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1.
Adv Sci (Weinh) ; : e2309559, 2024 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-38639394

RESUMO

Idiopathic short stature (ISS) is a common childhood condition with largely unknown underlying causes. Recent research highlights the role of circulating exosomes in the pathogenesis of various disorders, but their connection to ISS remains unexplored. In the experiments, human chondrocytes are cocultured with plasma exosomes from ISS patients, leading to impaired chondrocyte growth and bone formation. Elevated levels of a specific long non-coding RNA (lncRNA), ISSRL, are identified as a distinguishing factor in ISS, boasting high specificity and sensitivity. Silencing ISSRL in ISS plasma exosomes reverses the inhibition of chondrocyte proliferation and bone formation. Conversely, overexpression of ISSRL in chondrocytes impedes their growth and bone formation, revealing its mechanism of action through the miR-877-3p/GZMB axis. Subsequently, exosomes (CT-Exo-siISSRL-oeGH) with precise cartilage-targeting abilities are engineered, loaded with customized siRNA for ISSRL and growth hormone. This innovative approach offers a therapeutic strategy to address ISS by rectifying abnormal non-coding RNA expression in growth plate cartilage and delivering growth hormone with precision to promote bone growth. This research provides valuable insights into ISS diagnosis and treatment, highlighting the potential of engineered exosomes.

2.
Plant Physiol Biochem ; 208: 108468, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38507840

RESUMO

Cadmium (Cd) is a toxic heavy metal, increasingly accumulating in the environment and its presence in various environmental compartments represents a significant risk to human health via the food chain. Epigallocatechin-3-Gallate (EGCG) is a prominent secondary metabolite, which can safeguard plants from biotic and abiotic stress. However, the role of EGCG in flavonoid synthesis, nutrient acquisition and reactive oxygen species (ROS) metabolism under Cd stress remains unclear. Here, we examined the effects of EGCG and Cd treatment on leaf photochemical efficiency, cell ultrastructure, essential element acquisition, antioxidant system, and secondary metabolism in tomato (Solanum lycopersicum L.). The results showed that O2•-, H2O2, and malondialdehyde levels increased after Cd treatment, but Fv/Fm decreased significantly, suggesting that Cd induced oxidative stress and photoinhibition. However, EGCG mitigated the adverse effects of Cd-induced phytotoxicity in both the roots and leaves. A decrease in ROS accumulation under EGCG + Cd treatment was mainly attributed to the significant enhancement in antioxidant enzyme activity, flavonoid content, and PHENYLALANINE AMMONIA-LYASE expression in roots. Moreover, EGCG reduced Cd content but increased some essential nutrient contents in tomato plants. Transmission electron microscopy-based observations revealed that EGCG treatment safeguards leaf and root cell ultrastructure under Cd stress. This implies that tomato plants subjected to Cd stress experienced advantageous effects upon receiving EGCG treatment. The present work elucidated critical mechanisms by which EGCG induces tolerance to Cd, thereby providing a basis for future investigations into environmentally sustainable agricultural practices in areas contaminated with heavy metals, for utilizing naturally occurring substances found in plants.


Assuntos
Catequina , Catequina/análogos & derivados , Solanum lycopersicum , Humanos , Antioxidantes/metabolismo , Cádmio/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Peróxido de Hidrogênio/metabolismo , Estresse Oxidativo , Homeostase , Catequina/farmacologia , Catequina/metabolismo , Plantas/metabolismo , Raízes de Plantas/metabolismo
3.
Emotion ; 2024 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-38512195

RESUMO

Previous research has shown mixed results regarding the relationship between social class and children's prosocial behavior. The current study aims to further our understanding of these findings by exploring the relationship between social class and children's prosocial behavior in a moral context. Study 1 (N = 833) found that when a target child pursued a morally negative goal and subsequently experienced misfortune, children from higher social class, compared to those from lower social class, experienced greater schadenfreude and exhibited less prosocial behavior. The relation between social class and prosocial behavior was mediated by schadenfreude. Study 2 (N = 389) investigated whether the greater schadenfreude experienced by children from higher social class was due to a weaker empathic response to misfortune or a stronger sense of deservingness. The results revealed a sequential mediation effect of social class on prosocial behavior through deservingness and schadenfreude. These findings provide insight into the impact of social class on the development of children's moral judgment, emotions, and behavior. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

4.
Plants (Basel) ; 13(2)2024 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-38256755

RESUMO

Shading is an effective agronomic technique to protect tea plants from intense sunlight. However, there are currently very few studies on more effective shading methods to improve the quality of summer tea. In this study, 'Longjing43' plants were grown under four different shading treatments for 14 days, with no shading as the control. Among the four shading treatments, double-layer-net shadings had the most positive impact on the tea quality, resulting in higher levels of amino acids but lower levels of tea polyphenols. Additionally, double-layer-net shadings provided more suitable microenvironments for tea plants. The tea leaves in T4 (double nets 50 cm above the plant canopy) contained 16.13 mg∙g-1 of umami and sweet amino acids, which was significantly higher than in other treatments. T4 had the lowest air temperature and the most suitable and stable soil water content. Interestingly, the ratio of red light to far-red light in T4 was only 1.65, much lower than other treatments, which warrants further study. In conclusion, the microenvironment induced by shading can greatly affect the tea quality, and double-layer-net shading is better for improving the quality of summer tea.

5.
J Hazard Mater ; 466: 133544, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38244455

RESUMO

The Yangtze River is an important global channel for plastics and microplastics (MPs) to enter the sea. However, the existing research on MPs in the Yangtze River has primarily focused on the mainstream region, without regarding the occurrence, spatial distribution, and ecological risks associated with tributaries, as well as their relationship with the mainstream. To address this knowledge gap, we conducted a large-scale catchment-wide investigation of the surface water in the Yangtze River, encompassing MPs (48 µm-5 mm) of the mainstream and 15 important tributaries. Tributaries and upstream regions exhibited relatively higher levels of MPs compared with the mainstream and different sections of the river. The distribution of MPs is primarily influenced by the emission of arable land and the pH of water. Notably, the upstream tributary areas demonstrated the highest ecological risks associated with MPs. Further analysis highlighted that the tributaries accounted for a contribution ranging from 16% to 67% in quantity and from 14% to 90% in mass of the microplastics observed in the mainstream. Our results suggest that the pollution of tributaries and their associated ecological risk migration must be effectively regulated.

6.
J Colloid Interface Sci ; 658: 772-782, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38154240

RESUMO

Aerogels with 3D porous structures have been attracting increasing attention among functional materials due to their advantages of being lightweight and high specific surface area. Precise control of the porous structure of aerogel is essential to improve its performance. In this work, polylactic acid (PLA) aerogels with distinctly different microstructures were fabricated by precisely controlling the phase separation behavior of the ternary solution system. Rheological and theoretical analyses have revealed that the interactions between polymer molecules, solvents and non-solvents play a crucial role in determining the nucleation and growth of poor olymer and rich polymer phases. By adjusting the non-solvent type and the solution composition, aerogels with spider network structure, bead-like connected microsphere structure, and cluster petal structure were obtained. Ideal spinodal phase separation conditions were obtained to produce aerogels with a homogeneous fiber network structure. The optimum PLA aerogel achieved an extremely porosity of 96 % and a high specific surface area of 114 m2/g, which rendered it with excellent triboelectric generation performance. Thus, this work provides fundamental insights into the precise regulation of the phase separation behavior and the structure of the aerogel, which can help boost the performance and expand the applications of PLA aerogels.

7.
Neural Regen Res ; 19(8): 1789-1801, 2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-38103246

RESUMO

JOURNAL/nrgr/04.03/01300535-202408000-00033/figure1/v/2023-12-16T180322Z/r/image-tiff Social dysfunction is a risk factor for several neuropsychiatric illnesses. Previous studies have shown that the lateral septum (LS)-related pathway plays a critical role in mediating social behaviors. However, the role of the connections between the LS and its downstream brain regions in social behaviors remains unclear. In this study, we conducted a three-chamber test using electrophysiological and chemogenetic approaches in mice to determine how LS projections to ventral CA1 (vCA1) influence sociability. Our results showed that gamma-aminobutyric acid (GABA)-ergic neurons were activated following social experience, and that social behaviors were enhanced by chemogenetic modulation of these neurons. Moreover, LS GABAergic neurons extended their functional neural connections via vCA1 glutamatergic pyramidal neurons, and regulating LSGABA→vCA1Glu neural projections affected social behaviors, which were impeded by suppressing LS-projecting vCA1 neuronal activity or inhibiting GABAA receptors in vCA1. These findings support the hypothesis that LS inputs to the vCA1 can control social preferences and social novelty behaviors. These findings provide new insights regarding the neural circuits that regulate sociability.

8.
Cell Biochem Funct ; 41(8): 1106-1114, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38041420

RESUMO

The N-methyladenosine (m6A) modification of ribosomal RNA (rRNA) plays critical roles in regulating the function of ribosomes, the essential molecular machines that translate genetic information from mRNA into proteins. Specifically, m6A modification affects ribosome biogenesis, stability, and function by regulating the processing and maturation of rRNA, the assembly and composition of ribosomes, and the accuracy and efficiency of translation. Furthermore, m6A modification allows for dynamic regulation of translation in response to environmental and cellular signals. Therefore, a deeper understanding of the mechanisms and functions of m6A modification in rRNA will advance our knowledge of ribosome-mediated gene expression and facilitate the development of new therapeutic strategies for ribosome-related diseases.


Assuntos
RNA Ribossômico , Ribossomos , RNA Ribossômico/genética , RNA Ribossômico/metabolismo , Ribossomos/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Metilação
9.
BMC Psychiatry ; 23(1): 887, 2023 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-38017507

RESUMO

BACKGROUND: There is a complex relationship between social anxiety and sleep quality. However, network analysis studies of associations between social anxiety and sleep quality are lacking, particularly among patients with breast cancer. The current study aimed to extend this research to a sample of patients with breast cancer and to examine symptom-level associations between social anxiety and sleep quality using network analysis. METHODS: Network analysis was conducted to explore their associations and identify bridge items of social anxiety and sleep quality. RESULTS: The network structure revealed 9 important edges between social anxiety and sleep quality. "Subjective sleep quality" had the highest EI value in the network. "Working difficulty under watching" and "Sleep disorders" had the highest BEI values in their own communities. CONCLUSION: There are complex pathological correlation pathways between social anxiety and sleep quality in breast cancer patients. "Subjective sleep quality", "Working difficulty under watching" and "Sleep disorders" have the potential to be intervention targets for sleep disorder-social anxiety comorbidity. Medical staff can take corresponding interventions according to the the centrality indices and bridge centrality indicators identified in this study, which is likely to effectively reduce the comorbidity of sleep disorders and social anxiety.


Assuntos
Neoplasias da Mama , Transtornos do Sono-Vigília , Humanos , Feminino , Qualidade do Sono , Neoplasias da Mama/complicações , Medo , Comorbidade , Transtornos do Sono-Vigília/complicações , Transtornos do Sono-Vigília/epidemiologia , Ansiedade/complicações , Depressão
10.
Heliyon ; 9(7): e18369, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37539192

RESUMO

Depression and anxiety are the most common mental health disorders. Though they affect people at any age and occur more often in females, the pathophysiological changes under these conditions are less investigated. In the present study, we examined the effects of age and stress on depression- and anxiety-related behaviors in female mice. Saccharin preference and the open field test were carried out before and after chronic unpredictable stress in 4-, 14- and 25-month-old female mice. After behavioral tests, mRNA levels of monoamine receptors in the hippocampus were measured by real-time RT-PCR. Chronic unpredictable stress decreased saccharin preference in 4-, 14- and 25-month-old mice and the time spent in the center in the open field test in 25-month-old mice. For monoamine receptors, analysis of variance revealed significant effects of age on mRNA levels of Htr1a, Htr2a, Htr6, Adra1a, Adrb2, and Adrb3, significant effects of stress on mRNA levels of Htr4, Adra2c, Adrb1, and Adrb2, and interactions of age × stress on mRNA levels of Htr1a, Htr5b, Adra1d, Adra2a, Adra2c, and Adrb1. Chronic unpredictable stress decreased mRNA levels of Htr4, Htr5b, Adra2c, and Adrb1 in 4-month-old female mice. Correlations were observed between saccharin preference and mRNA levels of Htr4, Htr5b, Htr6, Adra1d, Adra2a, and Adra2c in 4-month-old mice and between the time spent in the center in the open field test and mRNA levels of Htr1b in 4-month-old mice, Htr3a, Htr7, and Adrb2 in 14-month-old mice, and Drd2 in 4- and 14-month-old mice. Our findings support that stress induces depression- and anxiety-related behaviors and the expression of hippocampal monoamine receptors in an age-dependent manner in female mice.

11.
Chemosphere ; 337: 139415, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37414301

RESUMO

The present study investigates the extracellular electron transfer (EET)-dependent anammox process as a promising approach for sustainable wastewater treatment. The study examines the performance and metabolic pathway of the EET-dependent anammox process in comparison to the nitrite-dependent anammox process. The EET-dependent reactor successfully achieved nitrogen removal with a maximum removal efficiency of 93.2%, although it exhibited a lower ability to sustain high nitrogen removal load when compared to the nitrite-dependent anammox process, which poses opportunity and challenge for ammonia-wastewater treatment under applied voltage conditions. Nitrite was identified as a critical factor responsible for the changes in microbial community structure, resulting in a significant reduction in nitrogen removal load in the absence of nitrite. The study further suggests that the Candidatus Kuenenia species could dominate the EET-dependent anammox process, while nitrifying and denitrifying bacteria also contribute to the nitrogen removal in this system.


Assuntos
Desnitrificação , Águas Residuárias , Oxirredução , Nitrogênio/metabolismo , Nitritos/metabolismo , Oxidação Anaeróbia da Amônia , Elétrons , Reatores Biológicos/microbiologia , Bactérias/metabolismo , Esgotos/microbiologia
12.
Zootaxa ; 5318(4): 543-554, 2023 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-37518260

RESUMO

Keys of the genera Hebecnema Schnabl, 1887 and Mydaea Robineau-Desvoidy, 1830 from China based on males are provided, including two new species Hebecnema kongi Wang, Li & Yang, sp. nov. and Mydaea apicinigra Wang, Li & Yang, sp. nov., respectively. Photographs of habitus and male genitalia as well as illustrations of the male genitalia of the new species are given.


Assuntos
Dípteros , Muscidae , Masculino , Animais , China , Distribuição Animal
13.
CNS Neurosci Ther ; 29(11): 3624-3643, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37309288

RESUMO

AIMS: Protein phosphatase Mg2+/Mn2+-dependent 1F (PPM1F) is a serine/threonine phosphatase, and its dysfunction in depression in the hippocampal dentate gyrus has been previously identified. Nevertheless, its role in depression of another critical emotion-controlling brain region, the medial prefrontal cortex (mPFC), remains unclear. We explored the functional relevance of PPM1F in the pathogenesis of depression. METHODS: The gene expression levels and colocalization of PPM1F in the mPFC of depressed mice were measured by real-time PCR, western blot and immunohistochemistry. An adeno-associated virus strategy was applied to determine the impact of knockdown or overexpression of PPM1F in the excitatory neurons on depression-related behaviors under basal and stress conditions in both male and female mice. The neuronal excitability, expression of p300 and AMPK phosphorylation levels in the mPFC after knockdown of PPM1F were measured by electrophysiological recordings, real-time PCR and western blot. The depression-related behavior induced by PPM1F knockdown after AMPKα2 knockout or the antidepressant activity of PPM1F overexpression after inhibiting acetylation activity of p300 was evaluated. RESULTS: Our results indicate that the expression levels of PPM1F were largely decreased in the mPFC of mice exposed to chronic unpredictable stress (CUS). Behavioral alterations relevant to depression emerged with short hairpin RNA (shRNA)-mediated genetic knockdown of PPM1F in the mPFC, while overexpression of PPM1F produced antidepressant activity and ameliorated behavioral responses to stress in CUS-exposed mice. Molecularly, PPM1F knockdown decreased the excitability of pyramidal neurons in the mPFC, and restoring this low excitability decreased the depression-related behaviors induced by PPM1F knockdown. PPM1F knockdown reduced the expression of CREB-binding protein (CBP)/E1A-associated protein (p300), a histone acetyltransferase (HAT), and induced hyperphosphorylation of AMPK, resulting in microglial activation and upregulation of proinflammatory cytokines. Conditional knockout of AMPK revealed an antidepressant phenotype, which can also block depression-related behaviors induced by PPM1F knockdown. Furthermore, inhibiting the acetylase activity of p300 abolished the beneficial effects of PPM1F elevation on CUS-induced depressive behaviors. CONCLUSION: Our findings demonstrate that PPM1F in the mPFC modulates depression-related behavioral responses by regulating the function of p300 via the AMPK signaling pathway.


Assuntos
Proteínas Quinases Ativadas por AMP , Córtex Pré-Frontal , Animais , Feminino , Masculino , Camundongos , Proteínas Quinases Ativadas por AMP/metabolismo , Antidepressivos/farmacologia , Modelos Animais de Doenças , Fosfoproteínas Fosfatases/genética , Fosfoproteínas Fosfatases/metabolismo , Fosfoproteínas Fosfatases/farmacologia , Córtex Pré-Frontal/metabolismo , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Estresse Psicológico/metabolismo
14.
Environ Res ; 231(Pt 2): 116192, 2023 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-37201701

RESUMO

The response characteristic and performance stabilization of anammox process under the stress of the potential organic pollutants support the application of ammonia-nitrogen wastewater treatment. In the present study, nitrogen removal performance was significantly suppressed with the addition of 4-chlorophenol. The activity of anammox process was inhibited by 14.23% (0.1 mg/L), 20.54% (1 mg/L) and 78.15% (10 mg/L), respectively. Metagenomic analysis revealed a significant decrease in the abundance of KEGG pathways associated with carbohydrate and amino acid metabolism with increasing 4-chlorophenol concentration. Metabolic pathway profiles suggest that putrescine is down-regulated at high 4-chlorophenol stress due to inhibition of nitrogen metabolism processes, while it is up-regulated to reduce oxidative damage. In addition, the presence of 4-chlorophenol induced an enhancement of EPS and bacterial debris decomposition, and a partial conversion of 4-chlorophenol to p-nitrophenol. This study unravels the mechanism of effect on anammox consortia in response to 4-CP, which could provide supplementary to facilitate its full-scale application.


Assuntos
Desnitrificação , Águas Residuárias , Oxidação Anaeróbia da Amônia , Nitrogênio/metabolismo , Oxirredução , Reatores Biológicos/microbiologia , Esgotos
15.
Small ; 19(38): e2301261, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37222124

RESUMO

Perovskite oxides stand out as emerging oxygen evolution reaction (OER) catalysts on account of their effective electrocatalytic performance and low costs. Nevertheless, perovskite oxides suffer from severe bubble overpotential and inhibited electrochemical performance in large current densities due to their small specific surface areas and structural compactness. Herein, the study highlights the electrospun nickel-substituted La0.5 Sr0.5 FeO3-δ (LSF) porous perovskite nanofibers, that is, La0.5 Sr0.5 Fe1-x Nix O3-δ (denoted as ES-LSFN-x, x = 0, 0.1, 0.3, and 0.5), as high-performance OER electrocatalysts. The most effective La0.5 Sr0.5 Fe0.5 Ni0.5 O3-δ (ES-LSFN-0.5) nanofibers suggest a larger specific surface area, higher porosity, and faster mass transfer than the counterpart sample prepared by conventional sol-gel method (SG-LSFN-0.5), showing notably increased geometric and intrinsic activities. The bubble visualization results demonstrate that the enriched and nano-sized porosity of ES-LSFN-0.5 enables reinforced aerophobicity and rapid detachment of oxygen bubbles, thereby reducing the bubble overpotential and enhancing the electrochemical performance. As a result, the ES-LSFN-0.5-based anion exchange membrane water electrolysis delivers a superior stability of 100 h while the SG-LSFN-0.5 counterpart degrades rapidly within 20 h under a current density of 100 mA cm-2 . The results highlight the advantage of porous electrocatalysts in optimizing the performance of large current density water electrolysis devices by reducing the bubble overpotential.

17.
ACS Appl Mater Interfaces ; 15(3): 4092-4100, 2023 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-36625719

RESUMO

Voltage reversal is a severe issue in proton exchange membrane fuel cells (PEMFCs), which can be overcome by adding oxygen evolution electrocatalysts (OER) based on iridium oxide (IrOX) to the anode catalyst layer. However, the crystal structure and antireversal properties of such anode materials have been rarely investigated. Herein, we report amorphous IrOX and explore the transformation of crystal structure under heat treatment to examine their antireversal performance in PEMFCs. It is found that heat treatment results in larger catalyst particles which consequences lower OER activity; however, it shows better voltage reverse tolerance (132.2 min). These investigations demonstrate that a balance is crucial between activity and durability in antireversal properties for PEMFCs. Physical characterizations reveal that improved stability and reversal tolerance is attributed to crystallinity and preferred orientation of IrOX crystals as well as existence of amorphous and crystalline IrOX. This work proposes a attempt to use the mixed phase IrOX in the antireversal anode catalyst and highlights the role of corresponding particle size and durability characteristics for the long-term durability of PEMFCs.

18.
Materials (Basel) ; 16(2)2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36676439

RESUMO

Steel-concrete composite girder bridges are subjected to reciprocal cyclic loading from vehicles, and the stud shear connectors are the key components for transmitting shear forces. Thus, it is necessary to study the fatigue performance of the stud shear connectors. At present, there are few studies on the fatigue crack propagation process of studs, and the variation curve of the crack depth of studs with the number of fatigue loading cycles is not clear. In this study, the degradation law of fatigue properties and the fatigue crack propagation law of stud shear connectors in steel-concrete composite structures are examined under fatigue loading. The fatigue properties, i.e., failure mode, the dynamic slip-fatigue number curve, cross-sectional characteristics, and the residual bearing capacity of the stud specimens, are first systematically studied through ten standard push-out specimen tests. The test results show that the relative value of the fatigue crack extension area increases, while the relative value of the residual bearing capacity of the studs decreases approximately linearly. Then, the expression of the relationship between the fatigue crack depth and the residual load-bearing capacity of the stud is proposed, based on the fatigue crack theory of fracture mechanics. Finally, combined with the ABAQUS and FRANC3D software, a fatigue crack propagation finite element analysis (FEA) model of the stud is established. The FEA results showed that the trends in the number of cyclic loads and the fatigue crack depth of studs are basically the same for the simulation curve, test curve and theoretical calculation curve.

19.
J Colloid Interface Sci ; 630(Pt A): 257-265, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36242885

RESUMO

Enriching the active sites and enhancing the intrinsic activity of a single site are two basic strategies for improving the activity toward the electrocatalytic oxygen evolution reaction (OER), and designing an advanced microstructure with a boosted pre-oxidation process can further guarantee durability toward long-term catalysis. Herein, we propose a dual oxidation strategy of a Co Prussian blue analog (Co PBA), which simultaneously achieves Co3+ active site enrichment, in situ CeO2 decoration and lattice disordering with abundant undercoordinated sites, realizing highly efficient and ultrastable OER performance. The dual oxidation process can induce the enrichment of high-valence Co ions by combined chemical oxidation and d-f electron coupling compared to the singly oxidized catalysts, thereby providing more active sites with enhanced intrinsic activity for the early triggered OER process. In addition, the disordered lattice can provide abundant reactive Co sites for the pre-oxidation process, thereby leading to obvious activation of the catalysts and remarkable operational stability due to the substantially accumulated Co3+ sites. Benefitting from the structural advantages of lattice-disordered dual-oxidized Co PBA nanocages, a low overpotential of 240 mV can be achieved for a 10 mA cm-2 current density, and the large catalytic current density and intrinsic activity are among the best compared to those of previously reported PBA-based and PBA-derived catalysts and even RuO2 and IrO2. In addition, ultrastable OER behavior with a 263 % activity enhancement in 150 h can result, making the dual-oxidized catalyst a promising candidate for water electrolysis.

20.
Small ; 19(1): e2205743, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36372523

RESUMO

Single-atom catalysts (SACs) are of tremendous current research due to maximized use of metal atoms and enhanced activity and selectivity for a great variety of chemical reactions. Hierarchically structured SACs have been explored to further increase the number and accessibility of active sites to realize the full potentials of SACs. However, though plausible-sounding, these supposed advantages of hierarchically structured SACs are largely untested. The assumed enhancing effects on the formation of intermediates on and the overall reaction kinetics remain largely unknown. Herein is reported a Fe-SAC with a hierarchical hollow structure (Fe/HH) that showed excellent activity in oxygen reduction reaction and proton exchange membrane fuel cell. Comparative experimental and computational studies with respect to Fe/SS-the counterpart of Fe/HH with a compact primary structure-reveal a significantly increased number of active sites and their utilization in Fe/HH as reflected by the facilitated formation of the rate-determining-step intermediate Fe-OOH*. This work thus establishes unambiguously the connection between the increased utilization of active sites and the enhanced kinetics of the electrocatalytic reduction of oxygen.


Assuntos
Hipóxia , Oxigênio , Humanos , Domínio Catalítico , Cinética , Membrana Celular
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