ABSTRACT
Pulmonary fibrosis is a formidable challenge in chronic and age-related lung diseases. Myofibroblasts secrete large amounts of extracellular matrix and induce pro-repair responses during normal wound healing. Successful tissue repair results in termination of myofibroblast activity via apoptosis; however, some myofibroblasts exhibit a senescent phenotype and escape apoptosis, causing over-repair that is characterized by pathological fibrotic scarring. Therefore, the removal of senescent myofibroblasts using senolytics is an important method for the treatment of pulmonary fibrosis. Procyanidin C1 (PCC1) has recently been discovered as a senolytic compound with very low toxicity and few side effects. This study aimed to determine whether PCC1 could improve lung fibrosis by promoting apoptosis in senescent myofibroblasts and to investigate the mechanisms involved. The results showed that PCC1 attenuates bleomycin (BLM)-induced pulmonary fibrosis in mice. In addition, we found that PCC1 inhibited extracellular matrix deposition and promoted the apoptosis of senescent myofibroblasts by increasing PUMA expression and activating the BAX signaling pathway. Our findings represent a new method of pulmonary fibrosis management and emphasize the potential of PCC1 as a senotherapeutic agent for the treatment of pulmonary fibrosis, providing hope for patients with pulmonary fibrosis worldwide. Our results advance our understanding of age-related diseases and highlight the importance of addressing cellular senescence in treatment.
Subject(s)
Bleomycin , Catechin , Cellular Senescence , Mice, Inbred C57BL , Myofibroblasts , Pulmonary Fibrosis , Animals , Bleomycin/toxicity , Myofibroblasts/metabolism , Myofibroblasts/drug effects , Pulmonary Fibrosis/chemically induced , Pulmonary Fibrosis/metabolism , Pulmonary Fibrosis/drug therapy , Pulmonary Fibrosis/pathology , Mice , Cellular Senescence/drug effects , Catechin/pharmacology , Catechin/analogs & derivatives , Proanthocyanidins/pharmacology , Apoptosis/drug effects , Male , Biflavonoids/pharmacology , Signal Transduction/drug effectsABSTRACT
Multi-component composite materials with a magnetic-dielectric synergistic effect exhibit satisfactory electromagnetic wave absorption performance. However, the effective construction of the structure for these multi-component materials to fully exploit the advantages of each component remains a challenge. Inspired by natural biomass, this study utilizes wood as the raw material and successfully prepares high-performance MoS2@Gd2O3/Mxene loaded porous carbon aerogel (MGMCA) composite material through a one-pot hydrothermal method and carbonization treatment process. With a delicate structural design, the MGMCA is endowed with abundant heterogeneous interface structures, favorable impedance matching characteristics, and a magnetic-dielectric synergistic system, thus demonstrating multiple electromagnetic wave loss mechanisms. Benefiting from these advantages, the obtained MGMCA exhibits outstanding electromagnetic wave absorption performance, with a minimum reflection loss of -57.5 dB at an ultra-thin thickness of only 1.9 mm. This research proposes a reliable strategy for the design of multi-component composite materials, providing valuable insight for the design of biomass-based materials as electromagnetic wave absorbers.
ABSTRACT
Pulmonary fibrosis is a chronic, progressive fibrosing interstitial disease. It is characterized by fibroblast proliferation, myofibroblast activation, and massive extracellular matrix deposition. These processes result in loss of lung parenchyma function. The transdifferentiation of alveolar epithelial type II (AEC2) to alveolar epithelial type I cells (AEC1) plays an important role in the epithelial repair after lung injury. Pulmonary fibrosis begins when this transdifferentiation process is blocked. Several recent studies have found that novel transitional state cells (intermediate states in the transdifferentiation of AEC2 to AEC1) can potentially regenerate the alveolar epithelium surface and promote a repair process. During the AEC2 to AEC1 trans-differentiation process after injury, AEC2 lose their specific markers and become transitional state cells. Furthermore, transdifferentiation of transitional state cells into AEC1 is the critical step for lung repair. However, transitional cells stagnate in the intermediate states in which failure of transdifferentiation to AEC1 may induce an inadequate repair process and pulmonary fibrosis. In this review, we focus on the traits, origins, functions, and activation of signaling pathways of the transitional state cell and its communication with other cells. We also provide a new opinion on pulmonary fibrosis pathogenesis mechanisms and novel therapeutic targets.
Subject(s)
Lung Injury , Pulmonary Fibrosis , Alveolar Epithelial Cells/metabolism , Cell Differentiation/physiology , Humans , Lung/pathology , Lung Injury/pathology , Pulmonary Fibrosis/metabolismABSTRACT
Idiopathic pulmonary fibrosis is a progressive and age-related disease that results from impaired lung repair following injury. Targeting senescent myofibroblasts with senolytic drugs attenuates pulmonary fibrosis, revealing a detrimental role of these cells in pulmonary fibrosis. The mechanisms underlying the occurrence and persistence of senescent myofibroblasts in fibrotic lung tissue require further clarification. In this study, we demonstrated that senescent myofibroblasts are resistant to apoptosis by upregulating the proapoptotic protein BAX and antiapoptotic protein BCL-2 and BCL-XL, leading to BAX inactivation. We further showed that high levels of inactive BAX-mediated minority mitochondrial outer membrane permeabilization (minority MOMP) promoted DNA damage and myofibroblasts senescence after insult by a sublethal stimulus. Intervention of minority MOMP via the inhibition of caspase activity by quinolyl-valyl-O-methylaspartyl-[2,6-difluorophenoxy]-methyl ketone (QVD-OPH) or BAX knockdown significantly reduced DNA damage and ultimately delayed the progression of senescence. Moreover, the BAX activator BTSA1 selectively promoted the apoptosis of senescent myofibroblasts, as BTSA1-activated BAX converted minority MOMP to complete MOMP while not injuring other cells with low levels of BAX. Furthermore, therapeutic activation of BAX with BTSA1 effectively reduced the number of senescent myofibroblasts in the lung tissue and alleviated both reversible and irreversible pulmonary fibrosis. These findings advance the understanding of apoptosis resistance and cellular senescence mechanisms in senescent myofibroblasts in pulmonary fibrosis and demonstrate a novel senolytic drug for pulmonary fibrosis treatment.
ABSTRACT
Single-atom catalysts (SACs), with precisely controlled metal atom distribution and adjustable coordination architecture, have gained intensive concerns as efficient oxygen reduction reaction (ORR) electrocatalysts in Zn-air batteries (ZAB). The attainment of a monodispersed state for metallic atoms anchored on the carbonaceous substrate remains the foremost research priority; however, the persistent challenges lie in the relatively weak metal-support interactions and the instability of captured single atom active sites. Furthermore, in order to achieve rapid transport of O2 and other reactive substances within the carbon matrix, manufacturing SACs based on multi-stage porous carbon substrates is highly anticipated. Here, we propose a methodology for the fabrication of carbon aerogels (CA)-supported SACs utilizing papermaking nanofibers, which incorporates advanced strategies for N-atom self-doping, defect/vacancy introduction, and single-atom interface engineering. Specifically, taking advantages of using green and energy-efficient feedstocks, combining with a direct pore-forming template volatilization and chemical vapor deposition approach, we successfully developed N-doped carbon aerogels immobilized with separated iron sites (Fe-SAC@N/CA-Cd). The obtained Fe-SAC@N/CA-Cd exhibited substantially large specific surface area (SBET = 1173 m2/g) and a multi-level pore structure, which can effectively mitigate the random aggregation of Fe atoms during pyrolysis. As a result, it demonstrated appreciable activity and stability in catalyzing the ORR progress (E1/2 = 0.88 V, Eonset = 0.96 V). Furthermore, the assembled liquid electrolyte-state Zn-air batteries (LES-ZAB) and all-solid-state Zn-air battery (ASS-ZAB) also provides encouraging performance, with a peak power density of 169 mW cm-2 for LES-ZAB and a maximum power density of 124 mW cm-2 for ASS-ZAB.
ABSTRACT
Personalized healthcare management is an emerging field that requires the development of environment-friendly, integrated, and electrochemical multimodal devices. In this study, the concept of integrated paper-based biosensors (IFP-Multi ) for personalized healthcare management is introduced. By leveraging ink printing technology and a ChatGPT-bioelectronic interface, these biosensors offer ultrahigh areal-specific capacitance (74633 mF cm-2 ), excellent mechanical properties, and multifunctional sensing and humidity power generation capabilities. More importantly, the IFP-Multi devices have the potential to simulate deaf-mute vocalization and can be integrated into wearable sensors to detect muscle contractions and bending motions. Moreover, they also enable monitoring of physiological signals from various body parts, such as the throat, nape, elbow, wrist, and knee, and successfully record sharp and repeatable signals generated by muscle contractions. In addition, the IFP-Multi devices demonstrate self-powered handwriting sensing and moisture power generation for sweat-sensing applications. As a proof-of-concept, a GPT 3.5 model-based fine-tuning and prediction pipeline that utilizes recorded physiological signals through IFP-Multi is showcased, enabling artificial intelligence with multimodal sensing capabilities for personalized healthcare management. This work presents a promising and ecofriendly approach to developing paper-based electrochemical multimodal devices, paving the way for a new era of healthcare advancements.
Subject(s)
Wearable Electronic Devices , Humans , Artificial Intelligence , Delivery of Health Care , Ink , PrintingABSTRACT
Rationale: Pulmonary fibrosis is a chronic progressive lung disease with limited therapeutic options. We previously revealed that there is iron deposition in alveolar epithelial type II cell (AECII) in pulmonary fibrosis, which can be prevented by the iron chelator deferoxamine. However, iron in the cytoplasm and the mitochondria has two relatively independent roles and regulatory systems. In this study, we aimed to investigate the role of mitochondrial iron deposition in AECII injury and pulmonary fibrosis, and to find potential therapeutic strategies. Methods: BLM-treated mice, MLE-12 cells, and primary AECII were employed to establish the mouse pulmonary fibrosis model and epithelial cells injury model, respectively. Mitochondrial transplantation, siRNA and plasmid transfection, western blotting (WB), quantitative real-time polymerase chain reaction (RT-qPCR), polymerase chain reaction (PCR), immunofluorescence, immunoprecipitation (IP), MitoSOX staining, JC-1 staining, oxygen consumption rate (OCR) measurement, and Cell Counting Kit-8 (CCK8) assay were utilized to elucidate the role of mitochondrial iron deposition in cell and lung fibrosis and determine its mechanism. Results: This study showed that prominent mitochondrial iron deposition occurs within AECII in bleomycin (BLM)-induced pulmonary fibrosis mouse model and in BLM-treated MLE-12 epithelial cells. Further, the study revealed that healthy mitochondria rescue BLM-damaged AECII mitochondrial iron deposition and cell damage loss. Mitoferrin-2 (MFRN2) is the main transporter that regulates mitochondrial iron metabolism by transferring cytosolic iron into mitochondria, which is upregulated in BLM-treated MLE-12 epithelial cells. Direct overexpression of MFRN2 causes mitochondrial iron deposition and cell damage. In this study, decreased ubiquitination of the ubiquitin ligase F-box/LRR-repeat protein 5 (FBXL5) degraded iron-reactive element-binding protein 2 (IREB2) and promoted MFRN2 expression as well as mitochondrial iron deposition in damaged AECII. Activation of the prostaglandin E2 receptor EP4 subtype (EP4) receptor signaling pathway counteracted mitochondrial iron deposition by downregulating IREB2-MFRN2 signaling through upregulation of FBXL5. This intervention not only reduced mitochondrial iron content but also preserved mitochondrial function and protected against AECII damage after BLM treatment. Conclusion: Our findings highlight the unexplored roles, mechanisms, and regulatory approaches of abnormal mitochondrial iron metabolism of AECII in pulmonary fibrosis. Therefore, this study deepens the understanding of the mechanisms underlying pulmonary fibrosis and offers a promising strategy for developing effective therapeutic interventions using the EP4 receptor activator.
Subject(s)
Alveolar Epithelial Cells , Bleomycin , Disease Models, Animal , Iron , Mitochondria , Pulmonary Fibrosis , Animals , Mitochondria/metabolism , Mitochondria/drug effects , Pulmonary Fibrosis/metabolism , Pulmonary Fibrosis/chemically induced , Mice , Iron/metabolism , Alveolar Epithelial Cells/metabolism , Alveolar Epithelial Cells/drug effects , Mice, Inbred C57BL , Cell Line , MaleABSTRACT
Improving the cellulose accessibility and reactivity in an efficient and convenient way has become the focused issue in the field of dissolving pulp manufacturing. We herein demonstrate a simple yet efficient strategy, namely a simultaneous microwave (MW)-assisted phosphotungstic acid (PTA) catalysis (MW-PTAsim). The MW-PTAsim treatment was efficient to improve Fock reactivity from 49.1 % to 85.8 % and decrease viscosity from 561 to 360 mL/g within 10 min, which was superior to the single MW treatment and the sequential MW-PTAseq treatment. Besides, the MW-PTAsim treated fiber had rougher and more fibrillated surfaces with an enhanced fiber accessibility, showing increased specific surface area (SSA) from 1.43 to 6.31 m2/g, mean pore diameter (MPD) from 6.92 to 11.20 nm and water retention value (WRV) from 101 % to 172 %. These positive enhancements are mainly due to a synergy that MW-enhanced rotation of PTA mediums was served as "spinning cutters" to attack the fibers, plus MW-accelerated PTA transfer and catalytic hydrolysis further improved the fiber accessibility. Moreover, PTA also demonstrates a high reusability and chemical stability. This process offers an effective and sustainable alternative for manufacturing a premium dissolving pulp.
Subject(s)
Cellulase , Microwaves , Phosphotungstic Acid , Cellulase/pharmacology , Wood , Molecular WeightABSTRACT
Single-atom catalysts (SACs) have opened up unprecedented possibilities for expediting oxygen reduction reaction (ORR) kinetics owing to their ultrahigh intrinsic activities. However, precisely controlling over the atomically dispersed metal-Nx sites on carbon support while fulfilling the utmost utilization of metal atoms remain the key obstacles. Here, atomically distributed Co-N4 sites anchored on N-doped carbon nanofibers aerogel (Co SAs/NCNA) is controllably attained through a direct pyrolysis of metal-chelated cellulose nanofibers (TOCNFs-Cd2+/Co2+) hydrogel precursor. The usage of Cd salt assists the assembly of cross-linked aerogel, creates a large number of interior micropores and defects, and favors the physical isolation of Co atoms. The hierarchically porous biomass carbon aerogel (2265.1 m2/g) offers an advantageous platform to facilitate accessibility of the catalytic centers, also renders rapid mass diffusion and electron-transfer paths throughout its 3D architecture. Notably, Co SAs/NCNA affords a paramount ORR activity and respectable durability when integrated into zinc-air battery devices.
Subject(s)
Nanofibers , Cobalt , Cellulose , Carbon , Zinc , Cadmium , Hydrogels , OxygenABSTRACT
Metal/nitrogen-doped carbon single-atom catalysts (M-N-C SACs) show excellent catalytic performance with a maximum atom utilization and customizable tunable electronic structure. However, precisely modulating the M-Nx coordination in M-N-C SACs remains a grand challenge. Here, we used a N-rich nucleobase coordination self-assembly strategy to precisely regulate the dispersion of metal atoms by controlling the metal ratio. Meanwhile, the elimination of Zn during pyrolysis produced porous carbon microspheres with a specific surface area of up to 1151 m2 g-1, allowing maximum exposure of Co-N4 sites and facilitating charge transport in the oxygen reduction reaction (ORR) process. Thereby, the monodispersed cobalt sites (Co-N4) in N-rich (18.49 at%) porous carbon microspheres (CoSA/N-PCMS) displayed excellent ORR activity under alkaline conditions. Simultaneously, the Zn-air battery (ZAB) assembled with CoSA/N-PCMS outperformed Pt/C+RuO2-based ZABs in terms of power density and capacity, proving that they have good prospects for practical application.
ABSTRACT
Five undescribed eudesmane sesquiterpenoids, artemilavanins A-E, and one undescribed rearranged eudesmane sesquiterpenoid, artemilavanin F, were isolated from the 95% ethanol extract of the aerial parts of Artemisia lavandulaefolia DC., along with ten known compounds. The structures and configurations of undescribed compounds were mainly elucidated by spectroscopic analyses and single-crystal X-ray diffraction analysis. Among all isolated compounds, artemilavanin F exhibited inhibitory activity on PANC-1 pancreatic cancer cells with IC50 of 9.69 ± 2.39 µM. Artemilavanin F inhibited PANC-1 cell proliferation by induction of G2/M cell cycle arrest and apoptosis mediated by downregulation of cyclin-dependent kinases and accumulation of reactive oxygen species. Moreover, artemilavanin F inhibited the colony formation, cell migration and sphere formation of PANC-1 cells, indicating the suppression of stem-cell-like phenotype of PANC-1 cells. Further results confirmed that the expression of cancer stem cell markers such as Bmi1, CD44, CD133 were inhibited by artemilavanin F. Downregulation of epithelial-mesenchymal transition (EMT) markers such as N-cadherin and Oct-4 indicated the potential of artemilavanin F in prevention of metastasis.
Subject(s)
Artemisia , Pancreatic Neoplasms , Sesquiterpenes, Eudesmane , Sesquiterpenes , Artemisia/chemistry , Pancreatic Neoplasms/drug therapy , Sesquiterpenes, Eudesmane/pharmacology , Sesquiterpenes, Eudesmane/analysis , Sesquiterpenes, Eudesmane/chemistry , Plant Components, Aerial/chemistry , Sesquiterpenes/chemistry , Molecular Structure , Pancreatic NeoplasmsABSTRACT
OBJECTIVE: Investigate the optimum time of acupuncture treatment in peripheral facial paralysis in order to provide evidence for clinical treatment. METHODS: CNKI, Wanfang, PubMed, Cochrane Library, and EMBASE databases were systematically searched from the inception dates to February 20, 2020. Studies limited to participants with acute peripheral facial paralysis treated with acupuncture and patients without information of the stage were excluded. The primary outcomes were effective rate and cure rate (based on facial nerve function scores). This meta-analysis is registered with PROSPERO, number CRD42020169870. RESULTS: 15 randomized controlled trials that enrolled 2847 participants met the selection criteria. There was no significant differences in the effective rate (RR, 1.22; 95% CI, 0.70-2.11) when comparing acupuncture to prednisone therapy in acute facial paralysis. Acupuncture treatment in the acute stage increased both the effective rate (RR, 1.03; 95% CI, 1.00-1.07) and the cure rate (RR, 1.34; 95% CI, 1.14-1.58) compared to that in the nonacute stage. CONCLUSIONS: In this meta-analysis, acupuncture showed a better effect in the acute stage than the nonacute stage for participants with peripheral facial paralysis. There was no statistical difference in the effective rate no matter the choice of acupuncture or prednisone therapies in the acute stage. These findings encourage early acupuncture treatment in peripheral facial paralysis.
Subject(s)
Acupuncture Therapy , Facial Paralysis/therapy , Acupuncture Therapy/statistics & numerical data , Acute Disease , China , Computational Biology , Facial Nerve/physiopathology , Facial Paralysis/physiopathology , Humans , Secondary Prevention/statistics & numerical data , Time Factors , Treatment OutcomeABSTRACT
Cellulose, as the most abundant natural polysaccharide, is an excellent material for developing green humidity sensors, especially due to its humidity responsiveness as a result of its rich hydrophilic groups. In combination with other components including carbon materials and polymers, cellulose and its derivatives can be used to design high-performance humidity sensors that meet various application requirements. This review summarizes the recent advances in the field of various cellulose-derived humidity sensors, with particular attention paid to different sensing mechanisms including resistance, capacitance, colorimetry and gravity, and so on. Furthermore, the roles of cellulose and its derivatives are highlighted. This work may promote the development of cellulose-derived humidity sensors, as well as other cellulose-based intelligent materials.
Subject(s)
Cellulose/chemistry , Equipment Design/methods , Humidity , Carbon/chemistry , Colorimetry/methods , Humans , Hydrophobic and Hydrophilic Interactions , Nanostructures/chemistry , Polymers/chemistry , Temperature , Water/chemistryABSTRACT
ABSTRACT: To investigate the correlation between the serum albumin level and the prognosis of patients with Bell's palsy.We retrospectively analyzed the clinical records of 311 inpatients with Bell's palsy (BP) in our hospital between September 2018 and October 2019. The patients were divided into 2 groups: the recovered group (with the House-Brackmann gradeâ≤â2) and the unrecovered group (with the House-Brackmann gradeâ>â2), according to the follow-up results within 3 months after discharge. Blood test indicators (white blood cell count, neutrophil-to-lymphocyte ratio, red cell distribution width, serum albumin level, globulin level) and basic clinical data (age, sex, course of the disease, inpatient days, comorbidity of hypertension, diabetes, and hepatitis B) of the 2 groups were compared to explore whether they were correlated with the prognosis of patients with Bell's palsy.The serum albumin level of patients with BP in the unrecovered group was significantly lower than that of the recovered group (medians [interquartile range], 40.75 [38.40, 43.85] vs 44 [42.10, 46.20], Pâ<â.001). Multivariate binary logistic regression revealed that serum albumin (odds ratio 0.772, 95% confidence interval 0.711-0.839, Pâ<â.001) was a protective factor for BP prognosis.Serum albumin is a protective factor for the prognosis of BP. Although more prospective clinical controlled trials are needed, our study provides valuable and crucial prognostic information for physicians.
Subject(s)
Bell Palsy/diagnosis , Serum Albumin/metabolism , Adolescent , Adult , Bell Palsy/blood , Bell Palsy/physiopathology , Biomarkers/blood , Female , Humans , Male , Medical Records , Middle Aged , Predictive Value of Tests , Prognosis , Retrospective Studies , Young AdultABSTRACT
Electrospun nanofiber membrane (ENM) shows great advantage and potential in wastewater treatment due to its unique properties. However, exploring a green and efficient ENM for remediation of complex wastewater, such as simultaneous containing oils, dyes and heavy metal ion, remains challenging. In this work, a cellulose-based photocatalytic ENM, is constructed for this purpose. The hybrid ENM is prepared via electrospinning deacetylated cellulose acetate/polyvinyl pyrrolidone (CeP) nanofibers as skeleton cores and in-situ synthesis of beta hydroxyl oxidize iron decorated iron-based MOF (ß-FeOOH@MIL-100(Fe)) heterojunctions as photocatalytic sheaths. The core-sheath structured ENM has ultrahigh MIL-100(Fe) loading (78 wt%), large surface areas (1105 m2/g) and well-dispersed ß-FeOOH nanorods. Thanks to these porous and hydrophilic MIL-100(Fe), along with a robust photocatalysis-Fenton synergy from ß-FeOOH@MIL-100(Fe), the as-prepared ENM shows outstanding performances with simultaneous high removal efficiency for oils (99.5 %), dyes (99.4 %) and chromium ion (Cr(VI)) (99.7 %). Additionally, the photocatalytic ENM can achieve a long-term reuse owing to its inherent self-cleaning function.
ABSTRACT
Cellulose nano-crystals (CNC) have attracted great interests as a novel nanostructured material in recent years, thanks to their excellent mechanical properties, high surface area and lightweight and biocompatibility etc. Due to its low charged group content, CNC prepared from the hydrochloric acid hydrolysis has poor dispersibility in water, which hinders its further applications. In this work, well-dispersed cellulose nano-crystals are successfully prepared using a two-step method, consisting of hydrochloric acid hydrolysis, followed by adsorption of hexadecyl trimethyl ammonium bromide (CTAB) onto CNC. Results show that CTAB at a low concentration (0.13-0.47 mM) provides effective steric barriers to minimize the CNC aggregation, which is supported by TEM images and particle size distribution of CNC. At high CTAB concentrations (>0.5 mM), CNC aggregation occurs, which is due to the "bridging" effect of CTAB.
ABSTRACT
The frequent oil spillages and the industrial discharge of organic contaminants have not only created severe environmental and ecological crises, but also cause a risk of fire and explosion. These environmental and safety issues emphasize the urgent need for materials that possess superior sorption capability and less flammability and thus can effectively and safely clean up the floating oils and water-insoluble organic compounds. Here we present the successful hydrophobic modification of the flame retardant melamine sponge with a commercial fluorosilicone, by using a facile one-step solvent-free approach and demonstrate that the resultant superhydrophobic sponge not only exhibits extraordinary absorption efficiency (including high capacity, superior selectivity, good recyclability, and simple recycling routes), but also retains excellent flame retardancy and robust stability. In comparison to conventional methods, which usually utilize massive organic solvents, the present approach does not involve any complicated process or sophisticated equipment nor generates any waste liquids, and thus is a more labor-saving, environment-friendly, energy-efficient and cost-effective strategy for the hydrophobic modification. Taking into account the critical role of hydrophobic porous materials, especially in the field of environmental remediation, the approach presented herein would be highly valuable for environmental remediation and industrial applications.
ABSTRACT
To alleviate the kinetic barriers associated with ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) in electrochemical systems, efficient nonprecious electrocatalysts are urgently required. Here we report a facile soft-template mediated approach for fabrication of nanostructured cobalt-iron double sulfides that are covalently entrapped in nitrogen-doped mesoporous graphitic carbon (Co0.5Fe0.5S@N-MC). Notably, with a positive half-wave potential (0.808 V) and a high diffusion-limiting current density, the composite material delivers unprecedentedly striking ORR electrocatalytic activity among recently reported nonprecious late transition metal chalcogenide materials in alkaline medium. Various characterization techniques, including X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, are conducted to elucidate the correlation between structural features and catalytic activities of the composite. Moderate substitution and well-dispersion of iron in bimetallic sulfide composites are believed to have positive effect on the adsorption and activation of oxygen-containing species, thus leading to conspicuous ORR and OER catalytic enhancement compared to their monometallic counterparts. Besides, the covalent bridge between active sulfide particles and mesoporous carbon shells provides facile pathways for electron and mass transport. Beneficially, the intimate coupling interaction renders prolonged electrocatalytic performances to the composite. Our results may possibly lend a new impetus to the rational design of bi- or multimetallic sulfides encapsulated in porous carbon with improved performance for electrocatalysis and energy storage applications.