The uniformly dispersed transition metal(Co, Ni and Fe) nanoparticles supported on the surface of La-promoted Mg O were prepared via a deposition-precipitation method for hydrogen production from catalytic decompositi...The uniformly dispersed transition metal(Co, Ni and Fe) nanoparticles supported on the surface of La-promoted Mg O were prepared via a deposition-precipitation method for hydrogen production from catalytic decomposition of ammonia. X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy, temperature-programmed reduction and temperature-programmed desorption were used to investigate the structure-activity relation of catalysts in NH3 decomposition. The results show that the strong interaction between active species and support can effectively prevent the active species from agglomerating during ammonia decomposition reaction. In addition, the introduction of La species not only facilitates the adsorption and decomposition of NH3 and desorption of N2, but also benefits the better dispersion of the active species. The prepared catalysts showed very high catalytic activity for ammonia decomposition compared with the same active composition samples that reported previously. Meanwhile, the catalysts showed excellent high-temperature stability and no any deactivation was observed, which are very promising candidates for the decomposition of ammonia to hydrogen.展开更多
Oxide-supported copper-containing materials have attracted considerable research attention as promising candidates for acrolein formation.Nevertheless,the elucidation of the structure-performance relationships for the...Oxide-supported copper-containing materials have attracted considerable research attention as promising candidates for acrolein formation.Nevertheless,the elucidation of the structure-performance relationships for these systems remains a scientific challenge.In this work,copper oxide clusters deposited on a high-surface-area silica support were synthesized via a deposition-precipitation approach and exhibited remarkable catalytic reactivity(up to 25.5%conversion and 66.8%selectivity)in the propylene-selective oxidation of acrolein at 300℃.Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy combined with X-ray absorption fine structure measurements of the catalyst before and after the reaction confirmed the transformation of the small-sized copper oxide(CuO)clusters into cuprous oxide(Cu2O)clusters.With the aid of in situ X-ray diffraction and in situ dual beam Fourier transform infrared spectroscopy(DB-FTIR),the allyl intermediate(CH2=CHCH2*)was clearly observed,along with the as-formed Cu2O species.The intermediate can react with oxygen atoms from neighboring Cu2O species to form acrolein during the catalytic process,and the small-sized Cu2O clusters play a crucial role in the generation of acrolein via the selective oxidation of propylene.展开更多
Iron-based single-atom catalysts with nitrogen-doped carbon as support(Fe-SA/NPC)are considered effective alternatives to replace Pt-group metals for scalable application in fuel cells.However,synthesizing high-loadin...Iron-based single-atom catalysts with nitrogen-doped carbon as support(Fe-SA/NPC)are considered effective alternatives to replace Pt-group metals for scalable application in fuel cells.However,synthesizing high-loading Fe-SA catalysts by a simple procedure remains challenging.Herein,we report a high-loading(7.5 wt%)Fe-SA/NPC catalyst prepared by carbon-assisted pyrolysis of metal complexes.Both the nitrogen-doped porous carbon(NPC)support with high specific surface area and ο-phenylenediamine(o-PD)play key roles role in the preparation of high-loading Fe-SA/NPC catalysts.The results of X-ray photoelectron spectroscopy,high-angle annular dark-field scanning transmission electron microscopy,and X-ray absorption fine structure spectroscopy experiments show that the Fe atoms are anchored on the carbon carriers in a single-atom site configuration and coordinated with four of the doped nitrogen atoms of the carbon substrates(Fe-N_(4)).The activities of the Fe-SA/NPC catalysts in the oxygen reduction reaction increased with increasing iron loading.The optimized 250Fe-SA/NPC-800 catalyst exhibited an onset potential 0.97 V of and a half-wave potential of 0.85 V.Our study provides a simple approach for the large-scale synthesis of high-loading single-atom catalysts.展开更多
Lithium-rich manganese-based oxide(LRMO)cathode has emerged as a particularly promising candidate for achieving high energy densities in lithium-ion batteries due to its capability to access anion redox reactions at h...Lithium-rich manganese-based oxide(LRMO)cathode has emerged as a particularly promising candidate for achieving high energy densities in lithium-ion batteries due to its capability to access anion redox reactions at high voltage.The successful implementation of LRMO in energy storage systems is contingent upon the enhancement of their rate capabilities.However,the underlying relationship between high-rate cycling and electrode degradation for LRMO,particularly concerning structural evolution,still remains unclear.Benefiting from the high time resolution abilities of liquid-metal-jet operando twodimensional X-ray diffraction,it is observed that the Li_(2)MnO_(3)phase in LRMO is gradually activated accompanied by the emergence of oxygen vacancies during cycling at 1 C(1 C=250 mA/g).Consequently,the crystal lattice flexibility of LRMO is systematically enhanced,thereby preventing the collapse of the bulk structure.While,continuous release of oxygen during extended cycling results in deteriorations of the self-adjusting damping effect of the structure,ultimately leading to a decline in capacity.The findings of this study not only contribute to a more profound understanding of the structural changes of LRMOs at high rates,but also provide novel perspectives for the rational design of LRMOs with superior rate performances.展开更多
In this work,tungsten oxide with different concentrations(0,0.4 at%,2.0 at%and 3.2 at%)was introduced to the ceria nanorods via a deposition-precipitation(DP)approach,and copper species of ca.10 at%were sequentially a...In this work,tungsten oxide with different concentrations(0,0.4 at%,2.0 at%and 3.2 at%)was introduced to the ceria nanorods via a deposition-precipitation(DP)approach,and copper species of ca.10 at%were sequentially anchored onto the modified ceria support by a similar DP route.The aim of the study was to investigate the effect of the amount of tungsten oxide(0,0.4 at%,2.0 at%,and 3.2 at%)modifier on the copper-ceria catalysts for CO oxidation reaction and shed light on the structure-activity relationship.By the aids of multiple characterization techniques including N2 adsorption,high-resolution transmission electron microscopy(HRTEM),powder X-ray diffraction(XRD),X-ray absorption fine structure(XAFS),and temperature-programmed reduction by hydrogen(H2-TPR)in combination with the catalytic performance for CO oxidation reaction,it is found that the copper-ceria samples maintain the crystal structure of the fluorite fcc CeO2 phase with the same nanorod-like morphology with the introduction of tungsten oxide,while the textural properties(the surface area,pore volume and pore size)of ceria support and copper-ceria catalysts are changed,and the oxidation states of copper and tungsten are kept the same as Cu2+and W6+before and after the reaction,but the introduction of tungsten oxide(WO3)significantly changes the metal-support interaction(transfer the CuOx clusters to Cu-[Ox]-Ce species),which delivers to impair the catalytic activity of copper-ceria catalysts for CO oxidation reaction.展开更多
Platinum catalyst for CO oxidation has been studied for decades,due to its high activity and good stability.In this work,we prepared three different lantha num oxide or hydroxide supports(LaO_(x)(OH)_(y)),and deposite...Platinum catalyst for CO oxidation has been studied for decades,due to its high activity and good stability.In this work,we prepared three different lantha num oxide or hydroxide supports(LaO_(x)(OH)_(y)),and deposited platinum(Pt) with 0.5 at% via an impregnation approach to synthesize Pt/LaO_(x)(OH)_(y) catalysts.However,we find that these catalysts perform a poor stability for the CO oxidation reaction.The fresh and used samples were comprehensively characterized by multiple techniques including power X-ray diffraction(XRD),X-ray absorption fine structure(XAFS),transmission electron microscopy(TEM),temperature-programmed reduction by carbon monoxide(CO-TPR) and thermogravimetric analysis(TGA),to demonstrate that the oxidized platinum atoms or clusters,without any component of Pt-Pt metallic bond,are highly dispersed on the surface of LaO_(x)(OH)_(y).Furthermore,the as-formed lanthanum carbonate(La_(2)O_(2)CO_(3)) during the exposure to ambient circumstances or in the reaction atmosphere of CO+O_(2),severely impair the reactivity of Pt/LaO_(x)(OH)_(y).On the basis of the obtained experimental results,we have drawn a conclusion that the oxidized P_(t)O_(x) atoms or PtxOy clusters are the active species for CO oxidation,while the formation of lanthanum carbonate is the origin of deactivation on reactivity.展开更多
A new X-ray absorption fine structure(XAFS)data-collection system based on the Experimental Physics and Industrial Control System software environment has been established at the BL14W1 beamline of the Shanghai Synchr...A new X-ray absorption fine structure(XAFS)data-collection system based on the Experimental Physics and Industrial Control System software environment has been established at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facility. The system provides for automatic sequential analysis of multiple samples for continuous high-throughput(HT) measurements. Specifically, 8 sample pellets are loaded into an alumina holder,and a high-precision two-dimensional translation stage is programmed to switch these samples automatically for collecting the XAFS spectrum of each sample in sequence.Experimenters implement HT measurements via a graphical user interface developed with Control System Studio.Finally, the successful operation of the HT XAFS system is demonstrated by running experiments on two groups of copper–ceria catalysts, each of which contains 8 different powder samples.展开更多
We present an efficient approach for the chemoselective synthesis of arylamines from nitroarenes and formate over an oxygen-implanted MoS2 catalyst（O-MoS2）.O-MoS2 was prepared by incomplete sul idation and reduction...We present an efficient approach for the chemoselective synthesis of arylamines from nitroarenes and formate over an oxygen-implanted MoS2 catalyst（O-MoS2）.O-MoS2 was prepared by incomplete sul idation and reduction of an ammonium molybdate precursor.A number of Mo-O bonds were implanted in the as-synthesized ultrathin O-MoS2 nanosheets.As a consequence of the different coordination geometries of O（Mo O2） and S（MoS2）,and lengths of the Mo-O and Mo-S bonds,the implanted Mo-O bonds induced obvious defects and more coordinatively unsaturated（CUS） Mo sites in O-MoS2,as confirmed by X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,high resolution transmission electron microscopy,and extended X-ray absorption fine structure characterization of various MoS2-based materials.O-MoS2 with abundant CUS Mo sites was found to efficiently catalyze the chemoselective reduction of nitroarenes to arylamines.展开更多
The development of non‐precious metal catalysts that facilitate the oxygen evolution reaction(OER)is important for the widespread application of hydrogen production by water splitting.Various perovskite oxides have b...The development of non‐precious metal catalysts that facilitate the oxygen evolution reaction(OER)is important for the widespread application of hydrogen production by water splitting.Various perovskite oxides have been employed as active OER catalysts,however,the underlying mechanism that occurs at the catalyst‐electrolyte interface is still not well understood,prohibiting the design and preparation of advanced OER catalysts.Here,we report a systematic investigation into the effect of proton dynamics on the catalyst‐electrolyte interfaces of four perovskite catalysts:La_(0.5)Sr_(0.5)CoO_(3‐δ)(LSCO),LaCoO_(3),LaFeO_(3),and LaNiO_(3).The pH‐dependent OER activities,H/D kinetic isotope effect,and surface functionalization with phosphate anion groups were investigated to elucidate the role of proton dynamics in the rate‐limiting steps of the OER.For oxides with small charge‐transfer energies,such as LSCO and LaNiO_(3),non‐concerted proton‐coupled electron transfer steps are involved in the OER,and the activity is strongly controlled by the proton dynamics on the catalyst surface.The results demonstrate the important role of interfacial proton transfer in the OER mechanism,and suggest that proton dynamics at the interface should carefully be considered in the design of future high‐performance catalysts.展开更多
Taming the electron transfer across metal–support interfaces appears to be an attractive yet challenging methodology to boost catalytic properties.Herein,we demonstrate a precise engineering strategy for the carbon s...Taming the electron transfer across metal–support interfaces appears to be an attractive yet challenging methodology to boost catalytic properties.Herein,we demonstrate a precise engineering strategy for the carbon surface chemistry of Pt/C catalysts—that is,for the electron-withdrawing/donating oxygencontaining groups on the carbon surface—to fine-tune the electrons of the supported metal nanoparticles.Taking the ammonia borane hydrolysis as an example,a combination of density functional theory(DFT)calculations,advanced characterizations,and kinetics and isotopic analyses reveals quantifiable relationships among the carbon surface chemistry,Pt charge state and binding energy,activation entropy/enthalpy,and resultant catalytic activity.After decoupling the influences of other factors,the Pt charge is unprecedentedly identified as an experimentally measurable descriptor of the Pt active site,contributing to a 15-fold increment in the hydrogen generation rate.Further incorporating the Pt charge with the number of Pt active sites,a mesokinetics model is proposed for the first time that can individually quantify the contributions of the electronic and geometric properties to precisely predict the catalytic performance.Our results demonstrate a potentially groundbreaking methodology to design and manipulate metal–carbon catalysts with desirable properties.展开更多
Copper-ceria sheets catalysts with different loadings of copper（2 wt.%, 5 wt.% and 10 wt.%） supported on ceria nanosheets were synthesized via a depositioneprecipitation（DP） method. The prepared catalysts were sys...Copper-ceria sheets catalysts with different loadings of copper（2 wt.%, 5 wt.% and 10 wt.%） supported on ceria nanosheets were synthesized via a depositioneprecipitation（DP） method. The prepared catalysts were systematically characterized with various structural and textural detections including X-ray diffraction（XRD）, Raman spectra, transmission electron microscopy（TEM）, X-ray absorption fine structure（XAFS）, and temperature-programmed reduction by hydrogen（H2-TPR）, and tested for the CO oxidation reaction. Notably, the sample containing 5 wt.% of Cu exhibited the best catalytic performance as a result of the highest number of active CuO species on the catalyst surface. Further increase of copper content strongly affects the dispersion of copper and thus leads to the formation of less active bulk CuO phase, which was verified by XRD and H2-TPR analysis. Moreover, on the basis of in-situ diffuse reflectance infrared Fourier transform spectroscopy（in-situ DRIFTS） results, the surface Cu~＋ species, which are derived from the reduction of Cu^（2＋）, are likely to play a crucial role in the catalyzing CO oxidation.Consequently, the superior catalytic performance of the copper-ceria sheets is mainly attributed to the highly dispersed CuOx cluster rather than Cu-[Ox]-Ce structure, while the bulk CuO phase is adverse to the catalytic activity of CO oxidation.展开更多
In this study,the support effects on the Pd-catalyzed semi-hydrogenation of acetylene have been investigated from the structural and kinetic perspectives.According to the results of kinetic analysis and X-ray photoele...In this study,the support effects on the Pd-catalyzed semi-hydrogenation of acetylene have been investigated from the structural and kinetic perspectives.According to the results of kinetic analysis and X-ray photoelectron spectroscopy,hydrogen temperature-programmed reduction,temperature-programmed hydride decomposition,and in situ X-ray diffraction measurements,using carbon nanotubes as support for Pd nanocatalysts with various sizes instead of a-Al_(2)O_(3) decreases the Pd^(0)3d binding energy and suppresses the formation of undesirable palladium hydride species,thus increasing the ethylene yield.Furthermore,X-ray absorption spectroscopy,high-resolution transmission electron microscopy,and C_(2)H_(4) temperature-programmed desorption studies combined with density-functional theory calculations reveal the existence of a unique Pd local environment,containing subsurface carbon atoms,that produces positive geometric effects on the acetylene conversion reaction.Therefore,tailoring the Pd local environment and electronic properties represents an effective strategy for the fabrication and design of highly active and selective Pd semi-hydrogenation catalysts.展开更多
Ceria supported platinum catalyst has now been widely studied due to its excellent activity for CO oxidatio n.However,the electron state of active metal center is still an open question.In this work,a ce ria nanorod s...Ceria supported platinum catalyst has now been widely studied due to its excellent activity for CO oxidatio n.However,the electron state of active metal center is still an open question.In this work,a ce ria nanorod support was prepared and platinum(Pt)with 0.9 at%was deposited using an impregnation method to obtain Pt/CeO_(2)catalyst.With the help of"light-off"experiment and temperatureprogrammed reduction under CO(CO-TPR)test,the conclusion is proposed that the process of hydrogen reduction can enhance the activity of CO oxidation reaction for the generation of optimal active Pt site.An innovative near-situ X-ray absorption fine structure(XAFS)technique was used to investigate the chemical state of central Pt atom during the reaction process,clearly demonstrating that the high oxidized state of Pt does harm to the activity for CO oxidation while the relatively reductive Pt exhibits high activity,and the different oxidized state and chemical environment of Pt during every process has been identified.Furthermore,the activity of our Pt/CeO_(2)catalyst is superior to that of most of the previous reports about CO catalytic oxidation by Pt based catalyst.Moreover,the optimal active species(Pt-O_(4))have been identified after hydrogen reduction,which could be a possible key strategy to control the oxidation of Pt.展开更多
Electrocatalytic CO2 reduction to CO is a sustainable process for energy conversion.However,this process is still hindered by the diffusi limited mass transfer,low electrical conductivity and catalytic activity.Theref...Electrocatalytic CO2 reduction to CO is a sustainable process for energy conversion.However,this process is still hindered by the diffusi limited mass transfer,low electrical conductivity and catalytic activity.Therefore,new strategies for catalyst design should be adopted to solve these problems and improve the electrocatalytic performa nee for CO production.Herein,we report a multiscale carb on foam confining〔single iron atoms prepared with the assistant of S1O2 template.The pore-enriched environment at the macro-scale facilitates the diffusion of reacta nts and products.The graphe ne nano sheets at the nano-scale promote the charge tran sfer duri ng the reaction.The single iron atoms con fined in carb on matrix at the atomic-scale provide the active sites for electrocatalytic CO2 reductio n to CO.The optimized catalyst achieves a CO Faradaic efficiency of 94.9%at a moderate potential of-0.5 V vs.RHE.Furthermore,the performance can be maintained over 60 hours due to the stable single iron atoms coordi nated with four n itroge n atoms in the carb on matrix.This work provides a promising strategy to improve both the activity and stability of single atom catalysts for electrocatalytic CO2 reduction to CO.展开更多
Exploring cost-effective catalysts with high catalytic performance and long-term stability has always been a general concern for environment protection and energy conversion.Here,Au nanoparticles(NPs)embedded CuOx-CeO...Exploring cost-effective catalysts with high catalytic performance and long-term stability has always been a general concern for environment protection and energy conversion.Here,Au nanoparticles(NPs)embedded CuOx-CeO2 core/shell nanospheres(Au@CuOx-CeO2 CSNs)have been successfully prepared through a versatile one-pot method at ambient conditions.The spontaneous auto-redox reaction between HAuCl4 and Ce(OH)3 in aqueous solution triggered the self-assembly growth of micro-/nanostructural Au@CuOx-CeO2 CSNs.Meanwhile,the CuOx clusters in Au@CuOx-CeO2 CSNs are capable of improving the anti-sintering ability of Au NPs and providing synergistic catalysis benefits.As a result,the confined Au NPs exhibited extraordinary thermal stability even at a harsh thermal condition up to 700℃.In addition,before and after the severe calcination process,Au@CuOx-CeO2 CSNs can exhibit enhanced catalytic activity and excellent recyclability towards the hydrogenation of p-nitrophenol compared to previously reported nanocatalysts.The synergistic catalysis path between Au/CuOx/CeO2 triphasic interfaces was revealed by density functional theory(DFT)calculations.The CuOx clusters around the embedded Au NPs can provide moderate adsorption strength of p-nitrophenol,while the adjacent CeO2-supported Au NPs can facilitate the hydrogen dissociation to form H*species,which contributes to achieve the efficient reduction of p-nitrophenol.This study opens up new possibilities for developing high-efficient and sintering-resistant micro-/nanostructural nanocatalysts by exploiting multiphasic systems.展开更多
Selective transfer hydrogenation of nitroarenes to amines with transition metal nanocatalysts is appealing due to its low-cost, moderate reaction conditions, good activity and excellent selectivity. Single-atom cataly...Selective transfer hydrogenation of nitroarenes to amines with transition metal nanocatalysts is appealing due to its low-cost, moderate reaction conditions, good activity and excellent selectivity. Single-atom catalysts (SACs) possessing advantages of maximum atom efficiency and particular electronic structure are expected to be more effective for this reaction, yet no report about it. Herein, cobalt single atoms anchored on N-doped ultrathin carbon nanosheets (denoted as CoSAs/NCNS) were produced and demonstrated as an outstanding SAC for selective transfer hydrogenation of nitroarenes to amines with formic acid as hydrogen donor. The turnover frequency (TOF) reached 110.6 h^-1, which was 20 times higher than the best results of cobalt nanopartides reported in literatures under similar reaction conditions. Moreover, CoSAs/NCNS exhibited excellent selectivity for a variety of nitroarenes bearing other reducible functionalities, such as iodo, cyano, keto, vinyl, alkynyl and ester groups. The findings further highlight the ability and advantages of SACs in heterogeneous catalysis.展开更多
Although single-atom catalysts significantly improve the atom utilization efficiency,the multistep preparation procedures are complicated and difficult to control.Herein,we demonstrate that one-step in situ synthesis ...Although single-atom catalysts significantly improve the atom utilization efficiency,the multistep preparation procedures are complicated and difficult to control.Herein,we demonstrate that one-step in situ synthesis of the single-atom Pt anchored in single-crystal MoC(Pt_(1)/MoC)by using facile and controllable arc-discharge strategy under extreme conditions.The high temperature(up to 4000℃)provides the sufficient energy for atom dispersion and overall stability by forming thermodynamically favourable metal-support interactions.The high-temperature-stabilized Pt1/MoC exhibits outstanding performance and excellent thermal stability as durable catalyst for selective quinoline hydrogenation.The initial turnover frequency of 3710 h^(-1)is greater than those of previously reported samples by an order of magnitude under 2 MPa H_(2)at 100℃.The catalyst also shows broad scope activity toward hydrogenation containing unsaturated groups of C=C,C=N,and C=O.The facile,one-step,and fast arc-discharge method provides an effective avenue for single-atom catalyst fabrication that is conventionally challenging.展开更多
A surge of interest has been brought to all-solid-state batteries(ASSBs)as they show great prospects for enabling higher energy density and improved safety compared to conventional liquid batteries.Na Super Ionic CONd...A surge of interest has been brought to all-solid-state batteries(ASSBs)as they show great prospects for enabling higher energy density and improved safety compared to conventional liquid batteries.Na Super Ionic CONductors(NaSICONs)proposed by Goodenough and Hong in 1976 are the most promising materials class for Nabased ASSBs owing to their excellent ion conductivity(>1mS cm−1),high thermal and chemical/electrochemical stability,as well as good chemical/electrochemical compatibility with electrode materials.The major challenge facing NaSICONtype electrolytes is the generally high interfacial resistance and thus sluggish charge transfer kinetics across the NaSICON/cathode interface.Great endeavors in the past few years have led to progress in the improvement of the ion-conducting property,and a dramatic decrease in the NaSICON/electrode interface resistance.Excellent cycling performance and rate capability have been achieved through interface engineering.In this review article,we summarize the state-of-theart findings for various derivatives of NaSICON structured solid electrolytes,with the aim of providing a deeper understanding of the underlying mechanism for the improvement of ion conductivity,and the intrinsic reasons for the enhanced interface charge transfer kinetics.These strategies can be readily extended to other solid electrolytes.We hope this review will inspire more work on NaSICONtype solid electrolytes and solid-state batteries.展开更多
Catalytic decomposition of NH3 to high purity hydrogen offers a promising strategy for fuel cells, but presents challenges for high hydrogen yields at comparatively low temperatures due to the lack of efficient cataly...Catalytic decomposition of NH3 to high purity hydrogen offers a promising strategy for fuel cells, but presents challenges for high hydrogen yields at comparatively low temperatures due to the lack of efficient catalysts. Here, we report the facile preparation of ultra-fine ruthenium（Ru） species dispersed on Mg O, which show excellent activity and high temperature stability for NH3 decomposition reaction. The hydrogen yield of the prepared Ru/Mg O catalysts reaches ca. 2,092 mmol H2 g–1 Ru min–1 at450 °C, far exceeding that of the previously reported most reactive Ru-based catalysts and the same chemical composition samples prepared by other approaches. Various characterization techniques containing X-ray absorption fine structure（XAFS）,in-situ diffuse reflectance infrared Fourier transform spectroscopy（in-situ DRTFTS） and temperature-programmed reduction/desorption（TPR/TPD） were carried out to explore the structure-function relation of the prepared Ru/Mg O catalysts. We found that the Ru species interact strongly with the Mg O support, which can efficiently protect the Ru species and Mg O support from agglomerating during NH3 decomposition test, maintaining the stability of the catalysts.展开更多
基金Financial supported from the Excellent Young Scientists Fund from the National Natural Science Foundation of China (NSFC) (Grant no. 21622106)other projects from the NSFC (Grant nos. 21773288 , 21805167 and 21771117)+4 种基金the Outstanding Scholar Fund (Grant no. JQ201703)the Doctoral Fund (Grant no. ZR2018BB010) from the Science Foundation of Shandong Province of Chinathe Taishan Scholar Project of Shandong Province of Chinathe Hundred Talents project of the Chinese Academy of Sciencesthe Foundation of State Key Laboratory of Coal Conversion (grant nos. J17-18-902)
文摘The uniformly dispersed transition metal(Co, Ni and Fe) nanoparticles supported on the surface of La-promoted Mg O were prepared via a deposition-precipitation method for hydrogen production from catalytic decomposition of ammonia. X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy, temperature-programmed reduction and temperature-programmed desorption were used to investigate the structure-activity relation of catalysts in NH3 decomposition. The results show that the strong interaction between active species and support can effectively prevent the active species from agglomerating during ammonia decomposition reaction. In addition, the introduction of La species not only facilitates the adsorption and decomposition of NH3 and desorption of N2, but also benefits the better dispersion of the active species. The prepared catalysts showed very high catalytic activity for ammonia decomposition compared with the same active composition samples that reported previously. Meanwhile, the catalysts showed excellent high-temperature stability and no any deactivation was observed, which are very promising candidates for the decomposition of ammonia to hydrogen.
文摘Oxide-supported copper-containing materials have attracted considerable research attention as promising candidates for acrolein formation.Nevertheless,the elucidation of the structure-performance relationships for these systems remains a scientific challenge.In this work,copper oxide clusters deposited on a high-surface-area silica support were synthesized via a deposition-precipitation approach and exhibited remarkable catalytic reactivity(up to 25.5%conversion and 66.8%selectivity)in the propylene-selective oxidation of acrolein at 300℃.Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy combined with X-ray absorption fine structure measurements of the catalyst before and after the reaction confirmed the transformation of the small-sized copper oxide(CuO)clusters into cuprous oxide(Cu2O)clusters.With the aid of in situ X-ray diffraction and in situ dual beam Fourier transform infrared spectroscopy(DB-FTIR),the allyl intermediate(CH2=CHCH2*)was clearly observed,along with the as-formed Cu2O species.The intermediate can react with oxygen atoms from neighboring Cu2O species to form acrolein during the catalytic process,and the small-sized Cu2O clusters play a crucial role in the generation of acrolein via the selective oxidation of propylene.
文摘Iron-based single-atom catalysts with nitrogen-doped carbon as support(Fe-SA/NPC)are considered effective alternatives to replace Pt-group metals for scalable application in fuel cells.However,synthesizing high-loading Fe-SA catalysts by a simple procedure remains challenging.Herein,we report a high-loading(7.5 wt%)Fe-SA/NPC catalyst prepared by carbon-assisted pyrolysis of metal complexes.Both the nitrogen-doped porous carbon(NPC)support with high specific surface area and ο-phenylenediamine(o-PD)play key roles role in the preparation of high-loading Fe-SA/NPC catalysts.The results of X-ray photoelectron spectroscopy,high-angle annular dark-field scanning transmission electron microscopy,and X-ray absorption fine structure spectroscopy experiments show that the Fe atoms are anchored on the carbon carriers in a single-atom site configuration and coordinated with four of the doped nitrogen atoms of the carbon substrates(Fe-N_(4)).The activities of the Fe-SA/NPC catalysts in the oxygen reduction reaction increased with increasing iron loading.The optimized 250Fe-SA/NPC-800 catalyst exhibited an onset potential 0.97 V of and a half-wave potential of 0.85 V.Our study provides a simple approach for the large-scale synthesis of high-loading single-atom catalysts.
基金financial supports from the National Natural Science Foundation of China(52372211,52371225 and 92472115)the Guangdong Province Major Talent Introducing Program(2021QN020687)+1 种基金the Shenzhen Basic Research Foundation(JCYJ20230807112503007)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2020A1515110176)。
文摘Lithium-rich manganese-based oxide(LRMO)cathode has emerged as a particularly promising candidate for achieving high energy densities in lithium-ion batteries due to its capability to access anion redox reactions at high voltage.The successful implementation of LRMO in energy storage systems is contingent upon the enhancement of their rate capabilities.However,the underlying relationship between high-rate cycling and electrode degradation for LRMO,particularly concerning structural evolution,still remains unclear.Benefiting from the high time resolution abilities of liquid-metal-jet operando twodimensional X-ray diffraction,it is observed that the Li_(2)MnO_(3)phase in LRMO is gradually activated accompanied by the emergence of oxygen vacancies during cycling at 1 C(1 C=250 mA/g).Consequently,the crystal lattice flexibility of LRMO is systematically enhanced,thereby preventing the collapse of the bulk structure.While,continuous release of oxygen during extended cycling results in deteriorations of the self-adjusting damping effect of the structure,ultimately leading to a decline in capacity.The findings of this study not only contribute to a more profound understanding of the structural changes of LRMOs at high rates,but also provide novel perspectives for the rational design of LRMOs with superior rate performances.
基金Project supported by National Natural Science Foundation of China(21773288,51902093)National Key Basic Research Program of China(2017YFA0403402)。
文摘In this work,tungsten oxide with different concentrations(0,0.4 at%,2.0 at%and 3.2 at%)was introduced to the ceria nanorods via a deposition-precipitation(DP)approach,and copper species of ca.10 at%were sequentially anchored onto the modified ceria support by a similar DP route.The aim of the study was to investigate the effect of the amount of tungsten oxide(0,0.4 at%,2.0 at%,and 3.2 at%)modifier on the copper-ceria catalysts for CO oxidation reaction and shed light on the structure-activity relationship.By the aids of multiple characterization techniques including N2 adsorption,high-resolution transmission electron microscopy(HRTEM),powder X-ray diffraction(XRD),X-ray absorption fine structure(XAFS),and temperature-programmed reduction by hydrogen(H2-TPR)in combination with the catalytic performance for CO oxidation reaction,it is found that the copper-ceria samples maintain the crystal structure of the fluorite fcc CeO2 phase with the same nanorod-like morphology with the introduction of tungsten oxide,while the textural properties(the surface area,pore volume and pore size)of ceria support and copper-ceria catalysts are changed,and the oxidation states of copper and tungsten are kept the same as Cu2+and W6+before and after the reaction,but the introduction of tungsten oxide(WO3)significantly changes the metal-support interaction(transfer the CuOx clusters to Cu-[Ox]-Ce species),which delivers to impair the catalytic activity of copper-ceria catalysts for CO oxidation reaction.
基金Project supported by the National Natural Science Foundation of China(21773288)National Key Basic Research Program of China(2017YFA0403402)。
文摘Platinum catalyst for CO oxidation has been studied for decades,due to its high activity and good stability.In this work,we prepared three different lantha num oxide or hydroxide supports(LaO_(x)(OH)_(y)),and deposited platinum(Pt) with 0.5 at% via an impregnation approach to synthesize Pt/LaO_(x)(OH)_(y) catalysts.However,we find that these catalysts perform a poor stability for the CO oxidation reaction.The fresh and used samples were comprehensively characterized by multiple techniques including power X-ray diffraction(XRD),X-ray absorption fine structure(XAFS),transmission electron microscopy(TEM),temperature-programmed reduction by carbon monoxide(CO-TPR) and thermogravimetric analysis(TGA),to demonstrate that the oxidized platinum atoms or clusters,without any component of Pt-Pt metallic bond,are highly dispersed on the surface of LaO_(x)(OH)_(y).Furthermore,the as-formed lanthanum carbonate(La_(2)O_(2)CO_(3)) during the exposure to ambient circumstances or in the reaction atmosphere of CO+O_(2),severely impair the reactivity of Pt/LaO_(x)(OH)_(y).On the basis of the obtained experimental results,we have drawn a conclusion that the oxidized P_(t)O_(x) atoms or PtxOy clusters are the active species for CO oxidation,while the formation of lanthanum carbonate is the origin of deactivation on reactivity.
基金supported by the National Natural Science Foundation of China under Grant No.21373259
文摘A new X-ray absorption fine structure(XAFS)data-collection system based on the Experimental Physics and Industrial Control System software environment has been established at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facility. The system provides for automatic sequential analysis of multiple samples for continuous high-throughput(HT) measurements. Specifically, 8 sample pellets are loaded into an alumina holder,and a high-precision two-dimensional translation stage is programmed to switch these samples automatically for collecting the XAFS spectrum of each sample in sequence.Experimenters implement HT measurements via a graphical user interface developed with Control System Studio.Finally, the successful operation of the HT XAFS system is demonstrated by running experiments on two groups of copper–ceria catalysts, each of which contains 8 different powder samples.
基金supported by the National Natural Science Foundation of China(21422308,21403216,21273231)Dalian Excellent Youth Foundation(2014J11JH126)~~
文摘We present an efficient approach for the chemoselective synthesis of arylamines from nitroarenes and formate over an oxygen-implanted MoS2 catalyst（O-MoS2）.O-MoS2 was prepared by incomplete sul idation and reduction of an ammonium molybdate precursor.A number of Mo-O bonds were implanted in the as-synthesized ultrathin O-MoS2 nanosheets.As a consequence of the different coordination geometries of O（Mo O2） and S（MoS2）,and lengths of the Mo-O and Mo-S bonds,the implanted Mo-O bonds induced obvious defects and more coordinatively unsaturated（CUS） Mo sites in O-MoS2,as confirmed by X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,high resolution transmission electron microscopy,and extended X-ray absorption fine structure characterization of various MoS2-based materials.O-MoS2 with abundant CUS Mo sites was found to efficiently catalyze the chemoselective reduction of nitroarenes to arylamines.
文摘The development of non‐precious metal catalysts that facilitate the oxygen evolution reaction(OER)is important for the widespread application of hydrogen production by water splitting.Various perovskite oxides have been employed as active OER catalysts,however,the underlying mechanism that occurs at the catalyst‐electrolyte interface is still not well understood,prohibiting the design and preparation of advanced OER catalysts.Here,we report a systematic investigation into the effect of proton dynamics on the catalyst‐electrolyte interfaces of four perovskite catalysts:La_(0.5)Sr_(0.5)CoO_(3‐δ)(LSCO),LaCoO_(3),LaFeO_(3),and LaNiO_(3).The pH‐dependent OER activities,H/D kinetic isotope effect,and surface functionalization with phosphate anion groups were investigated to elucidate the role of proton dynamics in the rate‐limiting steps of the OER.For oxides with small charge‐transfer energies,such as LSCO and LaNiO_(3),non‐concerted proton‐coupled electron transfer steps are involved in the OER,and the activity is strongly controlled by the proton dynamics on the catalyst surface.The results demonstrate the important role of interfacial proton transfer in the OER mechanism,and suggest that proton dynamics at the interface should carefully be considered in the design of future high‐performance catalysts.
基金the Natural Science Foundation of China(21922803,92034301,22008066,and 21776077)the China Postdoctoral Science Foundation(BX20190116)+1 种基金the Innovation Program of Shanghai Municipal Education Commission,the Program of Shanghai Academic/Tech-nology Research Leader(21XD1421000)111 Project of the Min-istry of Education of China(B08021)。
文摘Taming the electron transfer across metal–support interfaces appears to be an attractive yet challenging methodology to boost catalytic properties.Herein,we demonstrate a precise engineering strategy for the carbon surface chemistry of Pt/C catalysts—that is,for the electron-withdrawing/donating oxygencontaining groups on the carbon surface—to fine-tune the electrons of the supported metal nanoparticles.Taking the ammonia borane hydrolysis as an example,a combination of density functional theory(DFT)calculations,advanced characterizations,and kinetics and isotopic analyses reveals quantifiable relationships among the carbon surface chemistry,Pt charge state and binding energy,activation entropy/enthalpy,and resultant catalytic activity.After decoupling the influences of other factors,the Pt charge is unprecedentedly identified as an experimentally measurable descriptor of the Pt active site,contributing to a 15-fold increment in the hydrogen generation rate.Further incorporating the Pt charge with the number of Pt active sites,a mesokinetics model is proposed for the first time that can individually quantify the contributions of the electronic and geometric properties to precisely predict the catalytic performance.Our results demonstrate a potentially groundbreaking methodology to design and manipulate metal–carbon catalysts with desirable properties.
基金Project supported by the National Natural Science Foundation of China(21301107,21501109)the Excellent Young Scientists Fund from NSFC(21622106)+3 种基金the Taishan Scholar Project of Shandong Province of China,China Postdoctoral Science Foundation(2014M551891,2015T80706)Doctoral Funding of Shandong Province of China(BS2014CL008)Specialized Research Fund for the Doctoral Program of Higher Education(20130131120009)Postdoctoral Innovation Project Foundation of Shandong Province(201301008)
文摘Copper-ceria sheets catalysts with different loadings of copper（2 wt.%, 5 wt.% and 10 wt.%） supported on ceria nanosheets were synthesized via a depositioneprecipitation（DP） method. The prepared catalysts were systematically characterized with various structural and textural detections including X-ray diffraction（XRD）, Raman spectra, transmission electron microscopy（TEM）, X-ray absorption fine structure（XAFS）, and temperature-programmed reduction by hydrogen（H2-TPR）, and tested for the CO oxidation reaction. Notably, the sample containing 5 wt.% of Cu exhibited the best catalytic performance as a result of the highest number of active CuO species on the catalyst surface. Further increase of copper content strongly affects the dispersion of copper and thus leads to the formation of less active bulk CuO phase, which was verified by XRD and H2-TPR analysis. Moreover, on the basis of in-situ diffuse reflectance infrared Fourier transform spectroscopy（in-situ DRIFTS） results, the surface Cu~＋ species, which are derived from the reduction of Cu^（2＋）, are likely to play a crucial role in the catalyzing CO oxidation.Consequently, the superior catalytic performance of the copper-ceria sheets is mainly attributed to the highly dispersed CuOx cluster rather than Cu-[Ox]-Ce structure, while the bulk CuO phase is adverse to the catalytic activity of CO oxidation.
基金This work was financially supported by the Natural Science Foundation of China(21922803,21776077,and 22008067)the Innovation Program of Shanghai Municipal Education Commission,the Shanghai Natural Science Foundation(17ZR1407300 and 17ZR1407500)+4 种基金the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning,the Shanghai Rising-Star Program(17QA1401200)the China Postdoctoral Science Foundation(2020M681202)the Open Project of State Key Laboratory of Chemical Engineering(SKLChe-15C03)the State Key Laboratory of Organic-Inorganic Composites(oic-201801007)the Fundamental Research Funds for the Central Universities(222201718003).
文摘In this study,the support effects on the Pd-catalyzed semi-hydrogenation of acetylene have been investigated from the structural and kinetic perspectives.According to the results of kinetic analysis and X-ray photoelectron spectroscopy,hydrogen temperature-programmed reduction,temperature-programmed hydride decomposition,and in situ X-ray diffraction measurements,using carbon nanotubes as support for Pd nanocatalysts with various sizes instead of a-Al_(2)O_(3) decreases the Pd^(0)3d binding energy and suppresses the formation of undesirable palladium hydride species,thus increasing the ethylene yield.Furthermore,X-ray absorption spectroscopy,high-resolution transmission electron microscopy,and C_(2)H_(4) temperature-programmed desorption studies combined with density-functional theory calculations reveal the existence of a unique Pd local environment,containing subsurface carbon atoms,that produces positive geometric effects on the acetylene conversion reaction.Therefore,tailoring the Pd local environment and electronic properties represents an effective strategy for the fabrication and design of highly active and selective Pd semi-hydrogenation catalysts.
基金Project supported by Shanghai Large Scientific Facilities CenterNational Key Basic Research Program of China(2017YFA0403402)+1 种基金the National Natural Science Foundation of China(U1932119)This work was also supported by Shanghai Large Scientific Facilities Center.
文摘Ceria supported platinum catalyst has now been widely studied due to its excellent activity for CO oxidatio n.However,the electron state of active metal center is still an open question.In this work,a ce ria nanorod support was prepared and platinum(Pt)with 0.9 at%was deposited using an impregnation method to obtain Pt/CeO_(2)catalyst.With the help of"light-off"experiment and temperatureprogrammed reduction under CO(CO-TPR)test,the conclusion is proposed that the process of hydrogen reduction can enhance the activity of CO oxidation reaction for the generation of optimal active Pt site.An innovative near-situ X-ray absorption fine structure(XAFS)technique was used to investigate the chemical state of central Pt atom during the reaction process,clearly demonstrating that the high oxidized state of Pt does harm to the activity for CO oxidation while the relatively reductive Pt exhibits high activity,and the different oxidized state and chemical environment of Pt during every process has been identified.Furthermore,the activity of our Pt/CeO_(2)catalyst is superior to that of most of the previous reports about CO catalytic oxidation by Pt based catalyst.Moreover,the optimal active species(Pt-O_(4))have been identified after hydrogen reduction,which could be a possible key strategy to control the oxidation of Pt.
基金We gratefully acknowledge the financial support from the Ministry of Science and Technology of China(Nos.2016YFA0204100 and 2016YFA0200200)the National Natural Science Foundation of China(Nos.21573220 and 21802124)+2 种基金the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(No.QYZDB-SSW-JSC020)the DNL Cooperation Fund,CAS(No.DNL180201)We thank staff at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facilities(SSRF)for assistance with the X-ray absorption spectroscopy measurements.
文摘Electrocatalytic CO2 reduction to CO is a sustainable process for energy conversion.However,this process is still hindered by the diffusi limited mass transfer,low electrical conductivity and catalytic activity.Therefore,new strategies for catalyst design should be adopted to solve these problems and improve the electrocatalytic performa nee for CO production.Herein,we report a multiscale carb on foam confining〔single iron atoms prepared with the assistant of S1O2 template.The pore-enriched environment at the macro-scale facilitates the diffusion of reacta nts and products.The graphe ne nano sheets at the nano-scale promote the charge tran sfer duri ng the reaction.The single iron atoms con fined in carb on matrix at the atomic-scale provide the active sites for electrocatalytic CO2 reductio n to CO.The optimized catalyst achieves a CO Faradaic efficiency of 94.9%at a moderate potential of-0.5 V vs.RHE.Furthermore,the performance can be maintained over 60 hours due to the stable single iron atoms coordi nated with four n itroge n atoms in the carb on matrix.This work provides a promising strategy to improve both the activity and stability of single atom catalysts for electrocatalytic CO2 reduction to CO.
基金The authors are grateful for the financial support of the National Natural Science Foundation of China(Nos.21590791,21771005,21931001,and 21927901)Ministry of Science and Technology(MOST)of China(Nos.2014CB643803,2017YFA0205101,and 2017YFA0205104)+1 种基金The computational work was supported by the High-performance Computing Platform of Peking University.K.W.specifically thanks the National Postdoctoral Program for Innovative Talents under grant No.BX20190005the China Postdoctoral Science Foundation(No.2019M660293).
文摘Exploring cost-effective catalysts with high catalytic performance and long-term stability has always been a general concern for environment protection and energy conversion.Here,Au nanoparticles(NPs)embedded CuOx-CeO2 core/shell nanospheres(Au@CuOx-CeO2 CSNs)have been successfully prepared through a versatile one-pot method at ambient conditions.The spontaneous auto-redox reaction between HAuCl4 and Ce(OH)3 in aqueous solution triggered the self-assembly growth of micro-/nanostructural Au@CuOx-CeO2 CSNs.Meanwhile,the CuOx clusters in Au@CuOx-CeO2 CSNs are capable of improving the anti-sintering ability of Au NPs and providing synergistic catalysis benefits.As a result,the confined Au NPs exhibited extraordinary thermal stability even at a harsh thermal condition up to 700℃.In addition,before and after the severe calcination process,Au@CuOx-CeO2 CSNs can exhibit enhanced catalytic activity and excellent recyclability towards the hydrogenation of p-nitrophenol compared to previously reported nanocatalysts.The synergistic catalysis path between Au/CuOx/CeO2 triphasic interfaces was revealed by density functional theory(DFT)calculations.The CuOx clusters around the embedded Au NPs can provide moderate adsorption strength of p-nitrophenol,while the adjacent CeO2-supported Au NPs can facilitate the hydrogen dissociation to form H*species,which contributes to achieve the efficient reduction of p-nitrophenol.This study opens up new possibilities for developing high-efficient and sintering-resistant micro-/nanostructural nanocatalysts by exploiting multiphasic systems.
基金the financial support from the National Key R&D Program of China(2018YFA0208504)the National Natural Science Foundation of China(21573244 and21573245)the Youth Innovation Promotion Association of CAS(2017049)
文摘Selective transfer hydrogenation of nitroarenes to amines with transition metal nanocatalysts is appealing due to its low-cost, moderate reaction conditions, good activity and excellent selectivity. Single-atom catalysts (SACs) possessing advantages of maximum atom efficiency and particular electronic structure are expected to be more effective for this reaction, yet no report about it. Herein, cobalt single atoms anchored on N-doped ultrathin carbon nanosheets (denoted as CoSAs/NCNS) were produced and demonstrated as an outstanding SAC for selective transfer hydrogenation of nitroarenes to amines with formic acid as hydrogen donor. The turnover frequency (TOF) reached 110.6 h^-1, which was 20 times higher than the best results of cobalt nanopartides reported in literatures under similar reaction conditions. Moreover, CoSAs/NCNS exhibited excellent selectivity for a variety of nitroarenes bearing other reducible functionalities, such as iodo, cyano, keto, vinyl, alkynyl and ester groups. The findings further highlight the ability and advantages of SACs in heterogeneous catalysis.
基金This work was financially supported by the National Key Research and Development Program of China(2016YFB0901600)the NSF of China(21872166)the Key Research Program of Chinese Academy of Sciences(QYZDJ-SSW-JSC013 and KGZD-EW-T06).
文摘Although single-atom catalysts significantly improve the atom utilization efficiency,the multistep preparation procedures are complicated and difficult to control.Herein,we demonstrate that one-step in situ synthesis of the single-atom Pt anchored in single-crystal MoC(Pt_(1)/MoC)by using facile and controllable arc-discharge strategy under extreme conditions.The high temperature(up to 4000℃)provides the sufficient energy for atom dispersion and overall stability by forming thermodynamically favourable metal-support interactions.The high-temperature-stabilized Pt1/MoC exhibits outstanding performance and excellent thermal stability as durable catalyst for selective quinoline hydrogenation.The initial turnover frequency of 3710 h^(-1)is greater than those of previously reported samples by an order of magnitude under 2 MPa H_(2)at 100℃.The catalyst also shows broad scope activity toward hydrogenation containing unsaturated groups of C=C,C=N,and C=O.The facile,one-step,and fast arc-discharge method provides an effective avenue for single-atom catalyst fabrication that is conventionally challenging.
基金Guangdong Science and Technology Department,Grant/Award Number:2022A1515010961National Natural Science Foundation of China,Grant/Award Number:22109185。
文摘A surge of interest has been brought to all-solid-state batteries(ASSBs)as they show great prospects for enabling higher energy density and improved safety compared to conventional liquid batteries.Na Super Ionic CONductors(NaSICONs)proposed by Goodenough and Hong in 1976 are the most promising materials class for Nabased ASSBs owing to their excellent ion conductivity(>1mS cm−1),high thermal and chemical/electrochemical stability,as well as good chemical/electrochemical compatibility with electrode materials.The major challenge facing NaSICONtype electrolytes is the generally high interfacial resistance and thus sluggish charge transfer kinetics across the NaSICON/cathode interface.Great endeavors in the past few years have led to progress in the improvement of the ion-conducting property,and a dramatic decrease in the NaSICON/electrode interface resistance.Excellent cycling performance and rate capability have been achieved through interface engineering.In this review article,we summarize the state-of-theart findings for various derivatives of NaSICON structured solid electrolytes,with the aim of providing a deeper understanding of the underlying mechanism for the improvement of ion conductivity,and the intrinsic reasons for the enhanced interface charge transfer kinetics.These strategies can be readily extended to other solid electrolytes.We hope this review will inspire more work on NaSICONtype solid electrolytes and solid-state batteries.
基金supported by the Excellent Young Scientists Fund from National Natural Science Foundation of China (21622106)other projects from the National Natural Science Foundation of China (21773288, 21805167, 11574281, 21771117)+5 种基金the Outstanding Scholar Fund (JQ201703)the Doctoral Fund (ZR2018BB010)the Science Foundation of Shandong Province of Chinathe Taishan Scholar Project of Shandong Province of Chinathe National Key Basic Research Program of China (2017YFA0403402)the Future Program for Young Scholar of Shandong University
文摘Catalytic decomposition of NH3 to high purity hydrogen offers a promising strategy for fuel cells, but presents challenges for high hydrogen yields at comparatively low temperatures due to the lack of efficient catalysts. Here, we report the facile preparation of ultra-fine ruthenium（Ru） species dispersed on Mg O, which show excellent activity and high temperature stability for NH3 decomposition reaction. The hydrogen yield of the prepared Ru/Mg O catalysts reaches ca. 2,092 mmol H2 g–1 Ru min–1 at450 °C, far exceeding that of the previously reported most reactive Ru-based catalysts and the same chemical composition samples prepared by other approaches. Various characterization techniques containing X-ray absorption fine structure（XAFS）,in-situ diffuse reflectance infrared Fourier transform spectroscopy（in-situ DRTFTS） and temperature-programmed reduction/desorption（TPR/TPD） were carried out to explore the structure-function relation of the prepared Ru/Mg O catalysts. We found that the Ru species interact strongly with the Mg O support, which can efficiently protect the Ru species and Mg O support from agglomerating during NH3 decomposition test, maintaining the stability of the catalysts.
