It is highly important to develop ultrastable electrode materials for Li-ion batteries(LIBs),especially in the low temperature.Herein,we report Fe^(3+)-stabilized Ti_(3)C_(2)T_(x) MXene(donated as T/F-4:1)as the anode...It is highly important to develop ultrastable electrode materials for Li-ion batteries(LIBs),especially in the low temperature.Herein,we report Fe^(3+)-stabilized Ti_(3)C_(2)T_(x) MXene(donated as T/F-4:1)as the anode material,which exhibits an ultrastable low-temperature Li-ion storage property(135.2 m A h g^(-1)after300 cycles under the current density of 200 m A g^(-1)at-10℃),compared with the negligible capacity for the pure Ti_(3)C_(2)T_(x) MXene(26 m A h g^(-1)at 200 m A g^(-1)).We characterized as-made T/F samples via the Xray photoelectron spectroscopy(XPS),Fourier transformed infrared(FT-IR)and Raman spectroscopy,and found that the terminated functional groups(-O and-OH)in T/F are Li^(+) storage sites.Fe^(3+)-stabilization makes-O/-OH groups in MXene interlayers become active towards Li^(+),leading to much more active sites and thus an enhanced capacity and well cyclic stability.In contrast,only-O/-OH groups on the top and bottom surfaces of pure Ti_(3)C_(2)T_(x) MXene can be used to adsorb Li^(+),resulting in a low capacity.Transmission electron microscopy(TEM)and XPS data confirm that T/F-4:1 holds the highly stable solid electrolyte interphase(SEI)layer during the cycling at-10℃.Density functional theory(DFT)calculations further uncover that T/F has fast diffusion of Li^(+) and consequent better electrochemical performances than pure Ti_(3)C_(2)T_(x) MXene.It is believed that the new strategy used here will help to fabricate advanced MXene-based electrode materials in the energy storage application.展开更多
Hydroge nation of p-n itrophe nol(PNP)towards the con versi on to p-ami nophe no I(PAP)by metal catalysis is known as a simple and I eco-frie ndly tech nique for the production of corresp on ding in dustrial and pharm...Hydroge nation of p-n itrophe nol(PNP)towards the con versi on to p-ami nophe no I(PAP)by metal catalysis is known as a simple and I eco-frie ndly tech nique for the production of corresp on ding in dustrial and pharmaceutical in termediates.While continu ous efforts are paid for§more sustainable and greener procedures by using transition metal catalysts,atomic-precise reaction mechanism for the PNP-to-PAP is still illusive to be fully un derstood.Utilizi ng a dry-wet com bined strategy,here we have syn thesized water-soluble Pd8 nano clusters(NCs)with mercaptosuccinic acid(H2SMA)as the ligand,and the Pd8 NCs found high catalytic performance for the conversion of PNP-to-PAP,as identified by the electrospray ionization mass spectrometer(ESI-MS)measurement.The gradual changes over time of ultraviolet-visible(UV-vis)spectra of PNP really display the catalytic reduction by NaBH4 in presence of Pd8 NCs.Further,in-depth charge transfer interactions between PNP and the Pd8 clusters at the proton-rich conditions are investigated by natural bond orbital(NBO)analysis and electron density differenee(EDD)analysis.The exothermic and kinetic-favorable reaction pathways are addressed,based on successive PNP hydrogenation and H2O removal processes,clarifying the reaction mechanism of Pd catalysts.It is worth noting that this solid-state synthetic route for such Pd8 clusters enables gram-scale quantity of production in likely practical use.展开更多
Ammonia(NH3)ranks among the manufactured chemicals,with an annual production surpassing 182 million tons[1],which is an indispensable raw material for fertilizer industry and has been recognized as a promising carbon-...Ammonia(NH3)ranks among the manufactured chemicals,with an annual production surpassing 182 million tons[1],which is an indispensable raw material for fertilizer industry and has been recognized as a promising carbon-neutral energy carrier and has potential to partially supplant fossil fuels[2].展开更多
The palladium(Pd)-catalyzed Suzuki reaction is widely applied in the pharmaceutical industry,where constructing highly active and low-cost Pd sites are impendent.Here,we report the fabrication of a heterogeneous Pd/Ti...The palladium(Pd)-catalyzed Suzuki reaction is widely applied in the pharmaceutical industry,where constructing highly active and low-cost Pd sites are impendent.Here,we report the fabrication of a heterogeneous Pd/Tio2 catalyst via engineering of an electronic structure of a single Pd_(1)atom on monolayered Ti_(0.87)O_(2)nanosheet(Pd_(1)-Ti_(0.87)O_(2)).This catalyst motivated the kinetically sluggish C-Br cleavage,thus boosting the Suzuki reaction at room temperature.Pd_(1)-Ti_(0.87)O_(2)exhibited an outstanding activity with turnover frequency(TOF)of 11,110 h-1,exceeding that of PdCl_(2)and Pd(OAc)_(2)catalysts by a factor of>200.Various in situ techniques were employed to investigate the C-Br activation process,which showed that Pd_(1)kinetic-feasibly dissociated the chemisorbed bromobenzene,especially the C-Br bond cleavage.Theoretical calculations further revealed that the improved activity is ascribed to the optimized charge state of Pd_(1)within the Pd_(1)O4 realm via charge transfer.展开更多
基金supported financially by the Fundamental Research Funds for the Central Universities(Nos.2019RC021,2018JBZ107,2019RC035)the National Natural Science Foundation of China(Nos.51971056,91961125,51802013,21905019)+3 种基金the Key Program for International S&T Cooperation Projects of China from the Ministry of Science and Technology of China(No.2018YFE0124600)the Chemistry and Chemical Engineering Guangdong Laboratory(Nos.1932004 and 1911021)the financial support from Natural Science Foundation of Liaoning Province(No.20180510003)support from the“Excellent One Hundred”Project of Beijing Jiaotong University。
文摘It is highly important to develop ultrastable electrode materials for Li-ion batteries(LIBs),especially in the low temperature.Herein,we report Fe^(3+)-stabilized Ti_(3)C_(2)T_(x) MXene(donated as T/F-4:1)as the anode material,which exhibits an ultrastable low-temperature Li-ion storage property(135.2 m A h g^(-1)after300 cycles under the current density of 200 m A g^(-1)at-10℃),compared with the negligible capacity for the pure Ti_(3)C_(2)T_(x) MXene(26 m A h g^(-1)at 200 m A g^(-1)).We characterized as-made T/F samples via the Xray photoelectron spectroscopy(XPS),Fourier transformed infrared(FT-IR)and Raman spectroscopy,and found that the terminated functional groups(-O and-OH)in T/F are Li^(+) storage sites.Fe^(3+)-stabilization makes-O/-OH groups in MXene interlayers become active towards Li^(+),leading to much more active sites and thus an enhanced capacity and well cyclic stability.In contrast,only-O/-OH groups on the top and bottom surfaces of pure Ti_(3)C_(2)T_(x) MXene can be used to adsorb Li^(+),resulting in a low capacity.Transmission electron microscopy(TEM)and XPS data confirm that T/F-4:1 holds the highly stable solid electrolyte interphase(SEI)layer during the cycling at-10℃.Density functional theory(DFT)calculations further uncover that T/F has fast diffusion of Li^(+) and consequent better electrochemical performances than pure Ti_(3)C_(2)T_(x) MXene.It is believed that the new strategy used here will help to fabricate advanced MXene-based electrode materials in the energy storage application.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21722308 and 21802146)Beijing Natural Science Foundation(No.2192064)+2 种基金CAS Key Research Project of Frontier Science(No.QYZDB-SSWSLH024)Frontier Cross Project of National Laboratory for Molecular Sciences(No.051Z011BZ3)Z.X.L.acknowledges the National Thousand Youth Talents Program.
文摘Hydroge nation of p-n itrophe nol(PNP)towards the con versi on to p-ami nophe no I(PAP)by metal catalysis is known as a simple and I eco-frie ndly tech nique for the production of corresp on ding in dustrial and pharmaceutical in termediates.While continu ous efforts are paid for§more sustainable and greener procedures by using transition metal catalysts,atomic-precise reaction mechanism for the PNP-to-PAP is still illusive to be fully un derstood.Utilizi ng a dry-wet com bined strategy,here we have syn thesized water-soluble Pd8 nano clusters(NCs)with mercaptosuccinic acid(H2SMA)as the ligand,and the Pd8 NCs found high catalytic performance for the conversion of PNP-to-PAP,as identified by the electrospray ionization mass spectrometer(ESI-MS)measurement.The gradual changes over time of ultraviolet-visible(UV-vis)spectra of PNP really display the catalytic reduction by NaBH4 in presence of Pd8 NCs.Further,in-depth charge transfer interactions between PNP and the Pd8 clusters at the proton-rich conditions are investigated by natural bond orbital(NBO)analysis and electron density differenee(EDD)analysis.The exothermic and kinetic-favorable reaction pathways are addressed,based on successive PNP hydrogenation and H2O removal processes,clarifying the reaction mechanism of Pd catalysts.It is worth noting that this solid-state synthetic route for such Pd8 clusters enables gram-scale quantity of production in likely practical use.
文摘Ammonia(NH3)ranks among the manufactured chemicals,with an annual production surpassing 182 million tons[1],which is an indispensable raw material for fertilizer industry and has been recognized as a promising carbon-neutral energy carrier and has potential to partially supplant fossil fuels[2].
基金This study was supported financially by the National Natural Science Foundation of China(grant nos.91961125,21905019,and 21903001)the Fundamental Research Funds for the Central Universities(grant nos.2018JBZ107 and 2019RC035)+2 种基金the Ministry of Science and Technology of China(grant no.2018YFE0124600)the Chemistry and Chemical Engineering Guangdong Laboratory(grant no.1932004)the Natural Science Foundation of Anhui Province(grant no.1908085QB58)。
文摘The palladium(Pd)-catalyzed Suzuki reaction is widely applied in the pharmaceutical industry,where constructing highly active and low-cost Pd sites are impendent.Here,we report the fabrication of a heterogeneous Pd/Tio2 catalyst via engineering of an electronic structure of a single Pd_(1)atom on monolayered Ti_(0.87)O_(2)nanosheet(Pd_(1)-Ti_(0.87)O_(2)).This catalyst motivated the kinetically sluggish C-Br cleavage,thus boosting the Suzuki reaction at room temperature.Pd_(1)-Ti_(0.87)O_(2)exhibited an outstanding activity with turnover frequency(TOF)of 11,110 h-1,exceeding that of PdCl_(2)and Pd(OAc)_(2)catalysts by a factor of>200.Various in situ techniques were employed to investigate the C-Br activation process,which showed that Pd_(1)kinetic-feasibly dissociated the chemisorbed bromobenzene,especially the C-Br bond cleavage.Theoretical calculations further revealed that the improved activity is ascribed to the optimized charge state of Pd_(1)within the Pd_(1)O4 realm via charge transfer.
