This study explores the development of an organic-inorganic hybrid coating to enhance the corrosion resistance and photocatalytic properties of AZ31 Mg alloy modified by plasma electrolytic oxidation(PEO).The PEO proc...This study explores the development of an organic-inorganic hybrid coating to enhance the corrosion resistance and photocatalytic properties of AZ31 Mg alloy modified by plasma electrolytic oxidation(PEO).The PEO process typically generates a porous oxide layer,which can reduce corrosion protection by allowing corrosive agents to penetrate the substrate.To address this limitation,phenopyridine(PHEN)and 2-methylimidazole(2-IMD)were incorporated into the PEO surface to form a robust organic layer on the Mg alloy.Potassium hydroxide(KOH)was used to adjust the pH,improving the interaction and solubility between the organic molecules and the PEO coating.The hybrid coating exhibited unique twig-like surface structures that contributed to forming a multifunctional coating with high corrosion resistance and superior photocatalytic activity.The PEO-PHEN-2IMD sample on the Mg alloy demonstrated exceptional corrosion resistance,with the lowest corrosion current density(I_(corr))of 1.92×10^(-10) A/cm^(2),a high corrosion potential(E_(corr)),and the highest top layer resistance(R_(top))of 2.57×10^(6)Ω·cm^(2),indicating excellent barrier properties.Additionally,the coating achieved complete(100%)degradation of methylene blue(MB)within 30 min under visible light.Density Functional Theory(DFT)calculations provide deeper insights into the bonding mechanisms and interaction stability between PHEN,2-IMD,and the PEO layer on the Mg alloy and MB dye.These findings confirmed the enhanced performance of the hybrid coating in both corrosion resistance and photocatalytic applications.展开更多
Modulating metal-organic framework’s(MOF)crystallinity and size using a polymer,in conjunction with a high surface area of layered double hydroxide,yields an effective strategy for concurrently enhancing the electroc...Modulating metal-organic framework’s(MOF)crystallinity and size using a polymer,in conjunction with a high surface area of layered double hydroxide,yields an effective strategy for concurrently enhancing the electrochemical and photocatalytic performance.In this study,we present the development of an optimized nanocomposite,denoted as 0.5PVP/ZIF-67,developed on AZ31 magnesium alloy,serving as an efficient and durable multifunctional coating.This novel strategy aims to enhance the overall performance of the porous coating through the integration of microarc oxidation(MAO),ZnFe LDH backbone,and ZIF-67 formation facilitated by the addition of polyvinylpyrrolidone(PVP),resulting in a three-dimensional,highly efficient,and multifunctional material.The incorporation of 0.5 g of PVP proved to be effective in the size modulation of ZIF-67,which formed a corrosion-resistant top layer,improving the total polarization resistance(R_(p)=8.20×10^(8)).The dual functionality exhibited by this hybrid architecture positions it as a promising candidate for mitigating environmental pollution,degrading 97.93%of Rhodamine B dye in 45 min.Moreover,the sample displayed exceptional degradation efficiency(96.17%)after 5 cycles.This study illuminates the potential of nanocomposites as electrochemically stable and photocatalytically active materials,laying the foundation for the advancements of next-generation multifunctional frameworks.展开更多
The hybridization of metal-organic framework(MOF)with inorganic layers would lead to the discovery of novel hybrid materials that can provide a compelling strategy for enhancing its photocatalytic and electrochemical ...The hybridization of metal-organic framework(MOF)with inorganic layers would lead to the discovery of novel hybrid materials that can provide a compelling strategy for enhancing its photocatalytic and electrochemical response.In the present study,a highly efficient multifunctional hybrid material was developed by exploiting the defective layer formed on AZ31 Mg alloy through plasma electrolytic oxidation(PEO)as a nucleation and growth site for Co-MOF.The concentrations of the organic linker 2-Methylimidazole(2,MIm)and cobalt nitrate as a source of Co^(2+) ions were varied to control the growth of the obtained Co-MOF.Lower concentrations of the 2,MIm ligand favored the formation of leaf-like MOF structures through an anisotropic,two-dimensional growth,while higher concentrations led to rapid,isotropic nucleation and the creation of polyhedral Co-MOF structures.The sample characterized by polyhedral Co-MOF structures exhibited superior electrochemical stability,with the lowest corrosion current density(3.11×10^(-9) A/cm^(2))and the highest top layer resistance(2.34×10^(6)Ωcm^(2)),and demonstrated outstanding photocatalytic efficiency,achieving a remarkable 99.98%degradation of methylene blue,an organic pollutant,in model wastewater.To assess the active adsorption sites of the Co-MOF,density functional theory(DFT)was utilized.This study explores the changes in morphologies of the coatings of Co-MOF with the change of solution concentration to form coatings with enhanced properties on the metallic substrate,which could establish the groundwork for the development of next-generation multifunctional frameworks with diverse applications.展开更多
The self-assembly of hybrid inorganic-organic materials on stationary platforms plays a critical role in improving their structural stability and wide usability.In this work,a novel two-step hydrothermal approach is p...The self-assembly of hybrid inorganic-organic materials on stationary platforms plays a critical role in improving their structural stability and wide usability.In this work,a novel two-step hydrothermal approach is proposed for synthesizing stable and advanced hybrid coatings on metal-oxide platforms through the surface modification of layered double hydroxide(LDH)films using novel metal-organic frameworks(MOFs).Initially,Mg-Al LDH nanocontainers,grown on a magnesium oxide layer produced through plasma electrolytic oxidation(PEO)of AZ31 Mg alloy substrate,were intercalated with cobalt via an oxidation route,providing the metallic coordination center for the MOF formation.In the subsequent step,a pioneering technique is introduced,utilizing tryptophan as the organic linker for the first time at a pH of 10.The self-assembly of cobalt-tryptophan complex,driven by the strong bonding between electrophilic sites of monomers and nucleophilic sites,facilitated the formation of a MOF network having a cloud-like structure on the surface of MgAl LDH's film.The resulting MOF-LDH encapsulation containers demonstrate exceptional electrochemical stability when exposed to a 3.5 wt.%NaCl solution,surpassing the performance of PEO and pure LDH coatings.This enhanced stability is attributed to the development of a dense top layer and a stable composition within the self-assembled MOF,effectively sealing flaws and preventing the infiltration of corrosive ions into the underlying metallic substrate.The formation mechanism of MOFs on LDH galleries is investigated using density functional theory calculations.展开更多
Meeting the demands of complex and advanced applications requires the development of high-performance hybrid materials with unique properties.However,the integration of polymeric frameworks with MgO/WO_(3) composite l...Meeting the demands of complex and advanced applications requires the development of high-performance hybrid materials with unique properties.However,the integration of polymeric frameworks with MgO/WO_(3) composite layers faces challenges due to the lack of understanding of the formation mechanism and the challenge of determining the impact of self-assembled architecture on anticorrosive properties.In this study,we aimed to enhance the corrosion resistance of the MgO layer produced by plasma electrolysis(PE)of AZ31 Mg alloy by incorporating WO_(3) with partially phosphorated poly(vinyl alcohol)(PPVA).Two types of porous MgO layers were produced using the PE process with an alkaline-phosphate electrolyte,one with and one without WO_(3) nanoparticles,which were subsequently immersed in an aqueous solution of PPVA.Incorporating PPVA into the WO_(3)-MgO layer resulted in hybrids being deposited in a fragmented manner,creating a“laminar reef-like structure”that sealed most of the structural defects in the layer.The PPVA-sealed WO_(3)-based coating exhibited superior corrosion resistance compared to the other samples.Computational analyses were employed to explore the mechanism underlying the formation of PPVA/WO_(3) hybrids on the MgO layer.These findings suggest that PPVA-WO_(3)-MgO hybrid coatings can potentially improve corrosion resistance in various fields.展开更多
This study explores the dynamic interaction between environmentally sustainable plasma enhancer and quencher agents during the incorporation of SiO_(2) into a TiO_(2) layer,with the primary objective of simultaneously...This study explores the dynamic interaction between environmentally sustainable plasma enhancer and quencher agents during the incorporation of SiO_(2) into a TiO_(2) layer,with the primary objective of simultaneously augmenting protective and bioactive attributes.This enhancement is realized through the synergistic utilization of Tetraethyl orthosilicate(TE)and Stevia(ST)within a plasma-assisted oxidation process.To achieve this goal,Ti–6Al–4V alloy underwent oxidation in an electrolyte solution containing acetate-glycerophosphate,with the addition of TE and ST separately and in combination.TE,as a silicon oxide(SiO_(2))precursor,facilitates the creation of a calcium-rich,rough,porous layer by undergoing hydrolysis to generate silanol groups(Si–OH),which subsequently condense into silicon-oxygen-silicon(Si–O–Si)bonds,resulting in SiO_(2) formation.In contrast,ST acts as a plasma quencher,absorbing highly reactive plasma species during the oxidation process,reducing energy levels,and diminishing sparking intensity.The combination of TE and ST results in moderate sparking,balancing Stevia's quenching effect and TE's sparking influence.As a result,this coating exhibits enhanced corrosion resistance and bioactivity compared to using either ST or TE alone.The study highlights the potential of this synergistic approach for advanced TiO_(2)-based coatings.展开更多
Advanced hybrid materials with unique properties are essential for addressing the demands of increasingly complex applications.Despite their importance,the self-assembly of layered double hydroxides(LDH)with metallic ...Advanced hybrid materials with unique properties are essential for addressing the demands of increasingly complex applications.Despite their importance,the self-assembly of layered double hydroxides(LDH)with metallic oxide nanoparticles and dicarboxylic acids is constrained by a limited understanding of the formation mechanisms and difficulties in evaluating their anticorrosive performance.In this study,we developed a novel anticorrosive system by intercalating CeNiLDH with a complex of vanadium pentoxide(V2O5)nanoparticles and(2E)-but-2-enedioic acid((2E)-BDA)on a MgO layer created through plasma-electrolysis of AZ31 Mg alloy.This system was compared with LDH films intercalated with either V2O5 or(2E)-BDA alone.The intercalation of LDH with V_(2)O_(5)and(2E)-BDA resulted in a flower-like structure,while modification with their complex led to a more compact,cloud-like formation.These cloud-like structures,driven by enhanced absorption and robust hydrogen bonding throughout the hierarchical network,effectively suppress corrosion by delaying the movement of corrosive anions.This was reflected in a polarization resistance of 1.51×10^(10)Ω·cm^(2),which is approximately two orders of magnitude times higher than the resistance of the unmodified LDH film(3.41×10^(8)Ω·cm^(2)).Additionally,the corrosion current density(icorr)of the VOBDA sample showed a decrease by four orders of magnitude compared to the unmodified LDH sample,emphasizing the superior anticorrosive performance of this hybrid coating.Density functional theory(DFT)was used to elucidate the bonding and formation mechanisms between LDH and the inorganic-organic complex.展开更多
基金supported by the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)(No.2022R1A2C1006743).
文摘This study explores the development of an organic-inorganic hybrid coating to enhance the corrosion resistance and photocatalytic properties of AZ31 Mg alloy modified by plasma electrolytic oxidation(PEO).The PEO process typically generates a porous oxide layer,which can reduce corrosion protection by allowing corrosive agents to penetrate the substrate.To address this limitation,phenopyridine(PHEN)and 2-methylimidazole(2-IMD)were incorporated into the PEO surface to form a robust organic layer on the Mg alloy.Potassium hydroxide(KOH)was used to adjust the pH,improving the interaction and solubility between the organic molecules and the PEO coating.The hybrid coating exhibited unique twig-like surface structures that contributed to forming a multifunctional coating with high corrosion resistance and superior photocatalytic activity.The PEO-PHEN-2IMD sample on the Mg alloy demonstrated exceptional corrosion resistance,with the lowest corrosion current density(I_(corr))of 1.92×10^(-10) A/cm^(2),a high corrosion potential(E_(corr)),and the highest top layer resistance(R_(top))of 2.57×10^(6)Ω·cm^(2),indicating excellent barrier properties.Additionally,the coating achieved complete(100%)degradation of methylene blue(MB)within 30 min under visible light.Density Functional Theory(DFT)calculations provide deeper insights into the bonding mechanisms and interaction stability between PHEN,2-IMD,and the PEO layer on the Mg alloy and MB dye.These findings confirmed the enhanced performance of the hybrid coating in both corrosion resistance and photocatalytic applications.
基金supported by the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)(No.2022R1A2C1006743).
文摘Modulating metal-organic framework’s(MOF)crystallinity and size using a polymer,in conjunction with a high surface area of layered double hydroxide,yields an effective strategy for concurrently enhancing the electrochemical and photocatalytic performance.In this study,we present the development of an optimized nanocomposite,denoted as 0.5PVP/ZIF-67,developed on AZ31 magnesium alloy,serving as an efficient and durable multifunctional coating.This novel strategy aims to enhance the overall performance of the porous coating through the integration of microarc oxidation(MAO),ZnFe LDH backbone,and ZIF-67 formation facilitated by the addition of polyvinylpyrrolidone(PVP),resulting in a three-dimensional,highly efficient,and multifunctional material.The incorporation of 0.5 g of PVP proved to be effective in the size modulation of ZIF-67,which formed a corrosion-resistant top layer,improving the total polarization resistance(R_(p)=8.20×10^(8)).The dual functionality exhibited by this hybrid architecture positions it as a promising candidate for mitigating environmental pollution,degrading 97.93%of Rhodamine B dye in 45 min.Moreover,the sample displayed exceptional degradation efficiency(96.17%)after 5 cycles.This study illuminates the potential of nanocomposites as electrochemically stable and photocatalytically active materials,laying the foundation for the advancements of next-generation multifunctional frameworks.
基金supported by the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)(No.2022R1A2C1006743).
文摘The hybridization of metal-organic framework(MOF)with inorganic layers would lead to the discovery of novel hybrid materials that can provide a compelling strategy for enhancing its photocatalytic and electrochemical response.In the present study,a highly efficient multifunctional hybrid material was developed by exploiting the defective layer formed on AZ31 Mg alloy through plasma electrolytic oxidation(PEO)as a nucleation and growth site for Co-MOF.The concentrations of the organic linker 2-Methylimidazole(2,MIm)and cobalt nitrate as a source of Co^(2+) ions were varied to control the growth of the obtained Co-MOF.Lower concentrations of the 2,MIm ligand favored the formation of leaf-like MOF structures through an anisotropic,two-dimensional growth,while higher concentrations led to rapid,isotropic nucleation and the creation of polyhedral Co-MOF structures.The sample characterized by polyhedral Co-MOF structures exhibited superior electrochemical stability,with the lowest corrosion current density(3.11×10^(-9) A/cm^(2))and the highest top layer resistance(2.34×10^(6)Ωcm^(2)),and demonstrated outstanding photocatalytic efficiency,achieving a remarkable 99.98%degradation of methylene blue,an organic pollutant,in model wastewater.To assess the active adsorption sites of the Co-MOF,density functional theory(DFT)was utilized.This study explores the changes in morphologies of the coatings of Co-MOF with the change of solution concentration to form coatings with enhanced properties on the metallic substrate,which could establish the groundwork for the development of next-generation multifunctional frameworks with diverse applications.
基金supported by the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)(no.2022R1A2C1006743)。
文摘The self-assembly of hybrid inorganic-organic materials on stationary platforms plays a critical role in improving their structural stability and wide usability.In this work,a novel two-step hydrothermal approach is proposed for synthesizing stable and advanced hybrid coatings on metal-oxide platforms through the surface modification of layered double hydroxide(LDH)films using novel metal-organic frameworks(MOFs).Initially,Mg-Al LDH nanocontainers,grown on a magnesium oxide layer produced through plasma electrolytic oxidation(PEO)of AZ31 Mg alloy substrate,were intercalated with cobalt via an oxidation route,providing the metallic coordination center for the MOF formation.In the subsequent step,a pioneering technique is introduced,utilizing tryptophan as the organic linker for the first time at a pH of 10.The self-assembly of cobalt-tryptophan complex,driven by the strong bonding between electrophilic sites of monomers and nucleophilic sites,facilitated the formation of a MOF network having a cloud-like structure on the surface of MgAl LDH's film.The resulting MOF-LDH encapsulation containers demonstrate exceptional electrochemical stability when exposed to a 3.5 wt.%NaCl solution,surpassing the performance of PEO and pure LDH coatings.This enhanced stability is attributed to the development of a dense top layer and a stable composition within the self-assembled MOF,effectively sealing flaws and preventing the infiltration of corrosive ions into the underlying metallic substrate.The formation mechanism of MOFs on LDH galleries is investigated using density functional theory calculations.
基金supported by the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)(no.2022R1A2C1006743)。
文摘Meeting the demands of complex and advanced applications requires the development of high-performance hybrid materials with unique properties.However,the integration of polymeric frameworks with MgO/WO_(3) composite layers faces challenges due to the lack of understanding of the formation mechanism and the challenge of determining the impact of self-assembled architecture on anticorrosive properties.In this study,we aimed to enhance the corrosion resistance of the MgO layer produced by plasma electrolysis(PE)of AZ31 Mg alloy by incorporating WO_(3) with partially phosphorated poly(vinyl alcohol)(PPVA).Two types of porous MgO layers were produced using the PE process with an alkaline-phosphate electrolyte,one with and one without WO_(3) nanoparticles,which were subsequently immersed in an aqueous solution of PPVA.Incorporating PPVA into the WO_(3)-MgO layer resulted in hybrids being deposited in a fragmented manner,creating a“laminar reef-like structure”that sealed most of the structural defects in the layer.The PPVA-sealed WO_(3)-based coating exhibited superior corrosion resistance compared to the other samples.Computational analyses were employed to explore the mechanism underlying the formation of PPVA/WO_(3) hybrids on the MgO layer.These findings suggest that PPVA-WO_(3)-MgO hybrid coatings can potentially improve corrosion resistance in various fields.
基金supported by National Research Foundation of Korea:2021R1A4A1030243RS-2023-00222390)supported by the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)(No.2022R1A2C1006743).
文摘This study explores the dynamic interaction between environmentally sustainable plasma enhancer and quencher agents during the incorporation of SiO_(2) into a TiO_(2) layer,with the primary objective of simultaneously augmenting protective and bioactive attributes.This enhancement is realized through the synergistic utilization of Tetraethyl orthosilicate(TE)and Stevia(ST)within a plasma-assisted oxidation process.To achieve this goal,Ti–6Al–4V alloy underwent oxidation in an electrolyte solution containing acetate-glycerophosphate,with the addition of TE and ST separately and in combination.TE,as a silicon oxide(SiO_(2))precursor,facilitates the creation of a calcium-rich,rough,porous layer by undergoing hydrolysis to generate silanol groups(Si–OH),which subsequently condense into silicon-oxygen-silicon(Si–O–Si)bonds,resulting in SiO_(2) formation.In contrast,ST acts as a plasma quencher,absorbing highly reactive plasma species during the oxidation process,reducing energy levels,and diminishing sparking intensity.The combination of TE and ST results in moderate sparking,balancing Stevia's quenching effect and TE's sparking influence.As a result,this coating exhibits enhanced corrosion resistance and bioactivity compared to using either ST or TE alone.The study highlights the potential of this synergistic approach for advanced TiO_(2)-based coatings.
基金supported by the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)(No.2022R1A2C1006743).
文摘Advanced hybrid materials with unique properties are essential for addressing the demands of increasingly complex applications.Despite their importance,the self-assembly of layered double hydroxides(LDH)with metallic oxide nanoparticles and dicarboxylic acids is constrained by a limited understanding of the formation mechanisms and difficulties in evaluating their anticorrosive performance.In this study,we developed a novel anticorrosive system by intercalating CeNiLDH with a complex of vanadium pentoxide(V2O5)nanoparticles and(2E)-but-2-enedioic acid((2E)-BDA)on a MgO layer created through plasma-electrolysis of AZ31 Mg alloy.This system was compared with LDH films intercalated with either V2O5 or(2E)-BDA alone.The intercalation of LDH with V_(2)O_(5)and(2E)-BDA resulted in a flower-like structure,while modification with their complex led to a more compact,cloud-like formation.These cloud-like structures,driven by enhanced absorption and robust hydrogen bonding throughout the hierarchical network,effectively suppress corrosion by delaying the movement of corrosive anions.This was reflected in a polarization resistance of 1.51×10^(10)Ω·cm^(2),which is approximately two orders of magnitude times higher than the resistance of the unmodified LDH film(3.41×10^(8)Ω·cm^(2)).Additionally,the corrosion current density(icorr)of the VOBDA sample showed a decrease by four orders of magnitude compared to the unmodified LDH sample,emphasizing the superior anticorrosive performance of this hybrid coating.Density functional theory(DFT)was used to elucidate the bonding and formation mechanisms between LDH and the inorganic-organic complex.
