Publications by authors named "Hengyue Xu"

Innovations in self-assembly and aggregate engineering have led to membranes that better balance water permeability with salt rejection, overcoming traditional trade-offs. Here we demonstrate a strategy that uses multivalent H-bond interactions at the nano-confined space to manipulate controllable and organized crystallization. Specifically, we design amphiphilic oligomers featuring hydrophobic segments with strongly polar end-capped motifs.

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Atomic hydrogen (H*) plays a crucial role in electrochemical reduction technology towards various environmental and energy applications, but suffers from low utilization efficiency arisen from the undesirable H-H dimerization and the competitive adsorption between water molecule with reactants on the traditional adjacent catalytic sites. Herein, we anchored Pd single atoms on the naturally formed titanium oxide of titanium foam to construct Pd-O-Ti dual-site electrocatalyst with spatially isolated water dissociation and H* utilization site, which synchronously inhibits the H-H dimerization and the competitive adsorption of water molecule and targeted reactants. Experiments and theoretical calculations revealed that the Ti-O sites could synergistically dissociate water to H*, which overflowed to nearby Pd single-atom sites for designed reduction reactions and utilization benefiting from the hydrogen spillover ability of titanium oxide substrate.

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Inert hexagonal boron nitride (h-BN) is a prominent two-dimensional material known for its wide bandgap, thermal stability, and biocompatibility, but it resists functionalization due to strong B-N bonds. This study presents a method to fluorinate h-BN via cryomilling, resulting in ∼30 atom % fluorine loading (F-dBN). This modification prevents the formation of C-F bonds associated with adverse health effects, enhances biocompatibility, and introduces electron-withdrawing properties that improve the material's chemical reactivity and antibacterial efficiency while significantly reducing its bandgap from 5.

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The coupling of fast redox kinetics, high-energy density, and prolonged lifespan is a permanent aspiration for aqueous rechargeable zinc batteries, but which has been severely hampered by a narrow voltage range and suboptimal compatibility between the electrolytes and electrodes. Here, we unprecedentedly introduced an electric ambipolar effect for synergistic manipulation on Zn ternary-hydrated eutectic electrolyte (ZTE) enabling high-performance Zn-Br batteries. The electric ambipolar effect motivates strong dipole interactions among hydrated perchlorates and bipolar ligands of L-carnitine (L-CN) and sulfamide, which reorganized primary cations solvation sheath in a manner of forming Zn[(L-CN)(SA)(HO)] configuration and dynamically restricting desolvated HO molecules, thus ensuring a broadened electrochemical window of 2.

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Reducing green hydrogen production cost is critical for its widespread application. Proton-exchange-membrane water electrolyzers are among the most promising technologies, and significant research has been focused on developing more active, durable, and cost-effective catalysts to replace expensive iridium in the anode. Ruthenium oxide is a leading alternative while its stability is inadequate.

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Persulfates-based advanced oxidation processes are highly efficient in degrading refractory organic contaminants in wastewater. However, their practical application is often limited by the extensive consumption of catalysts and oxidants. Therefore, constructing catalysts with abundant and efficient reaction interfaces is essential for improving the efficiency of persulfate activation.

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Article Synopsis
  • Tetrahedral, pyramidal, and octahedral metal-oxygen coordinated ligands are key to metal-oxide structures, with their behavior during electrochemical oxidation being critical yet underexplored.
  • A study links oxygen-evolving performance to structural properties of model oxides, finding that pyramidal structures are more vulnerable to hydroxide (OH) attacks, leading to transformation into active amorphous CoOOH.
  • The research proposes an ion-tuning strategy to improve both activity and stability in metal oxides, addressing the challenge of balancing performance and structural durability in electrochemical applications.
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  • Encapsulating noble metal species in zeolites can improve the performance and efficiency of catalysts used in thermal and environmental reactions, particularly with Ru which is a cost-effective alternative.
  • The study developed a method combining hydrothermal processes and stepwise calcination to stabilize Ru clusters within MFI-type zeolite, leveraging special sites for better integration.
  • Results indicate that the unique environment created by the Ru clusters and MFI enhances catalytic activity for alkane oxidation even at low temperatures, while maintaining stability up to 1000°C, thus providing important insights for future catalyst design.
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Managing the redox reactions of polysulfides is crucial for improving the performance of lithium-sulfur batteries (LSBs). Herein, we introduce a progressive theoretical framework: the balanced d-band model, which is based on classical d-band center theory. Specifically, by optimizing the position of the d-band center in the middle between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of each sulfur species, balanced and fast oxidation and reduction reactions of the sulfur species can be achieved simultaneously.

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Locking molecular conformation are widely applied in molecular engineering for improved performance. However, locking via organic functional groups often changes the original molecular properties. Following the rigidity and stability of ionic interaction in ionic compounds, we suggested the use of a molecular-scale ionic compound, calcium carbonate oligomer, as a robust molecular segment to functionalize organic molecules.

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  • Nitrogen activation is crucial for sustainable ammonia production, and this study examines the efficiency of Group VIII single-atom catalysts anchored on MoS using density functional theory (DFT).
  • Osmium anchored on MoS (Os@MoS) is identified as the most effective catalyst due to its high nitrogen activation and low nitrogen reduction reaction overpotential (0.624 V), aided by an "electron drift" effect that weakens the N ≡ N bond.
  • The research reveals that orbital interactions significantly contribute to N activation, and it proposes a framework to design more efficient catalysts, showcasing the potential of Os@MoS for sustainable ammonia synthesis.
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Article Synopsis
  • * Metal-organic frameworks (MOFs) are highlighted as effective materials for enhancing electrochemical sensors due to their large surface area and customizable properties.
  • * The review discusses the advancements in MOF-based materials for detecting heavy metal ions, outlines various synthesis and modification techniques, and addresses current challenges and future prospects in this field.
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1D layered nanowires (NWs) are expected to be excellent electrode materials due to their efficient electron/ion transport and strain/stress relaxation. However, it is a great challenge to synthesize layered NWs by a top-down synthetic route. Herein, ultralong 1D layered KMnPS NWs (length: >100 µm; diameter: ≈300 nm) are synthesized for the first time using "K-ion chemical scissors", whose excellent sodium storage performance originates from the bifunctional structural unit, ingeniously combining the alloying energy storage functional unit (P-P dimer) with the quasi-intercalated functional unit ([MnS] framework).

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Aqueous zinc-iodine batteries (AZIBs) are highly appealing for energy requirements owing to their safety, cost-effectiveness, and scalability. However, the inadequate redox kinetics and severe shuttling effect of polyiodide ions impede their commercial viability. Herein, several Zn-MOF-derived porous carbon materials are designed, and the further preparation of iron-doped porous carbon (Fe-N-C, M9) with varied Fe doping contents is optimized based on a facile self-assembly/carbonization approach.

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Background: The invasion of luminal antigens and an aberrant immune response resulting from a disrupted physical epithelial barrier are the key characteristics of ulcerative colitis (UC). The restoration of damaged epithelial function is crucial for maintaining mucosal homeostasis and disease quiescence. Current therapies for UC primarily focus on suppressing inflammation.

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Reversible protonic ceramic electrochemical cells (R-PCECs) offer the potential for high-efficiency power generation and green hydrogen production at intermediate temperatures. However, the commercial viability of R-PCECs is hampered by the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) within conventional air electrodes operating at reduced temperatures. To address this challenge, this work introduces a novel approach based on the simultaneous optimization of bulk-phase metal-oxygen bonds and in-situ formation of a metal oxide nano-catalyst surface modification.

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Rationally designed defects in a crystal can confer unique properties. This study showcases a novel dual-defects engineering strategy to tailor the electrochemical response of metal-organic framework (MOF) materials used for electrochemical energy storage. Salicylic acid (SA) is identified as an effective modulator to control MOF-74 growth and induce structural defects, and cobalt cation doping is adopted for introducing a second type of defect.

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The detection of monoamine neurotransmitters is of paramount importance as the neurotransmitters are the chemical messengers regulating the gut-brain axis (GBA). It requires real-time, ultrasensitive, and selective sensing of the neurotransmitters in the gastric/intestinal fluid. However, multi-components present in the gastric/intestinal fluid make sensing challenging to achieve in terms of ultra-high sensitivity and selectivity.

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In this study, we analyzed the species in a model electrolyte consisting of a lithium salt, lithium bis(trifluoromethane sulfone)imide (LiTFSI), and a widely used neutral solvent propylene carbonate (PC) with excess infrared (IR) spectroscopy, ab initio molecular dynamics simulations (AIMD), and quantum chemical calculations. Complexing species including the charged ones [Li(PC), TFSI, TFSI(PC), TFSI(PC), and Li(TFSI)] are identified in the electrolyte. Quantum chemical calculations show strong Li···O(PC) interaction, which suggests that Li would transport in the mode of solvation-carriage.

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Efficient water dissociation to atomic hydrogen (H*) with restrained recombination of H* is crucial for improving the H* utilization for electrochemical dechlorination, but is currently limited by the lack of feasible electrodes. Herein, we developed a monolithic single-atom electrode with Co single atoms anchored on the inherent oxide layer of titanium foam (Co-TiO/Ti), which can efficiently dissociate water into H* and simultaneously inhibit the recombination of H*, by taking advantage of the single-atom reverse hydrogen spillover effect. Experimental and theoretical calculations demonstrated that H* could be rapidly generated on the oxide layer of titanium foam, and then overflowed to the adjacent Co single atom for the reductive dechlorination.

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Oligosaccharide degradation products of alginate (AOS) hold significant potential in diverse fields, including pharmaceuticals, health foods, textiles, and agricultural production. Enzymatic alginate degradation is appealing due to its mild conditions, predictable activity, high yields, and controllability. However, the alginate degradation often results in a complex mixture of oligosaccharides, necessitating costly purification to isolate highly active oligosaccharides with a specific degree of polymerization (DP).

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Investigations into lithium-sulfur batteries (LSBs) has focused primarily on the initial conversion of lithium polysulfides (LiPSs) to Li S . However, the subsequent solid-solid reaction from Li S to Li S and the Li S decomposition process should be equally prioritized. Creating a virtuous cycle by balancing all three chemical reaction processes is crucial for realizing practical LSBs.

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Here, by introducing polystyrenesulfonate (PSS) as a multifunctional bridging molecule to synchronously coordinate the interaction between the precursor and the structure-directing agent, we developed a mesoporous conductive polymer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) featuring adjustable size in the range of 105-1836 nm, open nanochannels, large specific surface area (105.5 m g), and high electrical conductivity (172.9 S cm).

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Stable cathodes with multiple redox-active centres affording a high energy density, fast redox kinetics and a long life are continuous pursuits for aqueous zinc-organic batteries. Here, we achieve a high-performance zinc-organic battery by tuning the electron delocalization within a designed fully conjugated two-dimensional hydrogen-bonded organic framework as a cathode material. Notably, the intermolecular hydrogen bonds endow this framework with a transverse two-dimensional extended stacking network and structural stability, whereas the multiple C = O and C = N electroactive centres cooperatively trigger multielectron redox chemistry with super delocalization, thereby sharply boosting the redox potential, intrinsic electronic conductivity and redox kinetics.

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Producing indispensable hydrogen and oxygen for social development via water electrolysis shows more prospects than other technologies. Although electrocatalysts have been explored for centuries, a universal activity descriptor for both hydrogen-evolution reaction (HER) and oxygen-evolution reaction (OER) is not yet developed. Moreover, a unifying concept is not yet established to simultaneously understand HER/OER mechanisms.

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