Despite one-dimensional （1D） semiconductor nanostructure arrays attracting increasing attention due to their many advantages, highly ordered TiO2 nanorod arrays （TiO2 NR） are rarely grown in situ on Ti substrates....Despite one-dimensional （1D） semiconductor nanostructure arrays attracting increasing attention due to their many advantages, highly ordered TiO2 nanorod arrays （TiO2 NR） are rarely grown in situ on Ti substrates. Herein, a feasible method to fabricate TiO2 NRs on Ti substrates by using a through-mask anodization process is reported. Self-ordered anodic aluminum oxide （AAO） overlaid on Ti substrate was used as a nanotemplate to induce the growth of TiO2 NRs. The NR length and diameter could be controlled by adjusting anodization parameters such as electrochemical anodization voltage, anodization time and temperature, and electrolyte composition. Furthermore, according to the proposed NR formation mechanism, the anodized Ti ions migrate and deposit in the AAO nanochannels to form Ti（OH）4 or amorphous TiO2 NRs under electric field, owing to the confinement effect of the template. Photoelectrochemical tests indicated that, after hydrogenation, the TiO2 NRs presented higher photocurrent density under simulated sunlight and visible light illuminations, suggesting their potential use in photoelectrochemical water splitting, photocatalysis, solar cells, and sensors.展开更多
Porous carbon-encapsulated Ni and Ni-Sn intermetallic compound catalysts were prepared by the one-pot extended Stöber method followed by carbonization and tested for in-situ hydrothermal deoxygenation of methyl p...Porous carbon-encapsulated Ni and Ni-Sn intermetallic compound catalysts were prepared by the one-pot extended Stöber method followed by carbonization and tested for in-situ hydrothermal deoxygenation of methyl palmitate with methanol as the hydrogen donor.During the catalyst preparation,Sn doping reduces the size of carbon spheres,and the formation of Ni-Sn intermetallic compounds restrain the graphitization,contributing to larger pore volume and pore diameter.Consequently,a more facile mass transfer occurs in carbon-encapsulated Ni-Sn intermetallic compound catalysts than in carbonencapsulated Ni catalysts.During the in-situ hydrothermal deoxygenation,the synergism between Ni and Sn favors palmitic acid hydrogenation to a highly reactive hexadecanal that easily either decarbonylate to n-pentadecane or is hydrogenated to hexadecanol.At high reaction temperature,hexadecanol undergoes dehydrogenation-decarbonylation,generating n-pentadecane.Also,the C-C bond hydrolysis and methanation are suppressed on Ni-Sn intermetallic compounds,favorable for increasing the carbon yield and reducing the H_(2) consumption.The npentadecane and n-hexadecane yields reached 88.1%and 92.8%on carbon-encapsulated Ni_(3) Sn_(2) intermetallic compound at 330℃.After washing and H_(2) reduction,the carbon-encapsulated Ni_(3) Sn_(2) intermetallic compound remains stable during three recycling cycles.This is ascribed to the carbon confinement that effectively suppresses the sintering and loss of metal particles under harsh hydrothermal conditions.展开更多
The development of novel simple, and convenient techniques for the fabrication of porous carbon materials with desirable properties, such as tunable pore structures and the presence of nitrogen functionalities, from r...The development of novel simple, and convenient techniques for the fabrication of porous carbon materials with desirable properties, such as tunable pore structures and the presence of nitrogen functionalities, from renewable and abundant biomasses is required. We herein describe an in situ directing method for the preparation of a nitrogen-doped flower-like porous carbon （NFPC） employing arbitrarily shaped MgO from bio-derived glucosamine chloride （GAH）. Experimental evidence demonstrated that the structure directing effect of the Mg（OH）2 nanosheets formed in situ from MgO hydrolysis was key to this process, with the original MgO morphology being irrelevant. Furthermore, this method was applicable for a wide variety of biomass-derived carbon precursors. The resulting NFPC exhibited a high nitrogen content of 〈9 wt.%, and was employed as a support to anchor small Ru nanoparticles （average size = 2.7 nm）. The resulting Ru/NFPC was highly active in heterogeneous hydrogenations of toluene and benzoic acid, which demonstrated the advantages of nitrogen doping in terms of boosting catalytic performance.展开更多
The Ru/C catalyst prepared by impregnation method was used for hydrogenation of 3,5-dimethylpyridine in a trickle bed reactor.Under the same reduction conditions(300°C in H_(2)),the catalytic activity of the non-...The Ru/C catalyst prepared by impregnation method was used for hydrogenation of 3,5-dimethylpyridine in a trickle bed reactor.Under the same reduction conditions(300°C in H_(2)),the catalytic activity of the non-in-situ reduced Ru/C-n catalyst was higher than that of the in-situ reduced Ru/C-y catalyst.Therefore,an in-situ H_(2)reduction and moderate oxidation method was developed to increase the catalyst activity.Moreover,the influence of oxidation temperature on the developed method was investigated.The catalysts were characterized by Brunauer–Emmett–Teller method,hydrogen temperature programmed reduction H_(2)-TPR,hydrogen temperature-programmed dispersion(H_(2)-TPD),X-ray diffraction,energy dispersive spectroscopy,X-ray photoelectron spectroscopy,Raman spectroscopy,O2 chemisorption and oxygen temperature-programmed dispersion(O2-TPD)analyses.The results showed that there existed an optimal Ru/RuO_(x)ratio for the catalyst,and the highest 3,5-dimethylpyridine conversion was obtained for the Ru/C-i1 catalyst prepared by in-situ H_(2)reduction and moderate oxidation(oxidized at 100°C).Excessive oxidation(200°C)resulted in a significant decrease in the Ru/RuO_(x)ratio of the in-situ H_(2)reduction and moderate oxidized Ru/C-i2 catalyst,the interaction between RuO_(x)species and the support changed,and the hard-to-reduce RuO_(x)species was formed,leading to a significant decrease in catalyst activity.The developed in-situ H_(2)reduction and moderate oxidation method eliminated the step of the non-in-situ reduction of catalyst outside the trickle bed reactor.展开更多
In this work,a novel in situ auto-reduction strategy was developed to encapsulate uniformly dispersed Pd clusters/nanoparticles in MIL-125-NH_(2).It is demonstrated that the amino groups in MIL-125-NH_(2)can react wit...In this work,a novel in situ auto-reduction strategy was developed to encapsulate uniformly dispersed Pd clusters/nanoparticles in MIL-125-NH_(2).It is demonstrated that the amino groups in MIL-125-NH_(2)can react with formaldehyde to form novel reducing groups(-NH-CH_(2)OH),which can in situ auto-reduce the encapsulated Pd^(2+)ions to metallic Pd clusters/nanoparticles.As no additional reductants are required,the strategy limits the aggregation and migration of Pd clusters and the formation of large Pd nanoparticles via controlling the amount of Pd^(2+)precursor.When applied as catalysts in the hydrogenation of phenol in the aqueous phase,the obtained Pd(1.5)/MIL-125-NH-CH_(2)OH catalyst with highly dispersed Pd clusters/nanoparticles with the size of around 2 nm exhibited 100%of phenol conversion and 100%of cyclohexanone selectivity at 70℃ after 5 h,as well as remarkable reusability for at least five cycles due to the large MOF surface area,the highly dispersed Pd clusters/nanoparticles and their excellent stability within the MIL-125-NH-CH_(2)OH framework.展开更多
The surface species formed from the adsorption of 1,3-butadiene and 1,3-butadiene hydrogenation over the fresh Mo2C/γ-Al2O3 catalyst was studied by in situ IR spectroscopy. It is found that 1,3-butadiene adsorption o...The surface species formed from the adsorption of 1,3-butadiene and 1,3-butadiene hydrogenation over the fresh Mo2C/γ-Al2O3 catalyst was studied by in situ IR spectroscopy. It is found that 1,3-butadiene adsorption on the Mo2C/γ-Al2O3 catalyst mainly forms π-adsorbed butadiene(πs and πd) and σ-bonded surface species. These species are adsorbed mainly on the surface Moδ+(0<δ<2) sites as evidenced by co-adsorption of 1,3-butadiene and CO on the fresh Mo2C/γ-Al2O3 catalyst. The IR spectrometric analysis show that hydrogenation of 1,3-butadiene over fresh Mo2C/γ-Al2O3 catalyst produces mainly butane coupled with a small portion of butene. The selectivity of butene during the hydrogenation of 1,3-butadiene over fresh Mo2C/γ-Al2O3 catalyst might be explained by the adsorption mode of adsorbed 1,3-butadiene. Additionally, the active sites of the fresh Mo2C/γ-Al2O3 catalyst may be covered by coke during the hydrogenation reaction of 1,3-butadiene. The treatment with hydrogen at 673 K cannot remove the coke deposits from the surface of the Mo2C/γ-Al2O3 catalyst.展开更多
基金Thanks for the financial support of the National Natural Science Foundation of China （Nos. 21303227, 21573259, and 51403220）, Qingdao science and tech- nology plan application foundation research project（No. 14-2-4-60-JCH） and the ＂Hundred Talents Pro- gram＂ of Chinese Academy of Sciences （D. A. W.）.
文摘Despite one-dimensional （1D） semiconductor nanostructure arrays attracting increasing attention due to their many advantages, highly ordered TiO2 nanorod arrays （TiO2 NR） are rarely grown in situ on Ti substrates. Herein, a feasible method to fabricate TiO2 NRs on Ti substrates by using a through-mask anodization process is reported. Self-ordered anodic aluminum oxide （AAO） overlaid on Ti substrate was used as a nanotemplate to induce the growth of TiO2 NRs. The NR length and diameter could be controlled by adjusting anodization parameters such as electrochemical anodization voltage, anodization time and temperature, and electrolyte composition. Furthermore, according to the proposed NR formation mechanism, the anodized Ti ions migrate and deposit in the AAO nanochannels to form Ti（OH）4 or amorphous TiO2 NRs under electric field, owing to the confinement effect of the template. Photoelectrochemical tests indicated that, after hydrogenation, the TiO2 NRs presented higher photocurrent density under simulated sunlight and visible light illuminations, suggesting their potential use in photoelectrochemical water splitting, photocatalysis, solar cells, and sensors.
文摘Porous carbon-encapsulated Ni and Ni-Sn intermetallic compound catalysts were prepared by the one-pot extended Stöber method followed by carbonization and tested for in-situ hydrothermal deoxygenation of methyl palmitate with methanol as the hydrogen donor.During the catalyst preparation,Sn doping reduces the size of carbon spheres,and the formation of Ni-Sn intermetallic compounds restrain the graphitization,contributing to larger pore volume and pore diameter.Consequently,a more facile mass transfer occurs in carbon-encapsulated Ni-Sn intermetallic compound catalysts than in carbonencapsulated Ni catalysts.During the in-situ hydrothermal deoxygenation,the synergism between Ni and Sn favors palmitic acid hydrogenation to a highly reactive hexadecanal that easily either decarbonylate to n-pentadecane or is hydrogenated to hexadecanol.At high reaction temperature,hexadecanol undergoes dehydrogenation-decarbonylation,generating n-pentadecane.Also,the C-C bond hydrolysis and methanation are suppressed on Ni-Sn intermetallic compounds,favorable for increasing the carbon yield and reducing the H_(2) consumption.The npentadecane and n-hexadecane yields reached 88.1%and 92.8%on carbon-encapsulated Ni_(3) Sn_(2) intermetallic compound at 330℃.After washing and H_(2) reduction,the carbon-encapsulated Ni_(3) Sn_(2) intermetallic compound remains stable during three recycling cycles.This is ascribed to the carbon confinement that effectively suppresses the sintering and loss of metal particles under harsh hydrothermal conditions.
基金Financial support from the National Natural Science Foundation of China （Nos. 91534114 and 21376208）, the Zhejiang Provincial Natural Science Foundation for Distinguished Young Scholars of China （No. LR13B030001）, the Fundamental Research Funds for the Central Universities, the Program for Zhejiang Leading Team of S＆T Innovation, the Partner Group Program of the Zhejiang University, and the Max- Planck Society is greatly appreciated.
文摘The development of novel simple, and convenient techniques for the fabrication of porous carbon materials with desirable properties, such as tunable pore structures and the presence of nitrogen functionalities, from renewable and abundant biomasses is required. We herein describe an in situ directing method for the preparation of a nitrogen-doped flower-like porous carbon （NFPC） employing arbitrarily shaped MgO from bio-derived glucosamine chloride （GAH）. Experimental evidence demonstrated that the structure directing effect of the Mg（OH）2 nanosheets formed in situ from MgO hydrolysis was key to this process, with the original MgO morphology being irrelevant. Furthermore, this method was applicable for a wide variety of biomass-derived carbon precursors. The resulting NFPC exhibited a high nitrogen content of 〈9 wt.%, and was employed as a support to anchor small Ru nanoparticles （average size = 2.7 nm）. The resulting Ru/NFPC was highly active in heterogeneous hydrogenations of toluene and benzoic acid, which demonstrated the advantages of nitrogen doping in terms of boosting catalytic performance.
文摘The Ru/C catalyst prepared by impregnation method was used for hydrogenation of 3,5-dimethylpyridine in a trickle bed reactor.Under the same reduction conditions(300°C in H_(2)),the catalytic activity of the non-in-situ reduced Ru/C-n catalyst was higher than that of the in-situ reduced Ru/C-y catalyst.Therefore,an in-situ H_(2)reduction and moderate oxidation method was developed to increase the catalyst activity.Moreover,the influence of oxidation temperature on the developed method was investigated.The catalysts were characterized by Brunauer–Emmett–Teller method,hydrogen temperature programmed reduction H_(2)-TPR,hydrogen temperature-programmed dispersion(H_(2)-TPD),X-ray diffraction,energy dispersive spectroscopy,X-ray photoelectron spectroscopy,Raman spectroscopy,O2 chemisorption and oxygen temperature-programmed dispersion(O2-TPD)analyses.The results showed that there existed an optimal Ru/RuO_(x)ratio for the catalyst,and the highest 3,5-dimethylpyridine conversion was obtained for the Ru/C-i1 catalyst prepared by in-situ H_(2)reduction and moderate oxidation(oxidized at 100°C).Excessive oxidation(200°C)resulted in a significant decrease in the Ru/RuO_(x)ratio of the in-situ H_(2)reduction and moderate oxidized Ru/C-i2 catalyst,the interaction between RuO_(x)species and the support changed,and the hard-to-reduce RuO_(x)species was formed,leading to a significant decrease in catalyst activity.The developed in-situ H_(2)reduction and moderate oxidation method eliminated the step of the non-in-situ reduction of catalyst outside the trickle bed reactor.
基金financial support from the National Natural Science Foundation of China(Grant No.51802015)the Research Department Closed Carbon Cycle Economy(CCCE)at the Ruhr-University Bochum,Fundamental Research Funds for the Central Universities(No.FRF-TP-20-005A3)the Fundamental Research Funds for the Central Universities and the Youth Teacher International Exchange&Growth Program(Grant No.QNXM20210016)。
文摘In this work,a novel in situ auto-reduction strategy was developed to encapsulate uniformly dispersed Pd clusters/nanoparticles in MIL-125-NH_(2).It is demonstrated that the amino groups in MIL-125-NH_(2)can react with formaldehyde to form novel reducing groups(-NH-CH_(2)OH),which can in situ auto-reduce the encapsulated Pd^(2+)ions to metallic Pd clusters/nanoparticles.As no additional reductants are required,the strategy limits the aggregation and migration of Pd clusters and the formation of large Pd nanoparticles via controlling the amount of Pd^(2+)precursor.When applied as catalysts in the hydrogenation of phenol in the aqueous phase,the obtained Pd(1.5)/MIL-125-NH-CH_(2)OH catalyst with highly dispersed Pd clusters/nanoparticles with the size of around 2 nm exhibited 100%of phenol conversion and 100%of cyclohexanone selectivity at 70℃ after 5 h,as well as remarkable reusability for at least five cycles due to the large MOF surface area,the highly dispersed Pd clusters/nanoparticles and their excellent stability within the MIL-125-NH-CH_(2)OH framework.
基金financially supported by the National Natural Science Foundation of China(No.20903054)Liaoning Provincial Natural Science Foundation(No.2014020107)+1 种基金Program for Liaoning excellent talents in university(No.LJQ2014041)sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry(SRF for ROCS,SEM)
文摘The surface species formed from the adsorption of 1,3-butadiene and 1,3-butadiene hydrogenation over the fresh Mo2C/γ-Al2O3 catalyst was studied by in situ IR spectroscopy. It is found that 1,3-butadiene adsorption on the Mo2C/γ-Al2O3 catalyst mainly forms π-adsorbed butadiene(πs and πd) and σ-bonded surface species. These species are adsorbed mainly on the surface Moδ+(0<δ<2) sites as evidenced by co-adsorption of 1,3-butadiene and CO on the fresh Mo2C/γ-Al2O3 catalyst. The IR spectrometric analysis show that hydrogenation of 1,3-butadiene over fresh Mo2C/γ-Al2O3 catalyst produces mainly butane coupled with a small portion of butene. The selectivity of butene during the hydrogenation of 1,3-butadiene over fresh Mo2C/γ-Al2O3 catalyst might be explained by the adsorption mode of adsorbed 1,3-butadiene. Additionally, the active sites of the fresh Mo2C/γ-Al2O3 catalyst may be covered by coke during the hydrogenation reaction of 1,3-butadiene. The treatment with hydrogen at 673 K cannot remove the coke deposits from the surface of the Mo2C/γ-Al2O3 catalyst.
