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1.
Sensors (Basel) ; 24(17)2024 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-39275372

RESUMO

Oil spill SAR images are characterized by high noise, low contrast, and irregular boundaries, which lead to the problems of overfitting and insufficient capturing of detailed features of the oil spill region in the current method when processing oil spill SAR images. An improved DeepLabV3+ model is proposed to address the above problems. First, the original backbone network Xception is replaced by the lightweight MobileNetV2, which significantly improves the generalization ability of the model while drastically reducing the number of model parameters and effectively addresses the overfitting problem. Further, the spatial and channel Squeeze and Excitation module (scSE) is introduced and the joint loss function of Bce + Dice is adopted to enhance the sensitivity of the model to the detailed parts of the oil spill area, which effectively solves the problem of insufficient capture of the detailed features of the oil spill area. The experimental results show that the mIOU and F1-score of the improved model in an oil spill region in the Gulf of Mexico reach 80.26% and 88.66%, respectively. In an oil spill region in the Persian Gulf, the mIOU and F1-score reach 81.34% and 89.62%, respectively, which are better than the metrics of the control model.

2.
Mol Carcinog ; 62(5): 613-627, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36727626

RESUMO

Cutaneous squamous cell carcinoma (cSCC) is one of the most common skin malignancies, and its incidence rate is increasing worldwide. Proline-rich 11 (PRR11) has been reported to be involved in the occurrence and development of various tumors. However, the role of PRR11 in cSCC remains unknown. In the present study, we observed upregulated expression of PRR11 in cSCC tissues and cell lines. Knockdown of PRR11 in the cSCC cell lines A431 and SCL-1 inhibited cell proliferation by inducing cell cycle arrest during the G1/S phase transition, promoted cell apoptosis, and reduced cell migration and invasion in vitro. Conversely, overexpression of PRR11 promoted cell proliferation, decreased cell apoptosis, and enhanced cell migration and invasion. PRR11 knockdown also inhibited cSCC tumor growth in a mouse xenograft model. Mechanistic investigations by RNA sequencing revealed that 891 genes were differentially expressed genes between cells with PRR11 knockdown and control cells. Enrichment analysis of different genes showed that the epidermal growth factor receptor (EGFR) signaling pathway was the top enriched pathway. We further validated that PRR11 induced EGFR pathway activity, which contributed to cSCC progression. These data suggest that PRR11 may serve as a novel therapeutic target in cSCC.


Assuntos
Carcinoma de Células Escamosas , Proteínas , Neoplasias Cutâneas , Animais , Humanos , Camundongos , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Linhagem Celular Tumoral , Proliferação de Células/genética , Receptores ErbB/genética , Transdução de Sinais , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/patologia , Proteínas/metabolismo
3.
BMC Microbiol ; 23(1): 265, 2023 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-37737154

RESUMO

BACKGROUND: Vitiligo has been correlated with an abnormal gut microbiota. We aimed to systematically identify characteristics of the gut microbial compositions, genetic functions, and potential metabolic features in patients with non-segmental vitiligo. METHODS: Twenty-five patients with non-segmental vitiligo and 25 matched healthy controls (HCs) were enrolled. Metagenomic sequencing and bioinformatic analysis were performed to determine the gut microbiota profiles. Differences in gut microbiota diversity and composition between patients with vitiligo and HCs were analyzed. Gene functions and gut metabolic modules were predicted with the Kyoto Encyclopedia of Gene and Genomes (KEGG) and MetaCyc databases. RESULTS: Compared with HCs, alpha diversity of intestinal microbiome in vitiligo patients was significantly reduced. At the species level, the relative abundance of Staphylococcus thermophiles was decreased, and that of Bacteroides fragilis was increased in patients with vitiligo compared with those of the HCs. Linear discriminant analysis (LDA) effect size (LEfSe) analysis revealed representative microbial markers of Lachnospiraceae_bacterium_BX3, Massilioclostridium_coli, TM7_phylum_sp_oral_taxon_348 and Bacteroides_fragilis for patients with vitiligo. KEGG gene function analysis showed that the NOD-like receptor signaling pathway was significantly enriched in patients with vitiligo. Gut metabolic modules (GMMs) analysis showed that cysteine degradation was significantly down-regulated, and galactose degradation was up-regulated in patients with vitiligo. A panel of 28 microbial features was constructed to distinguish patients with vitiligo from HCs. CONCLUSIONS: The gut microbial profiles and genetic functions of patients with vitiligo were distinct from those of the HCs. The identified gut microbial markers may potentially be used for earlier diagnosis and treatment targets.


Assuntos
Microbioma Gastrointestinal , Vitiligo , Humanos , Vitiligo/genética , Microbioma Gastrointestinal/genética , Metagenoma , Bacteroides fragilis , Clostridiales
4.
Nanotechnology ; 33(26)2022 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-35313291

RESUMO

Highly efficient and inexpensive electrocatalysts for oxygen evolution reaction (OER) are extensively studied for water splitting. Herein, a unique bimetallic nanocomposite CoNi(OH)2@NiCo2S4nanosheet arrays derived from metal-organic-frameworks (MOFs, CoNi-ZIF) is simply fabricated on Ni foam, endowing large specific surface area and outstanding electrical conductivity. Compared with their single-metallic counterparts, the bimetallic composite displays dramatically low overpotential and small Tafel slope as well as outstanding catalytic stability. The overpoptential at 20 mA cm-2for CoNi(OH)2@NiCo2S4is only 230 mV in comparison with Ni(OH)2@Ni3S2(266 mV), Co(OH)2@Co3S4(294 mV) and RuO2(η = 302 mV). First-principle calculations based on density functional theory (DFT) are carried out and reveal that the introduction of Ni in Co(OH)2helps lowered the energy difference of ΔGOOH*-ΔGO*, and thereby boosting the OER reactivity. This study provides an effective approach for the rational construction of low-cost metal hybrids.

5.
BMC Infect Dis ; 22(1): 299, 2022 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-35346084

RESUMO

BACKGROUND: This study explored disparities in characteristics and mortalities among four major transmission groups on antiretroviral therapy in northwest China as well as the survival impact of each transmission route. METHODS: We first examined disparities in demographics and clinical characteristics of the four transmission populations. Kaplan Meier analysis was subsequently conducted to compare survival rates among all groups. At last, Cox proportional hazards regression model was employed to analyze the survival impact of a transmission route among seven main categories of survival factors associated with all-cause mortalities. RESULTS: Survival analysis showed significant differences in all-cause, AIDS- and non-AIDS-related deaths among four HIV populations (all P < 0.05). Using homosexuals as the reference, Cox proportional hazards model further revealed that the risk of all-cause death for blood and plasma donors was significantly higher than that of the reference (aHR: 5.21, 95%CI: 1.54-17.67); the risk of non-AIDS-related death for heterosexuals (aHR: 2.07, 95%CI: 1.01-4.20) and that for blood and plasma donors (aHR: 19.81, 95%CI: 5.62-69.89) were both significantly higher than that of the reference. CONCLUSIONS: Significant disparities were found in characteristics and mortalities among the four transmission groups where mortality disparities were mainly due to non-AIDS-related death. Suggestions are provided for each group to improve their survivorship.


Assuntos
Síndrome da Imunodeficiência Adquirida , Infecções por HIV , Síndrome da Imunodeficiência Adquirida/tratamento farmacológico , Infecções por HIV/tratamento farmacológico , Humanos , Masculino , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Análise de Sobrevida
6.
Mediators Inflamm ; 2022: 5978271, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36110097

RESUMO

Psoriasis is a chronic inflammatory skin disease, and elevation of proinflammatory cytokine levels is a critical driver of the pathogenesis of psoriasis. Extracellular cold-inducible RNA-binding protein (eCIRP) has been shown to play a role in various acute and chronic inflammatory diseases. C23, a short peptide derived from CIRP, competitively binds CIRP receptors and reduces damage in inflammatory diseases. However, the effect of eCIRP in psoriasis has not been studied. In the present study, we investigated the role of eCIRP in the expression of proinflammatory cytokines in keratinocytes. Our data show that eCIRP expression was increased in the sera of psoriasis patients and imiquimod- (IMQ-) induced psoriatic mice and cells stimulated with proinflammatory cytokines (IL-1α, IL-17A, IL-22, oncostatin M, and TNF-α; mix M5). Recombinant human CIRP (rhCIRP) promoted the expression of the proinflammatory cytokines TNF-α, IL-6, and IL-8 and the activation of NF-kappaB (NF-κB) and ERK1/2 in cultured keratinocytes. We then found that the above effects of eCIRP could be blocked by C23 in both normal keratinocytes and M5-stimulated psoriatic keratinocytes. In addition, in vivo experiments revealed that C23 could effectively ameliorate IMQ-induced psoriatic dermatitis. TNF-α and IL-6 mRNA expressions were reduced in the skin lesions of mice with C23-treated IMQ-induced psoriasis, and this effect was accompanied by inhibition of the NF-κB and ERK1/2 signaling pathways. In summary, eCIRP plays an important role in the pathogenesis of psoriasis and may become a new target for psoriasis treatment.


Assuntos
NF-kappa B , Psoríase , Animais , Humanos , Imiquimode , Interleucina-17/metabolismo , Interleucina-6/metabolismo , Interleucina-8/metabolismo , Queratinócitos/metabolismo , Sistema de Sinalização das MAP Quinases , Camundongos , NF-kappa B/metabolismo , Oncostatina M/metabolismo , Psoríase/metabolismo , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/metabolismo , Transdução de Sinais , Fator de Necrose Tumoral alfa/metabolismo
7.
Chemistry ; 25(24): 6102-6107, 2019 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-30834604

RESUMO

Polymeric carbon nitride (CN) is a promising material for photocatalytic water splitting. However, CN in its pristine form tends to show moderate activity due to fast recombination of the charge carriers. The design of efficient photocatalytic system is therefore highly desired, but it still remains a great challenge in chemistry. In this work, a pyrene-based polymer able to serve as an electron donor to accelerate the interface charge carrier transfer of CN is presented. The construction of donor-acceptor (D-A) heterojunction was confirmed to significantly restrain the charge recombination and, thus, improve the proton reduction process. This study provides a promising strategy to achieve solar H2 production in an efficient and low-cost manner.

8.
Angew Chem Int Ed Engl ; 58(4): 1134-1137, 2019 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-30488529

RESUMO

Photosynthetic conversion of CO2 into fuel and chemicals is a promising but challenging technology. The bottleneck of this reaction lies in the activation of CO2 , owing to the chemical inertness of linear CO2 . Herein, we present a defect-engineering methodology to construct CO2 activation sites by implanting carbon vacancies (CVs) in the melon polymer (MP) matrix. Positron annihilation spectroscopy confirmed the location and density of the CVs in the MP skeleton. In situ diffuse reflectance infrared Fourier transform spectroscopy and a DFT study revealed that the CVs can function as active sites for CO2 activation while stabilizing COOH* intermediates, thereby boosting the reaction kinetics. As a result, the modified MP-TAP-CVs displayed a 45-fold improvement in CO2 -to-CO activity over the pristine MP. The apparent quantum efficiency of the MP-TAP-CVs was 4.8 % at 420 nm. This study sheds new light on the design of high-efficiency polymer semiconductors for CO2 conversion.

9.
Chemistry ; 24(69): 18529-18534, 2018 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-30091277

RESUMO

The rational construction of heterostructures by using layered semiconductors with two-dimensional (2D) nanosheet configurations is promising to improve the efficiency of CO2 photoreduction. Herein, the fabrication of layered heterojunction photocatalysts (PCN/ZnIn2 S4 ) by in situ growth of 2D ZnIn2 S4 nanosheets on the surfaces of ultrathin polymeric carbon nitride (PCN) layers is presented for greatly enhanced CO2 conversion with visible light. The solution-processed self-assembly strategy renders the building of uniform and intimate junctions between PCN layers and ZnIn2 S4 subunits, which remarkably accelerates the separation and transfer of photogenerated charge carriers. In addition, the layered composites can also promote CO2 adsorption and strengthen the visible-light absorption. Consequently, the optimized PCN/ZnIn2 S4 sheet-shaped composite shows reinforced photoactivity for deoxygenative CO2 conversion, affording a high CO-production rate of 44.6 µmol h-1 , which is 223 times higher than that of the pristine PCN nanosheets. Moreover, the heterojunction photocatalyst also exhibits high stability during repeated runs for five cycles.

10.
Angew Chem Int Ed Engl ; 57(28): 8674-8677, 2018 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-29790250

RESUMO

Metal-free carbonitride(CN) semiconductors are appealing light-transducers for photocatalytic redox reactions owing to the unique band gap and stability. To harness solar energy efficiently, CN catalysts that are active over a wider range of the visible spectrum are desired. Now a photochemical approach has been used to prepare a new-type triazine-based CN structure. The obtained CN shows extraordinary light-harvesting characteristics, with suitable semiconductor-redox potentials. The light absorption edge of the CN reaches up to 735 nm, which is significantly longer than that of the conventional CN semiconductor at about 460 nm. As expected, the CN can efficiently catalyze oxidation of alcohols and reduction of CO2 with visible light, even under red-light irradiation. The results represent an important step toward the development of red-light-responsive triazine-based structures for solar applications.

11.
Angew Chem Int Ed Engl ; 56(14): 3992-3996, 2017 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-28247456

RESUMO

The delamination of layered crystals that produces single or few-layered nanosheets while enabling exotic physical and chemical properties, particularly for semiconductor functions in optoelectronic applications, remains a challenge. Here, we report a facile and green approach to prepare few-layered polymeric carbon nitride (PCN) semiconductors by a one-step carbon/nitrogen steam reforming reaction. Bulky PCN, obtained from typical precursors including urea, melamine, dicyandiamide, and thiourea, are exfoliated into few-layered nanosheets, while engineering its surface carbon vacancies. The unique sheet structures with strengthened surface properties endow PCNs with more active sites, and an increased charge separation efficiency with a prolonged charge lifetime, drastically promoting their photoredox performance. After an assay of a H2 evolution reaction, an apparent quantum yield of 11.3 % at 405 nm was recorded for the PCN nanosheets, which is much higher than those of PCN nanosheets. This delamination method is expandable to other carbon-based 2D materials for advanced applications.

12.
Angew Chem Int Ed Engl ; 56(36): 10905-10910, 2017 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-28710859

RESUMO

Aerogel structures have attracted increasing research interest in energy storage and conversion owing to their unique structural features, and a variety of materials have been engineered into aerogels, including carbon-based materials, metal oxides, linear polymers and even metal chalcogenides. However, manufacture of aerogels from nitride-based materials, particularly the emerging light-weight carbon nitride (CN) semiconductors is rarely reported. Here, we develop a facile method based on self-assembly to produce self-supported CN aerogels, without using any cross-linking agents. The combination of large surface area, incorporated functional groups and three-dimensional (3D) network structure, endows the resulting freestanding aerogels with high photocatalytic activity for hydrogen evolution and H2 O2 production under visible light irradiation. This work presents a simple colloid chemistry strategy to construct 3D CN aerogel networks that shows great potential for solar-to-chemical energy conversion by artificial photosynthesis.

13.
Angew Chem Int Ed Engl ; 56(28): 8231-8235, 2017 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-28514048

RESUMO

Carbon-based catalysts have demonstrated great potential for the aerobic oxidative dehydrogenation reaction (ODH). However, its widespread application is retarded by the unavoidable deactivation owing to the appearance of coking or combustion under ODH conditions. The synthesis and characterization of porous structure of BCN nanosheets as well as their application as a novel catalyst for ODH is reported. Such BCN nanosheets consist of hybridized, randomly distributed domains of h-BN and C phases, where C, B, and N were confirmed to covalent bond in the graphene-like layers. Our studies reveal that BCN exhibits both high activity and selectivity in oxidative dehydrogenation of ethylbenzene to styrene, as well as excellent oxidation resistance. The discovery of such a simple chemical process to synthesize highly active BCN allows the possibility of carbocatalysis to be explored.

14.
Chemistry ; 21(23): 8561-8, 2015 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-25925432

RESUMO

Understanding the photoluminescence (PL) and photocatalytic properties of carbon nanodots (CNDs) induced by environmental factors such as pH through surface groups is significantly important to rationally tune the emission and photodriven catalysis of CNDs. Through adjusting the pH of an aqueous solution of CNDs, it was found that the PL of CNDs prepared by ultrasonic treatment of glucose is strongly quenched at pH 1 because of the formation of intramolecular hydrogen bonds among the oxygen-containing surface groups. The position of the strongest PL peak and its corresponding excitation wavelength strongly depend on the surface groups. The origins of the blue and green emissions of CNDs are closely related to the carboxyl and hydroxyl groups, respectively. The deprotonated COO(-) and CO(-) groups weaken the PL peak of the CNDs and shift it to the red. CNDs alone exhibit photocatalytic activity towards degradation of Rhodamine B at different pH values under UV irradiation. The photocatalytic activity of the CNDs is the highest at pH 1 because of the strong intramolecular hydrogen bonds formed among the oxygen-containing groups.

15.
Chemphyschem ; 16(14): 3058-63, 2015 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-26335796

RESUMO

Herein, multifunctional N-doped carbon nanodots (NCNDs) were prepared through the one-step hydrothermal treatment of yeast. Results show that the NCNDs can be used as a new photocatalyst to drive the water-splitting reaction under UV light. Moreover, the NCNDs can efficiently catalyze the hydrogen evolution reaction. Under visible-light irradiation, Eosin Y-sensitized NCNDs exhibit excellent activity for hydrogen evolution. The hydrogen evolution rate of NCNDs (without any modification and co-catalyst) reaches 107.1 µmol h(-1) (2142 µmol g(-1) h(-1) ). When Pt is loaded on the NCNDs, the hydrogen evolution rate reaches 491.2 µmol h(-1) (9824 µmol g(-1) h(-1)) under visible-light irradiation. In addition, the NCNDs show excellent fluorescent properties and can be applied as a fluorescent probe for the sensitive and selective detection of Fe(3+) .

16.
Chem Commun (Camb) ; 60(76): 10588-10591, 2024 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-39235278

RESUMO

In this paper, three neutral heterocycle-triazolotriazine compounds featuring multiple amino groups and nitro groups were designed and synthesized. Among them, compounds 2 and 6 exhibit high detonation performance (Dv = 8180 m s-1, 8650 m s-1; P = 26.40 GPa, 31.5 GPa), low sensitivities (IS > 40 J, FS > 360 N) and high thermal stabilities (Td = 319 °C, 320 °C) suggesting their potential as alternatives to the traditional thermal-stable explosive HNS (Dv = 7612 m s-1, P = 24.3 GPa, IS = 5 J, FS = 240 N; Td = 318 °C). Meanwhile, compound 4 displays excellent properties (Dv = 8810 m s-1, IS = 15 J, FS = 240 N, Td = 215 °C, ρ = 1.84 g cm-3) which is superior to traditional explosive RDX (Dv = 8795 m s-1, IS = 7.5 J, FS = 120 N, Td = 208 °C, ρ = 1.80 g cm-3) making it a promising candidate as a novel secondary explosive. This research not only advances the field of triazolotriazine-based energetic materials but also explores their potential applications as heat-resistant or high-energy explosives.

17.
Front Bioeng Biotechnol ; 12: 1434323, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39157444

RESUMO

Osteochondral lesions are common pathological alterations in synovial joints. Different techniques have been designed to achieve osteochondral repair, and tissue-engineered osteochondral grafts have shown the most promise. Histological assessments and related scoring systems are crucial for evaluating the quality of regenerated tissue, and the interpretation and comparison of various repair techniques require the establishment of a reliable and widely accepted histological method. To date, there is still no consensus on the type of histological assessment and scoring system that should be used for osteochondral repair. In this review, we summarize common osteochondral staining methods, discuss the criteria regarding high-quality histological images, and assess the current histological scoring systems for osteochondral regeneration. Safranin O/Fast green is the most widely used staining method for the cartilage layer, whereas Gomori and Van Gieson staining detect new bone formation. We suggest including the graft-host interface and more sections together with the basic histological information for images. An ideal scoring system should analyze both the cartilage and bone regions, especially for the subchondral bone plate. Furthermore, histological assessments should be performed over a longer period of time to minimize discrepancies caused by defect size and animal species.

18.
J Exp Clin Cancer Res ; 43(1): 205, 2024 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-39044280

RESUMO

BACKGROUND: Despite the use of targeted therapeutic approaches, T-cell acute lymphoblastic leukemia (T-ALL) is still associated with a high incidence of complications and a poor prognosis. Indisulam (also known as E7070), a newly identified molecular glue compound, has demonstrated increased therapeutic efficacy in several types of cancer through the rapid degradation of RBM39. This study aimed to evaluate the therapeutic potential of indisulam in T-ALL, elucidate its underlying mechanisms and explore the role of the RBM39 gene. METHODS: We verified the anticancer effects of indisulam in both in vivo and in vitro models. Additionally, the construction of RBM39-knockdown cell lines using shRNA confirmed that the malignant phenotype of T-ALL cells was dependent on RBM39. Through RNA sequencing, we identified indisulam-induced splicing anomalies, and proteomic analysis helped pinpoint protein changes caused by the drug. Comprehensive cross-analysis of these findings facilitated the identification of downstream effectors and subsequent validation of their functional roles. RESULTS: Indisulam has significant antineoplastic effects on T-ALL. It attenuates cell proliferation, promotes apoptosis and interferes with cell cycle progression in vitro while facilitating tumor remission in T-ALL in vivo models. This investigation provides evidence that the downregulation of RBM39 results in the restricted proliferation of T-ALL cells both in vitro and in vivo, suggesting that RBM39 is a potential target for T-ALL treatment. Indisulam's efficacy is attributed to its ability to induce RBM39 degradation, causing widespread aberrant splicing and abnormal translation of the critical downstream effector protein, THOC1, ultimately leading to protein depletion. Moreover, the presence of DCAF15 is regarded as critical for the effectiveness of indisulam, and its absence negates the ability of indisulam to induce the desired functional alterations. CONCLUSION: Our study revealed that indisulam, which targets RBM39 to induce tumor cell apoptosis, is an effective drug for treating T-ALL. Targeting RBM39 through indisulam leads to mis-splicing of pre-mRNAs, resulting in the loss of key effectors such as THOC1.


Assuntos
Leucemia-Linfoma Linfoblástico de Células T Precursoras , Proteínas de Ligação a RNA , Humanos , Proteínas de Ligação a RNA/metabolismo , Proteínas de Ligação a RNA/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/metabolismo , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patologia , Camundongos , Animais , Linhagem Celular Tumoral , Apoptose/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proliferação de Células/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto , Splicing de RNA , Sulfonamidas/farmacologia , Feminino
19.
ChemSusChem ; 16(15): e202300500, 2023 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-37078981

RESUMO

Recently, organic semiconductors have received much attention in the field of photocatalysis due to their tunable physicochemical properties. However, organic semiconductor photocatalysts typically suffer from severe charge recombination due to high exciton binding energy. Herein, we found that aggregation of pyrene results in a red-shift of the light absorption from UV to visible light region. Importantly, the aggregation can induce dipole polarization by spontaneous structural symmetry breaking, thus significantly accelerating the separation and transfer of charge carriers. As a result, the pyrene aggregates display enhanced hydrogen photosynthesis activity. Furthermore, the noncovalent interactions allow rational design of physicochemical and electronic properties of pyrene aggregates, further strengthening the charge separation and photocatalytic activity of aggregates. The quantum yield of pyrene aggregates for hydrogen production highly reaches 20.77 % at 400 nm. Moreover, we have also observed pyrene analogues (1-hydroxypyrene, 1-nitropyrene and perylene) after aggregation all display large dipole moments induced by structural symmetry breaking and therefore accelerate the separation of charge carriers, confirming its general principle. This work highlights the achievement of using aggregation-induced structural symmetry breaking to enable the separation and transfer of charge carriers.

20.
ACS Appl Mater Interfaces ; 15(37): 43953-43962, 2023 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-37682728

RESUMO

The rational design of high-efficiency, low-cost electrocatalysts for electrochemical water oxidation in alkaline media remains a huge challenge. Herein, combined strategies of metal doping and vacancy engineering are employed to develop unique Mo-doped cobalt oxide nanosheet arrays. The Mo dopants exist in the form of high-valence Mo6+, and the doping amount has a significant effect on the structure morphology, which transforms from 1D nanowires/nanobelts to 2D nanosheets and finally 3D nanoflowers. In addition, the introduction of vast oxygen vacancies helps to modulate the electronic states and increase the electronic conductivity. The optimal catalyst MoCoO-3 exhibits greatly increased active sites and enhanced reaction kinetics. It gives a dramatically lower overpotential at 50 mA cm-2 (288 mV), much smaller than that of the undoped counterpart (418 mV) and comparable to those of the recently reported electrocatalysts. Density functional theory results further verify that the increased electronic conductivity and optimized adsorption energy toward oxygen evolution reaction intermediates are mainly responsible for the enhanced catalytic activity. Moreover, the assembled two-electrode electrolyzer (MoCoO-3||Pt/C) exhibits superior performance with the cell potential decreased by 233 mV to reach a current density of 50 mA cm-2 with respect to the benchmark counterpart catalysts (RuO2||Pt/C). This work might contribute to the rational design of effective, low-cost electrocatalyst materials by combining multiple strategies.

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