DSpace collection: 期刊論文

Bimetallic nanoalloys planted on super-hydrophilic carbon nanocages featuring tip-intensified hydrogen evolution electrocatalysis

Wed, 09 Jul 2025 04:05:24 GMT

title: Bimetallic nanoalloys planted on super-hydrophilic carbon nanocages featuring tip-intensified hydrogen evolution electrocatalysis abstract: The insufficient availability and activity of interfacial water remain a major challenge for alkaline hydrogen evolution reaction (HER). Here, we propose an “on-site disruption and near-site compensation” strategy to reform the interfacial water hydrogen bonding network via deliberate cation penetration and catalyst support engineering. This concept is validated using tip-like bimetallic RuNi nanoalloys planted on super-hydrophilic and high-curvature carbon nanocages (RuNi/NC). Theoretical simulations suggest that tip-induced localized concentration of hydrated K+ facilitates optimization of interfacial water dynamics and intermediate adsorption. In situ synchrotron X-ray spectroscopy endorses an H* spillover-bridged Volmer‒Tafel mechanism synergistically relayed between Ru and Ni. Consequently, RuNi/NC exhibits low overpotential of 12 mV and high durability of 1600 h at 10 mA cm‒2 for alkaline HER, and demonstrates high performance in both water electrolysis and chlor-alkali electrolysis. This strategy offers a microscopic perspective on catalyst design for manipulation of the local interfacial water structure toward enhanced HER kinetics.

Surmounting scaling relationship on Cu-base diatomic catalysts by geminal-site-induced synergistic effect for high-selectivity CO2 electrochemical reduction to CO

Wed, 09 Jul 2025 04:05:22 GMT

title: Surmounting scaling relationship on Cu-base diatomic catalysts by geminal-site-induced synergistic effect for high-selectivity CO2 electrochemical reduction to CO abstract: Cu-based nanomaterials are regarded as the most promising alternatives for catalyzing electrochemical CO2 reduction reactions (ECO2RR). However, its development is impeded by the low selectivity. Improving the selectivity of ECO2RR plays a key role in the commercialized progress of Cu-based nanomaterials. Herein, we screened out the most potential diatomic site from representative Cu-based diatomic catalysts (DACs) and their responsive single-atomic catalysts through theoretical calculations and experiments. The theoretical calculations revealed that the synergistic effect between the diatomic sites in Cu-Mn and Cu-Fe DACs can assist them to break through the limit of scaling relationship and realize the high-selectivity ECO2RR to CO. This was verified by the electrochemical measurements that the as-synthesized nitrogen-doped carbon-supported Cu-Mn and Cu-Fe DACs (Cu-Mn/NC and Cu-Fe/NC) delivered high Faraday efficiency of CO (FECO >90 %) at a wide potential range. Furthermore, the Cu-Mn/NC displayed remarkable mass activity of 1760 A g−1, which is about 27.3 times of a Cu single-atom catalyst, and catalytic stability that goes through a 30-h electrolytic process without current attenuation at −0.6 V. Our work suggests that this synergistic effect can be used as a viable and general strategy to design DACs with high-selectivity ECO2RR for desired products.

Interrogation of 3d Transition Bimetallic Nanocrystal Nucleation and Growth Using In Situ Electron Microscope and Synchrotron X-ray Techniques

Wed, 09 Jul 2025 04:05:21 GMT

title: Interrogation of 3d Transition Bimetallic Nanocrystal Nucleation and Growth Using In Situ Electron Microscope and Synchrotron X-ray Techniques abstract: Understanding the nucleation and growth mechanism of 3d transition bimetallic nanocrystals (NCs) is crucial to developing NCs with tailored nanostructures and properties. However, it remains a significant challenge due to the complexity of 3d bimetallic NCs formation and their sensitivity to oxygen. Here, by combining in situ electron microscopy and synchrotron X-ray techniques, we elucidate the nucleation and growth pathways of Fe–Ni NCs. Interestingly, the formation of Fe–Ni NCs emerges from the assimilation of Fe into Ni clusters together with the reduction of Fe–Ni oxides. Subsequently, these NCs undergo solid-state phase transitions, resulting in two distinct solid solutions, ultimately dominated by γ-Fe3Ni2. Furthermore, we deconvolve the interplays between local coordination and electronic state concerning the growth temperature. We directly visualize the oxidation-state distributions of Fe and Ni at the nanoscale and investigate their changes. This work may reshape and enhance the understanding of nucleation and growth in atomic crystallization.

WS2 Moiré Superlattices Supporting Au Nanoclusters and Isolated Ru to Boost Hydrogen Production

Wed, 09 Jul 2025 04:05:19 GMT

title: WS2 Moiré Superlattices Supporting Au Nanoclusters and Isolated Ru to Boost Hydrogen Production abstract: Maximizing the catalytic activity of single-atom and nanocluster catalysts through the modulation of the interaction between these components and the corresponding supports is crucial but challenging. Herein, guided by theoretical calculations, a nanoporous bilayer WS2 Moiré superlattices (MSLs) supported Au nanoclusters (NCs) adjacent to Ru single atoms (SAs) (Ru1/Aun-2LWS2) is developed for alkaline hydrogen evolution reaction (HER) for the first time. Theoretical analysis suggests that the induced robust electronic metal–support interaction effect in Ru1/Aun-2LWS2 is prone to promote the charge redistribution among Ru SAs, Au NCs, and WS2 MSLs support, which is beneficial to reduce the energy barrier for water adsorption and thus promoting the subsequent H2 formation. As feedback, the well-designed Ru1/Aun-2LWS2 electrocatalyst exhibits outstanding HER performance with high activity (η10 = 19 mV), low Tafel slope (35 mV dec−1), and excellent long-term stability. Further, in situ, experimental studies reveal that the reconstruction of Ru SAs/NCs with S vacancies in Ru1/Aun-2LWS2 structure acts as the main catalytically active center, while high-valence Au NCs are responsible for activating and stabilizing Ru sites to prevent the dissolution and deactivation of active sites. This work offers guidelines for the rational design of high-performance atomic-scale electrocatalysts.

Defect-Rich SnO2 Nanofiber as an Oxygen-Defect-Driven Photoenergy Shield against UV Light Cell Damage

Wed, 31 Jul 2024 04:07:48 GMT

title: Defect-Rich SnO2 Nanofiber as an Oxygen-Defect-Driven Photoenergy Shield against UV Light Cell Damage abstract: Usually, most studies focus on toxic gas and photosensors by using electrospinning and metal oxide polycrystalline SnO2 nanofibers (PNFs), while fewer studies discuss cell–material interactions and photoelectric effect. In this work, the controllable surface morphology and oxygen defect (VO) structure properties were provided to show the opportunity of metal oxide PNFs to convert photoenergy into bio-energy for bio-material applications. Using the photobiomodulation effect of defect-rich polycrystalline SnO2 nanofibers (PNFs) is the main idea to modulate the cell–material interactions, such as adhesion, growth direction, and reactive oxygen species (ROS) density. The VO structures, including out-of-plane oxygen defects (op-VO), bridge oxygen defects (b-VO), and in-plane oxygen defects (ip-VO), were studied using synchrotron analysis to investigate the electron transfer between the VO structures and conduction bands. These intragrain VO structures can be treated as generation-recombination centers, which can convert various photoenergies (365–520 nm) into different current levels that form distinct surface potential levels; this is referred to as the photoelectric effect. PNF conductivity was enhanced 53.6-fold by enlarging the grain size (410 nm2) by increasing the annealing temperature, which can improve the photoelectric effect. In vitro removal of reactive oxygen species (ROS) can be achieved by using the photoelectric effect of PNFs. Also, the viability and shape of human bone marrow mesenchymal stem cells (hMSCs-BM) were also influenced significantly by the photobiomodulation effect. The cell damage and survival rate can be prevented and enhanced by using PNFs; metal oxide nanofibers are no longer only environmental sensors but can also be a bio-material to convert the photoenergy into bio-energy for biomedical science applications.

Encaging Co nanoparticle in atomic CoN4-dispersed graphite nanopocket evokes high oxygen reduction activity for flexible Zn-air battery

Fri, 08 Mar 2024 04:07:20 GMT

title: Encaging Co nanoparticle in atomic CoN4-dispersed graphite nanopocket evokes high oxygen reduction activity for flexible Zn-air battery abstract: Rational design of oxygen reduction reaction (ORR) electrocatalysts with indestructible active sites for high-performance Zn-air batteries (ZABs) remains a significant challenge. Herein, we achieve an innovative active site design by encaging Co nanoparticles within the Co−N4 atomic sites-dispersed graphite nanopocket (CoSAs-NPs/NC), leading to outstanding alkaline ORR activity and stability, and consequently ultra-high power density of 193.8 mW cm–2 and specific capacity of 819.1 mAh gZn–1 at 10 mA cm–2 of a primary ZAB assembled, along with impressive power density of 73.4 mW cm–2 and charging/discharging stability up to 110 cycles of a flexible solid-state ZAB. Theoretical calculations unveil the enhanced ORR kinetics can be traced to the significantly optimized local electronic structure of Co−N4 sites with upshifted d-band center and reduced energy barrier of rate-limiting step by the encaged Co nanoparticle. This study showcases a creative conformational design for guiding the construction of valid synergy in hybridized metal/single-atom catalysts.

Strain-Controlled Intermetallic PtZn Nanoparticles via N-Doping Propel Highly Efficient Oxygen Reduction Electrocatalysis

Fri, 08 Mar 2024 04:07:19 GMT

title: Strain-Controlled Intermetallic PtZn Nanoparticles via N-Doping Propel Highly Efficient Oxygen Reduction Electrocatalysis abstract: Targeting high-performance yet cost-effective Pt-based catalysts with low Pt usage and high Pt utilization remains a big challenge in the oxygen reduction reaction (ORR) electrocatalysis. In this work, we demonstrate delicate engineering of strain control via N-doping in ordered PtZn intermetallic nanoparticles supported on N-doped carbon (PtZnN/NC). Benefiting from the ameliorated compressive strain and consequently greatly optimized electronic structures, PtZnN/NC displays ultrahigh ORR activity and durability in both acidic and alkaline media, with respective high mass activities of 297.5 and 80.7 A gPt–1 at 0.9 VRHE, exceeding those of benchmark Pt/C by 8.3- and 2.8-folds. Theoretical calculations reveal that the N-doping effectively lowers the d-band center of PtZnN, resulting in loose binding of *OH on the PtZnN surface, which facilitates the potential-determining step with a reduced energy barrier. This work successfully offers strategic guidance for strain equilibration in alloys via N-doping toward the rational design of advanced electrocatalysts.

Evolution of Superconductivity in K2-xFe4+ySe5: X-ray Absorption and Emission Spectroscopic Studies

Wed, 11 Oct 2023 04:05:32 GMT

title: Evolution of Superconductivity in K2-xFe4+ySe5: X-ray Absorption and Emission Spectroscopic Studies

Role of Interfacial Defects in Photoelectrochemical Properties of BiVO4 Coated on ZnO Nanodendrites: X-ray Spectroscopic and Microscopic Investigation

Wed, 11 Oct 2023 04:05:29 GMT

title: Role of Interfacial Defects in Photoelectrochemical Properties of BiVO4 Coated on ZnO Nanodendrites: X-ray Spectroscopic and Microscopic Investigation abstract: Synchrotron-based X-ray spectroscopic and microscopic techniques are used to identify the origin of enhancement of the photoelectrochemical (PEC) properties of BiVO4 (BVO) that is coated on ZnO nanodendrites (hereafter referred to as BVO/ZnO). The atomic and electronic structures of core–shell BVO/ZnO nanodendrites have been well-characterized, and the heterojunction has been determined to favor the migration of charge carriers under the PEC condition. The variation of charge density between ZnO and BVO in core–shell BVO/ZnO nanodendrites with many unpaired O 2p-derived states at the interface forms interfacial oxygen defects and yields a band gap of approximately 2.6 eV in BVO/ZnO nanocomposites. Atomic structural distortions at the interface of BVO/ZnO nanodendrites, which support the fact that there are many interfacial oxygen defects, affect the O 2p–V 3d hybridization and reduce the crystal field energy 10Dq ∼2.1 eV. Such an interfacial atomic/electronic structure and band gap modulation increase the efficiency of absorption of solar light and electron–hole separation. This study provides evidence that the interfacial oxygen defects act as a trapping center and are critical for the charge transfer, retarding electron–hole recombination, and high absorption of visible light, which can result in favorable PEC properties of a nanostructured core–shell BVO/ZnO heterojunction. Insights into the local atomic and electronic structures of the BVO/ZnO heterojunction support the fabrication of semiconductor heterojunctions with optimal compositions and an optimal interface, which are sought to maximize solar light utilization and the transportation of charge carriers for PEC water splitting and related applications.

Bandgap Shrinkage and Charge Transfer in 2D Layered SnS2 Doped with V for Photocatalytic Efficiency Improvement

Wed, 11 Oct 2023 04:05:26 GMT

title: Bandgap Shrinkage and Charge Transfer in 2D Layered SnS2 Doped with V for Photocatalytic Efficiency Improvement abstract: Effects of electronic and atomic structures of V-doped 2D layered SnS2 are studied using X-ray spectroscopy for the development of photocatalytic/photovoltaic applications. Extended X-ray absorption fine structure measurements at V K-edge reveal the presence of VO and VS bonds which form the intercalation of tetrahedral OVS sites in the van der Waals (vdW) gap of SnS2 layers. X-ray absorption near-edge structure (XANES) reveals not only valence state of V dopant in SnS2 is ≈4+ but also the charge transfer (CT) from V to ligands, supported by V Lα,β resonant inelastic X-ray scattering. These results suggest V doping produces extra interlayer covalent interactions and additional conducting channels, which increase the electronic conductivity and CT. This gives rapid transport of photo-excited electrons and effective carrier separation in layered SnS2. Additionally, valence-band photoemission spectra and S K-edge XANES indicate that the density of states near/at valence-band maximum is shifted to lower binding energy in V-doped SnS2 compare to pristine SnS2 and exhibits band gap shrinkage. These findings support first-principles density functional theory calculations of the interstitially tetrahedral OVS site intercalated in the vdW gap, highlighting the CT from V to ligands in V-doped SnS2.

Design of Ru-Ni diatomic sites for efficient alkaline hydrogen oxidation

Wed, 11 Oct 2023 04:05:22 GMT

title: Design of Ru-Ni diatomic sites for efficient alkaline hydrogen oxidation abstract: Anion exchange membrane fuel cells are limited by the slow kinetics of alkaline hydrogen oxidation reaction (HOR). Here, we establish HOR catalytic activities of single-atom and diatomic sites as a function of *H and *OH binding energies to screen the optimal active sites for the HOR. As a result, the Ru-Ni diatomic one is identified as the best active center. Guided by the theoretical finding, we subsequently synthesize a catalyst with Ru-Ni diatomic sites supported on N-doped porous carbon, which exhibits excellent catalytic activity, CO tolerance, and stability for alkaline HOR and is also superior to single-site counterparts. In situ scanning electrochemical microscopy study validates the HOR activity resulting from the Ru-Ni diatomic sites. Furthermore, in situ x-ray absorption spectroscopy and computational studies unveil a synergistic interaction between Ru and Ni to promote the molecular H2 dissociation and strengthen OH adsorption at the diatomic sites, and thus enhance the kinetics of HOR.

A single-atom library for guided monometallic and high-entropy designs

Wed, 11 Oct 2023 04:05:19 GMT

title: A single-atom library for guided monometallic and high-entropy designs

Temperature‐Dependent Structures of Single‐Atom Catalysts

Wed, 11 Oct 2023 04:05:16 GMT

title: Temperature‐Dependent Structures of Single‐Atom Catalysts abstract: Single-atom catalysts (SACs) have the unique coordination environment and electronic structure due to the quantum size effect, which plays an essential role in facilitating catalytic reactions. However, due to the limited understanding of the formation mechanism of single atoms, achieving the modulation of the local atomic structure of SACs is still difficult and challenging. Herein, we have prepared a series of Ni SACs loaded on nitrogen-doped carbon substrates with different parameters using a dissolution-and-carbonization method to systematically investigate the effect of temperature on the structure of the SACs. The results of characterization and electrochemical measurements are analyzed to reveal the uniform law between temperature and the metal loading, bond length, coordination number, valence state and CO2 reduction performance, showing the feasibility of controlling the structure of SACs through temperature to regulate the catalytic performance. This is important for the understanding of catalytic reaction mechanisms and the design of efficient catalysts.

Disordered Au Nanoclusters for Efficient Ammonia Electrosynthesis

Wed, 11 Oct 2023 04:05:11 GMT

title: Disordered Au Nanoclusters for Efficient Ammonia Electrosynthesis abstract: The electrochemical nitrogen (N2) reduction reaction (N2RR) under mild conditions is a promising and environmentally friendly alternative to the traditional Haber-Bosch process with high energy consumption and greenhouse emission for the synthesis of ammonia (NH3), but high-yielding production is rendered challenging by the strong nonpolar N≡N bond in N2 molecules, which hinders their dissociation or activation. In this study, disordered Au nanoclusters anchored on two-dimensional ultrathin Ti3C2Tx MXene nanosheets are explored as highly active and selective electrocatalysts for efficient N2-to-NH3 conversion, exhibiting exceptional activity with an NH3 yield rate of 88.3±1.7 μg h−1 mgcat.−1 and a faradaic efficiency of 9.3±0.4 %. A combination of in situ near-ambient pressure X-ray photoelectron spectroscopy and operando X-ray absorption fine structure spectroscopy is employed to unveil the uniqueness of this catalyst for N2RR. The disordered structure is found to serve as the active site for N2 chemisorption and activation during the N2RR process.

Chemically coupling SnO2 quantum dots and MXene for efficient CO2 electroreduction to formate and Zn–CO2 battery

Fri, 28 Jul 2023 04:05:12 GMT

title: Chemically coupling SnO2 quantum dots and MXene for efficient CO2 electroreduction to formate and Zn–CO2 battery abstract: Electrochemical conversion of CO2 into formate is a promising strategy for mitigating the energy and environmental crisis, but simultaneously achieving high selectivity and activity of electrocatalysts remains challenging. Here, we report low-dimensional SnO2 quantum dots chemically coupled with ultrathin Ti3C2Tx MXene nanosheets (SnO2/MXene) that boost the CO2 conversion. The coupling structure is well visualized and verified by high-resolution electron tomography together with nanoscale scanning transmission X-ray microscopy and ptychography imaging. The catalyst achieves a large partial current density of −57.8 mA cm−2 and high Faradaic efficiency of 94% for formate formation. Additionally, the SnO2/MXene cathode shows excellent Zn–CO2 battery performance, with a maximum power density of 4.28 mW cm−2, an open-circuit voltage of 0.83 V, and superior rechargeability of 60 h. In situ X-ray absorption spectroscopy analysis and first-principles calculations reveal that this remarkable performance is attributed to the unique and stable structure of the SnO2/MXene, which can significantly reduce the reaction energy of CO2 hydrogenation to formate by increasing the surface coverage of adsorbed hydrogen.

In situ TEM investigation of indium oxide/titanium oxide nanowire heterostructures growth through solid state reactions

Thu, 06 Jul 2023 04:05:34 GMT

title: In situ TEM investigation of indium oxide/titanium oxide nanowire heterostructures growth through solid state reactions abstract: Heterostructured TiO2/In2O3 nanowires have been extensively applied in various photonic devices; their performance is highly related to the microstructures, which has not been, however, clearly understood; thus, it is important to investigate the microstructural evolution of the material during processing. In this work, the crystallinity and microstructure of TiO2/In2O3 nanowires were successfully controlled with the variation of annealing temperatures via solid-state reactions. The dynamic phase transformation process was demonstrated by in situ transmission electron microscope (TEM). Moreover, the elemental information at different states was identified by energy dispersive spectroscopy (EDS). It is found that different annealing temperatures would contribute to different solid-state reactions and nanowire heterostructures. Additionally, photoresponse studies show characteristics enhancement for such nanoheterostructures. This study provides the knowledge of the fundamental science in kinetics of heterostructured nanostructures, which benefits the improvement of the performance for future photonic applications.

Enhancement in the Detection Ability of Metal Oxide Sensors Using Defect‐Rich Polycrystalline Nanofiber Devices

Tue, 21 Dec 2021 04:10:19 GMT

title: Enhancement in the Detection Ability of Metal Oxide Sensors Using Defect‐Rich Polycrystalline Nanofiber Devices abstract: The development of SnO2 and TiO2 polycrystalline nanofiber devices (PNFDs) has been widely researched as a method of protecting humans from household air pollution. PNFDs have three significant advantages. The nanofibers before the annealing process are polymer‐rich materials, which can be used as particulate material (PM) filters. The multiporous nanofibers fabricated by the annealing process have numerous defects that can serve as generation‐recombination centers for electron–hole pairs, enabling the PNFDs to serve as multiple‐wavelength light (from 365 to 940 nm) detectors. Lastly, the numerous surface/interface defects can drastically enhance the toxic gas detection ability. The toxic gas detection range of PNFDs for CO(g) and NO(g) is from 400 to 50 ppm and 400 to 50 ppb, respectively. Quick response times and recovery properties are key parameters for commercial applications. The recovery time of NO(g) detection can be improved from 1 ks to 40 s and the PNFD operating temperature lowered to 50 °C. These results indicate that SnO2 and TiO2 PNFDs have good potential for commercialization and use as toxic gas and photon sensors in daily lives.

The effect of turbulent viscous shear stress on red blood cell hemolysis

Thu, 11 Dec 2014 09:08:18 GMT

title: The effect of turbulent viscous shear stress on red blood cell hemolysis abstract: Non-physiologic turbulent flow occurs in medical cardiovascular devices resulting in hemodynamic stresses that may damage red blood cells (RBC) and cause hemolysis. Hemolysis was previously thought to result from Reynolds shear stress (RSS) in turbulent flows. A more recent hypothesis suggests that turbulent viscous shear stresses (TVSS) at spatial scales similar in size to RBCs are related to their damage. We applied two-dimensional digital particle image velocimetry to measure the flow field of a free-submerged axisymmetric jet that was utilized to hemolyze porcine RBCs in selected locations. Assuming a dynamic equilibrium for the sub-grid scale (SGS) energy flux between the resolved and the sub-grid scales, the SGS energy flux was calculated from the strain rate tensor computed from the resolved velocity fields. The SGS stress was determined by the Smagorinsky model, from which the turbulence dissipation rate and then TVSS were estimated. Our results showed the hemolytic threshold of the Reynolds stresses was up to 517 Pa, and the TVSSs were at least an order of magnitude less than the RSS. The results provide further insight into the relationship between turbulence and RBC damage.