Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 155
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Nature ; 633(8028): 58-62, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39232150

RESUMO

The canonical theory for planet formation in circumstellar disks proposes that planets are grown from initially much smaller seeds1-5. The long-considered alternative theory proposes that giant protoplanets can be formed directly from collapsing fragments of vast spiral arms6-11 induced by gravitational instability12-14-if the disk is gravitationally unstable. For this to be possible, the disk must be massive compared with the central star: a disk-to-star mass ratio of 1:10 is widely held as the rough threshold for triggering gravitational instability, inciting substantial non-Keplerian dynamics and generating prominent spiral arms15-18. Although estimating disk masses has historically been challenging19-21, the motion of the gas can reveal the presence of gravitational instability through its effect on the disk-velocity structure22-24. Here we present kinematic evidence of gravitational instability in the disk around AB Aurigae, using deep observations of 13CO and C18O line emission with the Atacama Large Millimeter/submillimeter Array (ALMA). The observed kinematic signals strongly resemble predictions from simulations and analytic modelling. From quantitative comparisons, we infer a disk mass of up to a third of the stellar mass enclosed within 1″ to 5″ on the sky.

2.
Small ; : e2404598, 2024 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-39291878

RESUMO

The endowment of metal organic frameworks (MOF) with superior electrocatalytic performance without compromising their structural/compositional superiorities is of great significance for the development of renewable energy devices, yet remains a grand challenge. Herein, a deliberate partial amorphization strategy is developed to construct a heterostructured electrocatalyst consisting of crystalline Co-MOF and amorphous Co-S nanoflake arrays aligned on the carbon cloth (CC) substrate (abbreviated as Co-MOF/Co-S@CC hereafter) through a rapid sulfuration method. The simultaneous implement of crystalline-amorphous (c-a) heterostructure and nanoflake arrayed architecture on CC substrate renders the Co-MOF/Co-S@CC with abundant and tight active sites, accelerated charge transfer rate, regulated electronic structures, and reinforced structural stability. As such, the obtained Co-MOF/Co-S@CC electrode demonstrates outstanding electrochemical hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances with the overpotentials of 64 and 217 mV at 10 mA cm-2, respectively. Moreover, a two-electrode electrolyzer assembled by Co-MOF/Co-S@CC electrodes exhibits the lower cell voltages and larger current densities than those of Pt/C and RuO2 counterparts, excellent reversibility and prominent long-term stability, representing a great prospect for feasible H2 production. This adopted concept of c-a heterostructure for electronic regulation may bring about insightful inspiration for designing high-performance electrocatalysts for sustainable energy systems.

3.
Chemistry ; : e202402930, 2024 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-39269730

RESUMO

Sp2-carbon (sp2-c) covalent organic frameworks (COFs), featuring distinctive π-conjugated network structures, facilitate the migration of photo-generated carriers, rendering them exceptionally appealing for applications in photoelectrochemical water splitting. However, owing to the powdery nature of COFs, leaving anchor the sp2-c COFs powder tightly onto a conductive substrate challenging. Here, we propose a method for preparing photoactive substance-conductive substrate integrated photocathodes through copper surface-mediated knoevenagel polycondensation (Cu-SMKP), this approach results in a uniform and stable sp2-c COF film, directly grown on commercial copper foam (COFTh-Cu). The COFTh-Cu demonstrates a high H2-evolution photocurrent density of 56 µA cm-2 at 0.3 V versus RHE, sustaining stability for 12 hours. The as-prepared COFTh-Cu represents a 4.5-fold increase in current density compared to traditional spin-coating methods and outperforms most COF photocathodes without cocatalysts. This innovative copper surface-mediated approach for preparing photocathodes opens up a crucial pathway towards the realization of highly active COF photocathodes.

4.
FASEB J ; 37(12): e23295, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37984844

RESUMO

C-natriuretic peptide (CNP) is the central regulator of oocyte meiosis progression, thus coordinating synchronization of oocyte nuclear-cytoplasmic maturation. However, whether CNP can independently regulate cytoplasmic maturation has been long overlooked. Mitochondrial DNA (mtDNA) accumulation is the hallmark event of cytoplasmic maturation, but the mechanism underlying oocyte mtDNA replication remains largely elusive. Herein, we report that CNP can directly stimulate oocyte mtDNA replication at GV stage, and deficiency of follicular CNP may contribute largely to lower mtDNA copy number in in vitro matured oocytes. The mechanistic study showed that cAMP-PKA-CREB1 signaling cascade underlies the regulatory role of CNP in stimulating mtDNA replication and upregulating related genes. Of interest, we also report that CNP-NPR2 signaling is inhibited in aging follicles, and this inhibition is implicated in lower mtDNA copy number in oocytes from aging females. Together, our study provides the first direct functional link between follicular CNP and oocyte mtDNA replication, and identifies its involvement in aging-associated mtDNA loss in oocytes. These findings, not only update the current knowledge of the functions of CNP in coordinating oocyte maturation but also present a promising strategy for improving in vitro fertilization outcomes of aging females.


Assuntos
DNA Mitocondrial , Técnicas de Maturação in Vitro de Oócitos , Feminino , Humanos , DNA Mitocondrial/genética , Peptídeo Natriurético Tipo C/genética , Peptídeo Natriurético Tipo C/farmacologia , Oócitos/fisiologia , Meiose , Peptídeos Natriuréticos/genética , Vasodilatadores
5.
Biotechnol Bioeng ; 121(1): 53-70, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-37691172

RESUMO

Recombinant adeno-associated virus (rAAV) is rapidly emerging as the preferred delivery vehicle for gene therapies, with promising advantages in safety and efficacy. Key challenges in systemic in-vivo rAAV gene therapy applications are the gap in production capabilities versus potential market demand and complex production process. This review summarizes current available information on rAAV upstream manufacturing processes and proposed optimizations for production. The advancements in rAAV production media were reviewed with proposals to speed up the cell culture process development. Furthermore, major methods for genetic element delivery to host cells were summarized with their advantages, limitations, and future directions for optimization. In addition, culture vessel selection criteria were listed based on production cell system, scale, and development stage. Process control at the production step was also outlined with an in-depth understanding of production kinetics and quality control.


Assuntos
Dependovirus , Vetores Genéticos , Vetores Genéticos/genética , Dependovirus/genética , Técnicas de Cultura de Células , Terapia Genética
6.
Anal Bioanal Chem ; 2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-39085422

RESUMO

Hydrolytic nanozyme-based visual colorimetry has emerged as a promising strategy for the detection of aluminum ions. However, most studies focus on simulating the structure of natural enzymes while neglecting to regulate the rate of hydrolysis-related steps, leading to low enzyme-like activity for hydrolytic nanozymes. Herein, we constructed a ruthenium dioxide (RuO2) in situ embedded cerium oxide (CeO2) nanozyme (RuO2/CeO2) with a Lewis acid-base pair (Ce-O-Ru-OH), which can simulate the catalytic behavior of phosphatase (PPase) and can be quantitatively quenched by Al3+ to achieve accurate and sensitive Al3+ colorimetric sensing detection. The incorporation of Ru into CeO2 nanorods accelerates the dissociation of H2O, followed by subsequent combination of hydroxide species to Lewis acidic Ce-O sites. This synergistic effect facilitates substrate activation and significantly enhances the hydrolysis activity of the nanozyme. The results show that the RuO2/CeO2 nanozyme exhibits a limit of detection as low as 0.5 ng/mL. We also demonstrate their efficacy in detecting Al3+ in various practical food samples. This study offers novel insights into the advancement of highly sensitive hydrolytic nanozyme engineering for sensing applications.

7.
Angew Chem Int Ed Engl ; 63(5): e202313599, 2024 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-37891153

RESUMO

Heterogeneous catalysts with targeted functionality can be designed with atomic precision, but it is challenging to retain the structure and performance upon the scaled-up manufacturing. Particularly challenging is to ensure the "atomic economy", where every catalytic site is most gainfully utilized. Given the emerging synergistic integration of human- and artificial intelligence (AI)-driven augmented designs (AD), augmented analytics (AA), and augmented reality manufacturing (AM) platforms, this minireview focuses on single-atom heterogeneous catalysts (SAHCs) and examines the current status, challenges, and future perspectives of translating atomic-level structural precision and data-driven discovery to next-generation industrial manufacturing. We critically examine the atomistic insights into structure-driven SAHCs functionality and discuss the opportunities and challenges on the way towards the synergistic human-AI collaborative data-driven platform capable of monitoring, analyzing, manufacturing, and retaining the atomic-scale structure and functions. Enhanced by the atomic-level AD, AA, and AM, evolving from the current high-throughput capabilities and digital materials manufacturing acceleration, this synergistic human-AI platform is promising to enable atom-efficient and atomically precise heterogeneous catalyst production.

8.
Angew Chem Int Ed Engl ; : e202409125, 2024 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-39115054

RESUMO

Coordination engineering strategy for optimizing the catalytic performance of single-atom catalysts (SACs) has been rapidly developed over the last decade. However, previous reports on copper SACs for nitrate reduction reactions (NO3RR) have mostly focused on symmetric coordination configurations such as Cu-N4 and Cu-N3. In addition, the mechanism in terms of the regulation of coordination environment and catalytic properties of SACs has not been well demonstrated. Herein, we disrupted the local symmetric structure of copper atoms by introducing unsaturated heteroatomic coordination of Cu-O and Cu-N to achieve the coordination desymmetrization of Cu-N1O2 SACs. The Cu-N1O2 SACs exhibit an efficient nitrate-to-ammonia conversion with a high FE of ~96.5 % and a yield rate of 3120 µg NH3 h-1 cm-2 at -0.60 V vs RHE. As indicated by in situ Raman spectra, the catalysts facilitate the accumulation of NO3 - and the selective adsorption of *NO2, which were further confirmed by the theoretical study of surface dipole moment and orbital hybridization. Our work illustrated the correlation between the coordination desymmetrization and the catalytic performance of copper SACs for NO3RR.

9.
J Biol Chem ; 298(1): 101456, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34861240

RESUMO

Well-orchestrated maternal-fetal cross talk occurs via secreted ligands, interacting receptors, and coupled intracellular pathways between the conceptus and endometrium and is essential for successful embryo implantation. However, previous studies mostly focus on either the conceptus or the endometrium in isolation. The lack of integrated analysis impedes our understanding of early maternal-fetal cross talk. Herein, focusing on ligand-receptor complexes and coupled pathways at the maternal-fetal interface in sheep, we provide the first comprehensive proteomic map of ligand-receptor pathway cascades essential for embryo implantation. We demonstrate that these cascades are associated with cell adhesion and invasion, redox homeostasis, and the immune response. Candidate interactions and their physiological roles were further validated by functional experiments. We reveal the physical interaction of albumin and claudin 4 and their roles in facilitating embryo attachment to endometrium. We also demonstrate a novel function of enhanced conceptus glycolysis in remodeling uterine receptivity by inducing endometrial histone lactylation, a newly identified histone modification. Results from in vitro and in vivo models supported the essential role of lactate in inducing endometrial H3K18 lactylation and in regulating redox homeostasis and apoptotic balance to ensure successful implantation. By reconstructing a map of potential ligand-receptor pathway cascades at the maternal-fetal interface, our study presents new concepts for understanding molecular and cellular mechanisms that fine-tune conceptus-endometrium cross talk during implantation. This provides more direct and accurate insights for developing potential clinical intervention strategies to improve pregnancy outcomes following both natural and assisted conception.


Assuntos
Histonas , Útero , Animais , Implantação do Embrião/fisiologia , Endométrio/metabolismo , Feminino , Histonas/metabolismo , Ligantes , Gravidez , Proteômica , Ovinos , Útero/metabolismo
10.
Circulation ; 146(20): 1518-1536, 2022 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-36102189

RESUMO

BACKGROUND: Direct cardiac reprogramming of fibroblasts into cardiomyocytes has emerged as a promising strategy to remuscularize injured myocardium. However, it is insufficient to generate functional induced cardiomyocytes from human fibroblasts using conventional reprogramming cocktails, and the underlying molecular mechanisms are not well studied. METHODS: To discover potential missing factors for human direct reprogramming, we performed transcriptomic comparison between human induced cardiomyocytes and functional cardiomyocytes. RESULTS: We identified TBX20 (T-box transcription factor 20) as the top cardiac gene that is unable to be activated by the MGT133 reprogramming cocktail (MEF2C, GATA4, TBX5, and miR-133). TBX20 is required for normal heart development and cardiac function in adult cardiomyocytes, yet its role in cardiac reprogramming remains undefined. We show that the addition of TBX20 to the MGT133 cocktail (MGT+TBX20) promotes cardiac reprogramming and activates genes associated with cardiac contractility, maturation, and ventricular heart. Human induced cardiomyocytes produced with MGT+TBX20 demonstrated more frequent beating, calcium oscillation, and higher energy metabolism as evidenced by increased mitochondria numbers and mitochondrial respiration. Mechanistically, comprehensive transcriptomic, chromatin occupancy, and epigenomic studies revealed that TBX20 colocalizes with MGT reprogramming factors at cardiac gene enhancers associated with heart contraction, promotes chromatin binding and co-occupancy of MGT factors at these loci, and synergizes with MGT for more robust activation of target gene transcription. CONCLUSIONS: TBX20 consolidates MGT cardiac reprogramming factors to activate cardiac enhancers to promote cardiac cell fate conversion. Human induced cardiomyocytes generated with TBX20 showed enhanced cardiac function in contractility and mitochondrial respiration.


Assuntos
Fármacos Cardiovasculares , Reprogramação Celular , Mitocôndrias , Contração Miocárdica , Miócitos Cardíacos , Proteínas com Domínio T , Humanos , Reprogramação Celular/efeitos dos fármacos , Reprogramação Celular/genética , Reprogramação Celular/fisiologia , Cromatina/genética , Cromatina/metabolismo , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Fibroblastos/fisiologia , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitocôndrias/fisiologia , Miocárdio/metabolismo , Miocárdio/patologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/fisiologia , Proteínas com Domínio T/genética , Proteínas com Domínio T/metabolismo , Contração Miocárdica/efeitos dos fármacos , Contração Miocárdica/genética , Contração Miocárdica/fisiologia , Fármacos Cardiovasculares/farmacologia , Fármacos Cardiovasculares/uso terapêutico
11.
Small ; 19(41): e2302738, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37291982

RESUMO

Metal-organic frameworks (MOFs) and their derivatives have attracted much attention in the field of photo/electrocatalysis owing to their ultrahigh porosity, tunable properties, and superior coordination ability. Regulating the valence electronic structure and coordination environment of MOFs is an effective way to enhance their intrinsic catalytic performance. Rare earth (RE) elements with 4f orbital occupancy provide an opportunity to evoke electron rearrangement, accelerate charged carrier transport, and synergize the surface adsorption of catalysts. Therefore, the integration of RE with MOFs makes it possible to optimize their electronic structure and coordination environment, resulting in enhanced catalytic performance. In this review, progress in current research on the use of RE-modified MOFs and their derivatives for photo/electrocatalysis is summarized and discussed. First, the theoretical advantages of RE in MOF modification are introduced, with a focus on the roles of 4f orbital occupancy and RE ion organic coordination ligands. Then, the application of RE-modified MOFs and their derivatives in photo/electrocatalysis is systematically discussed. Finally, research challenges, future opportunities, and prospects for RE-MOFs are also discussed.

12.
Small ; 19(10): e2206781, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36534826

RESUMO

The rational design of ingenious strategies to boost the intrinsic activity and stability of ruthenium (Ru) is of great importance for the substantial progression of water electrolysis technology. Based on Mott-Schottky effect, electronic regulation within a metal/semiconductor hybrid electrocatalyst represents a versatile strategy to boost the electrochemical performance. Herein, a typical Mott-Schottky hydrogen evolution reaction (HER) electrocatalyst composed of uniform ultrafine Ru nanoclusters in situ anchored on N-doped carbon nanofibers (abbreviated as Ru@N-CNFs hereafter) through a feasible and scalable "phenolic resin-bridged" strategy is reported. Both spectroscopy analyses and density functional theory calculations manifest that such rectifying contact can induce the spontaneous electron transfer from Ru to N-doped carbon nanofibers to generate a built-in electric field, thus enormously promoting the charge transfer efficiency and HER intrinsic activity. Moreover, the seamless immobilization of Ru nanoclusters on the substrate can prevent the active sites from unfavorable migration, coarsening, and detachment, rendering the excellent structural stability. Consequently, the well-designed Ru@N-CNFs afford prominent pH-universal HER performances with small overpotentials of 16 and 17 mV at 10 mA cm-2 and low Tafel slopes of 31.8 and 28.5 mV dec-1 in acidic and alkaline electrolytes, respectively, which are superior to the state-of-the-art commercial Pt/C and Ru/C benchmarks.

13.
Small ; 19(28): e2301324, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37005337

RESUMO

The design of economical, efficient, and robust bifunctional oxygen electrocatalysts is greatly imperative for the large-scale commercialization of rechargeable Zn-air battery (ZAB) technology. Herein, the neoteric design of an advanced bifunctional electrocatalyst composed of CoN/Co3 O4 heterojunction hollow nanoparticles in situ encapsulated in porous N-doped carbon nanowires (denoted as CoN/Co3 O4 HNPs@NCNWs hereafter) is reported. The simultaneous implementation of interfacial engineering, nanoscale hollowing design, and carbon-support hybridization renders the synthesized CoN/Co3 O4 HNPs@NCNWs with modified electronic structure, improved electric conductivity, enriched active sites, and shortened electron/reactant transport pathways. Density functional theory computations further demonstrate that the construction of a CoN/Co3 O4 heterojunction can optimize the reaction pathways and reduce the overall reaction barriers. Thanks to the composition and architectural superiorities, the CoN/Co3 O4 HNPs@NCNWs exhibit distinguished oxygen reduction reaction and oxygen evolution reaction performance with a low reversible overpotential of 0.725 V and outstanding stability in KOH medium. More encouragingly, the homemade rechargeable liquid and flexible all-solid-state ZABs utilizing CoN/Co3 O4 HNPs@NCNWs as the air-cathode deliver higher peak power densities, larger specific capacities, and robust cycling stability, exceeding the commercial Pt/C + RuO2 benchmark counterparts. The concept of heterostructure-induced electronic modification herein may shed light on the rational design of advanced electrocatalysts for sustainable energy applications.

14.
Small ; 19(5): e2206531, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36445024

RESUMO

Layered double-hydroxide (LDH) has been considered an important class of electrocatalysts for the oxygen evolution reaction (OER), but the adsorption-desorption behaviors of oxygen intermediates on its surface still remain unsatisfactory. Apart from transition-metal doping to solve this electrocatalytic problem of LDH, rare-earth (RE) species have sprung up as emerging dopants owing to their unique 4f valence-electronic configurations. Herein, the Er is chosen as a RE model to improve OER activity of LDH via constructing nickel foam supported Er-doped NiFe-LDH catalyst (Er-NiFe-LDH@NF). The optimal Er-NiFe-LDH@NF exhibits a low overpotential (191 mV at 10 mA cm-2 ), high turnover frequency (0.588 s-1 ), and low activation energy (36.03 kJ mol-1 ), which are superior to Er-free sample. Electrochemical in situ Raman spectra reveal the facilitated transition of Ni-OH into Ni-OOH for promoted OER kinetics through the Er doping effect. Theoretical calculations demonstrate that the introduction of Er facilitates the spin crossover of valence electrons by optimizing the d band center of NiFe-LDH, which leads to the GO -GHO closer to the optimal activity of the kinetic OER volcano by balancing the bonding strength of *O and *OH. Moreover, the Er-NiFe-LDH@NF presents high practicability in electrochemical water-splitting devices with a low driving potential of and a well-extended driving period.

15.
Small ; 19(45): e2303329, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37438567

RESUMO

The development of atomically dispersed iron-nitrogen-carbon (Fe─N─C) catalysts as an alternative to precious platinum holds great potential for the substantial progress of a variety of oxygen reduction reaction (ORR)-associated energy conversion technologies. Nevertheless, the precise synthesis of Fe─N─C single atomic catalysts (SACs) with a high density of accessible active sites and pronounced electrocatalytic performance still remains an enormous challenge. Herein, an innovative extended Stöber method is designed for the controllable preparation of monodisperse small-sized N-doped carbon colloidal nanospheres (≈40 nm) anchoring atomically isolated Fe─N4 sites (abbreviated as Fe-SA@N-CNSs hereafter) with a narrow size distribution and high uniformity. Benefiting from the single Fe─N4 moieties and the unique spherical carbon substrate, the resultant Fe-SA@N-CNSs exhibit excellent ORR activity, outstanding long-term durability, and methanol tolerance in KOH electrolyte. More impressively, when further assembled into a flexible solid-state rechargeable zinc-air battery (ZAB), the Fe-SA@N-CNSs-driven ZAB delivers a higher open circuit voltage, a larger power density, and robust cycling/mechanical stability, outperforming the state-of-the-art Pt/C-based counterpart and further testifying the great potential of the as-prepared Fe-SA@N-CNSs in diverse ORR-related practical energy devices. The developed extended Stöber method provides an efficient and versatile avenue toward the preparation of a series of well-defined SACs for diverse electrocatalytic systems.

16.
Chemistry ; 29(41): e202301252, 2023 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-37194695

RESUMO

Exploring efficient, affordable and stable electrocatalyst toward hydrogen evolution reaction (HER) is of great scientific significance for the practical implementation of the water splitting. The heteroatom doping represents a serviceable strategy to further elevate the catalytic performance for a transition metal-based electrocatalyst because of the electronic regulation effect. Herein, a reliable self-sacrificial template-engaged approach is proposed to synthesize O-doped CoP (denoted as O-CoP) microflowers, which simultaneously considers the regualtion of electronic configuration via anion doping and sufficient exposure of active sites via nanostructure engineering. The suitable O incorporation content in CoP matrix could tremendously modify the electronic configuration, accelerate the charge transfer, promote the exposure of active sites, strengthen the electrical conductivity, and adjust the adsorption state of H*. Consequently, the optimized O-CoP microflowers with optimal O concentration display a remarkable HER property with a small overpotential of 125 mV to afford a current density of 10 mA cm-2 , a low Tafel slope of 68 mV dec-1 and long-term durability for 32 h under alkaline electrolyte, manifesting a considerable potential application for hydrogen production at large scale. The integration of anion incorporation and architecture engineering in this work will bring in a depth insight for the design of low-cost and effective electrocatalysts in energy conversion and storage systems.

17.
Chemistry ; 29(32): e202300398, 2023 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-37042548

RESUMO

Concave nanostructure with highly branched architecture and abundant step atoms is one kind of desirable materials for energy conversion devices. However, current synthetic strategies for non-noble metal-based NiCoP concave nanostructure still remain challenging. Herein, we demonstrate a site-selective chemical etching and subsequent phosphorating strategy to fabricate highly branched NiCoP concave nanocrosses (HB-NiCoP CNCs). The HB-NiCoP CNCs are consisted of six axial arms in three-dimensional space and each protruding arm is equipped with high-density atomic steps, ledges and kinks. As an electrocatalyst towards oxygen evolution reaction, the HB-NiCoP CNCs exhibit remarkably enhanced activity and stability, with small overpotential of 289 mV to reach 10 mA cm-2 , surpassing the NiCoP nanocages and commercial RuO2 . The superior OER performance of HB-NiCoP CNCs is originated from the highly branched concave structure, the synergistic effect between bimetal Ni and Co atoms, as well as the electronic structure modulation from P.


Assuntos
Braço , Níquel , Eletrônica , Oxigênio
18.
Angew Chem Int Ed Engl ; 62(52): e202314565, 2023 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-37943183

RESUMO

The active-site density, intrinsic activity, and durability of Pd-based materials for oxygen reduction reaction (ORR) are critical to their application in industrial energy devices. This work constructs a series of carbon-based rare-earth (RE) oxides (Gd2 O3 , Sm2 O3 , Eu2 O3 , and CeO2 ) by using RE metal-organic frameworks to tune the ORR performance of the Pd sites through the Pd-REx Oy interface interaction. Taking Pd-Gd2 O3 /C as a representative, it is identified that the strong coupling between Pd and Gd2 O3 induces the formation of the Pd-O-Gd bridge, which triggers charge redistribution of Pd and Gd2 O3 . The screened Pd-Gd2 O3 /C exhibits impressive ORR performance with high onset potential (0.986 VRHE ), half-wave potential (0.877 VRHE ), and excellent stability. Similar ORR results are also found for Pd-Sm2 O3 /C, Pd-Eu2 O3 /C, and Pd-CeO2 /C catalysts. Theoretical analyses reveal that the coupling between Pd and Gd2 O3 promotes electron transfer through the Pd-O-Gd bridge, which induces the antibonding-orbital occupancy of Pd-*OH for the optimization of *OH adsorption in the rate-determining step of ORR. The pH-dependent microkinetic modeling shows that Pd-Gd2 O3 is close to the theoretical optimal activity for ORR, outperforming Pt under the same conditions. By its ascendancy in ORR, the Pd-Gd2 O3 /C exhibits superior performance in Zn-air battery as an air cathode, implying its excellent practicability.

19.
Small ; 18(29): e2202782, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35754168

RESUMO

The precise and comprehensive manipulation of the component, size, and geometric nano-architecture of platinum-based electrocatalysts into porous and hollow structure can effectively impart the catalysts with substantially improved electrochemical performance, yet remain formidably challenging. Herein, a straightforward fabrication of porous platinum-copper alloyed nanobowls (abbreviated as Pt3 Cu NBs hereafter) assembled by ultrafine nanoparticles (≈2.9 nm) via a one-pot hydrothermal approach with the assistance of a structure-directing agent of N,N'-methylenebisacrylamide (MBAA) is reported. The involvement of MBAA plays a decisive role in the formation of Pt-MBAA complex solid nanospheres, which serve as the self-sacrificial reactive template for the deposition/growth of Pt3 Cu nanoparticles and the eventual formation of the asymmetric open-shelled nanobowls. Benefitting from the 3D sufficient accessibility of exterior/interior surfaces, high atom-utilization efficiency, and PtCu bimetallic alloy synergy, the self-supported Pt3 Cu NBs demonstrate remarkably enhanced activity, better anti-poisoning capability, and reinforced robustness for the methanol oxidation reaction (MOR) as compared with the commercial Pt black benchmark, exhibiting great application promises in practical fuel cell systems. It is envisaged that the innovative self-templated synthetic strategy outlined here may provide a perspective to design a range of porous bowl-shaped high-performance nanocatalysts.

20.
Small ; 18(35): e2204063, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35934833

RESUMO

Engineering Pt-free catalysts for hydrogen evolution reaction (HER) with high activity and stability is of great significance in electrochemical hydrogen production. Herein, in situ chemical H intercalation into ultrafine Pd to activate this otherwise HER-inferior material to form the ultrafine IrPdH hydride as an efficient and stable HER electrocatalyst is proposed. The formation of PdIrH depends on a new hydrogenation strategy via using ethanol as the hydrogen resource. It is demonstrated that H atoms in IrPdH originate from the OH and CH2  of ethanol, which fills the gap of ethanol as the hydrogen source for the preparation of Pd hydride. Thanks to the incorporation of H/Ir atoms and ultrafine structure, the IrPdH exhibits superior HER activity and stability in the whole pH range. The IrPdH delivers very low overpotentials of 14, 25 and 60 mV at a current density of 10 mA cm-2 respectively in 0.5 m H2 SO4 , 1 m KOH, and 1 m PBS electrolytes, which are much better than those of commercial Pt/C and most reported noble metal electrocatalysts. Theoretical calculations confirm that interstitial hydrogen availably refines the electronic density of Pd and Ir sites, which optimizes the adsorption of *H and leads to the significant enhancement of HER performance.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA