Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Resultados 1 - 20 de 36
Filtrar
1.
Nano Lett ; 24(9): 2719-2726, 2024 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-38377427

RESUMEN

Plasmonic Cu@semiconductor heteronanocrystals (HNCs) have many favorable properties, but the synthesis of solid structures is often hindered by the nanoscale Kirkendall effect. Herein, we present the use of an atomically thin Au3Cu palisade interlayer to reduce lattice mismatch and mediate the Kirkendall effect, enabling the successive topological synthesis of Cu@Au3Cu@Ag, Cu@Au3Cu@Ag2S, and further transformed solid Cu@Au3Cu@CdS core-shell HNCs via cation exchange. The atomically thin and intact Au3Cu palisade interlayer effectively modulates the diffusion kinetics of Cu atoms as demonstrated by experimental and theoretical investigations and simultaneously alleviates the lattice mismatch between Cu and Ag as well as Cu and CdS. The Cu@Au3Cu@CdS HNCs feature exceptional crystallinity and atomically organized heterointerfaces between the plasmonic metal and the semiconductor. This results in the efficient plasmon-induced injection of hot electrons from Cu@Au3Cu into the CdS shell, enabling the Cu@Au3Cu@CdS HNCs to achieve high activity and selectivity for the photocatalytic reduction of CO2 to CO.

2.
J Am Chem Soc ; 146(19): 13527-13535, 2024 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-38691638

RESUMEN

Closing the carbon and nitrogen cycles by electrochemical methods using renewable energy to convert abundant or harmful feedstocks into high-value C- or N-containing chemicals has the potential to transform the global energy landscape. However, efficient conversion avenues have to date been mostly realized for the independent reduction of CO2 or NO3-. The synthesis of more complex C-N compounds still suffers from low conversion efficiency due to the inability to find effective catalysts. To this end, here we present amorphous bismuth-tin oxide nanosheets, which effectively reduce the energy barrier of the catalytic reaction, facilitating efficient and highly selective urea production. With enhanced CO2 adsorption and activation on the catalyst, a C-N coupling pathway based on *CO2 rather than traditional *CO is realized. The optimized orbital symmetry of the C- (*CO2) and N-containing (*NO2) intermediates promotes a significant increase in the Faraday efficiency of urea production to an outstanding value of 78.36% at -0.4 V vs RHE. In parallel, the nitrogen and carbon selectivity for urea formation is also enhanced to 90.41% and 95.39%, respectively. The present results and insights provide a valuable reference for the further development of new catalysts for efficient synthesis of high-value C-N compounds from CO2.

3.
Mult Scler ; : 13524585241286671, 2024 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-39392718

RESUMEN

OBJECTIVES: The objectives were to understand the employment impacts of myelin oligodendrocyte glycoprotein-associated antibody disease (MOGAD) on adults in an international cohort by determining lost employment, work hours, and wages. BACKGROUND: Clinically, MOGAD can be associated with significant disability; however, its socioeconomic consequences for adults are barely reported. METHODS: Participants of potential working age (18-70 years old) with neurologist-diagnosed MOGAD were recruited from clinical sites in 13 countries, April 2022 to August 2023. Each participant completed a one-time survey. Regression models assessed associations with post-MOGAD (1) unemployment and (2) work hours. RESULTS: A total of 117 participants (66.7% female), mean age 39.7 years, median disease duration 3 years (25th, 75th percentile: 1, 7) were analyzed. Employment post-MOGAD reduced from 74 (63.2%) to 57 (48.7%) participants. Participants employed pre-diagnosis reduced their work hours, on average, from 31.6 hours/week to 19.5 hours/week post-diagnosis. Residence in a high-income country was statistically significantly associated with post-diagnosis employment and higher weekly work hours. Depressed mood was associated with unemployment. MOGAD-related pain and history of myelitis were independently associated with lost work hours. CONCLUSION: MOGAD can have significant impacts on adult employment, particularly in non-high-income countries. Depressed mood and pain are potentially modifiable factors related to socioeconomic status in MOGAD.

4.
Health Qual Life Outcomes ; 22(1): 80, 2024 Sep 19.
Artículo en Inglés | MEDLINE | ID: mdl-39300432

RESUMEN

BACKGROUND: This study evaluates the health-related quality of life (HRQoL) of persons with diffuse large B-cell lymphoma (DLBCL) by using EQ-5D-5L and SF-6Dv2 and compares the measurement properties of the two instruments. METHOD: DLBCL patients were identified via a patient group and were surveyed using web-based questionnaires. Demographic information, socioeconomic status (SES), clinical characteristics, and EQ-5D-5L and SF-6Dv2 responses were collected and statistically described. The association between the EQ-5D-5L and SF-6Dv2 dimensions were analyzed using the Spearman's correlation coefficient, whereas the correlation of the utility scores was evaluated using Pearson's correlation coefficient. The agreement between the responses of the two instruments were examined using a Bland-Altman (B-A) plot. A one-way analysis of variance (ANOVA) was performed to compare the utility scores across subgroups in different clinical states (a t-test was used if there were two subgroups). In addition, the graded response model (GRM) was used to describe the discrimination ability and difficulty characteristics of the dimensions in the two instruments. RESULTS: In total, 582 valid responses were collected, among which 477 respondents were associated with initial-treatment and 105 respondents were relapsed/refractory (RR) patients. The mean (standard deviation [SD]) EQ-5D-5L and SF-6Dv2 utility scores of the DLBCL patients were 0.828 (0.222) and 0.641 (0.220), respectively. The correlation between the EQ-5D-5L and SF-6Dv2 dimensions ranged from 0.299 to 0.680, and the correlation between their utility scores was 0.787. The B-A plot demonstrated an acceptable but not strong agreement between EQ-5D-5L and SF-6Dv2 utility scores. The GRM model results indicated that all dimensions of each instrument were highly discriminating overall, but EQ-5D-5L had suboptimal discriminative power among patients with good health. CONCLUSION: Both the EQ-5D-5L and SF-6Dv2 showed valid properties to assess the HRQoL of DLBCL patients. However, utility scores derived from the two instruments had substantial difference, thereby prohibiting the interchangeable use of utilities from the two instruments.


Asunto(s)
Linfoma de Células B Grandes Difuso , Calidad de Vida , Humanos , Linfoma de Células B Grandes Difuso/psicología , Linfoma de Células B Grandes Difuso/terapia , Masculino , Femenino , China , Persona de Mediana Edad , Calidad de Vida/psicología , Encuestas y Cuestionarios , Adulto , Anciano , Psicometría/instrumentación , Estado de Salud
5.
Nano Lett ; 23(7): 2905-2914, 2023 Apr 12.
Artículo en Inglés | MEDLINE | ID: mdl-36961203

RESUMEN

Strain engineering is an attractive strategy for improving the intrinsic catalytic performance of heterogeneous catalysts. Manipulating strain on the short-range atomic scale to the local structure of the catalytic sites is still challenging. Herein, we successfully achieved atomic strain modulation on ultrathin layered vanadium oxide nanoribbons by an ingenious intercalation chemistry method. When trace sodium cations were introduced between the V2O5 layers (Na+-V2O5), the V-O bonds were stretched by the atomically strained vanadium sites, redistributing the local charges. The Na+-V2O5 demonstrated excellent photooxidation performance, which was approximately 12 and 14 times higher than that of pristine V2O5 and VO2, respectively. Complementary spectroscopy analysis and theoretical calculations confirmed that the atomically strained Na+-V2O5 had a high surficial charge density, improving the activation of oxygen molecules and contributing to the excellent photocatalytic property. This work provides a new approach for the rational design of strain-equipped catalysts for selective photooxidation reactions.

6.
Anal Chem ; 95(23): 9107-9115, 2023 06 13.
Artículo en Inglés | MEDLINE | ID: mdl-37257081

RESUMEN

Although great achievements have been made in the study of artificial enzymes, the design of nanozymes with high catalytic activities of natural enzymes and the further establishment of sensitive biosensors still remain challenging. Here, two nanozymes, i.e., ZnCoFe three-atom nanozyme (TAzyme) and Sn single-atom nanozyme (SAzyme)/Ti3C2Tx, are developed, which show peroxidase-like catalytic activities by catalyzing the reaction of hydrogen peroxide (H2O2), 4-aminoantipyrine (4-AAP), and phenolic acids to generate colorimetric reactions. The involvement of different phenolic acids leads to the generation of different color products. These subtle color-variation profiles between these phenolic acids prompt us to exploit an electronic tongue based on the two nanozymes to distinguish phenolic acids. Data interpretation by the pattern recognition method, such as linear discriminant analysis (LDA), displays good clustering separation of six different phenolic acids at concentrations of 0.1 µM to 1 mM, validating the effectiveness of the colorimetric nanozyme sensor array.


Asunto(s)
Técnicas Biosensibles , Peróxido de Hidrógeno , Peróxido de Hidrógeno/análisis , Peroxidasa , Peroxidasas , Colorimetría
7.
Small ; 19(11): e2207235, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36650994

RESUMEN

Developing robust and highly active bifunctional electrocatalysts for overall water splitting is critical for efficient sustainable energy conversion. Herein, heteroatom-doped amorphous/crystalline ruthenium oxide-based hollow nanocages (M-ZnRuOx (MCo, Ni, Fe)) through delicate control of composition and structure is reported. Among as-synthesized M-ZnRuOx nanocages, Co-ZnRuOx nanocages deliver an ultralow overpotential of 17 mV at 10 mA cm-2 and a small Tafel slope of 21.61 mV dec-1 for hydrogen evolution reaction (HER), surpassing the commercial Pt/C catalyst, which benefits from the synergistic coupling effect between electron regulation induced by Co doping and amorphous/crystalline heterophase structure. Moreover, the incorporation of Co prevents Ru from over-oxidation under oxygen evolution reaction (OER) operation, realizing the leap from a monofunctional to multifunctional electrocatalyst and then Co-ZnRuOx nanocages exhibit remarkable OER catalytic activity as well as overall water splitting performance. Combining theory calculations with spectroscopy analysis reveal that Co is not only the optimal active site, increasing the number of exposed active sites while also boosting the long-term durability of catalyst by modulating the electronic structure of Ru atoms. This work opens a considerable avenue to design highly active and durable Ru-based electrocatalysts.

8.
Small ; 19(15): e2207036, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36599617

RESUMEN

Recently, single-atom catalysts are attracting much attention in sensor field due to their remarkable peroxidase- or oxidase-like activities. Herein, peroxidase-like FeCoZn triple-atom catalyst supported on S- and N-doped carbon derived from ZIF-8 (FeCoZn-TAC/SNC) serves as a proof-of-concept nanozyme. In this paper, a dual-channel nanozyme-based colorimetric sensor array is presented for identifying seven preservatives in food. Further experiments reveal that the peroxidase-like activity of the FeCoZn TAzyme enables it to catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) and o-phenylenediamine (OPD) in the presence of H2 O2 , yielding the blue oxTMB and yellow oxOPD, respectively. However, food preservatives are adsorbed on the nanozyme surface through π-π stacking interaction and hydrogen bond, and the reduction in catalytic activity of FeCoZn TAzyme causes differential colorimetric signal variations, which provide unique "fingerprints" for each food preservative.


Asunto(s)
Conservantes de Alimentos , Peroxidasa , Colorimetría , Nariz Electrónica , Oxidorreductasas , Peroxidasas , Colorantes , Peróxido de Hidrógeno
9.
J Am Chem Soc ; 144(42): 19619-19626, 2022 Oct 26.
Artículo en Inglés | MEDLINE | ID: mdl-36223550

RESUMEN

Ruthenium-based materials are considered great promising candidates to replace Pt-based catalysts for hydrogen production in alkaline conditions. Herein, we adopt a facile method to rationally design a neoteric Schottky catalyst in which uniform ultrafine ruthenium nanoparticles featuring lattice compressive stress are supported on nitrogen-modified carbon nanosheets (Ru NPs/NC) for efficient hydrogen evolution reaction (HER). Lattice strain and Schottky junction dual regulation ensures that the Ru NPs/NC catalyst with an appropriate nitrogen content displays superb H2 evolution in alkaline media. Particularly, Ru NPs/NC-900 with 1.3% lattice compressive strain displays attractive activity and durability for the HER with a low overpotential of 19 mV at 10 mA cm-2 in 1.0 M KOH electrolyte. The in situ X-ray absorption fine structure measurements indicate that the low-valence Ru nanoparticle with shrinking Ru-Ru bond acts as catalytic active site during the HER process. Furthermore, multiple spectroscopy analysis and density functional theory calculations demonstrate that the lattice strain and Schottky junction dual regulation tunes the electron density and hydrogen adsorption of the active center, thus enhancing the HER activity. This strategy provides a novel concept for the design of advanced electrocatalysts for H2 production.

10.
Small ; 18(13): e2105883, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34918467

RESUMEN

Atomically dispersed metal sites (ADMSs) attract immense attention because they can be used in the fields of energy and environmental protection as they are characterized by high atomic utilization efficiency and exhibit high activity. Various supports for anchoring isolated metal atoms are developed to construct ADMSs characterized by highly stable and well-defined structures. This can be achieved by increasing the number of anchoring sites and reinforcing metal-support interactions. MXenes, a new series of 2D nanomaterials, exhibit promising potential in stabilizing isolated metal atoms because of their large specific surface areas and unique surface properties. The high conductivity and hydrophilicity of MXenes can be attributed to the nature of surface functionalization and the properties of tunable structures of the materials. Benefiting from these excellent properties, MXenes can find their applications in various fields. Herein, the precise characterization methods that can be followed to study ADMSs, the construction of MXene-supported ADMSs using theoretical predictions, and experimental modulation strategies are summarized, and their corresponding applications in electrocatalysis, organocatalysis, and advanced battery systems are systematically illustrated. It is hoped that this review will provide insights that can be used for the further development of MXene-supported ADMSs.

11.
Small ; 18(33): e2203422, 2022 08.
Artículo en Inglés | MEDLINE | ID: mdl-35871552

RESUMEN

In heterogeneous catalysis, metal particle morphology and size can influence markedly the activity. It is of great significance to rationally design and control the synthesis of Pt at the atomic level to demonstrate the structure-activity relationship toward electrocatalysis. Herein, a powerful strategy is reported to synthesize graphene-supported platinum-based electrocatalyst, that is, nanocatalysts with controllable size can be prepared by iced photochemical method, including single atoms (Pt-SA@HG), nanoclusters (Pt-Clu@HG), and nanocrystalline (Pt-Nc@HG). The Pt-SA@HG exhibits unexpected electrocatalytic hydrogen evolution reaction (HER) performances with 13 mV overpotential at 10 mA cm-2 current densities which surpass Pt-Clu@HG and Pt-Nc@HG. The in situ X-ray absorption fine structure spectroscopy (XAFS) and density functional theory (DFT) calculations determine the Pt-C3 active site is linchpin to the excellent HER performance of Pt-SA@HG. Compared with the traditional Pt-Nx coordination structure, the pure carbon coordinated Pt-C3 site is more favorable for HER. This work opens up a new way to adjust the metal particle size and catalytic performance of graphene at a multiscale level.


Asunto(s)
Grafito , Catálisis , Grafito/química , Hidrógeno , Hielo , Platino (Metal)
12.
Stroke ; 47(4): 929-35, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26869385

RESUMEN

BACKGROUND AND PURPOSE: We investigated secular trends in the age of stroke onset and stroke incidence in a low-income population in rural China. METHODS: The study population was recruited from a population-based stroke surveillance study conducted in a township in Tianjin, China, from 1992 to 2014. The trends in mean age and incidence of first-ever stroke were assessed by sex and stroke subtype. Risk factor surveys were conducted in the same population in both 1991 and 2011. RESULTS: A total of 1053 patients experienced first-ever stroke from 1992 to 2014. The mean age of stroke onset in men significantly decreased by 0.28 years annually overall, by 0.56 years for intracerebral hemorrhage, and by 0.22 years for ischemic stroke (P<0.05). However, a similar trend was not observed in women. The age-standardized first-ever stroke incidence in the same population significantly increased across sex and stroke subtypes, increased by 6.3% overall, 5.5% for men, 7.9% for women, 4.6% for intracerebral hemorrhage, and 7.3% for ischemic stroke (P<0.05) during 1992 to 2014. Concurrently, the prevalence of hypertension, diabetes mellitus, obesity, current smoking, and alcohol consumption increased significantly in young and middle-aged adults from 1991 to 2011. CONCLUSIONS: The age of stroke onset tends to be younger among low-income population in China after the dramatic increased incidence of stroke during the gradual extension of life expectancy of population in China. These findings suggested that stroke burden will continue to increase in the long time, unless the risk factors in low-income populations are effectively controlled.


Asunto(s)
Isquemia Encefálica/epidemiología , Esperanza de Vida , Pobreza , Accidente Cerebrovascular/epidemiología , Factores de Edad , Edad de Inicio , Anciano , Anciano de 80 o más Años , China/epidemiología , Femenino , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Prevalencia , Factores de Riesgo , Factores Sexuales
13.
J Stroke Cerebrovasc Dis ; 24(10): 2277-84, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26169546

RESUMEN

Stroke has a greater effect on women. However, sex differences in outcome and factors associated with outcome among elderly patients are unknown. From January 2009 to December 2011, 810 patients with acute ischemic stroke aged 75 years or older were recruited in China. Clinical profile and risk factors were recorded. Outcomes and associated risk factors at 12 and 36 months after stroke were assessed by sex. Hypertension, diabetes mellitus, dyslipidemias, and obesity prevalence rates were higher in women than in men; opposite trends were found for smoking and alcohol consumption. The mortality rate at 12 months after stroke was significantly greater in men than in women (23.3% versus 16.6%, P = .015). Large-artery atherothrombotic and cardioembolic stroke subtypes were risk factors for mortality, recurrence, and dependency in both sexes. In men, atrial fibrillation was a risk factor of mortality at 12 months after stroke (relative ratio [RR], 2.12; 95% confidence interval [CI], 1.38-3.27), but obesity was a protective factor of mortality at 36 months after stroke (RR, .30; 95% CI, .10-.94). However, in women, atrial fibrillation was a risk factor of recurrence at 12 months (RR, 2.32; 95% CI, 1.31-4.12) and dependency at 36 months after stroke (RR, 7.68; 95% CI, 1.60-36.82). We assessed sex differences in stroke outcomes and associated risk factors at 12 and 36 months after stroke in a large hospital-based stroke registry of elderly patients from Northern China. Thus, it is crucial to emphasize risk management to elderly patients to reduce mortality, recurrence, and dependency after stroke.


Asunto(s)
Envejecimiento , Isquemia Encefálica/complicaciones , Caracteres Sexuales , Accidente Cerebrovascular/epidemiología , Accidente Cerebrovascular/etiología , Anciano , Anciano de 80 o más Años , China , Femenino , Estudios de Seguimiento , Humanos , Masculino , Estudios Retrospectivos , Factores de Riesgo , Accidente Cerebrovascular/complicaciones , Accidente Cerebrovascular/mortalidad , Tasa de Supervivencia , Factores de Tiempo
14.
Stroke ; 45(6): 1626-31, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24736241

RESUMEN

BACKGROUND AND PURPOSE: Sex differences in secular trends of stroke incidence are rarely reported. We aimed to explore sex differences in incidence and mortality of stroke in rural China from 1992 to 2012. METHODS: In 1992, 14 920 residents were recruited to participate in the Tianjin Brain Study, a population-based study on stroke surveillance. Stroke events and all deaths were annually registered. RESULTS: We observed 908 incident strokes (366 in women) from 1992 to 2012. Women were significantly younger than men (64±12 versus 68±11 years) in 1992 to 1998 (P=0.024). The incidence of first-ever stroke per 100 000 person-years for men was 166 in 1992 to 1998, 227 in 1999 to 2005, and 376 in 2006 to 2012; for women, the rates were 86 (1992-1998), 148 (1999-2005), and 264 (2006-2012). From 1992 to 2012, the incidence grew annually by 5.8% in men and 8.0% in women. The male/female incidence ratio declined significantly: 1.9 in 1992 to 1998, 1.5 in 1999 to 2005, and 1.4 in 2006 to 2012. There were no significant sex differences in mortality. The prevalence of obesity and diabetes mellitus, the levels of total cholesterol and triglycerides, and the age of menopause and reproductive years in women concurrently increased in 2011. CONCLUSIONS: There was a significant increase in the incidence of first-ever stroke in women annually and a declining trend in the male/female rate ratio in rural China during the past 21 years. These results suggest that stroke will become one of the major diseases affecting women in future decades in China.


Asunto(s)
Pueblo Asiatico , Población Rural , Caracteres Sexuales , Accidente Cerebrovascular/mortalidad , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , China/epidemiología , Complicaciones de la Diabetes/mortalidad , Femenino , Humanos , Incidencia , Masculino , Menopausia , Persona de Mediana Edad , Obesidad/complicaciones , Obesidad/mortalidad , Prevalencia , Estudios Retrospectivos , Accidente Cerebrovascular/etiología
15.
ACS Nano ; 18(12): 8863-8875, 2024 Mar 26.
Artículo en Inglés | MEDLINE | ID: mdl-38416566

RESUMEN

Efficient catalysts are needed to accelerate the conversion and suppress the shuttling of polysulfides (LiPSs) to promote the further development of lithium-sulfur (Li-S) batteries. Intermetallic niobium boride (NbB2) has indefinite potential due to superior catalytic activity. Nonetheless, the lack of a rational understanding of catalysis creates a challenge for the design of catalysts. Herein, a NbB2/reduced graphene oxide-modified PP separator (NbB2/rGO/PP) is rationally designed. Essential, an in-depth insight into the catalysis mechanism of NbB2 toward LiPSs is established based on experiments and multiperspective measurement characterization, ab initio molecular dynamics (AIMD), and density functional theory (DFT). It has been uncovered that the actual catalyst that interacts with LiPSs in NbB2 is the passivated surface with an oxide layer (O2-NbB2), which occurs through B-O-Li and Nb-O-Li bonds, rather than the clean NbB2 surface. And the decomposition barrier of Li2S is greatly reduced by a substantial margin, dropping from 3.390 to 0.93 and 0.85 eV on the Nb-O and B-O surfaces, respectively, with fast Li+ diffusivity. Consequently, the cell with NbB2/rGO/PP as a functional separator achieves a high discharge capacity of 873 mAh g-1 at 1C after 100 cycles. Moreover, the benefits of NbB2/rGO/PP can be effectively maintained even at a high sulfur loading of 7.06 mg cm-2 without significant reduction and with a low electrolyte/sulfur ratio of 8 µL mg-1s. This study enhances our understanding of the catalytic mechanism of Li-S systems and presents a promising approach for developing electrocatalysts that are resilient to poisoning.

16.
J Chin Polit Sci ; : 1-22, 2023 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-37359767

RESUMEN

Despite the massive amount of data and sophisticated computing capacity, Big Tech has evolved into the new data sovereigns that governments must accept in the data era. Data mining and application determine the true value of data; in this regard, Big Tech is tough to replace. The so-called "Fourth Industrial Revolution" is reshaping the emerging global order, and at its core are Big Tech firms. They not only express their concerns and spread their values and ideologies but also make their strong presence felt in international affairs, as Big Tech appears to be transforming into a new type of Leviathan. With access to significant amounts of data, the rise of Big Tech poses a challenge to sovereignty's exclusivity and superiority, assuming the position of de facto data sovereign. The article holds that the Big Tech firms, by virtue of their technical advantages, have not only deconstructed the traditional concept of sovereignty, but also formed a complex symbiotic relationship.

17.
Nanoscale ; 15(32): 13459-13465, 2023 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-37548298

RESUMEN

Developing efficient and stable oxygen reduction reaction (ORR) catalysts to replace the precious Pt/C is very important for the industrial application of proton-exchange membrane fuel cells. Herein, using bismuth-based metal-organic frameworks as the substrate to disperse copper ions, we prepared a catalyst containing both Cu single atoms and Cu nanoparticles (CuSACuNP/BiCN) by a pyrolysis method. In 0.1 M KOH electrolyte, the electrocatalytic ORR performance of CuSACuNP/BiCN was superior to that of commercial Pt/C. With a hierarchical porous architecture, CuSACuNP/BiCN displayed a half-wave potential of 0.86 V vs. RHE and a diffusion-limiting current density of 5.82 mA cm-2 with a four-electron transfer process. In addition, it was stable during a 12-hour durability test. This study provides guidance for the synthesis of advanced Cu-based nano-single-atom catalytic materials for ORR applications.

18.
ACS Appl Mater Interfaces ; 15(22): 26363-26372, 2023 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-37232289

RESUMEN

Nanozymes with high activity and stability have emerged as a potential alternative to natural enzymes in the past years, but the relationship between the electronic metal-support interactions (EMSI) and catalytic performance in nanozymes still remains unclear. Herein, a copper nanoparticle nanozyme supported on N-doped Ti3C2Tx (Cu NPs@N-Ti3C2Tx) is successfully synthesized and the modulation of EMSI is achieved by introducing N species. The stronger EMSI between Cu NPs and Ti3C2Tx, involving electronic transfer and an interface effect, is revealed by X-ray photoelectron spectroscopy, soft X-ray absorption spectroscopy, and hard X-ray absorption fine spectroscopy at the atomic level. Consequently, Cu NPs@N-Ti3C2Tx nanozyme exhibits remarkable peroxidase-like activity, surpassing its counterpart (Cu NPs, Ti3C2Tx, Cu NPs-Ti3C2Tx), suggesting that EMSI significantly enhances catalytic performance. Benefiting from the excellent performance, the colorimetric platform based on Cu NPs@N-Ti3C2Tx nanozyme for detecting astaxanthin is constructed and shows a wide linear detection range of 0.01-50 µM and a limit of detection of 0.015 µM in the sunscreens. Density functional theory is further conducted to reveal that the excellent performance is ascribed to the stronger EMSI. This work opens an avenue for studying the influence of EMSI toward catalytic performance of nanozyme.


Asunto(s)
Cobre , Nanopartículas , Cobre/química , Titanio , Nitrógeno , Nanopartículas/química , Antioxidantes , Peroxidasas
19.
ACS Nano ; 17(21): 21838-21849, 2023 Nov 14.
Artículo en Inglés | MEDLINE | ID: mdl-37909679

RESUMEN

The electrochemical nitrogen reduction reaction (eNRR) under mild conditions emerges as a promising approach to produce ammonia (NH3) compared to the typical Haber-Bosch process. Herein, we design an asymmetrically coordinated p-block antimony single-atom catalyst immobilized on nitrogen-doped Ti3C2Tx (Sb SA/N-Ti3C2Tx) for eNRR, which exhibits ultrahigh NH3 yield (108.3 µg h-1 mgcat-1) and excellent Faradaic efficiency (41.2%) at -0.3 V vs RHE. Complementary in situ spectroscopies with theoretical calculations reveal that the nitrogen-bridged two titanium atoms triggered by an adjacent asymmetrical Sb-N1C2 moiety act as the active sites for facilitating the protonation of the rate-determining step from *N2 to *N2H and the kinetic conversion of key intermediates during eNRR. Moreover, the introduction of Sb-N1C2 promotes the formation of oxygen vacancies to expose more titanium sites. This work presents a strategy for single-atom-decorated ultrathin two-dimensional materials with the aim of simultaneously enhancing NH3 yield and Faradaic efficiency for electrocatalytic nitrogen reduction.

20.
Adv Sci (Weinh) ; 10(29): e2303206, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37547975

RESUMEN

Despite the desirability of metal-organic frameworks (MOFs) as heterogeneous photocatalysts, current strategies available to enhance the performance of MOF photocatalysts are complicated and expensive. Herein, a simple strategy is presented for improving the activity of MOF photocatalysts by regulating the atomic interface structure of the metal active sites on the MOF. In this study, MOF (PCN-222) is hybridized with cellulose acetate (CA@PCN-222) through an optimized atomic interface strategy, which lowers the average valence state of Zr ions. The electronic metal-support interaction mechanism of CA@PCN-222 is revealed by evaluating the photocatalytic CO2 reduction reaction (CO2 RR). The experimental results suggested that the electron migration efficiency at the atomic interface of the MOFs strongly coupled with cellulose is significantly improved. In particular, the CO2 RR to formate activity of CA@PCN-222 photocatalyst greatly increased from 778.2 to 2816.0 µmol g-1 compared with pristine PCN-222 without cellulose acetate. The findings suggest that the strongly coupled metal-ligand moiety at the atomic interface of MOFs may play a synergistic role in heterogeneous catalysts.

SELECCIÓN DE REFERENCIAS
Detalles de la búsqueda