Developing low-cost and sustainable catalytic systems to realize efficient nitrogen fixation has always been the pursued goal.Here,we report an efficient electrocatalyst synthesized via a simple self-assembly process ...Developing low-cost and sustainable catalytic systems to realize efficient nitrogen fixation has always been the pursued goal.Here,we report an efficient electrocatalyst synthesized via a simple self-assembly process from supramolecular cucurbit[6]uril(Q[6])and a heteropolyacid for nitrogen oxidation.The asprepared self-assembly material Q[6]-PMA with high stability and specific surface area shows a prominent activity in the electrocatalytic nitrogen oxidation reaction(NOR).展开更多
Carboxylic acid-functionalized single walled carbon nanotubes(SWNTs)prepared via the reaction of an amino acid,NH2(CH2)nCO2H where n=1(glycine,GLY),5(6-aminohexanoic acid,AHA),10(11-aminoundecanoic acid,AUDA),with fl ...Carboxylic acid-functionalized single walled carbon nanotubes(SWNTs)prepared via the reaction of an amino acid,NH2(CH2)nCO2H where n=1(glycine,GLY),5(6-aminohexanoic acid,AHA),10(11-aminoundecanoic acid,AUDA),with fl uorinated single walled carbon nanotubes(F-SWNTs)have been characterized by MAS 13C NMR spectroscopy.The ease of observing the aliphatic CH2 groups and the resolution of the signal are dependent on the length of the amino acid’s aliphatic chain.We have proposed that where substituent chains are short(making NMR data collection difficult)chemical modification to extend the chain length should alleviate analysis problems.In this regard,we have investigated the esterifi cation of the carboxylic acid termini.The amino acid-functionalized SWNTs were esterified with an appropriate alcohol to ensure parity of the overall substituent length,i.e.,GLY-SWNT(C1)+1-dodecanol(C_(12))=DOD-GLY-SWNT(1),AHA-SWNT(C_(5))+1-octanol(C_(8))=OCT-AHA-SWNT(2),and AUDA-SWNT(C_(10))+1-propanol(C_(3))=PRO-AUDA-SWNT(3).The 13C NMR shift for the sp3 nitrogen-substituted carbon atoms of the SWNT sidewall is observed atδ≈75 ppm.Increasing the length of SWNT sidewall functional groups enhances the ability to observe the sidewall sp^(3)carbon.The methylene carbon signal intensity is less attenuated in the dipolar dephasing spectrum of the ester-functionalized SWNTs than their associated amino acid derivatives,suggesting more motional freedom of the side chain in the solid state.The confi rmation of the dipolar dephasing spectral effects was assisted by the characterization of the ester of AUDA-SWNT with 1,3-propanediol:PPD-AUDA-SWNT(4).展开更多
基金supported by the National Natural Science Foundation of China(No.22161011).
文摘Developing low-cost and sustainable catalytic systems to realize efficient nitrogen fixation has always been the pursued goal.Here,we report an efficient electrocatalyst synthesized via a simple self-assembly process from supramolecular cucurbit[6]uril(Q[6])and a heteropolyacid for nitrogen oxidation.The asprepared self-assembly material Q[6]-PMA with high stability and specific surface area shows a prominent activity in the electrocatalytic nitrogen oxidation reaction(NOR).
基金Financial support for this work is provided by the Robert A.Welch Foundation,and the National Science Foundation through the Center for Biological and Environmental Nanotechnology(EEC-0647452).
文摘Carboxylic acid-functionalized single walled carbon nanotubes(SWNTs)prepared via the reaction of an amino acid,NH2(CH2)nCO2H where n=1(glycine,GLY),5(6-aminohexanoic acid,AHA),10(11-aminoundecanoic acid,AUDA),with fl uorinated single walled carbon nanotubes(F-SWNTs)have been characterized by MAS 13C NMR spectroscopy.The ease of observing the aliphatic CH2 groups and the resolution of the signal are dependent on the length of the amino acid’s aliphatic chain.We have proposed that where substituent chains are short(making NMR data collection difficult)chemical modification to extend the chain length should alleviate analysis problems.In this regard,we have investigated the esterifi cation of the carboxylic acid termini.The amino acid-functionalized SWNTs were esterified with an appropriate alcohol to ensure parity of the overall substituent length,i.e.,GLY-SWNT(C1)+1-dodecanol(C_(12))=DOD-GLY-SWNT(1),AHA-SWNT(C_(5))+1-octanol(C_(8))=OCT-AHA-SWNT(2),and AUDA-SWNT(C_(10))+1-propanol(C_(3))=PRO-AUDA-SWNT(3).The 13C NMR shift for the sp3 nitrogen-substituted carbon atoms of the SWNT sidewall is observed atδ≈75 ppm.Increasing the length of SWNT sidewall functional groups enhances the ability to observe the sidewall sp^(3)carbon.The methylene carbon signal intensity is less attenuated in the dipolar dephasing spectrum of the ester-functionalized SWNTs than their associated amino acid derivatives,suggesting more motional freedom of the side chain in the solid state.The confi rmation of the dipolar dephasing spectral effects was assisted by the characterization of the ester of AUDA-SWNT with 1,3-propanediol:PPD-AUDA-SWNT(4).
