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1.
Nat Mater ; 22(1): 100-108, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36266572

RESUMO

Iridium-based electrocatalysts remain the only practical anode catalysts for proton exchange membrane (PEM) water electrolysis, due to their excellent stability under acidic oxygen evolution reaction (OER), but are greatly limited by their high cost and low reserves. Here, we report a nickel-stabilized, ruthenium dioxide (Ni-RuO2) catalyst, a promising alternative to iridium, with high activity and durability in acidic OER for PEM water electrolysis. While pristine RuO2 showed poor acidic OER stability and degraded within a short period of continuous operation, the incorporation of Ni greatly stabilized the RuO2 lattice and extended its durability by more than one order of magnitude. When applied to the anode of a PEM water electrolyser, our Ni-RuO2 catalyst demonstrated >1,000 h stability under a water-splitting current of 200 mA cm-2, suggesting potential for practical applications. Density functional theory studies, coupled with operando differential electrochemical mass spectroscopy analysis, confirmed the adsorbate-evolving mechanism on Ni-RuO2, as well as the critical role of Ni dopants in stabilization of surface Ru and subsurface oxygen for improved OER durability.

2.
Eur Spine J ; 33(3): 1245-1255, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38212411

RESUMO

PURPOSE: The overwhelming inflammatory response plays a critical role in the secondary injury cascade of traumatic spinal cord injury (tSCI). The systemic immune inflammatory index (SII) and systemic inflammatory response index (SIRI) are two novel inflammatory biomarkers. The SII was calculated based on lymphocyte, neutrophil, and platelet counts, while the SIRI was calculated based on lymphocyte, neutrophil, and monocyte counts. Their prognostic value in patients with tSCI remains unclear. METHODS: Patients with tSCI admitted within 24 h of trauma were retrospectively and consecutively enrolled. Peripheral blood samples were collected on admission. The primary outcome was American Spinal Injury Association Impairment Scale (AIS) grade conversion at discharge. Multivariable logistic regression analysis was performed to determine the relationship between SII and SIRI and AIS grade conversion. We performed receiver operating characteristic curve (ROC) analysis to assess the discriminative ability of SII, and SIRI in predicting AIS grade conversion. RESULTS: Among 280 included patients, 77 (27.5%) had improved AIS grade conversion at discharge. After adjustment for confounders, SII was independently associated with AIS grade conversion (per SD, odds ratio [OR], 0.68; 95% confidence interval [CI] 0.47-0.98, p = 0.040), while the association between SIRI and AIS grade conversion was insignificant (per 1 SD, OR, 0.77; 95% CI 0.55-1.08, p = 0.130). The ROC analysis revealed that the SII had the best predictive value for AIS grade conversion (area under curve: 0.608, 95% CI 0.536-0.678). CONCLUSIONS: Increased SII was independently associated with a decreased likelihood of improved AIS grade conversion.


Assuntos
Traumatismos da Medula Espinal , Traumatismos da Coluna Vertebral , Humanos , Prognóstico , Estudos Retrospectivos , Traumatismos da Medula Espinal/complicações , Síndrome de Resposta Inflamatória Sistêmica , Inflamação
3.
Neurocrit Care ; 40(2): 506-514, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37316678

RESUMO

BACKGROUND: Fibrinogen has been identified as a modulator of the coagulation and inflammatory process. There is uncertainty about the relationship between the dynamic profile of fibrinogen levels and its impact on clinical outcomes in patients with acute ischemic stroke treated with endovascular thrombectomy. METHODS: We consecutively enrolled patients with acute ischemic stroke who underwent endovascular thrombectomy. Fibrinogen was measured on admission and during hospitalization. The change in fibrinogen (Δfibrinogen) was calculated as the highest follow-up fibrinogen minus admission fibrinogen, with a positive Δfibrinogen indicating an increase in fibrinogen level. Functional outcome was assessed by the modified Rankin Scale at 3 months. Poor outcome was defined as modified Rankin Scale > 2. RESULTS: A total of 346 patients were included (mean age 67.4 ± 13.6 years, 52.31% men). The median fibrinogen on admission was 2.77 g/L (interquartile range 2.30-3.39 g/L). The median Δfibrinogen was 1.38 g/L (interquartile range 0.27-2.79 g/L). Hyperfibrinogenemia (> 4.5 g/L) on admission was associated with an increased risk of poor outcome [odds ratio (OR) 5.93, 95% confidence interval (CI) 1.44-24.41, p = 0.014]. There was a possible U-shaped association of Δfibrinogen with outcomes, with an inflection point of - 0.43 g/L (p = 0.04). When Δfibrinogen was < - 0.43 g/L, a higher decrease in fibrinogen (lower Δfibrinogen value) was associated with a higher risk of poor outcome (OR 0.22, 95% CI 0.02-2.48, p = 0.219). When Δfibrinogen was > - 0.43 g/L, the risk of poor outcome increased with increasing fibrinogen (OR 1.27, 95% CI 1.04-1.54, p = 0.016). CONCLUSIONS: In patients with endovascular thrombectomy, hyperfibrinogenemia on admission was associated with poor functional outcomes at 3 months, whereas Δfibrinogen was associated with poor 3-month outcomes in a possible U-shaped manner.


Assuntos
Isquemia Encefálica , Procedimentos Endovasculares , AVC Isquêmico , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Isquemia Encefálica/cirurgia , Procedimentos Endovasculares/efeitos adversos , Fibrinogênio , AVC Isquêmico/cirurgia , AVC Isquêmico/complicações , Trombectomia , Resultado do Tratamento
4.
Int Heart J ; 65(1): 94-99, 2024 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-38148008

RESUMO

Acute ischemic stroke (AIS) can be complicated by heart failure involving preserved ejection fraction (HFpEF) or reduced ejection fraction (HFrEF), and whether or not the prognosis differs between the 2 types of patients remains unclear. We compared the clinical characteristics and outcomes of the 2 types of patients at 3 months after the stroke.We retrospectively analyzed patients who, between 1 January 2018 and 1 January 2021, experienced AIS that was complicated by HFrEF or HFpEF. All patients had been prospectively registered in the Chengdu Stroke Registry. Poor outcome was defined as a modified Rankin Scale (mRS) score of 2-6 at 3 months. Univariate and binary logistic regression was used to assess whether HFpEF was associated with a significantly worse prognosis than HFrEF.Among the final sample of 108 patients (60.2% men; mean age, 73.08 ± 10.82 years), 75 (69.4%) had HFpEF. Compared to HFrEF patients, those with HFpEF were older (P = 0.002), were more likely to have chronic kidney disease (P = 0.033), and were more likely to experience a poor outcome (P = 0.022). After adjustments, HFpEF was associated with significantly greater risk of poor outcome than HFrEF (OR 4.13, 95%CI 1.20-15.79, P = 0.029). However, rates of hemorrhagic transformation or mortality at 3 months after AIS did not differ significantly between the 2 types of heart failure (all P > 0.05).Patients with AIS involving HFpEF experience worse outcomes than those with HFrEF and therefore may require special monitoring and management. Our findings need to be verified in large prospective studies.


Assuntos
Insuficiência Cardíaca , AVC Isquêmico , Masculino , Humanos , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Feminino , Volume Sistólico , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/epidemiologia , Estudos Retrospectivos , Estudos Prospectivos , Hospitalização , Fatores de Risco , Prognóstico
5.
Inorg Chem ; 62(13): 5262-5269, 2023 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-36947415

RESUMO

Porous carbon-supported atomically ordered intermetallic compounds (IMCs) are promising electrocatalysts in boosting oxygen reduction reaction (ORR) for fuel cell applications. However, the formation mechanism of IMC structures under high temperatures is poorly understood, which hampers the synthesis of highly ordered IMC catalysts with promoted ORR performance. Here, we employ high-temperature X-ray diffraction and energy-dispersive spectroscopic elemental mapping techniques to study the formation process of IMCs, by taking PtCo for example, in an industry-relevant impregnation synthesis. We find that high-temperature annealing is crucial in promoting the formation of alloy particles with a stoichiometric Co/Pt ratio, which in turn is the precondition for transforming the disordered alloys to ordered intermetallic structures at a relatively low temperature. Based on the findings, we accordingly synthesize highly ordered L10-type PtCo catalysts with a remarkable ORR performance in fuel cells.

6.
Small ; 18(31): e2202916, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35810451

RESUMO

Platinum-based atomically ordered alloys (i.e., intermetallic compounds) have distinct advantages over disordered solid solution counterparts in boosting the cathodic oxygen-reduction reaction (ORR) in proton-exchange-membrane fuel cells. Nevertheless, the pivotal role of ordering degree of intermetallic catalysts in promoting ORR performance has been ignored heavily so far, probably owing to the lack of synthetic routes for controlling the ordering degree, especially for preparing highly ordered intermetallic catalysts. Herein, a family of intermetallic PtFe catalysts with similar particle size of 3-4 nm but varied ordering degree in a wide range of 10-70% are prepared. After constructing the PtFe/Pt core/shell structure with around 3 Pt-layer skin, a positive correlation between the ordering degree of the intermetallic catalysts and their ORR activity and durability is identified. Notably, the highly ordered PtFe/Pt catalyst exhibits a high mass activity of 0.92 A mgPt -1 at 0.9 ViR-corrected as cathode catalyst in H2 -O2 fuel cell, with only 24% loss after accelerated durability tests. The ordering degree-dependent performance can be ascribed to the compressive strain effect induced by the intermetallic PtFe core with smaller lattice parameters, and the more thermodynamically stable intermetallic structure compared to disordered alloys.

7.
Chemistry ; 27(1): 145-157, 2021 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-32706127

RESUMO

The development of low-cost catalysts containing earth-abundant elements as alternatives to Pt-based catalysts for the oxygen reduction reaction (ORR) is crucial for the large-scale commercial application of proton exchange membrane fuel cells (PEMFCs). Nonprecious metal-nitrogen-carbon (M-N-C) materials represent the most promising candidates to replace Pt-based catalysts for PEMFCs applications. However, the high-temperature pyrolysis process for the preparation of M-N-C catalysts frequently leads to high structural heterogeneity, that is, the coexistence of various metal-containing sites and N-doped carbon structures. Unfortunately, this impedes the identification of the predominant catalytic active structure, and thus, the further development of highly efficient M-N-C catalysts for the ORR. This Minireview, after a brief introduction to the development of M-N-C ORR catalysts, focuses on the commonly accepted views of predominant catalytic active structures in M-N-C catalysts, including atomically dispersed metal-Nx sites, metal nanoparticles encapsulated with nitrogen-doped carbon structures, synergistic action between metal-Nx sites and encapsulated metal nanoparticles, and metal-free nitrogen-doped carbon structures.

8.
Angew Chem Int Ed Engl ; 59(4): 1627-1633, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31674103

RESUMO

The development of metal-N-C materials as efficient non-precious metal (NPM) catalysts for catalysing the oxygen reduction reaction (ORR) as alternatives to platinum is important for the practical use of proton exchange membrane fuel cells (PEMFCs). However, metal-N-C materials have high structural heterogeneity. As a result of their high-temperature synthesis they often consist of metal-Nx sites and graphene-encapsulated metal nanoparticles. Thus it is hard to identify the active structure of metal-N-C catalysts. Herein, we report a low-temperature NH4 Cl-treatment to etch out graphene-encapsulated nanoparticles from metal-N-C catalysts without destruction of co-existing atomically dispersed metal-Nx sites. Catalytic activity is much enhanced by this selective removal of metallic nanoparticles. Accordingly, we can confirm the spectator role of graphene-encapsulated nanoparticles and the pivotal role of metal-Nx sites in the metal-N-C materials for ORR in the acidic medium.

9.
Angew Chem Int Ed Engl ; 58(33): 11311-11316, 2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31095839

RESUMO

Harvesting non-emissive spin-triplet charge-transfer (CT) excitons of organic semiconductors is fundamentally important for increasing the operation efficiency of future devices. Here we observe thermally activated delayed fluorescence (TADF) in a 1:2 CT cocrystal of trans-1,2-diphenylethylene (TSB) and 1,2,4,5-tetracyanobenzene (TCNB). This cocrystal system is characterized by absorption spectroscopy, variable-temperature steady-state and time-resolved photoluminescence spectroscopy, single-crystal X-ray diffraction, and first-principles calculations. These data reveal that intermolecular CT in cocrystal narrows the singlet-triplet energy gap and therefore facilitates reverse intersystem crossing (RISC) for TADF. These findings open up a new way for the future design and development of novel TADF materials.

10.
J Am Chem Soc ; 140(16): 5339-5342, 2018 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-29522681

RESUMO

Two-dimensional molecular crystals (2DMCs) are a promising candidate for flexible and large-area electronics. Their large-area production requires both low nuclei density and 2D crystal growth mode. As an emerging type of material, their large-area production remains a case-by-case practice. Here we present a general, efficient strategy for large-area 2DMCs. The method grows crystals on water surface to minimize the density of nuclei. By controlling the interfacial tension of the water/solution system with a phase transfer surfactant, the spreading area of the solvent increases tens of times, leading to the space-confined 2D growth of molecular crystals. As-grown sub-centimeter-sized 2DMCs floating on the water surface can be easily transferred to arbitrary substrates for device applications.

11.
Biomacromolecules ; 15(12): 4396-402, 2014 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-25325164

RESUMO

Inspired by photonic nanostructures in nature, such as the hair-like chaetae on the body of sea mice, inverse opal photonic crystals films were fabricated with chitosan, a kind of biomacromolecule found in nature. First, monodispersed polystyrene (PS) colloidal crystal templates with different particle sizes were prepared. The inverse opal films (IOFs) were fabricated through in situ cross-linking of the PS templates. The IOFs contain periodically ordered interconnecting pores that endow the films with photonic stop bands and structural colors, which are visible to the naked eye. The IOFs exhibit rapid reversible changes in their structural colors and reflectance peaks in response to alcohols and phenols. Possible mechanisms for the shifts in the IOF's reflectance peaks are proposed. The changes in the IOFs in response to alcohols and phenols provide a potential way to visually detect these organic solvents.


Assuntos
Quitosana/química , Compostos Orgânicos/química , Fótons , Solventes/química , Cristalização , Nanoestruturas/química , Tamanho da Partícula , Poliestirenos/química
12.
Nanotechnology ; 25(13): 135707, 2014 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-24598357

RESUMO

An environmentally friendly new approach to prepare reduced graphene oxide (RGO) was developed by using glycylglycine (glygly) as both a reducing and stabilizing agent. Graphene oxide (GO) was transformed to RGO with the appropriate pH, temperature and reducing agent/GO ratio. The RGO was characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, xray diffraction, xray photoelectron spectroscopy (XPS), and transmission electron microscopy. The RGO aqueous suspension showed extraordinary stability in the absence of any external stabilizing reagents. The XPS analysis showed that this excellent stability is due to modifications of the RGO nanosheets by the glygly molecules. The modified RGO complex with copper shows good catalytic performance for reduction of 4-nitrophenol to 4-aminophenol.

13.
Am J Transl Res ; 16(4): 1401-1414, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38715837

RESUMO

OBJECTIVES: To explore how the circular non-coding RNA circ_0072088 influences the progression of breast carcinoma (BC) by affecting cell behavior. METHODS: We measured the levels of circ_0072088, microRNA-607 (miR-607), and ring finger protein 2 (RNF2) mRNA levels in BC tissues and cell lines using quantitative real-time PCR. We also conducted cell counting kit-8 (CCK-8), BrdU incorporation, and flow cytometry assays to assess cell viability, cell cycle, and apoptosis, respectively. RESULTS: We observed increased levels of circ_0072088 and RNF2, and decreased levels of miR-607 in BC tissues. Overexpressing circ_0072088 promoted BC cell proliferation and cell cycle progression while inhibiting apoptosis. Conversely, silencing circ_0072088 had the opposite effects. Our data suggest that circ_0072088 directly targets and downregulates miR-607, which in turn upregulates RNF2, a target of miR-607. Moreover, miR-607 overexpression could mitigate the pro-proliferative and anti-apoptotic effects of circ_0072088 on BC cells. CONCLUSION: Circ_0072088 drives BC progression by downregulating miR-607 and upregulating RNF2, thereby promoting cell proliferation and cycle progression while reducing apoptosis.

14.
Mol Neurobiol ; 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38565785

RESUMO

The relationship of single nucleotide polymorphisms (SNPs) in COL4A2 gene with risk and outcome of primary intracerebral hemorrhage (ICH) in the Chinese Han population remains unclear, which was investigated in this study. Primary ICH patients and non-stroke controls of Chinese Han ethnicity were enrolled. The genotypes of 8 tag-SNPs were determined using a custom-by-design 48-Plex SNPscan Kit. Poor 3-month outcome was defined as modified Rankin Scale score 4-6. Logistic regression was employed to examine association between COL4A2 variants and risk and poor outcome of primary ICH. 323 patients with primary ICH and 376 stroke-free controls were included. Compared to controls, the rs1049931 G and rs1049906 C alleles were associated with increased ICH risk (p = 0.027 and 0.033), and these two allele counts increased this risk after adjustments respectively (additive model: adjusted OR [aOR] 1.41, 95% CI 1.03-1.94, corrected p = 0.043; aOR 1.37, 95% CI 1.01-1.86, corrected p = 0.043). The rs1049931 AG/GG and rs1049906 CT/CC genotypes showed increased susceptibility to non-lobar hemorrhage (aOR 1.63, 95% CI 1.06-2.50, p = 0.025; aOR 1.63, 95% CI 1.07-2.47, p = 0.022). Haplotype analysis revealed an association between rs1049906-rs1049931 haplotype CG and ICH risk (OR 1.36, 95% CI 1.05-1.78, p = 0.021). Regarding clinical outcome, the rs3803230 C allele (dominant model: aOR 1.94, 95% CI 1.04-3.63, p = 0.037) and haplotype AC of rs7990214-rs3803230 (OR 1.98, 95% CI 1.13-3.46, p = 0.015) contributed to 3-month poor outcome. The COL4A2 polymorphisms are associated with an increased risk of primary ICH, mainly non-lobar hemorrhage, and with long-term poor outcome after ICH in Chinese Han population.

15.
CNS Neurosci Ther ; 30(3): e14701, 2024 03.
Artigo em Inglês | MEDLINE | ID: mdl-38544366

RESUMO

AIMS: The relationship between heme oxygenase-1 (HO-1) and human ischemic stroke outcome remains unclear, which was investigated in this study. METHODS: Acute ischemic stroke patients admitted within 24 h were enrolled. Serum HO-1 levels at baseline were measured via ELISA. Poor 3-month functional outcome was defined as modified Rankin Scale (mRS) score 3-6. Multivariable-adjusted binary logistic regression and restricted cubic spline models were employed to examine association between serum HO-1 and functional outcome. HO-1's additive prognostic utility was assessed by net reclassification index (NRI) and integrated discrimination improvement (IDI). RESULTS: Of 194 eligible patients, 79 (40.7%) developed poor functional outcomes at 3-month follow-up. The highest quartile of serum HO-1 was independently associated with a lower risk of poor functional outcome (adjusted OR 0.13, 95% CI 0.04-0.45; p = 0.001) compared with the lowest HO-1 category. The relationship between higher HO-1 levels and reduced risk of poor functional outcome was linear and dose responsive (p = 0.002 for linearity). Incorporating HO-1 into the analysis with conventional factors significantly improved reclassification for poor functional outcomes (NRI = 41.2%, p = 0.004; IDI = 5.0%, p = 0.004). CONCLUSIONS: Elevated serum HO-1 levels at baseline were independently associated with improved 3-month functional outcomes post-ischemic stroke. Serum HO-1 measurement may enhance outcome prediction beyond conventional clinical factors.


Assuntos
Isquemia Encefálica , AVC Isquêmico , Acidente Vascular Cerebral , Humanos , AVC Isquêmico/complicações , Acidente Vascular Cerebral/complicações , Biomarcadores , Heme Oxigenase-1 , Prognóstico , Fatores de Risco
16.
bioRxiv ; 2024 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-38293207

RESUMO

Ischemic stroke-induced mitochondrial dysfunction in the blood-brain barrier-forming brain endothelial cells ( BECs ) results in long-term neurological dysfunction post-stroke. We previously reported that intravenous administration of human BEC ( hBEC )-derived mitochondria-containing extracellular vesicles ( EVs ) showed a potential efficacy signal in a mouse middle cerebral artery occlusion ( MCAo ) model of stroke. We hypothesized that EVs harvested from donor species homologous to the recipient species ( e.g., mouse) may improve therapeutic efficacy, and therefore, use of mouse BEC ( mBEC )-derived EVs may improve post-stroke outcomes in MCAo mice. We investigated if EVs derived from the same species as the recipient cell (mBEC-EVs and recipient mBECs or hBECs-EVs and recipient hBECs) show a greater EV mitochondria delivery efficiency than cross-species EVs and recipient cells (mBEC-EVs and recipient hBECs or vice versa ). Our results showed that mBEC-EVs outperformed hBEC-EVs in transferring EV mitochondria to the recipient ischemic mBECs, and improved mBEC mitochondrial function via increasing oxygen consumption rate. mBEC-EVs significantly reduced brain infarct volume and improved behavioral recovery compared to vehicle-injected MCAo mice. Our data suggests that mBEC-EVs show superior therapeutic efficacy in a mouse MCAo stroke model compared to hBEC-EVs-supporting the continued use of mBEC-EVs to optimize the therapeutic potential of mitochondria-containing EVs in preclinical studies.

17.
Nanoscale Horiz ; 9(1): 132-142, 2023 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-37850320

RESUMO

Atomically-thin monolayer WS2 is a promising channel material for next-generation Moore's nanoelectronics owing to its high theoretical room temperature electron mobility and immunity to short channel effect. The high photoluminescence (PL) quantum yield of the monolayer WS2 also makes it highly promising for future high-performance optoelectronics. However, the difficulty in strictly growing monolayer WS2, due to its non-self-limiting growth mechanism, may hinder its industrial development because of the uncontrollable growth kinetics in attaining the high uniformity in thickness and property on the wafer-scale. In this study, we report a scalable process to achieve a 4 inch wafer-scale fully-covered strictly monolayer WS2 by applying the in situ self-limited thinning of multilayer WS2 formed by sulfurization of WOx films. Through a pulsed supply of sulfur precursor vapor under a continuous H2 flow, the self-limited thinning process can effectively trim down the overgrown multilayer WS2 to the monolayer limit without damaging the remaining bottom WS2 monolayer. Density functional theory (DFT) calculations reveal that the self-limited thinning arises from the thermodynamic instability of the WS2 top layers as opposed to a stable bottom monolayer WS2 on sapphire above a vacuum sublimation temperature of WS2. The self-limited thinning approach overcomes the intrinsic limitation of conventional vapor-based growth methods in preventing the 2nd layer WS2 domain nucleation/growth. It also offers additional advantages, such as scalability, simplicity, and possibility for batch processing, thus opening up a new avenue to develop a manufacturing-viable growth technology for the preparation of a strictly-monolayer WS2 on the wafer-scale.

18.
Adv Sci (Weinh) ; 10(28): e2303448, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37544890

RESUMO

Piezo-assisted photocatalysis (namely, piezo-photocatalysis), which utilizes mechanical energy to modulate spatial and energy distribution of photogenerated charge carriers, presents a promising strategy for molecule activation and reactive oxygen species (ROS) generation toward applications such as environmental remediation. However, similarly to photocatalysis, piezo-photocatalysis also suffers from inferior charge separation and utilization efficiency. Herein, a Z-scheme heterojunction composed of single Ag atoms-anchored polymeric carbon nitride (Ag-PCN) and SnO2- x is developed for efficient charge carrier transfer/separation both within the catalyst and between the catalyst and surface oxygen molecules (O2 ). As revealed by charge dynamics analysis and theoretical simulations, the synergy between the single Ag atoms and the Z-scheme heterojunction initiates a cascade electron transfer from SnO2- x to Ag-PCN and then to O2 adsorbed on Ag. With ultrasound irradiation, the polarization field generated within the piezoelectric hybrid further accelerates charge transfer and regulates the O2 activation pathway. As a result, the Ag-PCN/SnO2- x catalyst efficiently activates O2 into ·O2 - , ·OH, and H2 O2 under co-excitation of visible light and ultrasound, which are consequently utilized to trigger aerobic degradation of refractory antibiotic pollutants. This work provides a promising strategy to maneuver charge transfer dynamics for efficient piezo-photocatalysis by integrating single-atom catalysts (SACs) with Z-scheme heterojunction.

19.
J Phys Chem Lett ; 13(16): 3549-3555, 2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35420438

RESUMO

Atomically ordered intermetallic alloys with unique electronic and geometrical structures are highly attractive for heterogeneous catalysis and electrocatalysis. However, the formation of intermetallic phases generally requires high-temperature annealing to overcome the kinetic energy barrier of atom ordering, which unfortunately causes high material heterogeneity and thus makes it challenging to identify the exact contribution of ordered structures to the improved performance. Here, we prepared a family of small-sized intermetallic core/shell Pt3M@Pt (M = Mn or Fe) catalysts with varied ordering degree by a high-temperature sulfur-confined method. We identified a strong correlation between the ordering degree of the intermetallic Pt3M core of the catalysts and their electrocatalytic activity for the methanol oxidation reaction. Density functional theory calculations show that the intermetallic Pt3M core induces a compressive strain on the Pt-skin, which weakens the CO* binding, lowers the free energy change from CO* to COOH*, and therefore promotes electrocatalytic methanol oxidation.

20.
ACS Appl Mater Interfaces ; 14(36): 41275-41282, 2022 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-36064330

RESUMO

X-ray imaging and computed tomography (CT) technology, as the important non-destructive measurements, can observe internal structures without destroying the detected sample, which are always used in biological diagnosis to detect tumors, pathologies, and bone damages. It is always a challenge to find materials with a low detection limit, a short exposure time, and high resolution to reduce X-ray damage and acquire high-contrast images. Here, we described a low-cost and high-efficient method to prepare centimeter-sized anthracene crystals, which exhibited intense X-ray radioluminescence with a detection limit of ∼0.108 µGy s-1, which is only one-fifth of the dose typically used for X-ray diagnostics. Additionally, the low absorption reduced the damage in radiation and ensured superior cycle performance. X-ray detectors based on anthracene crystals also exhibited an extremely high resolution of 40 lp mm-1. The CT scanning and reconstruction of a foam sample were then achieved, and the detailed internal structure could be clearly observed. These indicated that organic crystals are expecting to be leading candidate low-cost materials for low-dose and highly sensitive X-ray detection and CT scanning.

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