and Nanomaterials for Biosensing

Learning from nature is one of the most promising ways to develop advanced functional materials. Here, inspired by blood coagulation, novel fibrin‐boned bionanocomposites are reported as efficient immobilization matrices of biomacromolecules and nanomaterials for biosensing. Glucose oxidase (GOx), Au nanoparticles (AuNPs), and Fe₃O₄ magnetic nanoparticles (MNPs) are adopted as the model biomacromolecules and nanomaterials. By integrating the thrombin‐triggered coagulation of fibrin with advanced surficial modification techniques, four kinds of immobilization strategies are developed and evaluated. Digital imaging, UV‐vis spectroscopy, scanning/transmission electron microscopy, electrochemical methods, and N₂ adsorption‐desorption isotherms are used to investigate the formation, immobilization efficiency, and performance of various bionanocomposites. The fibrin‐boned networks show inherent biocompatibility, excellent adsorbability, porosity, and functionalization ability, endowing the bionanocomposites with high efficiencies in capturing AuNPs, MNPs and GOx (99%, 98%, and 57% captured under the given conditions, respectively), as well as significant mass‐transfer and biocatalysis efficiencies. Therefore, the fibrin‐boned bionanocomposites show great potential for biosensing, for example, a fibrin‐AuNPs‐GOx‐glutaraldehyde bionanocomposites modified Au electrode is highly sensitive to glucose (145 μA cm^?2 mM^?1) allowing for a limit of detection down to 25 nM, being much superior to those of the reported analogues. The presented experimental platform/strategy may find wide applications in the development of other bio/nano‐materials/devices.     

One‐Pot Preparation of Polymer–Enzyme–Metallic Nanoparticle Composite Films for High‐Performance Biosensing of Glucose and Galactose

New polymer–enzyme–metallic nanoparticle composite films with a high‐load and a high‐activity of immobilized enzymes and obvious electrocatalysis/nano‐enhancement effects for biosensing of glucose and galactose are designed and prepared by a one‐pot chemical pre‐synthesis/electropolymerization (CPSE) protocol. Dopamine (DA) as a reductant and a monomer, glucose oxidase (GOx) or galactose oxidase (GaOx) as the enzyme, and HAuCl₄ or H₂PtCl₆ as an oxidant to trigger DA polymerization and the source of metallic nanoparticles, are mixed to yield polymeric bionanocomposites (PBNCs), which are then anchored on the electrode by electropolymerization of the remaining DA monomer. The prepared PBNC material has good biocompatibility, a highly uniform dispersion of the nanoparticles with a narrow size distribution, and high load/activity of the immobilized enzymes, as verified by transmission/scanning electron microscopy and electrochemical quartz crystal microbalance. The thus‐prepared enzyme electrodes show a largely improved amperometric biosensing performance, e.g., a very high detection sensitivity (99 or 129 µA cm^?2 mM ^?1 for glucose for Pt PBNCs on bare or platinized Au), a sub‐micromolar limit of detection for glucose, and an excellent durability, in comparison with those based on conventional procedures. Also, the PBNC‐based enzyme electrodes work well in the second‐generation biosensing mode. The proposed one‐pot CPSE protocol may be extended to the preparation of many other functionalized PBNCs for wide applications.     

A Versatile Nanoplatform Based on Metal-Phenolic Networks Inhibiting Tumor Growth and Metastasis by Combined Starvation/Chemodynamic/Immunotherapy

Although much progress has been made by multifunctional nanoplatforms in the treatment of cancer, several defects of existing nanoplatforms, such as tedious preparation, poor biocompatibility, and failure to activate the immune system, have limited their clinical applications. Herein, a versatile nanosystem of folic acid-modified metal-phenolic networks (MPNs) loaded with GOx and CHA (F-MGC) is fabricated by the easy self-assembly of MPNs, during which glucose oxidase (GOx) and chlorogenic acid (CHA) are concurrently loaded. The resulting nanosystem, having a folic acid-modified surface and inherent acid sensitivity, shows versatility in being able to target tumors and release active ingredients in the weakly acidic tumor microenvironment (TME). Based on the catalysis of GOx and Fe³⁺, the cascade reaction aroused by F-MGC efficiently consumes glucose in the TME and produces abundant cytotoxic hydroxyl radicals, thereby causing the starving and chemodynamic death of cancer cells. In addition, CHA can reshape M2 tumor-associated macrophages (TAMs) into the M1 type, so as to change the immunosuppressive state of TME. The immunogenic cell death (ICD) that occurs from the starvation and chemodynamic therapy, in conjunction with the CHA-induced TAMs polarization, further activates the immune system. Overall, the easily prepared nanoplatform has excellent biocompatibility and effectively inhibits tumor growth and metastasis.     

MXene/Fluoropolymer-Derived Laser-Carbonaceous All-Fibrous Nanohybrid Patch for Soft Wearable Bioelectronics

While state-of-the-art skin-adhering fibrous electrodes have distinct benefits in personal wearable bioelectronics, considerable challenges persist in the production of fibrous-based soft conductive biosensing nanomaterials and their integration into efficient multisensing platforms. Here, an electrochemical-electrophysiological multimodal biosensing patch based on MXene/fluoropolymer nanofiber-derived hierarchical porous TiO₂ nanocatalyst interconnected 3D fibrous carbon nanohybrid electrodes is reported. The nanohybrid electrode is produced via a one-step laser carbonaceous thermal oxidation, resulting in excellent elctroconductivity (sheet resistance = 15.6 Ω sq⁻¹), rich active edges for effective electron transmission, and abundant support for enzyme immobilization. The features are attributed to three synergistic effects: i) conductivity of the interior, unoxidized MXene layers, ii) quick heterogeneous electron transmission of the exterior TiO₂ nanoparticles, and iii) the porous disordered carbon's electron “bridge” effects. Based on the foregoing, the nanohybrid modified biosensing patch integrated into textile is demonstrated to be capable of simultaneously and precisely monitoring sweat glucose with pH adjustment (sensitivity of 77.12 µA mm ⁻¹ cm⁻² within physiological concentrations of 0.01–2 × 10⁻³ m ) and electrocardiogram signals (signal-to-noise ratio = 37.63 dB). This novel approach paves the way for controlled investigations of the nanohybrid, for several functionalization and design options, and for the mass manufacturing capabilities required in real-world applications.     

Targeted Magnetic Resonance Imaging/Near-Infrared Dual-Modal Imaging and Ferroptosis/Starvation Therapy of Gastric Cancer with Peritoneal Metastasis

Accurate identification and visualization of peritoneal metastases (PM) are clinically essential to improving the prognosis for gastric cancer. However, owing to the multifocal spread of peritoneal metastasis nodules, small size, and close contact with adjacent organs, identifying and completely removing them during surgery is extremely challenging, resulting in cancer treatment failure and recurrence. This study develops a T₁-weighted magnetic resonance imaging (MRI) contrast agent (FeGdNP)-loaded indocyanine green/glucose oxidase (ICG/GOx) with conjugation of an RGD dimer (RGD2) and acid-labile polymer mPEG (FeGdNP-ICG/GOx-RGD2-mPEG). Compared with commercial Magnevist, the proposed FeGdNP-ICG/GOx-RGD2-mPEG shows a two to three-fold higher tumor ΔSNR in MRI of peritoneal metastasis and subcutaneous animal models. Compared with free ICG, the increased fluorescent signal of FeGdNP-ICG/GOx-RGD2-mPEG allows for the detection of tiny tumor metastatic nodules (<3 mm), and the removal of the peritoneum transplanted tumors. Abundant gluconic acid and H₂O₂ are generated during the GOx-mediated glucose depletion process in cancer cells, thereby enhancing Fenton reaction efficiency. Accumulated toxic ·OH can damage the mitochondrial function and induce the release of mitochondrial reactive oxygen species, which activates the ferroptosis pathway. The data indicate the potential of the nanoparticles for MRI preoperative diagnosis, intraoperative fluorescence-guided navigation, and ferroptosis tumor therapy.     

Co–Ferrocene MOF/Glucose Oxidase as Cascade Nanozyme for Effective Tumor Therapy

Chemodynamic therapy (CDT), enabling selective therapeutic effects and low side effect, attracts increasing attention in recent years. However, limited intracellular content of H₂O₂ and acid at the tumor site restrains the lasting Fenton reaction and thus the anticancer efficacy of CDT. Herein, a nanoscale Co–ferrocene metal–organic framework (Co‐Fc NMOF) with high Fenton activity is synthesized and combined with glucose oxidase (GOx) to construct a cascade enzymatic/Fenton catalytic platform (Co‐Fc@GOx) for enhanced tumor treatment. In this system, Co‐Fc NMOF not only acts as a versatile and effective delivery cargo of GOx molecules to modulate the reaction conditions, but also possesses excellent Fenton effect for the generation of highly toxic ?OH. In the tumor microenvironment, GOx delivered by Co‐Fc NMOF catalyzes endogenous glucose to gluconic acid and H₂O₂. The intracellular acidity and the on‐site content of H₂O₂ are consequently promoted, which in turn favors the Fenton reaction of Co‐Fc NMOF and enhances the generation of reactive oxygen species (ROS). Both in vitro and in vivo results demonstrate that this cascade enzymatic/Fenton catalytic reaction triggered by Co‐Fc@GOx nanozyme enables remarkable anticancer properties.     

Controllably Engineering Mesoporous Surface and Dimensionality of SnO2 toward High‐Performance CO2 Electroreduction

Currently, the precise control of the architecture and surface of functional materials for high‐performance still remains a great challenge. Here, a feasible approach is presented to synchronously manipulate mesoporous surface and dimensionality of SnO₂ catalysts into hierarchically mesoporous nanosheets and nanospheres within one simple reaction system. By adjustment of the hydrophobic chain length of different fluorinated surfactants, 0D SnO₂ nanospheres with average size of 165 nm, and 2D SnO₂ ulthrathin nanosheets with thickness of 22.5 nm with the distinct dimensionalities are separately obtained (one stone, two birds), both of which are well decorated with ordered mesopore arrays on their surfaces (pore size of 16 nm). The following calcination gave rise to the formation of hierarchically mesopores (5 and 16 nm, respectively) with high crystallization and improved surface area (96.8 m² g^?1). The resultant mesoporous SnO₂ nanosheets as catalyst for CO₂ electroreduction reaction (CO₂ RR) exhibit excellent selectivity, with a high Faraday efficiency (FE) of HCOOH reaching up to 90.0% at ?1.3 V and C₁ FE of 97.4% at ?1.2 V versus reversible hydrogen electrode, as well as long‐term stability, which is among the best performance compared to reported SnO₂ materials, thanks to the collective contributions of the unique architecture and mesoporous structure.     

Blade-Coated Carbon Electrode Perovskite Solar Cells to Exceed 20% Efficiency Through Protective Buffer Layers

Perovskite solar cells with carbon electrode have a commercial impact because of their facile scalability, low-cost, and stability. In these devices, it remains a challenge to design an efficient hole transport layer (HTL) for robust interfacing with perovskite on one side and carbon on another. Herein, an organic/inorganic double planar HTL is constructed based on polythiophene (P3HT) and nickel oxide (NiOx) nanoparticles to address the named challenge. Through adding an alkyl ammonium bromide (CTAB) modified NiOx nanoparticle layer on P3HT, the planar HTL achieves a cascade type-II energy level alignment at the perovskite/HTL interfaces and a preferential ohmic contact at NiOx/carbon electrode, which greatly benefits in charge collection while suppressing charge transfer recombination. Besides, compared with the single P3HT layer, the planar composite enables a robust interfacial contact by protecting perovskite from being corroded by carbon paste during fabrication. As a result, the blade-coated FA_0.6MA_0.4PbI₃ perovskite solar cells (fabricated in ambient air in fume hood) with carbon electrode deliver an efficiency of 20.14%, the highest value for bladed coated carbon and perovskite solar cells, and withstand 275 h maximum power point tracking in air without encapsulation (95% efficiency retained).     

Stepwise Degradable Nanocarriers Enabled Cascade Delivery for Synergistic Cancer Therapy

Hypoxia‐activated prodrugs have brought new opportunities for safe and effective tumor ablation, but their therapeutic efficacy is limited by insufficient activation in tumor microenvironments. Herein, a novel cascade delivery system with tandem functions by integrating a hypoxia‐activated prodrug (AQ4N) and glucose oxidase (GOx) is designed to improve its efficacy. Innovative yolk–shell organosilica nanoparticles with a tetrasulfide bridged composition, a small‐pore yolk, and a large‐pore shell featuring a shell‐to‐yolk stepwise degradability are constructed as a carrier for AQ4N and GOx, one enzyme that catalyzes the oxidation of glucose to produce hydrogen peroxide. The glutathione (GSH) is depleted by tetrasulfide bond in the framework and induces shell degradation for fast release of GOx, which in turn induces starvation (glucose removal), oxidative cytotoxicity (H₂O₂ production and GSH depletion), and hypoxia (oxygen consumption). Finally, the hypoxia activates the liberated prodrug AQ4N for chemotherapy. The cascading and synergistic functions including GSH depletion, starvation, oxidative cytotoxicity, and chemotherapy lead to improved performance in tumor inhibition and antimetastasis.     

The Synergistic Effect of Prussian‐Blue‐Grafted Carbon Nanotube/Poly(4‐vinylpyridine) Composites for Amperometric Sensing

Because of its high activity and selectivity toward the reduction of hydrogen peroxide and oxygen, Prussian blue (PB) is usually considered as an “artificial enzyme peroxidase” and has been extensively used in the construction of electrochemical biosensors. In this study, we report on the construction of amperometric biosensors via grafting PB nanoparticles on the polymeric matrix of multiwalled carbon nanotubes (MWCNTs) and poly(4‐vinylpyridine) (PVP). The MWCNT/PVP/PB composite films were synthesized by casting films of MWCNTs wrapped with PVP on gold electrodes followed by electrochemical deposition of PB on the MWCNT/PVP matrix. The electrode modified with the MWCNT/PVP/PB composite film shows prominent electrocatalytic activity toward the reduction of hydrogen peroxide, which can be explained by the remarkable synergistic effect of the MWCNTs and PB. Therefore, fast amperometric response of this sensor to hydrogen peroxide was observed with a detection sensitivity of 1.3 μA μM ^–1 of H₂O₂ per square centimeter area and a detection limit of 25 nM . These results are much better than those reported for PB‐based amperometric sensors. In addition, a glucose biosensor fabricated by casting an additional glucose oxidase (GOD) containing Nafion film above the MWCNT/PVP/PB composite film shows promise for the sensitive and fast detection of glucose. The observed high stability, high sensitivity, and high reproducibility of the MWCNT/PVP/PB composite films make them promising for the reliable and durable detection of hydrogen peroxide and glucose.     

Biodegradable Calcium Phosphate Nanotheranostics with Tumor-Specific Activatable Cascade Catalytic Reactions-Augmented Photodynamic Therapy

Photodynamic therapy (PDT) is exploited as a promising strategy for cancer treatment. However, the hypoxic solid tumor and the lack of tumor-specific photosensitizer administration hinder the further application of oxygen (O₂)-dependent PDT. In this study, a biodegradable and O₂ self-supplying nanoplatform for tumor microenvironment (TME)-specific activatable cascade catalytic reactions-augmented PDT is reported. The nanoplatform (named GMCD) is constructed by coloading catalase (CAT) and sinoporphyrin sodium (DVDMS) in the manganese (Mn)-doped calcium phosphate mineralized glucose oxidase (GOx) nanoparticles. The GMCD can effectively accumulate in tumor sites to achieve an “off to on” fluorescence transduction and a TME-activatable magnetic resonance imaging. After internalization into cancer cells, the endogenous hydrogen peroxide (H₂O₂) can be catalyzed to generate O₂ by CAT, which not only promotes GOx catalytic reaction to consume more intratumoral glucose, but also alleviates tumor hypoxia and enhances the production of cytotoxic singlet oxygen from light-triggered DVDMS. Moreover, the H₂O₂ generated by GOx-catalysis can be converted into highly toxic hydroxyl radicals by Mn²⁺-mediated Fenton-like reaction, further amplifying the oxidative damage of cancer cells. As a result, GMCD displays superior therapeutic effects on 4T1-tumor bearing mice by a long term cascade catalytic reactions augmented PDT.     

Effects of the surface morphologies of ZnO nanotube arrays on the performance of amperometric glucose sensors

Amperometric glucose sensors have been fabricated with glucose oxidase (GOx) immobilized on ZnO nanotubes (ZnONTs) by physical adsorption. The ZnONTs were formed through selective dissolution of ZnO nanorods (ZnONRs) which were hydrothermally synthesized on Au cylindrical spiral (AuCS) electrodes. With the etching temperature regulated, the surface morphologies of the ZnONT arrays were tailored and their effects on the performance of the corresponding glucose sensors were investigated. It is found that at 65 °C the as-prepared ZnONT arrays show a Gaussian rough surface with larger surface area and better hydrophilicity, and have an effective solid–liquid interface with GOx solution, which further results in desirable GOx immobilization. Therefore favorable performance of the ZnONT-based glucose sensor was obtained, such as the sensitivity 2.63 μA/(mM cm²), linear range 0–6.5 mM, low detection limit 8 μM (S/N=3) and Michaelis-Menten constant 5.24 mM, which are superior to that of the ZnONR-based one. Moreover, the ZnONT-based glucose sensor exhibits good long-term stability, and excellent anti-interference ability to uric acid and ascorbic acid. The results can also be used for the performance optimization and the process standardization of other ZnONT-based amperometric biosensors.     

Rising Mesopores to Realize Direct Electrochemistry of Glucose Oxidase toward Highly Sensitive Detection of Glucose

Direct electrochemistry, a direct electron transfer process between enzymes and electrode possesses, has important fundamental significance in bioelectrochemistry while offering very efficient electrocatalysis for enzyme‐based sensors. Herein, the pore structure of bacterial cellulose porous carbon nanofibers (BPCNFs) is tailored by controlled thermal carbonization. It is discovered that rising mesopores can realize a fast direct electrochemistry of glucose oxidase (GOx) for highly sensitive detection of glucose, achieving a sensitivity of 123.28 µA mmol L^?1 cm^?2 and a detection limit of 0.023 µmol L^?1. The enhancement mechanism for the mesopores is ascribed to the most adequate mesopores of BPCNF₉₀₀, which offer size‐matched “nests” to trap GOx for intimate contacts with the conductive carbon nanofiber enabling fast direct electrochemistry. In addition, with the BPCNF₉₀₀ sensing platform, the mechanisms for GOx‐direct‐electrochemistry‐catalyzed glucose oxidation and oxygen reduction are systematically investigated to further clarify the confusions of glucose sensing in air and N₂‐saturated solutions. This work demonstrates fundamental insights for the direct electrochemistry enabled by rationally designing a pore structure matching the target proteins, thus possessing universal significance in protein‐based electrochemical devices while offering a facile route to fabricate a highly sensitive glucose sensor for practical clinic diagnosis.     

Hierarchical Integrated Hybrid Structural Electrodes Based on Co-N/C and Mo-doped NiCo-LDH@Co-N/C Anchored on MX/CF for High Energy Density Fiber-Shaped Supercapacitor

The judicious design of highly electrochemically active materials on 1D fiber substrate to form a hierarchical integrated hybrid structure is an efficient technique to improve the limited cylindrical space and volumetric energy density of fiber-shaped supercapacitors (FSCs). Herein, a 3D negative electrode, consisting of vertically aligned interconnected mesoporous Co-N/C leaf-like structure on 1D MXene-carbon fiber (Co-N/C@MX/CF) is prepared by controlling the composition and morphology. At the same time, a 3D positive electrode is also prepared by introducing Mo in NiCo-LDH anchored on Co-N/C@MX/CF (Mo-NiCo-LDH@Co-N/C@MX/CF) by electrodeposition method. Benefitting from the systematic hierarchical structures with highly accessible surface area, adequate pore size and easy permeation of electrolyte, both positive and negative electrodes demonstrate highly improved electrochemical performance with areal capacity/capacitance of 0.96 mAh cm⁻²/4.55 mF cm⁻² at a current density of 3.86 mA cm⁻², respectively. Furthermore, the fiber-shaped solid-state hybrid supercapacitor (FSHSC) based on Mo_1.5NiCo-LDH@Co-N/C@MX/CF(+)//Co-N/C_0.5@MX/CF(−) is fabricated, exhibiting compelling energy density of 86.72 mWh cm⁻³ at a power density of 480.30 mW cm⁻³ with an outstanding capacitance retention of 80.2% after 20000 galvanostatic-charge-discharge cycles. This study puts forward a new perspective on the development of highly efficient FSCs for practical application.     

Si/SiO2@Graphene Superstructures for High-Performance Lithium-Ion Batteries

The superstructure composed of various functional building units is promising nanostructure for lithium-ion batteries (LIBs) anodes with extreme volume change and structure instability, such as silicon-based materials. Here, a top-down route to fabricate Si/SiO₂@graphene superstructure is demonstrated through reducing silicalite-1 with magnesium reduction and depositing carbon layers. The successful formation of superstructure lies on the strong 3D network formed by the bridged-SiO₂ matrix coated around silicon nanoparticles. Furthermore, the mesoporous Si/SiO₂ with amorphous bridged SiO₂ facilitates the deposition of graphene layers, resulting in excellent structural stability and high ion/electron transport rate. The optimized Si/SiO₂@graphene superstructure anode delivers an outstanding cycling life for ≈1180 mAh g⁻¹ at 2 A g⁻¹ over 500 cycles, excellent rate capability for ≈908 mAh g⁻¹ at 12 A g⁻¹, great areal capacity for ≈7 mAh cm⁻² at 0.5 mA cm⁻², and extraordinary mechanical stability. A full cell test using LiFePO₄ as the cathode manifests a high capacity of 134 mAh g⁻¹ after 290 loops. More notably, a series of technologies disclose that the Si/SiO₂@graphene superstructure electrode can effectively maintain the film between electrode and electrolyte in LIBs. This design of Si/SiO₂@graphene superstructure elucidates a promising potential for commercial application in high-performance LIBs.     

Synthesis of 3D Mesoporous Wall-Like MnO<Subscript>2</Subscript> with Improved Electrochemical Performance

Manganese dioxide (MnO₂) with mesoporous framework self-assembled by ultrathin nanosheets was synthesized via a facile hydrothermal strategy without any binders and substrates. The wall-like structure of this electrode material for supercapacitors can provide more attaching points for active material and shorten the diffusion paths of electrons and ions, leading to a high specific capacitance (SC) of 400 F g^?1 at current density of 1 A g^?1 and the good cyclic stability up to 3000 cycles. Meanwhile, the relationships among structure, specific surface area, pore size and electrochemical properties have been discussed. It indicated that three-dimensional (3D) wall-like δ-MnO₂ is a promising electrochemical electrode candidate for supercapacitors.     

Simultaneously Crafting Single-Atomic Fe Sites and Graphitic Layer-Wrapped Fe3C Nanoparticles Encapsulated within Mesoporous Carbon Tubes for Oxygen Reduction

The rational design and facile synthesis of 1D hollow tubular carbon-based materials with highly efficient oxygen reduction reaction (ORR) performance remains a challenge. Herein, a simple yet robust route is employed to simultaneously craft single-atomic Fe sites and graphitic layer-wrapped Fe₃C nanoparticles (Fe₃C@GL NPs) encapsulated within 1D N-doped hollow mesoporous carbon tubes (denoted Fe-N-HMCTs). The successional compositional and structural crafting of the hydrothermally self-templated polyimide tubes (PITs), enabled by Fe species incorporation and acid leaching treatment, respectively, yields Fe-N-HMCTs that are subsequently exploited as the ORR electrocatalyst. Remarkably, an alkaline electrolyte capitalizing on Fe-N-HMCTs achieves excellent ORR activity (onset potential, 0.992 V; half-wave potential, 0.872 V), favorable long-term stability, and strong methanol tolerance, outperforming the state-of-the-art Pt/C catalyst. Such impressive ORR performances of the Fe-N-HMCTs originate from the favorable configuration of active sites (i.e., atomically dispersed Fe-N_x sites and homogeneously incorporated Fe₃C@GL NPs) in conjunction with the advantageous 1D hollow tubular architecture containing adequate mesoporous surface. This work offers a new view to fabricate earth-abundant 1D Fe-N-C electrocatalysts with well-designed architecture and outstanding performance for electrochemical energy conversion and storage.     

Highly Ordered Mesoporous Silicon Carbide Ceramics with Large Surface Areas and High Stability

Highly ordered mesoporous silicon carbide ceramics have been successfully synthesized with yields higher than 75 % via a one‐step nanocasting process using commercial polycarbosilane (PCS) as a precursor and mesoporous silica as hard templates. Mesoporous SiC nanowires in two‐dimensional (2D) hexagonal arrays (p6m) can be easily replicated from a mesoporous silica SBA‐15 template. Small‐angle X‐ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images show that the SiC nanowires have long‐range regularity over large areas because of the interwire pillar connections. A three‐dimensional (3D) bicontinuous cubic mesoporous SiC structure (Ia3d) can be fabricated using mesoporous silica KIT‐6 as the mother template. The structure shows higher thermal stability than the 2D hexagonal mesoporous SiC, mostly because of the 3D network connections. The major constituent of the products is SiC, with 12 % excess carbon and 14 % oxygen measured by elemental analysis. The obtained mesoporous SiC ceramics are amorphous below 1200 °C and are mainly composed of randomly oriented β‐SiC crystallites after treatment at 1400 °C. N₂‐sorption isotherms reveal that these ordered mesoporous SiC ceramics have high Brunauer–Emmett–Teller (BET) specific surface areas (up to 720 m² g^–1), large pore volumes (～ 0.8 cm³ g^–1), and narrow pore‐size distributions (mean values of 2.0–3.7 nm), even upon calcination at temperatures as high as 1400 °C. The rough surface and high order of the nanowire arrays result from the strong interconnections of the SiC products and are the main reasons for such high surface areas. XRD, N₂‐sorption, and TEM measurements show that the mesoporous SiC ceramics have ultrahigh stability even after re‐treatment at 1400 °C under a N₂ atmosphere. Compared with 2D hexagonal SiC nanowire arrays, 3D cubic mesoporous SiC shows superior thermal stability, as well as higher surface areas (590 m² g^–1) and larger pore volumes (～ 0.71 cm³ g^–1).     

High Yield Electrosynthesis of Hydrogen Peroxide from Water Using Electrospun CaSnO3@Carbon Fiber Membrane Catalysts with Abundant Oxygen Vacancy

Hydrogen peroxide (H₂O₂) production by electrochemical two-electron water oxidation reaction (2e-WOR) is a promising approach, where high-performance electrocatalysts play critical roles. Here, the synthesis of nanostructured CaSnO₃ confined in conductive carbon fiber membrane with abundant oxygen vacancy (O_V) as a new generation of 2e-WOR electrocatalyst is reported. The CaSnO₃@carbon fiber membrane can be directly used as a self-standing electrode, exhibiting a record-high H₂O₂ production rate of 39.8 µmol cm⁻² min⁻¹ and a selectivity of ≈90% (at 2.9 V vs reversible hydrogen electrode). The CaSnO₃@carbon fiber membrane design improves not only the electrical conductivity and stability of catalysts but also the inherent activity of CaSnO₃. Density functional theory calculation further indicates the crucial role of O_V in increasing the adsorption free energy toward oxygen intermediates associated with the competitive four-electron water oxidation reaction pathway, thus enhancing the activity and selectivity of 2e-WOR. The findings pave a new avenue to the rational design of electrocatalysts for H₂O₂ production from water.