Publications by authors named "Xi-Wen Du"

The interaction of defects has been proven effective in regulating the mechanical properties of structural materials, while its influence on the physicochemical performance of functional materials has been rarely reported. Herein, we synthesized Ag nanorods with dense stacking faults and investigated how the defect interaction affects the catalytic properties. We found that the stacking faults can couple with each other to form a unique structure of opposite atoms with extortionately high tensile strain.

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A zinc-infiltration process was adopted to prepare silver-doped copper nanosheet arrays. The larger atomic radius of Ag introduces tensile stress, which lowers the electron density at the s-orbitals of Cu atoms and improves the adsorption capability for hydrogen atoms. As a catalyst for hydrogen evolution, these silver doped copper nanosheet arrays achieved a low overpotential of 103 mV at 10 mA cm in 1 M KOH, which is 604 mV lower than that of pure copper foil.

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Single-crystal planes are ideal platforms for catalytic research. In this work, rolled copper foils with predominantly (220) planes were used as the starting material. By using temperature gradient annealing, which caused grain recrystallization in the foils, they were transformed to those with (200) planes.

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Article Synopsis
  • Free energy calculation of small molecules or ions in water is crucial for electrochemistry, but traditional methods often have limitations due to their reliance on complex ab initio approaches.
  • The authors developed a hybrid method combining ab initio molecular dynamics (AIMD) with an implicit solvent model, utilizing a small water cluster around the ion to accurately compute ion solvation energy.
  • Their results show excellent agreement with experimental data for solvation voltages and energies, and they also obtained important hydration properties like radial pair distribution functions, while highlighting some remaining challenges with their method.
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The work function can serve as a characteristic quantity to evaluate the catalytic activity due to its relationship with the surface structure of a material. However, what factors determine the influence of the work function on the electrochemical performance are still unclear. Herein, we elucidate the effect of the work function of Ag on the electrochemical reduction of CO to CO by controlling the ratio of exposed crystalline planes.

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Article Synopsis
  • Metallic materials with special surface structures are in demand due to their unique properties, but creating bulk materials with specific crystal faces at the nanoscale is challenging.
  • The study presents a new method that combines ion implantation and oxidation-etching to modify the surface of a copper plate, exposing Cu(100) crystal planes.
  • The resulting Cu plate shows improved catalytic performance in hydrogen evolution reactions, requiring only 273 mV to achieve a current density of 10 mA/cm, indicating better efficiency due to its unique surface structure.
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A self-supported silver electrode was prepared by plasma spraying and used for catalysing the hydrogen evolution reaction. Thanks to the non-equilibrium synthetic conditions, the silver catalyst exposes high-energy (200) crystal planes, which enhance the adsorption of hydrogen and improve the intrinsic catalytic activity. As a result, the silver catalyst delivers an overpotential of 349 mV at 10 mA cm, which was much lower than those of Ag foil (742 mV) and commercial Ag powder (657 mV).

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Article Synopsis
  • - The text discusses the development of a highly active copper catalyst for the hydrogen evolution reaction (HER) by using friction stir welding (FSW), which creates high-energy surfaces.
  • - FSW effectively mixes iron and copper, leading to a transformation of iron phases that facilitates the growth of energy-efficient copper planes, enhancing the catalyst's performance compared to platinum.
  • - The study highlights that the high-energy surface structure allows better adsorption of hydrogen, improving HER efficiency, and positions FSW as a cost-effective method for large-scale catalyst production.
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As a metal-free photocatalyst, graphitic carbon nitride (g-CN) shows great potential for photocatalytic water splitting, although its performance is significantly limited by structural defects due to incomplete polymerization. In the present work, we successfully synthesize highly conjugated g-CN nanofoam through an iodide substitution technique. The product possesses a high polymerization degree, low defect density, and large specific surface area; as a result, it achieves a hydrogen evolution rate of 9.

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The surface of an electrocatalyst undergoes dynamic chemical and structural transformations under electrochemical operating conditions. There is a dynamic exchange of metal cations between the electrocatalyst and electrolyte. Understanding how iron in the electrolyte gets incorporated in the nickel hydroxide electrocatalyst is critical for pinpointing the roles of Fe during water oxidation.

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Engineering high-performance electrocatalysts is of great importance for energy conversion and storage. As an efficient strategy, element doping has long been adopted to improve catalytic activity, however, it has not been clarified how the valence state of dopant affects the catalytic mechanism and properties. Herein, it is reported that the valence state of a doping element plays a crucial role in improving catalytic performance.

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Metallic catalysts with nanopores are advantageous on improving both activity and selectivity, while the reason behind that remains unclear all along. In this work, porous Zn nanoparticles (P-Zn) were adopted as a model catalyst to investigate the catalytic behavior of metallic nanopores. In situ X-ray absorption spectroscopy, in situ Fourier transform infrared spectroscopy, and density functional theory (DFT) analyses reveal that the concave surface of nanopores works like a pincer to capture and clamp CO and H O precursors simultaneously, thus lowering the energy barriers of CO electroreduction.

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Water electrolysis in alkaline electrolyte is an attractive way toward clean hydrogen energy via the hydrogen evolution reaction (HER), whereas the sluggish water dissociation impedes the following hydrogen evolution. Noble metal oxides possess promising capability for catalyzing water dissociation and hydrogen evolution; however, they are never utilized for the HER due to the instability under the reductive potential. Here it is shown that compressive strain can stabilize RhO clusters and promote their catalytic activity.

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Phase engineering of nanomaterials (PEN) offers a promising route to rationally tune the physicochemical properties of nanomaterials and further enhance their performance in various applications. However, it remains a great challenge to construct well-defined crystalline@amorphous core-shell heterostructured nanomaterials with the same chemical components. Herein, the synthesis of binary (Pd-P) crystalline@amorphous heterostructured nanoplates using Cu P nanoplates as templates, via cation exchange, is reported.

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Article Synopsis
  • - This study focuses on creating cost-effective and efficient photocatalysts for water splitting to convert solar energy into hydrogen fuel, eliminating the need for expensive noble metal co-catalysts.
  • - The researchers used an intense laser method to create L-NiCo nanosheets from a nickel-cobalt alloy, which have a specific nonstoichiometric composition that enhances their performance in sunlight.
  • - The resulting photocatalyst achieved a hydrogen production rate of 1.7 μmol/h under standard sunlight conditions and demonstrated an apparent quantum yield of 1.38% at a wavelength of 380 nm.
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Architecting grain crystallographic orientation can modulate charge distribution and chemomechanical properties for enhancing the performance of polycrystalline battery materials. However, probing the interplay between charge distribution, grain crystallographic orientation, and performance remains a daunting challenge. Herein, we elucidate the spatially resolved charge distribution in lithium layered oxides with different grain crystallographic arrangements and establish a model to quantify their charge distributions.

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Engineering surface structure of catalysts is an efficient way towards high catalytic performance. Here, we report on the synthesis of regular iridium nanospheres (Ir NSs), with abundant atomic steps prepared by a laser ablation technique. Atomic steps, consisting of one-atom level covering the surface of such Ir NSs, were observed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) The prepared Ir NSs exhibited remarkably enhanced activity both for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acidic medium.

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The electroreduction of carbon dioxide (CO ) toward high-value fuels can reduce the carbon footprint and store intermittent renewable energy. The iodide-ion-assisted synthesis of porous copper (P-Cu) microspheres with a moderate coordination number of 7.7, which is beneficial for the selective electroreduction of CO into multicarbon (C ) chemicals is reported.

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  • FeCo2O4 nanoparticles were created using a technique called laser fragmentation, which leads to the formation of oxygen vacancies.
  • These oxygen vacancies help lower energy barriers, making it easier for reactions to occur.
  • This improvement boosts both the oxygen evolution and reduction reactions at the same time.
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The practical scale-up of renewable energy technologies will require catalysts that are more efficient and durable than present ones. This is, however, a formidable challenge that will demand a new capability to tailor the electronic structure. Here, an original electronic structure tailoring of CoO by Ni and Zn dual doping is reported.

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Introduction of lattice strain into catalysts is a facile way to modify catalytic behaviour. Here, we report the synthesis of Pd nanoparticles with compressive strain by pulsed laser ablation of a Pd target immersed in an aqueous solution. The intensive quenching effect induces obvious compressive strain which improves the ORR performance of the Pd nanoparticles significantly.

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Low-cost and high-performance catalysts are of great significance for electrochemical water splitting. Here, it is reported that a laser-synthesized catalyst, porous Co Ni (OH) nanosheets, is highly active for catalyzing overall water splitting. The porous nanosheets exhibit low overpotentials for hydrogen evolution reaction (95 mV@10 mA cm ) and oxygen evolution reaction (235 mV@10 mA cm ).

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Oxygen evolution reaction (OER) is a pivotal reaction in many technologies for renewable energy, such as water splitting, metal-air batteries, and regenerative fuel cells. However, this reaction is known to be kinetically sluggish and proceeds at rather high overpotential due to the universal scaling relationship, namely, the adsorption energies of intermediates are linearly correlated and cannot be optimized simultaneously. Several approaches have been proposed to break the scaling relationship by introducing additional active sites; however, positive experimental results are still absent.

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Article Synopsis
  • A hybrid electrocatalyst called CoO/r-NLG was created using pyrolysis of cobalt iron precursors and N-doped graphene.
  • * It features a high density of pyridinic-N-Co bonds which enhances its performance.
  • * This electrocatalyst demonstrated excellent reversible oxygen reduction and evolution reactions, with a low efficiency loss of 0.635 V in a potassium hydroxide solution.
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