Tuning the reactivity of TiO_(2)layer with uniform distribution of Sub-5 nm Fe_(2)O_(3)particles via in situ voltage-assisted oxidation for robust catalytic reduction

The trade-off between efficiency and stability has limited the application of TiO_(2)as a catalyst due to its poor surface reactivity.Here,we present a modification of a TiO_(2)layer with highly stable Sub-5 nm Fe_(2)O_(3)nanoparticles(NP)by modulating its structure-surface reactivity relationship to attain efficiency-stability balance via a voltage-assisted oxidation approach.In situ simultaneous oxidation of the Ti substrate and Fe precursor using high-energy plasma driven by high voltage resulted in uniform distribution of Fe_(2)O_(3)NP embedded within porous TiO_(2)layer.Comprehensive surface characterizations with density functional theory demonstrated an improved electronic transition in TiO_(2)due to the presence of surface defects from reactive oxygen species and possible charge transfer from Ti to Fe;it also unexpectedly increased the active site in the TiO_(2)layer due to uncoordinated electrons in Sub-5 nm Fe_(2)O_(3)NP/TiO_(2)catalyst,thereby enhancing the adsorption of chemical functional groups on the catalyst.This unique embedded structure exhibited remarkable improvement in reducing 4-nitrophenol to 4-aminophenol,achieving approximately 99%efficiency in 20 min without stability decay after 20 consecutive cycles,outperforming previously reported TiO_(2)-based catalysts.This finding proposes a modified-electrochemical strategy enabling facile construction of TiO_(2)with nanoscale oxides extandable to other metal oxide systems.

Confinement and synergy effects of supported-confined bimetal catalysts with superior stability and catalytic activity

Bimetallic nanocrystals have attracted considerable attention because of their complicated systems,which are far superior to those of their individual constituents.A TiO_(2)-confined PtMnP bimetallic catalyst(PtMnP@TiO_(2)) was prepared using an ultrasonic-assisted coincident strategy,which demonstrated exceptional catalytic activity in the universal hydrogen evolution reaction (HER).Owing to the bimetallic synergistic effect and TiO_(2) confinement,PtMnP@TiO_(x)showed ultrasmall metal nanoparticles (NPs),a higher active Pt^(0) content,adequate activation at the porous surface,and abundant acid sites.Simulations were performed to visualize the strain properties of Mn and Pt during the bending process and demonstrate the high activity of Pt.The Pt-Mn bimetallic catalysts were enriched with Pt NPs,convoyed by electron transfer from Mn to Pt.Briefly,PtMnP@TiO_(2) showed robust evolution reaction activities (an overpotential of 220 mV at a current density of 10 mA cm^(-2) and a Tafel slope of 186 mV dec^(-1))and the ability to contrast stated catalysts without ultrasonication-plasma.This protocol revealed that the geometrical and electronic effects of Pt and P surrounding the Mn species in PtMnP@TiO_(2) were crucial for increasing the catalytic activity (99%) and durability (over 20 cycles),which were far superior to those of other reported catalysts.

Well-defined high entropy-metal nanoparticles:Detection of the multi-element particles by deep learning

Characterizing and control the chemical compositions of multi-element particles as single metal nanoparticles(mNPs) on the surfaces of catalytic metal oxide supports is challenging.This can be attributed to the heterogeneity and large size at the nanoscale,the poorly defined catalyst nanostructure,and thermodynamic immiscibility of the strongly repelling metallic elements.To address these challenges,an ultrasonic-assisted coincident electro-oxidation-reduction-precipitation(U-SEO-P) is presented to fabricate ultra-stable PtRuAgCoCuP NPs,which produces numerous active intermediates and induces strong metal-support interactions.To sort the active high-entropy mNPs,individual NPs are described on the support surface and the role of deep learning in understanding/predicting the features of PtRuAgCoCu@TiO_(x) catalysts is explained.Notably,this deep learning approach required minimal to no human input.The as-prepared PtRuAgCoCu@TiO_(x) catalysts can be used to catalyze various important chemical reactions,such as a high reduction conversion(100% in 30 s),with no loss of catalytic activity even after 20 cycles of nitroarene and ketone/aldehyde,which is several times higher than commercial Pt@TiO_(x) owing to individual PtRuAgCoCuP NPs on TiO_(x) surface.In this study,we present the "Totally Defined Catalysis" concept,which has enormous potential for the advancement of high-activity catalysts in the reduction of organic compounds.

Recent Advances in Multifunctional Reticular Framework Nanoparticles:A Paradigm Shift in Materials Science Road to a Structured Future

Porous organic frameworks(POFs)have become a highly sought-after research domain that offers a promising avenue for developing cutting-edge nanostructured materials,both in their pristine state and when subjected to various chemical and structural modifications.Metal–organic frameworks,covalent organic frameworks,and hydrogen-bonded organic frameworks are examples of these emerging materials that have gained significant attention due to their unique properties,such as high crystallinity,intrinsic porosity,unique structural regularity,diverse functionality,design flexibility,and outstanding stability.This review provides an overview of the state-of-the-art research on base-stable POFs,emphasizing the distinct pros and cons of reticular framework nanoparticles compared to other types of nanocluster materials.Thereafter,the review highlights the unique opportunity to produce multifunctional tailoring nanoparticles to meet specific application requirements.It is recommended that this potential for creating customized nanoparticles should be the driving force behind future synthesis efforts to tap the full potential of this multifaceted material category.

Experimental and theoretical investigation of high-entropy-alloy/support as a catalyst for reduction reactions

Control of chemical composition and incorporation of multiple metallic elements into a single metal nanoparticle(NP)in an alloyed or a phase-segregated state hold potential scientific merit;however,developing libraries of such structures using effective strategies is challenging owing to the thermodynamic immiscibility of repelling constituent metallic elements.Herein,we present a one-pot interfacial plasma-discharge-driven(IP-D)synthesis strategy for fabricating stable high-entropy-alloy(HEA)NPs exhibiting ultrasmall size on a porous support surface.Accordingly,an electric field was applied for 120 s to enhance the incorporation of multiple metallic elements(i.e.,CuAgFe,CuAgNi,and CuAgNiFe)into ally HEA-NPs.Further,NPs were attached to a porous magnesium oxide surface via rapid cooling.With solar light as the sole energy input,the CuAgNiFe catalyst was investigated as a reusable and sustainable material exhibiting excellent catalytic performance(100%conversion and 99% selectivity within1 min for a hydrogenation reaction)and consistent activity even after 20 cycles for a reduction reaction,considerably outperforming the majority of the conventional photocatalysts.Thus,the proposed strategy establishes a novel method for designing and synthesizing highly efficient and stable catalysts for the convertion of nitroarenes to anilines via chemical reduction.

Improving the electrochemical stability of AZ31 Mg alloy in a 3.5wt.%NaCl solution via the surface functionalization of plasma electrolytic oxidation coating

The unique interactions between hexadecanoic acid(HA)and albumin(ALB)molecules on the surface of the porous layer of AZ31 Mg alloy were exploited to fabricate a novel hybrid composite film with excellent electrochemical stability in a 3.5 wt.%Na Cl solution.Herein,the inorganic layer(IL)obtained by plasma electrolytic oxidation of AZ31 Mg alloy in an alkaline-phosphate-WO_(3)electrolyte was soaked in an organic solution composed of ALB and HA for 10 and 24 h at 60℃.Although albumin and HA may coexist on the same surface of IL,the higher reactivity of ALB molecules would prevent the formation of a thick layer of HA.The donor-acceptor complexes formed due to the unique interactions between ALB and/or HA and IL surface would reduce the area exposed to the corrosive species which in turn would efficiently protect the substrate from corrosion.The porous structure of the IL would provide preferable sites for the physical and chemical locking triggered by charge-transfer phenomena,leading to the inhomogeneous nucleation and crystal growth of a flowery flakes-like organic layer.DFT calculations were performed to reveal the primary bonding modes between the ALB,HA,and IL and to assess the mechanistic insights into the formation of such novel hybrid composites.

Fabrication of branch-like Aph@LDH-MgO material through organic-inorganic hybrid conjugation for excellent anti-corrosion performance

Layered double hydroxides(LDH)frameworks have shown significant enhancement in stability and reusability,and their tailorable architecture brings new insight into the development of the next generation of hybrid materials,which attracted considerable attention in many fields over the years.One of the factors contributing to the widespread applicability of layered double hydroxides is their adaptable composition,which can accommodate a wide spectrum of potential anionic guests.This exceptional property makes the LDH system simple to adjust for various applications.However,most LDH systems are synthesized in situ in an autoclave at high temperatures and pressures that severely restrict the industrial use of such coating systems.In this study,LDH was directly synthesized on a magnesium alloy that had undergone plasma electrolytic oxidation(PEO)treatment in the presence of ethylenediaminetetraacetic acid,thereby avoiding the use of hydrothermal autoclave conditions.This LDH system was compared with a hybrid architecture consisting of organic-inorganic self-assembly.An organic layer was fabricated on top of the LDH film using 4-Aminophenol(Aph)compound,resulting in a smart hierarchical structure that can provide a robust Aph@LDH film with excellent anti-corrosion performance.At the molecular level,the conjugation characteristics and adsorption mechanism of Aph molecule were studied using two levels of theory as follows.First,Localized orbit locator(LOL)-πisosurface,electrostatic potential(ESP)distribution,and average local ionization energy(ALIE)on the molecular surface were used to highlight localization region,reveal the favorable electrophilic and nucleophilic attacks,and clearly explore the type of interactions that occurred around interesting regions.Second,first-principles based on density functional theory(DFT)was applied to study the hybrid mechanism of Aph on LDH system and elucidate their mutual interactions.The experimental and computational analyses suggest that the highπ-electron density and delocalization characteristics of the functional groups and benzene ring in the Aph molecule played a leading role in the synergistic effects arising from the combination of organic and inorganic coatings.This work provides a promising approach to design advanced hybrid materials with exceptional electrochemical performance.

Electrochemical response of MgO/Co_(3)O_(4) oxide layers produced by plasma electrolytic oxidation and post treatment using cobalt nitrate

This work looked into the influence of the sealing treatment on the structural feature and electrochemical response of AZ31 Mg alloy coated via plasma electrolytic oxidation(PEO).Here,the inorganic layers produced by PEO in an alkaline-phosphate electrolyte were subsequently immersed for different periods in cold(60°C)and hot(100°C)aqueous solutions containing either 1 or 3 gr of cobalt nitrate hexahydrate in the presence of hydrogen peroxide as an initiator.The results showed that the sealing treatments in the hot solutions could trigger the hydration reactions of PEO coating which would largely assist the surface incorporation of Co_(3)O_(4)into the coating.In contrast,the sealing in cold solutions led to less compact coatings,which was attributed to the fact the hydration reactions would be restricted at 60°C.A nearly fully sealed coating with a porosity of~0.5%was successfully formed on the sample immersed in the hot solution containing 1 gr of cobalt nitrate hexahydrate.Thus,the electrochemical stability of this fully sealed coating was superior to the other samples as it had the lowest corrosion current density(4.71×10^(-10)A·cm^(-2))and the highest outer layer resistance(3.81×10^(7)Ω·cm^(2)).The composite coatings developed in this study are ideal for applications requiring high electrochemical stability.

Advanced prediction of organic–metal interactions through DFT study and electrochemical displacement approach

Heterocyclic compounds are the promising biological compounds as nature-friendly for the corrosion protection of metallic surface.In this work,three heterocyclic compounds such as 1-azanaphthalene-8-ol(8-AN),2-methylquinoline-8-ol(8-MQ),and 8-quinolinol-5-sulfonic acid(8-QSA)were used as green compounds,and their anti-corrosion performance for AZ31 Mg in saline water was discussed on the basis of impedance interpretation and surface analysis.Findings found that the electrochemical performance was improved in the order of 8-AN>8-MQ>8-QSA,demonstrating the electron donor effect of N-heterocycles to form coordination complexes on the magnesium surface.From the electrochemical performance,the protective layer constructed at the optimal concentration reinforces the barrier against aggressive environments,with potential inhibition efficiency of 87.4%,99.0%,and 99.9%for 8-QSA,8-MQ,and 8-AN,respectively.Quantum chemical parameters and electron density distribution for free organic species in the absence and presence of Mg^(2+)cation were evaluated using density functional theory(DFT).Upon the formation of coordination complexes between organic compound and Mg^(2+),energy gap underwent change about ΔE=5.7 eV in the 8-AN/Mg^(2+)system.Furthermore,the adsorption of heterocyclic compounds on Mg surface reveals the formation of strong covalent bonds with Mg atoms,which further confirmed by the electron density difference and projected density of states analyses.Based on theoretical calculations,three inhibitors can adsorb on the metal surface in both parallel and perpendicular orientations via C,O and N atoms.In the parallel configuration,the C-Mg,N-Mg and O-Mg bond distances are between 2.11 and 2.25˚A,whereas the distances in the case of perpendicular adsorption are between 2.20 and 2.40˚A(covalent bonds via O and N atoms).The results indicated that parallel configurations are energetically more stable,in which the adsorption energies are-4.48 eV(8-AN),-4.28 eV(8-MQ)and-3.82 eV(8-QSA)compared to that of perpendicular adsorption(-3.65,-3.40,and-2.63 eV).As a result,experimental and theoretical studies were in well agreement and confirm that the nitrogen and oxygen atoms will be the main adsorption sites.

Nucleation and growth behavior of coating film on Mg–Al–Zn alloy with different surface topographies via plasma electrolytic oxidation

This work was made to investigate how nucleation and growth behavior of the coating film were affected by surface topographies of Mg–Al–Zn alloy substrate during the initial stage of plasma electrolytic oxidation(PEO).To satisfy this end,a single substrate was prepared by mechanical treatment exhibiting rough and smooth regions with an equal area on the surface.The rough region with prominent hills and grooves induced the breakdown of passive film,which was indicated by an early appearance of plasma discharge on the rough region since nucleation of coating film occurred preferentially around the hills.However,the coating film grown on the grooves was somewhat thicker and more porous than the film grown on the hills and smooth regions.This was due to the fact that the growth of the coating film was found to be localized in the presence of rough region,which was in line with the discharge activities.Herein,the nucleation and growth behavior during the initial stage of PEO will be discussed schematically on the basis of microstructural interpretation.

Origin of the synergistic effects of bimetallic nanoparticles coupled with a metal oxide heterostructure for accelerating catalytic performance

Precisely tuning bicomponent intimacy during reactions by traditional methods remains a formidable challenge in the fabrication of highly active and stable catalysts because of the difficulty in constructing well-defined catalytic systems and the occurrence of agglomeration during assembly.To overcome these limitations,a PtRuPNiO@TiO_(x)catalyst on a Ti plate was prepared by ultrasound-assisted low-voltage plasma electrolysis.This method involves the oxidation of pure Ti metal and co-reduction of strong metals at 3000◦C,followed by sonochemical ultrasonication under ambient conditions in an aqueous solution.The intimacy of the bimetals in PtRuPNiO@TiOx is tuned,and the metal nanoparticles are uniformly distributed on the porous titania coating via strong metal-support interactions by leveraging the instantaneous high-energy input from the plasma discharge and ultrasonic irradiation.The intimacy of PtRuPNiO@TiO_(x)increases the electron density on the Pt surface.Consequently,the paired sites exhibit a high hydrogen evolution reaction activity(an overpotential of 220 mV at a current density of 10 mA cm^(−2)and Tafel slope of 186 mV dec^(−1)),excellent activity in the hydrogenation of 4-nitrophenol with a robust stability for up to 20 cycles,and the ability to contrast stated catalysts without ultrasonication and plasma electrolysis.This study facilitates industrially important reactions through synergistic chemical interactions.

Effect of Deformation Temperature on Microstructure and Mechanical Properties of AZ31 Mg Alloy Processed by Differential-Speed Rolling

A differential-speed rolling(DSR) was applied to AZ31 magnesium alloy sample at different rolling temperatures of 473,523,573,and 623 K with 1-pass and 2-pass operations.The microstructural evolution and mechanical properties of the deformed samples were investigated.The rolling temperature was found to be an important parameter affecting the microstructural development.After DSR at 473 K,the microstructure was more homogeneous than that obtained after deformation by equal-speed rolling(ESR).The fully recrystallized microstructures were generated after DSR at 573 and 623 K.As to mechanical properties,the yield strength(YS) and ultimate tensile strength(UTS) decreased monotonously with increasing rolling temperature.In contrast,the elongation of the DSR-deformed samples was improved as the rolling temperature increased.The strain hardening exponent(n) calculated by Hollomon equation increased with increasing the rolling temperature,which would explain an increase in the uniform elongation.

Plastic anisotropy calculation of severely-deformed Al-Mg-Si alloy considering texture changes in electron backscatter diffraction

The investigation studied the plastic anisotropy of the severely-deformed Al-Mg-Si alloy by considering texture changes.The sample deformed via asymmetrical rolling under cross-shear condition was annealed at 598 K where recrystallization was in progress.It is found upon annealing that the intensity of Cube({001}<100>)was comparable to those of plane-strain components while the intensities of shear components remained constant despite their instabilities in the recrystallization regime.After annealing,the average Lankford value(r)of the present sample was close to a unity whereas the in-plane anisotropy(△r)decreased,resulting in nearly isotropic characteristics of Al-Mg-Si alloy.

A Self‑Regenerable Fiber Sloughing Its Heavy Metal Skin for Ultrahigh Separation Capability

Developing efficient separation materials for recovering metal resources from aqueous environments is crucial for the sustainable water–food–energy nexus,which addresses the interdependence between energy production,water production,and energy consumption.Various material-based separation processes have demonstrated outstanding performance.However,electric energy and chemicals are used to frequently replace the separation materials used in such processes owing to their short life span.This study presents a methodology for designing the self-regenerable fiber(SRF)according to the types of metals through a self-regeneration model.The SRF can semi-permanently recover the metal resources from water through a repetitive adsorption–crystallization–detachment process of metal ions on its surface.The ionic metal resources are adsorbed and crystallized with the counter-anions on the SRF surface.Next,the metal crystals are self-detached from the SRF surface by the collision between the crystals and curvature and non-sticky surface of the SRF.Thus,a module containing the SRF maintains its metal recovery capability even during continuous injection of the metal solution without its replacement.These findings highlight the significance of interfacial engineering and further guide the rational design of energy/environmentally friendly resource recovery modules.