Transition metal-based compounds can serve as pre-catalysts to obtain genuine oxygen evolution reaction(OER)electrocatalysts in the form of oxyhydroxides through electrochemical activation.However,the role and existen...Transition metal-based compounds can serve as pre-catalysts to obtain genuine oxygen evolution reaction(OER)electrocatalysts in the form of oxyhydroxides through electrochemical activation.However,the role and existence form of leached oxygen anions are still controversial.Herein,we selected iron selenite-wrapped hydrated nickel molybdate(denoted as NiMoO/FeSeO)as a pre-catalyst to study the oxyanion effect.It is surprising to find that SeO_(2)-exists in the catalyst in the form of intercalation,which is different from previous studies that suggest that anions are doped with residual elements after electrochemical activation,or adsorbed on the catalyst surface.The experiment and theoretical calculations show that the existence of SeO_(4)^(2-)intercalation effectively adjusts the electronic structure of NiFeOOH,promotes intramolecular electron transfer and O-O release,and thus lowers the reaction energy barrier.As expected,the synthesized NiFeOOH-SeO only needs 202 and 285 mV to attain 100 and 1000 mA cm^(-2)in 1 M KOH.Further,the anion exchange membrane water electrolyzer(AEMWE)consisting of NiFeOOHSeO anode and Pt/C cathode can reach 1 A cm^(-2)at 1.70 V and no significant attenuation within 300 h.Our findings provide insights into the mechanism,by which the intercalated oxyanions enhance the OER performance of NiFeOOH,thereby facilitating large-scale hydrogen production through AEMWE.展开更多
Zwitterionic glycine was employed to modify Fe/Mg-layered double hydroxides(LDH)to realize an GFe/Mg-LDH adsorbent with high adsorption capacities of oxygen-containing anions including As(Ⅴ),P(Ⅴ)and Cr(Ⅵ).When the ...Zwitterionic glycine was employed to modify Fe/Mg-layered double hydroxides(LDH)to realize an GFe/Mg-LDH adsorbent with high adsorption capacities of oxygen-containing anions including As(Ⅴ),P(Ⅴ)and Cr(Ⅵ).When the Fe/Mg mole ratio was 0.02 mol/0.02 mol,the G-Fe/Mg-LDH has a good adsorption performance.The optimum adsorption pH value of G-Fe/Mg-LDH for oxygen-containing anions was 6.The selectivity of three oxygen-containing anions was Cr(Ⅵ)展开更多
Cationic hydrogel with magnetic property was synthesized via radical polymerization and its removal capacity of chromate from contaminated water was found to be 200 mg/g.Using Fourier transform infrared spectroscopy（...Cationic hydrogel with magnetic property was synthesized via radical polymerization and its removal capacity of chromate from contaminated water was found to be 200 mg/g.Using Fourier transform infrared spectroscopy（FT-IR） study,the mechanism of chromate removal by hydrogel was found to be non-specific adsorption,mainly due to ion exchange,as evidenced by the positively charged functional group,trimethyl ammonium-N＋（CH3）3,in the monomer.Verifications were accordingly determined by testing di？erent oxyanion adsorption onto the hydrogel.The results of the chromate adsorption experiments illustrated that the amount of chromate adsorbed was nearly equal to that of the chloride released from the hydrogel,which is part of the evidence for ion exchange.Single and multi-oxyanion adsorption experiments were also performed,and it was demonstrated that ion removal was species independent,but charge dependent,another characteristic of the ion exchange process.It was found that the same Langmuir model can be applied to best fit the findings of single and multi-oxyanion adsorption,which further indicates the mechanism of chromate removal is attributed to ion exchange.In view of the above,the background anions compete for adsorption sites with chromate,evidenced by inhibitive chromate removal in the presence of background electrolytes in the batch studies,further echoing the ion exchange mechanism.展开更多
The adsorption and post adsorption behavior of schwertmannite with various oxyanions were investigated for clean-up contaminated water with hazardous oxyanions and safe disposal of spent schwertmannite. The result of ...The adsorption and post adsorption behavior of schwertmannite with various oxyanions were investigated for clean-up contaminated water with hazardous oxyanions and safe disposal of spent schwertmannite. The result of adsorption experiments showed that the maximum capacities of oxyanions adsorption onto schwertmannite are 1.023, 0.934, 0.723 and 0.313 mmol/g for arsenate, phosphate, chromate and selenate, respectively. Based on the differences in the adsorption capacities, the selectivity of oxyanion adsorption on schwertmannite decreases as the order: arsenate ≥ phosphate > chromate >> selenate. Change in the Zeta potential after adsorption by arsenate, phosphate and chromate were very different from those after adsorption by selenate and of the original schwertmannite. This difference implies that the adsorption mechanism on schwertmannite with arsenate, phosphate and chromate is different from that with selenate and sulfate. Arsenate, phosphate, and chromate ions form inner-sphere complexes with the surface of schwertmannite, while selenate and sulfate ions form outer-sphere complexes with the surface of schwertmannite. Based on a comparison with anion adsorption, strong base anions form inner-sphere complexes, which induce a strong adsorption with schwertmannite as well as it is conducive to high adsorption capacity. From the results of aging experiments, schwertmannite with sulfate and selenate changed to a more stable phase, goethite, in a short time, whereas there is no change in the XRD patterns of schwertmannite with arsenate and phosphate after 30 days. The stability of schwertmannite after the adsorption increased in the following order: sulfate ≌ selenate «chromate ≌ arsenate. The solubility of schwertmannite with different oxyanions was calculated according to solid solution theory. The solubility of schwertmannite decreased after adsorption of oxyanions with high selectivity. It is concluded that oxyanions with high selectivity can stabilize schwertmannite by decreasing the solubility of the schwertmannite after adsorption of the oxyanions.展开更多
Efficient and durable oxygen evolution reaction(OER)requires the electrocatalyst to bear abundant active sites,optimized electronic structure as well as robust component and mechanical stability.Herein,a bimetallic la...Efficient and durable oxygen evolution reaction(OER)requires the electrocatalyst to bear abundant active sites,optimized electronic structure as well as robust component and mechanical stability.Herein,a bimetallic lanthanum-nickel oxysulfide with rich oxygen vacancies based on the La_(2)O_(2)S prototype is fabricated as a binder-free precatalyst for alkaline OER.The combination of advanced in situ and ex situ characterizations with theoretical calculation uncovers the synergistic effect among La,Ni,O,and S species during OER,which assures the adsorption and stabilization of the oxyanion SO_(4)^(2-)onto the surface of the deeply reconstructed porous heterostructure composed of confining Ni OOH nanodomains by La(OH)_3 barrier.Such coupling,confinement,porosity and immobilization enable notable improvement in active site accessibility,phase stability,mass diffusion capability and the intrinsic Gibbs free energy of oxygen-containing intermediates.The optimized electrocatalyst delivers exceptional alkaline OER activity and durability,outperforming most of the Ni-based benchmark OER electrocatalysts.展开更多
Two pH-responsive amphiphilic diblock copolymers, namely polyisobutylene-block-poly[2-（N,N- dimethylamino）ethyl methaerylate] （PIB-b-PDMAEMA） and polyisobutylene-block-poly（metharylic acid） （PIB-b-PMAA）, were ...Two pH-responsive amphiphilic diblock copolymers, namely polyisobutylene-block-poly[2-（N,N- dimethylamino）ethyl methaerylate] （PIB-b-PDMAEMA） and polyisobutylene-block-poly（metharylic acid） （PIB-b-PMAA）, were synthesized via oxyanion-initiated polymerization, and their multiple self-assembly behaviors have been studied. An exo-01efin-terminated highly reactive polyisobutylene （HRPIB） was first changed to hydroxyl-terminated PIB （PIB-OH） via hydroboration-oxidation of C =C double bond in the chain end, and then reacted with KH to yield a potassium alcoholate of PIB （PIB-O-K＋）. PIB-O-K＋ was immediately used as a macroinitiator to polymerize DMAEMA monomer, resulting in a cationic diblock copolymer PIB-b-PDMAEMA. With the similar synthesis procedure, the anionic diblock copolymer PIB-b- PMAA could be prepared via a combination of oxyanion-initiated polymerization of tert-butyl methacrylate （tBMA） and subsequent hydrolysis of tert-butyl ester groups in PtBMA block. The functional PIB and block copolymers have been fully characterized by 1H-NMR, FT-IR spectroscopy, and gel permeation chromatography （GPC）. These samples allowed us to systematically investigate the effects of block composition on the pH responsivity and various self-assembled morphologies of the copolymers in THF/water mixed solvent. Transmission electron microscopy （TEM） images revealed that these diblock copolymers containing small amount of original PIB without exo-olefin-terminated group are able to self-assemble into micelles, vesicles with different particle sizes and cylindrical aggregates, depending on various factors including block copolymer composition, solvent polarity and pH value.展开更多
Enzymes fold into three-dimensional structures for spatial arrangement of amino acid residues and formation of specific motifs within their active sites,enabling their remarkable catalytic properties.Replicating such ...Enzymes fold into three-dimensional structures for spatial arrangement of amino acid residues and formation of specific motifs within their active sites,enabling their remarkable catalytic properties.Replicating such intricate folding and functional group distribution in synthetic systems could allow for efficient and mild catalysis with significant potential in green chemistry,but achieving this remains a major challenge.Inspired by structure and function of oxyanion hole-a fundamental structural feature in hydrolases,we designed a surfactant system comprising an aza-crown ether core and an alkyl tail,which self-assembles into tail-totail bilayer nanostructures capable of catalyzing hydrolytic reactions.The theoretical and experimental results reveal that the alkyl chain enhances the protonation and organization of the aza-crown ether,promoting ester substrate access and stabilizing the transition state,reminiscent of natural oxyanion hole mechanisms.It is observed that the alkylated aza-crown ether exhibits a 43.3-fold increase in catalytic efficiency(k_(cat)/K_(m))compared to its non-alkylated counterpart.Additionally,the self-assembled alkylated aza-crown ether demonstrates efficient CO_(2) hydration activity,resembling the function of carbonic anhydrase.This work offers a model for how simple molecules can evolve sophisticated catalysts through structural and functional optimization,offering new insights for the design of bioinspired catalyst in green chemistry.展开更多
In the present contribution,we demonstrate that the sluggish kinetics of oxygen evolution reaction(OER)over the bismuth sulfide(Bi_(2)S_(3))photoanode,which severely restricts its photoelectrochemical activity,is mark...In the present contribution,we demonstrate that the sluggish kinetics of oxygen evolution reaction(OER)over the bismuth sulfide(Bi_(2)S_(3))photoanode,which severely restricts its photoelectrochemical activity,is markedly accelerated by employing a sulfatecontaining electrolyte.First-principle calculation points to the spontaneous adsorption of sulfate(SO_(4)^(2−))on Bi_(2)S_(3)and its capacity of stabilizing the OER intermediates through hydrogen bonding,which is further reinforced by increasing the local density of states near the Fermi level of Bi_(2)S_(3).Meanwhile,the electron transfer is also promoted to synergistically render the ratedetermining step(from O*to OOH*)of OER over Bi_(2)S_(3)kinetically facile.Last but not least,benefitting from such enhanced OER activity and efficient charge separation resulted from depositing Bi_(2)S_(3)on the zinc oxide nanorods(ZnO NRs),forming a core–shell heterojunction,its photocurrent density achieves 8.61 mA·cm^(−2)at 1.23 VRHE,far surpassing those reported for additional Bi_(2)S_(3)-based and several state-of-the-art photoanodes in the literature and further exceeding their theoretical limit.The great promise of the Bi_(2)S_(3)/ZnO NRs is in view of such outperformance,the superior Faradaic yield of oxygen of more than~80%and the outstanding half-cell applied bias photon-to-current efficiency of~1%well corroborated.展开更多
Hyperbranched poly(3-ethyl-3-oxetanemetha-nol)-graft-poly(2-dimethylaminoethyl methacrylate) (HP-g-DMA) with a three-demensional structure was synthesized via oxyanionic polymerization. The hydroxyl groups of hyper-br...Hyperbranched poly(3-ethyl-3-oxetanemetha-nol)-graft-poly(2-dimethylaminoethyl methacrylate) (HP-g-DMA) with a three-demensional structure was synthesized via oxyanionic polymerization. The hydroxyl groups of hyper-branched poly(3-ethyi-3-oxetanemethanol) (HP) reacted with KH and conversed into potassium alcoholate macroinitiators with high initiating efficiencies. High monomer conversion (】95%) was obtained and no residual macroinitiators or monomer was observed. UV-visible spectra indicate that the aqueous solution of the HP-g-DMA exhibited the lowermost critical solution temperature (LCST). The LCST was influ-enced by the chain length of DMA and pH condition of solu-tion. It is found that LCST decreased with increasing DMA chain length or increasing pH value of solution.展开更多
In-silico and experimental investigations were conducted to explore the effects of substituting hydrophobic residues;Val, Met, Leu, Ile, Trp and Phe into the oxyanion Q114 of T1 lipase. We hypothesized that the oxyani...In-silico and experimental investigations were conducted to explore the effects of substituting hydrophobic residues;Val, Met, Leu, Ile, Trp and Phe into the oxyanion Q114 of T1 lipase. We hypothesized that the oxyanion Q114, involved in substrate binding is also associated with modulation of conformational stability and in conferring specific enzyme attributes. The insilico investigations accurately predicted the quality of the protein packing in some of the variants. Our study found by altering the hydrophobicity of the oxyanion 114, remarkably altered enzyme conformational stability and catalytic attributes. Substitution with Leu resulted improvements in four out of the six tested characteristics. The hydrophobic Leu might have improved local structure folding and increased hydrophobic interactions with other residues in the vicinity of the mutation. The Met variant showed higher activity over the wild-type in hydrolyzing a wider range of natural oils. The bulky amino acids, Phe and Trp negatively affected T1 lipase and resulted in the largest disruption of protein stability and inferior enzyme characteristics. We have successfully illustrated that a single point residue changes at oxyanion 114 could result in a myriad of enzyme attributes, which implied there was some interplay between hydrophobicity and conformation for lipase catalytic functions.展开更多
The proline iminopeptidase (PchPiPA) of the white-rot fungi Phanerochaete chrysosporium is an exopeptidase specific to catalyze hydrolysis of the N-terminal proline of peptides or proteins. Its catalytic cavity is com...The proline iminopeptidase (PchPiPA) of the white-rot fungi Phanerochaete chrysosporium is an exopeptidase specific to catalyze hydrolysis of the N-terminal proline of peptides or proteins. Its catalytic cavity is comprised of a catalytic triad (Ser107, Asp264 and His292) and an oxyanion hole (His38, Gly39, Gly40 and Pro41). In this work, several amino acid residues involved in the catalytic cavity were selected for investigation of their influences on the catalytic activity by site-directed mutagenesis. It was shown that mutation of residues (Gly39 and Gly40) involved in oxyanion hole resulted in almost complete loss of catalytic activity largely due to changes in kcat. The other residues (Gly42 and Cys45) lined at the entrance of the active cavity also yielded a profound negative effect on the activity. Mutation of the other two residues Arg130 and Gly131 which were flanked spatially by the nucleophilic attacking active site of Ser107, caused different effects on the activity. R130Aincreased catalytic efficiency due to changes in both kcat and Km;while G131V decreased the value of kcat/Km mainly due to changes in kcat. And T111Aalso caused a negative effect on the kcat. Conclusively, these amino acid residues involved in active cavity were more susceptible to be negatively affected by mutation, suggested that the active cavity of proline iminopeptidase might evolve to be less plausible.展开更多
基金supported by the National Natural Science Foundation of China(22075196,U22A20418,21878204)the Research Project Supported by Shanxi Scholarship Council of China(2022-050).
文摘Transition metal-based compounds can serve as pre-catalysts to obtain genuine oxygen evolution reaction(OER)electrocatalysts in the form of oxyhydroxides through electrochemical activation.However,the role and existence form of leached oxygen anions are still controversial.Herein,we selected iron selenite-wrapped hydrated nickel molybdate(denoted as NiMoO/FeSeO)as a pre-catalyst to study the oxyanion effect.It is surprising to find that SeO_(2)-exists in the catalyst in the form of intercalation,which is different from previous studies that suggest that anions are doped with residual elements after electrochemical activation,or adsorbed on the catalyst surface.The experiment and theoretical calculations show that the existence of SeO_(4)^(2-)intercalation effectively adjusts the electronic structure of NiFeOOH,promotes intramolecular electron transfer and O-O release,and thus lowers the reaction energy barrier.As expected,the synthesized NiFeOOH-SeO only needs 202 and 285 mV to attain 100 and 1000 mA cm^(-2)in 1 M KOH.Further,the anion exchange membrane water electrolyzer(AEMWE)consisting of NiFeOOHSeO anode and Pt/C cathode can reach 1 A cm^(-2)at 1.70 V and no significant attenuation within 300 h.Our findings provide insights into the mechanism,by which the intercalated oxyanions enhance the OER performance of NiFeOOH,thereby facilitating large-scale hydrogen production through AEMWE.
文摘Zwitterionic glycine was employed to modify Fe/Mg-layered double hydroxides(LDH)to realize an GFe/Mg-LDH adsorbent with high adsorption capacities of oxygen-containing anions including As(Ⅴ),P(Ⅴ)and Cr(Ⅵ).When the Fe/Mg mole ratio was 0.02 mol/0.02 mol,the G-Fe/Mg-LDH has a good adsorption performance.The optimum adsorption pH value of G-Fe/Mg-LDH for oxygen-containing anions was 6.The selectivity of three oxygen-containing anions was Cr(Ⅵ)
基金supported by the Hong Kong Research Grants Council under grant HKUST RGC 617309
文摘Cationic hydrogel with magnetic property was synthesized via radical polymerization and its removal capacity of chromate from contaminated water was found to be 200 mg/g.Using Fourier transform infrared spectroscopy（FT-IR） study,the mechanism of chromate removal by hydrogel was found to be non-specific adsorption,mainly due to ion exchange,as evidenced by the positively charged functional group,trimethyl ammonium-N＋（CH3）3,in the monomer.Verifications were accordingly determined by testing di？erent oxyanion adsorption onto the hydrogel.The results of the chromate adsorption experiments illustrated that the amount of chromate adsorbed was nearly equal to that of the chloride released from the hydrogel,which is part of the evidence for ion exchange.Single and multi-oxyanion adsorption experiments were also performed,and it was demonstrated that ion removal was species independent,but charge dependent,another characteristic of the ion exchange process.It was found that the same Langmuir model can be applied to best fit the findings of single and multi-oxyanion adsorption,which further indicates the mechanism of chromate removal is attributed to ion exchange.In view of the above,the background anions compete for adsorption sites with chromate,evidenced by inhibitive chromate removal in the presence of background electrolytes in the batch studies,further echoing the ion exchange mechanism.
文摘The adsorption and post adsorption behavior of schwertmannite with various oxyanions were investigated for clean-up contaminated water with hazardous oxyanions and safe disposal of spent schwertmannite. The result of adsorption experiments showed that the maximum capacities of oxyanions adsorption onto schwertmannite are 1.023, 0.934, 0.723 and 0.313 mmol/g for arsenate, phosphate, chromate and selenate, respectively. Based on the differences in the adsorption capacities, the selectivity of oxyanion adsorption on schwertmannite decreases as the order: arsenate ≥ phosphate > chromate >> selenate. Change in the Zeta potential after adsorption by arsenate, phosphate and chromate were very different from those after adsorption by selenate and of the original schwertmannite. This difference implies that the adsorption mechanism on schwertmannite with arsenate, phosphate and chromate is different from that with selenate and sulfate. Arsenate, phosphate, and chromate ions form inner-sphere complexes with the surface of schwertmannite, while selenate and sulfate ions form outer-sphere complexes with the surface of schwertmannite. Based on a comparison with anion adsorption, strong base anions form inner-sphere complexes, which induce a strong adsorption with schwertmannite as well as it is conducive to high adsorption capacity. From the results of aging experiments, schwertmannite with sulfate and selenate changed to a more stable phase, goethite, in a short time, whereas there is no change in the XRD patterns of schwertmannite with arsenate and phosphate after 30 days. The stability of schwertmannite after the adsorption increased in the following order: sulfate ≌ selenate «chromate ≌ arsenate. The solubility of schwertmannite with different oxyanions was calculated according to solid solution theory. The solubility of schwertmannite decreased after adsorption of oxyanions with high selectivity. It is concluded that oxyanions with high selectivity can stabilize schwertmannite by decreasing the solubility of the schwertmannite after adsorption of the oxyanions.
基金supported by National MCF Energy R&D Program of China(2018YFE0306105)National Key R&D Program of China(2020YFA0406104,2020YFA0406101)+10 种基金Innovative Research Group Project of the National Natural Science Foundation of China(51821002)National Natural Science Foundation of China(52201269,51725204,21771132,51972216,52041202)Natural Science Foundation of Jiangsu Province(BK20210735)Natural Science Foundation of the Higher Education Institutions of Jiangsu Province(21KJB430043)Collaborative Innovation Center of Suzhou Nano Science&Technologythe 111 ProjectSuzhou Key Laboratory of Functional Nano&Soft MaterialsJiangsu Key Laboratory for Advanced Negative Carbon Technologiesthe funding from Alexander von Humboldt(AvH)FoundationGusu leading talent plan for scientific and technological innovation and entrepreneurship(ZXL2022487)support from the German Federal Ministry of Education and Research in the framework of the project Catlab(03EW0015A/B)。
文摘Efficient and durable oxygen evolution reaction(OER)requires the electrocatalyst to bear abundant active sites,optimized electronic structure as well as robust component and mechanical stability.Herein,a bimetallic lanthanum-nickel oxysulfide with rich oxygen vacancies based on the La_(2)O_(2)S prototype is fabricated as a binder-free precatalyst for alkaline OER.The combination of advanced in situ and ex situ characterizations with theoretical calculation uncovers the synergistic effect among La,Ni,O,and S species during OER,which assures the adsorption and stabilization of the oxyanion SO_(4)^(2-)onto the surface of the deeply reconstructed porous heterostructure composed of confining Ni OOH nanodomains by La(OH)_3 barrier.Such coupling,confinement,porosity and immobilization enable notable improvement in active site accessibility,phase stability,mass diffusion capability and the intrinsic Gibbs free energy of oxygen-containing intermediates.The optimized electrocatalyst delivers exceptional alkaline OER activity and durability,outperforming most of the Ni-based benchmark OER electrocatalysts.
基金financially supported by the National Natural Science Foundation of China (Nos. 20974074 and 21074078)Natural Science Foundation of Jiangsu Province for Rolling Support Project (BK2011045)+1 种基金a project funded by the PriorityAcademic Program Development of Jiangsu Higher Education Institutions, State Key Lab of Chemical Resource Engineering(Beijing University of Chemical Technology)the Innovation Project of Graduate Students of Jiangsu Province, China(CXZZ11_0091)
文摘Two pH-responsive amphiphilic diblock copolymers, namely polyisobutylene-block-poly[2-（N,N- dimethylamino）ethyl methaerylate] （PIB-b-PDMAEMA） and polyisobutylene-block-poly（metharylic acid） （PIB-b-PMAA）, were synthesized via oxyanion-initiated polymerization, and their multiple self-assembly behaviors have been studied. An exo-01efin-terminated highly reactive polyisobutylene （HRPIB） was first changed to hydroxyl-terminated PIB （PIB-OH） via hydroboration-oxidation of C =C double bond in the chain end, and then reacted with KH to yield a potassium alcoholate of PIB （PIB-O-K＋）. PIB-O-K＋ was immediately used as a macroinitiator to polymerize DMAEMA monomer, resulting in a cationic diblock copolymer PIB-b-PDMAEMA. With the similar synthesis procedure, the anionic diblock copolymer PIB-b- PMAA could be prepared via a combination of oxyanion-initiated polymerization of tert-butyl methacrylate （tBMA） and subsequent hydrolysis of tert-butyl ester groups in PtBMA block. The functional PIB and block copolymers have been fully characterized by 1H-NMR, FT-IR spectroscopy, and gel permeation chromatography （GPC）. These samples allowed us to systematically investigate the effects of block composition on the pH responsivity and various self-assembled morphologies of the copolymers in THF/water mixed solvent. Transmission electron microscopy （TEM） images revealed that these diblock copolymers containing small amount of original PIB without exo-olefin-terminated group are able to self-assemble into micelles, vesicles with different particle sizes and cylindrical aggregates, depending on various factors including block copolymer composition, solvent polarity and pH value.
基金supported in part by the National Natural Science Foundation of China(No.52173194)the Beijing Natural Science Foundation(No.2232017)the Fundamental Research Funds for the Central Universities(No.buctrc201902).
文摘Enzymes fold into three-dimensional structures for spatial arrangement of amino acid residues and formation of specific motifs within their active sites,enabling their remarkable catalytic properties.Replicating such intricate folding and functional group distribution in synthetic systems could allow for efficient and mild catalysis with significant potential in green chemistry,but achieving this remains a major challenge.Inspired by structure and function of oxyanion hole-a fundamental structural feature in hydrolases,we designed a surfactant system comprising an aza-crown ether core and an alkyl tail,which self-assembles into tail-totail bilayer nanostructures capable of catalyzing hydrolytic reactions.The theoretical and experimental results reveal that the alkyl chain enhances the protonation and organization of the aza-crown ether,promoting ester substrate access and stabilizing the transition state,reminiscent of natural oxyanion hole mechanisms.It is observed that the alkylated aza-crown ether exhibits a 43.3-fold increase in catalytic efficiency(k_(cat)/K_(m))compared to its non-alkylated counterpart.Additionally,the self-assembled alkylated aza-crown ether demonstrates efficient CO_(2) hydration activity,resembling the function of carbonic anhydrase.This work offers a model for how simple molecules can evolve sophisticated catalysts through structural and functional optimization,offering new insights for the design of bioinspired catalyst in green chemistry.
基金supported by the National Natural Science Foundation of China and Shanghai Jiao Tong University(Nos.22109096,WF220528005 and ZXDF280001/024).
文摘In the present contribution,we demonstrate that the sluggish kinetics of oxygen evolution reaction(OER)over the bismuth sulfide(Bi_(2)S_(3))photoanode,which severely restricts its photoelectrochemical activity,is markedly accelerated by employing a sulfatecontaining electrolyte.First-principle calculation points to the spontaneous adsorption of sulfate(SO_(4)^(2−))on Bi_(2)S_(3)and its capacity of stabilizing the OER intermediates through hydrogen bonding,which is further reinforced by increasing the local density of states near the Fermi level of Bi_(2)S_(3).Meanwhile,the electron transfer is also promoted to synergistically render the ratedetermining step(from O*to OOH*)of OER over Bi_(2)S_(3)kinetically facile.Last but not least,benefitting from such enhanced OER activity and efficient charge separation resulted from depositing Bi_(2)S_(3)on the zinc oxide nanorods(ZnO NRs),forming a core–shell heterojunction,its photocurrent density achieves 8.61 mA·cm^(−2)at 1.23 VRHE,far surpassing those reported for additional Bi_(2)S_(3)-based and several state-of-the-art photoanodes in the literature and further exceeding their theoretical limit.The great promise of the Bi_(2)S_(3)/ZnO NRs is in view of such outperformance,the superior Faradaic yield of oxygen of more than~80%and the outstanding half-cell applied bias photon-to-current efficiency of~1%well corroborated.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 29974017).
文摘Hyperbranched poly(3-ethyl-3-oxetanemetha-nol)-graft-poly(2-dimethylaminoethyl methacrylate) (HP-g-DMA) with a three-demensional structure was synthesized via oxyanionic polymerization. The hydroxyl groups of hyper-branched poly(3-ethyi-3-oxetanemethanol) (HP) reacted with KH and conversed into potassium alcoholate macroinitiators with high initiating efficiencies. High monomer conversion (】95%) was obtained and no residual macroinitiators or monomer was observed. UV-visible spectra indicate that the aqueous solution of the HP-g-DMA exhibited the lowermost critical solution temperature (LCST). The LCST was influ-enced by the chain length of DMA and pH condition of solu-tion. It is found that LCST decreased with increasing DMA chain length or increasing pH value of solution.
文摘In-silico and experimental investigations were conducted to explore the effects of substituting hydrophobic residues;Val, Met, Leu, Ile, Trp and Phe into the oxyanion Q114 of T1 lipase. We hypothesized that the oxyanion Q114, involved in substrate binding is also associated with modulation of conformational stability and in conferring specific enzyme attributes. The insilico investigations accurately predicted the quality of the protein packing in some of the variants. Our study found by altering the hydrophobicity of the oxyanion 114, remarkably altered enzyme conformational stability and catalytic attributes. Substitution with Leu resulted improvements in four out of the six tested characteristics. The hydrophobic Leu might have improved local structure folding and increased hydrophobic interactions with other residues in the vicinity of the mutation. The Met variant showed higher activity over the wild-type in hydrolyzing a wider range of natural oils. The bulky amino acids, Phe and Trp negatively affected T1 lipase and resulted in the largest disruption of protein stability and inferior enzyme characteristics. We have successfully illustrated that a single point residue changes at oxyanion 114 could result in a myriad of enzyme attributes, which implied there was some interplay between hydrophobicity and conformation for lipase catalytic functions.
文摘The proline iminopeptidase (PchPiPA) of the white-rot fungi Phanerochaete chrysosporium is an exopeptidase specific to catalyze hydrolysis of the N-terminal proline of peptides or proteins. Its catalytic cavity is comprised of a catalytic triad (Ser107, Asp264 and His292) and an oxyanion hole (His38, Gly39, Gly40 and Pro41). In this work, several amino acid residues involved in the catalytic cavity were selected for investigation of their influences on the catalytic activity by site-directed mutagenesis. It was shown that mutation of residues (Gly39 and Gly40) involved in oxyanion hole resulted in almost complete loss of catalytic activity largely due to changes in kcat. The other residues (Gly42 and Cys45) lined at the entrance of the active cavity also yielded a profound negative effect on the activity. Mutation of the other two residues Arg130 and Gly131 which were flanked spatially by the nucleophilic attacking active site of Ser107, caused different effects on the activity. R130Aincreased catalytic efficiency due to changes in both kcat and Km;while G131V decreased the value of kcat/Km mainly due to changes in kcat. And T111Aalso caused a negative effect on the kcat. Conclusively, these amino acid residues involved in active cavity were more susceptible to be negatively affected by mutation, suggested that the active cavity of proline iminopeptidase might evolve to be less plausible.
