Hydrogen bonds play a pivotal role in governing both proton conduction and dielectric properties in functional materials.However,the direct mechanistic relationship between these two properties,as mediated by hydrogen...Hydrogen bonds play a pivotal role in governing both proton conduction and dielectric properties in functional materials.However,the direct mechanistic relationship between these two properties,as mediated by hydrogen bonds,remains poorly understood.Here,we address this gap by investigating the role of hydrogen-bonded motifs in coordination polymers(CPs),focusing on how their structural dynamics influence both proton transport and dielectric relaxation.To this end,two CPs,{(H_(3)tren)_(2)[Zn_(3)(PO_(4))_(4)]·6H_(2)O}(ZnPO_(4)-H_(3)tren-H_(2)O)and{(H_(3)tren)_(2)[Zn_(3)(PO_(4))_(4)]·2H_(2)ta}(ZnPO_(4)-H_(3)tren-H_(2)ta,tren=tri(2-aminoethyl)amine and H_(2)ta=terephthalic acid),featuring analogous host frameworks but distinct hydrogenbonded networks,were rationally designed and synthesized by modulating the vip molecules through substituent effects.Despite their structural similarity,ZnPO_(4)-H_(3)tren-H_(2)O and ZnPO_(4)-H_(3)tren-H_(2)ta exhibit markedly different proton conductivities of 4.55×10^(-4) and 3.41×10^(-3 )S cm^(-1),respectively,at 353 K and~97%relative humidity(RH).The nearly one-order-of-magnitude difference is attributed to the dissociation of the H_(2)ta molecule,which provides a more acidic proton source.Moreover,we found that the pronounced non-Debye relaxation behavior at low temperatures in ZnPO_(4)-H_(3)tren-H_(2)O leads to an increased activation energy for proton conduction,in contrast to the relaxation-free behavior of ZnPO_(4)-H_(3)tren-H_(2)ta.The difference is attributed to variations in the dynamics of their hydrogen-bonded motifs.Furthermore,dielectric relaxation of H_(3)tren^(3+)ions at high temperatures was also observed in both materials.Molecular dynamics simulations corroborate these findings,capturing the distinct dynamic behaviors of water clusters and H_(3)tren^(3+)ions.Beyond fundamental insights,both CPs exhibit high dielectric constants and moderate conductivities under ambient conditions,highlighting their potential as dispersed-phase components in electrorheological fluids.This study unveils a mechanistic link between dielectric relaxation and proton conduction,offering design principles for multifunctional materials that integrate proton conductivity with desirable dielectric properties.展开更多
Highly proton-conductive metal-organic coordination polymers(MOCPs)have attracted a great deal of attention because of their potential applications in proton exchange membrane fuel cells and electrochemical sensors.Cu...Highly proton-conductive metal-organic coordination polymers(MOCPs)have attracted a great deal of attention because of their potential applications in proton exchange membrane fuel cells and electrochemical sensors.Currently,the precise control of proton conductivity is mainly achieved through the rational design of organic ligands and the effective modification of pore structures.In contrast,little attention has been paid to the influence of metal ions of MOCPs on their proton conductivities due to the absence of isostructural compounds for comparison and analysis.Herein,we designed three MOCPs{[(H_(3)O^(+))_(2)][Zn(pzdc)_(2)]}_(n),{[(H_(3)O^(+))_(2)][Mn(pzdc)_(2)]}_(n)and[Cu(Hpzdc)_(2)·2H_(2)O]n(H_(2)pzdc=2,3-pyrazinedicarboxylic acid)with very similar chemical formulae and single-crystal structures as models to investigate how the coordination interactions/abilities of metal ions affect their proton conductivities and water stabilities.Remarkably,these three MOCPs show proton conductivities as high as 10^(-3)S cm^(-1)at 323 K and∼97%RH along with excellent stabilities to temperature,water,acid and base(over a broad pH range of 0-12).Density functional theory(DFT)calculations show that the binding energies of the O-H bonds of the carboxyl groups in the solvation models are a predominant factor in precisely tuning the proton conductivity at∼97%RH.Furthermore,the extraordinary stabilities,especially in water,are more likely to be associated with the coordination interactions resulting in a significant decrease in the system energies of the generated coordination compounds.These results provide a novel perspective for the design and synthesis of MOCPs with high proton conductivity and good stability.展开更多
The electrocatalytic oxygen evolution reaction(OER)under neutral or near-neutral conditions has attracted research interest due to its environmental friendliness and economic sustainability in comparison with currentl...The electrocatalytic oxygen evolution reaction(OER)under neutral or near-neutral conditions has attracted research interest due to its environmental friendliness and economic sustainability in comparison with currently available acidic and alkaline conditions.However,it is challenging to identify electrocatalytically active species in the OER procedure under neutral environments due to non-crystalline forms of catalysts.展开更多
基金support from the National Natural Science Foundation of China(21401147,21403048 and 21771047)the Natural Science Basic Research Program of Shaanxi Province(2024JC-YBMS-084)the Xi’an City Project of Scientific and Technical Personnel in University and Institute Servicing Enterprises(24GXFW0019).
文摘Hydrogen bonds play a pivotal role in governing both proton conduction and dielectric properties in functional materials.However,the direct mechanistic relationship between these two properties,as mediated by hydrogen bonds,remains poorly understood.Here,we address this gap by investigating the role of hydrogen-bonded motifs in coordination polymers(CPs),focusing on how their structural dynamics influence both proton transport and dielectric relaxation.To this end,two CPs,{(H_(3)tren)_(2)[Zn_(3)(PO_(4))_(4)]·6H_(2)O}(ZnPO_(4)-H_(3)tren-H_(2)O)and{(H_(3)tren)_(2)[Zn_(3)(PO_(4))_(4)]·2H_(2)ta}(ZnPO_(4)-H_(3)tren-H_(2)ta,tren=tri(2-aminoethyl)amine and H_(2)ta=terephthalic acid),featuring analogous host frameworks but distinct hydrogenbonded networks,were rationally designed and synthesized by modulating the vip molecules through substituent effects.Despite their structural similarity,ZnPO_(4)-H_(3)tren-H_(2)O and ZnPO_(4)-H_(3)tren-H_(2)ta exhibit markedly different proton conductivities of 4.55×10^(-4) and 3.41×10^(-3 )S cm^(-1),respectively,at 353 K and~97%relative humidity(RH).The nearly one-order-of-magnitude difference is attributed to the dissociation of the H_(2)ta molecule,which provides a more acidic proton source.Moreover,we found that the pronounced non-Debye relaxation behavior at low temperatures in ZnPO_(4)-H_(3)tren-H_(2)O leads to an increased activation energy for proton conduction,in contrast to the relaxation-free behavior of ZnPO_(4)-H_(3)tren-H_(2)ta.The difference is attributed to variations in the dynamics of their hydrogen-bonded motifs.Furthermore,dielectric relaxation of H_(3)tren^(3+)ions at high temperatures was also observed in both materials.Molecular dynamics simulations corroborate these findings,capturing the distinct dynamic behaviors of water clusters and H_(3)tren^(3+)ions.Beyond fundamental insights,both CPs exhibit high dielectric constants and moderate conductivities under ambient conditions,highlighting their potential as dispersed-phase components in electrorheological fluids.This study unveils a mechanistic link between dielectric relaxation and proton conduction,offering design principles for multifunctional materials that integrate proton conductivity with desirable dielectric properties.
基金financial support of the National Natural Science Foundation of China(21401147,21403048 and 21771047)the Natural Science Basic Research Plan in the Shaanxi Province of China(2019JM-397)+1 种基金the Special Project of Talent Cultivation in the West Region of China Scholarship Council(201808615077)the Innovation Training Project for College Students in Shaanxi Province of China(S202210709091)。
文摘Highly proton-conductive metal-organic coordination polymers(MOCPs)have attracted a great deal of attention because of their potential applications in proton exchange membrane fuel cells and electrochemical sensors.Currently,the precise control of proton conductivity is mainly achieved through the rational design of organic ligands and the effective modification of pore structures.In contrast,little attention has been paid to the influence of metal ions of MOCPs on their proton conductivities due to the absence of isostructural compounds for comparison and analysis.Herein,we designed three MOCPs{[(H_(3)O^(+))_(2)][Zn(pzdc)_(2)]}_(n),{[(H_(3)O^(+))_(2)][Mn(pzdc)_(2)]}_(n)and[Cu(Hpzdc)_(2)·2H_(2)O]n(H_(2)pzdc=2,3-pyrazinedicarboxylic acid)with very similar chemical formulae and single-crystal structures as models to investigate how the coordination interactions/abilities of metal ions affect their proton conductivities and water stabilities.Remarkably,these three MOCPs show proton conductivities as high as 10^(-3)S cm^(-1)at 323 K and∼97%RH along with excellent stabilities to temperature,water,acid and base(over a broad pH range of 0-12).Density functional theory(DFT)calculations show that the binding energies of the O-H bonds of the carboxyl groups in the solvation models are a predominant factor in precisely tuning the proton conductivity at∼97%RH.Furthermore,the extraordinary stabilities,especially in water,are more likely to be associated with the coordination interactions resulting in a significant decrease in the system energies of the generated coordination compounds.These results provide a novel perspective for the design and synthesis of MOCPs with high proton conductivity and good stability.
基金support of the National Natural Science Foundation of China(21401147)the Natural Science Basic Research Plan in Shaanxi Province of China(2019JM-397)the Special Project of Talent Cultivation in the West Region of China Scholarship Council(201808615077).
文摘The electrocatalytic oxygen evolution reaction(OER)under neutral or near-neutral conditions has attracted research interest due to its environmental friendliness and economic sustainability in comparison with currently available acidic and alkaline conditions.However,it is challenging to identify electrocatalytically active species in the OER procedure under neutral environments due to non-crystalline forms of catalysts.
