The electrocatalytic N_(2)reduction reaction(NRR)is expected to supersede the traditional Haber-Bosch technology for NH3 production under ambient conditions.The activity and selectivity of electrochemical NRR are rest...The electrocatalytic N_(2)reduction reaction(NRR)is expected to supersede the traditional Haber-Bosch technology for NH3 production under ambient conditions.The activity and selectivity of electrochemical NRR are restricted to a strong polarized electric field induced by the catalyst,correct electron transfer direction,and electron tunneling distance between bare electrode and active sites.By coupling the chemical vapor deposition method with the poly(methyl methacylate)-transfer method,an ultrathin sandwich catalyst,i.e.,Fe atoms(polarized electric field layer)sandwiched between ultrathin(within electron tunneling distance)BN(catalyst layer)and graphene film(conducting layer),is fabricated for electrocatalytic NRR.The sandwich catalyst not only controls the transfer of electrons to the BN surface in the correct direction under applied voltage but also suppresses hydrogen evolution reaction by constructing a neutral polarization electric field without metal exposure.The sandwich electrocatalyst NRR system achieve NH3 yield of 8.9μg h^(−1)cm^(−2)and Faradaic Efficiency of 21.7%.The N_(2)adsorption,activation,and polarization electric field changes of three sandwich catalysts(BN-Fe-G,BN-Fe-BN,and G-Fe-G)during the electrocatalytic NRR are investigated by experiments and density functional theory simulations.Driven by applied voltage,the neutral polarized electric field induced by BN-Fe-G leads to the high activity of electrocatalytic NRR.展开更多
A stable PNIPAM/Fe_3O_4/g-C_3N_4 composite photocatalyst was designed and prepared by a thermal photoinitiation technology.The structure and properties of the materials were characterized and the composite photocataly...A stable PNIPAM/Fe_3O_4/g-C_3N_4 composite photocatalyst was designed and prepared by a thermal photoinitiation technology.The structure and properties of the materials were characterized and the composite photocatalyst was found to show good stability for tetracycline degradation.The sample not only retained the magnetic properties of Fe_3O_4,allowing it to be recycled,but its photocatalytic properties could also be changed by controlling the temperature of the reaction system.The degradation intermediate products of tetracycline were further investigated by MS.This work provides a new facile strategy for the development of intelligent and recyclable photocatalytic materials.展开更多
The polarization switching plays a crucial role in controlling the final products in the catalytic pro-cess.The effect of polarization orientation on nitrogen reduction was investigated by anchoring transition metal a...The polarization switching plays a crucial role in controlling the final products in the catalytic pro-cess.The effect of polarization orientation on nitrogen reduction was investigated by anchoring transition metal atoms to form active centers on ferroelectric material In_(2)Se_(3).During the polariza-tion switching process,the difference in surface electrostatic potential leads to a redistribution of electronic states.This affects the interaction strength between the adsorbed small molecules and the catalyst substrate,thereby altering the reaction barrier.In addition,the surface states must be considered to prevent the adsorption of other small molecules(such as *O,*OH,and *H).Further-more,the V@↓-In_(2)Se_(3) possesses excellent catalytic properties,high electrochemical and thermody-namic stability,which facilitates the catalytic process.Machine learning also helps us further ex-plore the underlying mechanisms.The systematic investigation provides novel insights into the design and application of two-dimensional switchable ferroelectric catalysts for various chemical processes.展开更多
Transition metal catalysts M-N-C（M = Co,Fe,Mn） were synthesized by a template-free method by heating meso-tetraphenyl porphyrins（i.e.CoTPP,FeTPPCl,MnTPPCl） precursors.The catalysts were characterized by N2 adsorpt...Transition metal catalysts M-N-C（M = Co,Fe,Mn） were synthesized by a template-free method by heating meso-tetraphenyl porphyrins（i.e.CoTPP,FeTPPCl,MnTPPCl） precursors.The catalysts were characterized by N2 adsorption-desorption,thermogravimetry,high-resolution transmission electron microscopy,and Raman and X-ray photoelectron spectroscopy.The selective oxidation of ethylbenzene with molecular oxygen under a solvent-free condition was carried out to explore the catalytic performance of the M-N-Cs,which exhibited different catalytic performance.That was ascribed to the difference in M（Co,Fe,Mn） and different graphitization degree forming during the heating process,in which M（Co,Fe,Mn） might have different catalytic activity on the formation of the M-N-C catalyst.All the M-N-C composites had remarkable recyclability in the selective oxidation of ethylbenzene.展开更多
Owing to Fe being the most abundant and least expensive transition metal on the earth,the utilization of Fe-based catalysts for catalytic hydrogenation has attracted worldwide attention.In this work,a series of N-dope...Owing to Fe being the most abundant and least expensive transition metal on the earth,the utilization of Fe-based catalysts for catalytic hydrogenation has attracted worldwide attention.In this work,a series of N-doped C supported Fe catalysts(Fe-N-C)were prepared by co-pyrolysis of cellulose and ferric chloride under ammonia atmosphere.Characterization methods such as elemental analysis,atomic absorption spectroscopy,nitrogen adsorption-desorption isotherms,transmission electron microscopy,high-resolution transmission electron microscopy,X-ray diffraction,and X-ray photoelectron spectroscopy were carried out to explore the physicochemical properties of the catalysts.Using hydrogenation of nitrobenzene as a model reaction,the catalysts prepared at different pyrolysis temperatures displayed different activities.Fe-N-C-700 exhibited the best activity among these catalysts,with the yield of aniline being up to 98.0%under 5 MPa H2 at 120℃ after 12 h.Combined with the results of catalyst characterization and comparative tests,the transformation of Fe species and the generation of N-doped C,especially graphitized N-doped C,in the catalyst may be the main factors affecting the activity.A kinetic study was carried out and the apparent activation energy was obtained as 31.53 kJ/mol.The stability of the catalyst was also tested and no significant decrease in the activity was observed after 5 runs.展开更多
Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells.Fe-N compounds with excellent electrocatalytic oxygen...Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells.Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells,which focuses on the Fe-N4 single-atom catalysts and the iron nitride materials(such as Fe2N and Fe3N).A hybridized catalyst having a hierarchical porous structure with regular macropores could enable the desired mass transfer efficiency in the catalytic process.In this study,we have constructed a new type of hybrid catalyst having iron and iron-nitrogen alloy nanoparticles(Fe-N austenite,termed as Fe-NA)embedded in the three-dimensional ordered macroporous N-doped carbon(3DOM Fe/Fe-NA@NC)by direct pyrolysis of single-source dicyandiamide-based iron metal-organic frameworks.The as-synthesized composites preserve the hierarchical porous carbon framework with ordered macropores and high specific surface area,incorporating the uniformly dispersed iron/iron-nitrogen austenite nanoparticles.Thereby,the striking architectural configuration embedded with highly active catalytic species delivers a superior oxygen reduction activity with a half-wave potential of 0.88 V and a subsequent superior Zn-air battery performance with high open-circuit voltage and continuous stability as compared to those using a commercial 20%Pt/C catalyst.展开更多
Proton exchange membrane fuel cells suffer from the sluggish kinetics of the oxygen reduction reaction(ORR)and the high cost of Pt catalysts.In the present work,a high‐performance ORR catalystbased on Fe,N,S‐doped p...Proton exchange membrane fuel cells suffer from the sluggish kinetics of the oxygen reduction reaction(ORR)and the high cost of Pt catalysts.In the present work,a high‐performance ORR catalystbased on Fe,N,S‐doped porous carbon(FeNS‐PC)was synthesized using melamine formaldehyderesin as C and N precursors,Fe(SCN)3as Fe and S precursors,and CaCl2as a template via a two‐stepheat treatment without a harsh template removal step.The results show that the catalyst treated at900℃(FeNS‐PC‐900)had a high surface area of775m2/g,a high mass activity of10.2A/g in anacidic medium,and excellent durability;the half‐wave potential decreased by only20mV after10000potential cycles.The FeNS‐PC‐900catalyst was used as the cathode in a proton exchangemembrane fuel cell and delivered a peak power density of0.49W/cm2.FeNS‐PC‐900therefore hasgood potential for use in practical applications.展开更多
Two series of ZSM-5 and beta zeolites were pretreated in 1.0 mol/L HNO3 solution at room temper-ature for various time periods. The catalytic performances of their Fe-exchanged products in N2O decomposition were evalu...Two series of ZSM-5 and beta zeolites were pretreated in 1.0 mol/L HNO3 solution at room temper-ature for various time periods. The catalytic performances of their Fe-exchanged products in N2O decomposition were evaluated. The Fe-zeolite catalysts were characterized using N2 adsorp-tion-desorption, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, ultra-violet-visible spectroscopy, temperature-programmed desorption of NH3, and scanning and trans-mission electron microscopies. For the ZSM-5 zeolite, acid leaching primarily takes place on the crystal surface and the particle size is reduced, therefore the pore channels are shortened. However, because of the good stability of MFI zeolites, the acid does not greatly penetrate the pore channels and new mesopores are not created. For the beta zeolite, because the amorphous material is in-clined to dissolve（deagglomerate）, some of the micropores are slightly dilated. The improved cata-lytic activities can be explained by the increased active Fe loading as a result of structural changes.展开更多
文摘The electrocatalytic N_(2)reduction reaction(NRR)is expected to supersede the traditional Haber-Bosch technology for NH3 production under ambient conditions.The activity and selectivity of electrochemical NRR are restricted to a strong polarized electric field induced by the catalyst,correct electron transfer direction,and electron tunneling distance between bare electrode and active sites.By coupling the chemical vapor deposition method with the poly(methyl methacylate)-transfer method,an ultrathin sandwich catalyst,i.e.,Fe atoms(polarized electric field layer)sandwiched between ultrathin(within electron tunneling distance)BN(catalyst layer)and graphene film(conducting layer),is fabricated for electrocatalytic NRR.The sandwich catalyst not only controls the transfer of electrons to the BN surface in the correct direction under applied voltage but also suppresses hydrogen evolution reaction by constructing a neutral polarization electric field without metal exposure.The sandwich electrocatalyst NRR system achieve NH3 yield of 8.9μg h^(−1)cm^(−2)and Faradaic Efficiency of 21.7%.The N_(2)adsorption,activation,and polarization electric field changes of three sandwich catalysts(BN-Fe-G,BN-Fe-BN,and G-Fe-G)during the electrocatalytic NRR are investigated by experiments and density functional theory simulations.Driven by applied voltage,the neutral polarized electric field induced by BN-Fe-G leads to the high activity of electrocatalytic NRR.
基金supported by the National Natural Science Foundation of China(31470434,21406090,21576124,21676124,21507047)the Project of Science and Technology Development Plan of Taicang(TC2015NY05)~~
文摘A stable PNIPAM/Fe_3O_4/g-C_3N_4 composite photocatalyst was designed and prepared by a thermal photoinitiation technology.The structure and properties of the materials were characterized and the composite photocatalyst was found to show good stability for tetracycline degradation.The sample not only retained the magnetic properties of Fe_3O_4,allowing it to be recycled,but its photocatalytic properties could also be changed by controlling the temperature of the reaction system.The degradation intermediate products of tetracycline were further investigated by MS.This work provides a new facile strategy for the development of intelligent and recyclable photocatalytic materials.
文摘The polarization switching plays a crucial role in controlling the final products in the catalytic pro-cess.The effect of polarization orientation on nitrogen reduction was investigated by anchoring transition metal atoms to form active centers on ferroelectric material In_(2)Se_(3).During the polariza-tion switching process,the difference in surface electrostatic potential leads to a redistribution of electronic states.This affects the interaction strength between the adsorbed small molecules and the catalyst substrate,thereby altering the reaction barrier.In addition,the surface states must be considered to prevent the adsorption of other small molecules(such as *O,*OH,and *H).Further-more,the V@↓-In_(2)Se_(3) possesses excellent catalytic properties,high electrochemical and thermody-namic stability,which facilitates the catalytic process.Machine learning also helps us further ex-plore the underlying mechanisms.The systematic investigation provides novel insights into the design and application of two-dimensional switchable ferroelectric catalysts for various chemical processes.
基金supported by the National Natural Science Foundation of China (21103045, 1210040, 1103312)State Key Laboratory of Heavy Oil at China University of Petroleum (SKCHOP201504)Key Laboratory of Mineralogy and Metallogeny of the Chinese Academy of Sciences at Guangzhou Institute of Geochemistry(KLMM20150103)~~
文摘Transition metal catalysts M-N-C（M = Co,Fe,Mn） were synthesized by a template-free method by heating meso-tetraphenyl porphyrins（i.e.CoTPP,FeTPPCl,MnTPPCl） precursors.The catalysts were characterized by N2 adsorption-desorption,thermogravimetry,high-resolution transmission electron microscopy,and Raman and X-ray photoelectron spectroscopy.The selective oxidation of ethylbenzene with molecular oxygen under a solvent-free condition was carried out to explore the catalytic performance of the M-N-Cs,which exhibited different catalytic performance.That was ascribed to the difference in M（Co,Fe,Mn） and different graphitization degree forming during the heating process,in which M（Co,Fe,Mn） might have different catalytic activity on the formation of the M-N-C catalyst.All the M-N-C composites had remarkable recyclability in the selective oxidation of ethylbenzene.
基金supported by the National Natural Science Foundation of China (51876200, 21572213)the DNL Cooperation Fund, CAS (DNL180301)~~
文摘Owing to Fe being the most abundant and least expensive transition metal on the earth,the utilization of Fe-based catalysts for catalytic hydrogenation has attracted worldwide attention.In this work,a series of N-doped C supported Fe catalysts(Fe-N-C)were prepared by co-pyrolysis of cellulose and ferric chloride under ammonia atmosphere.Characterization methods such as elemental analysis,atomic absorption spectroscopy,nitrogen adsorption-desorption isotherms,transmission electron microscopy,high-resolution transmission electron microscopy,X-ray diffraction,and X-ray photoelectron spectroscopy were carried out to explore the physicochemical properties of the catalysts.Using hydrogenation of nitrobenzene as a model reaction,the catalysts prepared at different pyrolysis temperatures displayed different activities.Fe-N-C-700 exhibited the best activity among these catalysts,with the yield of aniline being up to 98.0%under 5 MPa H2 at 120℃ after 12 h.Combined with the results of catalyst characterization and comparative tests,the transformation of Fe species and the generation of N-doped C,especially graphitized N-doped C,in the catalyst may be the main factors affecting the activity.A kinetic study was carried out and the apparent activation energy was obtained as 31.53 kJ/mol.The stability of the catalyst was also tested and no significant decrease in the activity was observed after 5 runs.
文摘Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells.Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells,which focuses on the Fe-N4 single-atom catalysts and the iron nitride materials(such as Fe2N and Fe3N).A hybridized catalyst having a hierarchical porous structure with regular macropores could enable the desired mass transfer efficiency in the catalytic process.In this study,we have constructed a new type of hybrid catalyst having iron and iron-nitrogen alloy nanoparticles(Fe-N austenite,termed as Fe-NA)embedded in the three-dimensional ordered macroporous N-doped carbon(3DOM Fe/Fe-NA@NC)by direct pyrolysis of single-source dicyandiamide-based iron metal-organic frameworks.The as-synthesized composites preserve the hierarchical porous carbon framework with ordered macropores and high specific surface area,incorporating the uniformly dispersed iron/iron-nitrogen austenite nanoparticles.Thereby,the striking architectural configuration embedded with highly active catalytic species delivers a superior oxygen reduction activity with a half-wave potential of 0.88 V and a subsequent superior Zn-air battery performance with high open-circuit voltage and continuous stability as compared to those using a commercial 20%Pt/C catalyst.
基金supported by the National Basic Research Program of China (973 Program,2015CB932303)the National Natural Science Founda-tion of China (21373175,21621091)~~
文摘Proton exchange membrane fuel cells suffer from the sluggish kinetics of the oxygen reduction reaction(ORR)and the high cost of Pt catalysts.In the present work,a high‐performance ORR catalystbased on Fe,N,S‐doped porous carbon(FeNS‐PC)was synthesized using melamine formaldehyderesin as C and N precursors,Fe(SCN)3as Fe and S precursors,and CaCl2as a template via a two‐stepheat treatment without a harsh template removal step.The results show that the catalyst treated at900℃(FeNS‐PC‐900)had a high surface area of775m2/g,a high mass activity of10.2A/g in anacidic medium,and excellent durability;the half‐wave potential decreased by only20mV after10000potential cycles.The FeNS‐PC‐900catalyst was used as the cathode in a proton exchangemembrane fuel cell and delivered a peak power density of0.49W/cm2.FeNS‐PC‐900therefore hasgood potential for use in practical applications.
基金supported by the National Natural Science Foundation of China (21307144,21307007)Science of Technology Development Plan of Jilin Province of China (20140520150JH)~~
文摘Two series of ZSM-5 and beta zeolites were pretreated in 1.0 mol/L HNO3 solution at room temper-ature for various time periods. The catalytic performances of their Fe-exchanged products in N2O decomposition were evaluated. The Fe-zeolite catalysts were characterized using N2 adsorp-tion-desorption, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, ultra-violet-visible spectroscopy, temperature-programmed desorption of NH3, and scanning and trans-mission electron microscopies. For the ZSM-5 zeolite, acid leaching primarily takes place on the crystal surface and the particle size is reduced, therefore the pore channels are shortened. However, because of the good stability of MFI zeolites, the acid does not greatly penetrate the pore channels and new mesopores are not created. For the beta zeolite, because the amorphous material is in-clined to dissolve（deagglomerate）, some of the micropores are slightly dilated. The improved cata-lytic activities can be explained by the increased active Fe loading as a result of structural changes.
