Anodic oxygen evolution reaction(OER)is essential to participate in diverse renewable energy conversion and storage processes,while most OER electrocatalysts present satisfactory catalytic performance in only alkaline...Anodic oxygen evolution reaction(OER)is essential to participate in diverse renewable energy conversion and storage processes,while most OER electrocatalysts present satisfactory catalytic performance in only alkaline or acidic medium,limiting their practical applications in many aspects.Herein,we have designed and prepared Ir-CeO_(2)-C nanofibers(NFs)via an electrospinning and a relatively low-temperature calcination strategy for OER application in both alkaline and acidic conditions.Density functional theory(DFT)simulations demonstrate the high catalytic active sites of Ir atoms for OER,that the formation of Ir–O bonds at the interface between Ir and CeO_(2)can modulate the electron density of the relevant Ir atoms to promote the OER activity.In addition,the unique nanofibrous heterostructure increases the exposed active sites and promotes the electrical conductivity.Therefore,the prepared Ir-CeO_(2)-C nanofibrous catalyst delivers an excellent OER property in both alkaline and acidic solutions.Impressively,the overpotentials to reach 10 mA·cm^(−2)are only 279 and 283 mV in the alkaline and acidic electrolyte,respectively,with favorable long-term stabilities.In addition,the two-electrode overall water splitting set-ups equipped with Ir-CeO_(2)-C NFs as anode and commercial Pt/C as cathode provide a cell voltage of 1.54 and 1.53 V to drive 10 mA·cm^(−2)in the alkaline and acidic electrolyte,respectively,which are much lower than Pt/C||IrO_(2)and lots of transition metal oxides-based electrolyzers.This research presents an efficient means to design OER catalysts with superior properties in both alkaline and acidic solutions.展开更多
Ordered mesoporous ceria and ceria-zirconia with high specific surface area were prepared by nanocasting of a mesoporous silica KIT-6 template and used for soot oxidation.The as-synthesized ordered mesoporous ceria an...Ordered mesoporous ceria and ceria-zirconia with high specific surface area were prepared by nanocasting of a mesoporous silica KIT-6 template and used for soot oxidation.The as-synthesized ordered mesoporous ceria and ceria-zirconia were characterized by XRD,TEM,Nitrogen adsorption-desorption,Raman spectroscopy,and XRF.The results indicate that mesoporous ceria and ceria-zirconia possess highly ordered mesoporous structure,and exhibited excellent catalytic performance in soot oxidation.T_（50） of mesoporous ceria and ceria-zirconia are 475 and 470 ℃,respectively.The high catalytic activity of mesoporous materials can be attributed to the mesoporous structure and small crystallite size.Moreover,aged mesoporous materials exhibit high catalytic activity.展开更多
Modified substrates as outer heterogeneous catalysts was employed to reduce the soot generated from incomplete combustion of diesel or diesel/biodiesel blends, a process that harms the environment and public health. T...Modified substrates as outer heterogeneous catalysts was employed to reduce the soot generated from incomplete combustion of diesel or diesel/biodiesel blends, a process that harms the environment and public health. The unique storage properties of ceria （CeO2） makes it one of the most efficient catalysts available to date. Here, we proposed that ceria-based catalysts can lower the temperature at which soot combustion occurs; more specifically, from 610℃ to values included in the diesel exhausts operation range （300-450℃）. The sol-gel method was used to synthesize mixed oxide-based catalysts （CeO2：ZnO）; the resulting catalysts were deposited onto cordierite substrates. In addition, the morphological and structural properties of the material were evaluated by XRD, BET, TPR-H2, and SEM. Thermogravimetric （TG/DTA） analysis revealed that the presence of the catalyst decreased the soot combustion temperature by 200℃ on average, indicating that the oxygen species arise at low temperatures in this situation, promoting highly reactive oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy （DRS） showed that catalyst-impregnated cordierite samples efficiently oxidized soot in a diesel/biodiesel stationary motor： soot emission decreased by more than 70%.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
基金the National Natural Science Foundation of China(Nos.51973079 and 21673093)the Natural Science Foundation of Fujian Province(No.2020J01147)+1 种基金Research Foundation of Academy of Carbon Neutrality of Fujian Normal University(No.TZH2022-05)Minjiang Scholar and Startup Fund for High-level Talent at Fujian Normal University.
文摘Anodic oxygen evolution reaction(OER)is essential to participate in diverse renewable energy conversion and storage processes,while most OER electrocatalysts present satisfactory catalytic performance in only alkaline or acidic medium,limiting their practical applications in many aspects.Herein,we have designed and prepared Ir-CeO_(2)-C nanofibers(NFs)via an electrospinning and a relatively low-temperature calcination strategy for OER application in both alkaline and acidic conditions.Density functional theory(DFT)simulations demonstrate the high catalytic active sites of Ir atoms for OER,that the formation of Ir–O bonds at the interface between Ir and CeO_(2)can modulate the electron density of the relevant Ir atoms to promote the OER activity.In addition,the unique nanofibrous heterostructure increases the exposed active sites and promotes the electrical conductivity.Therefore,the prepared Ir-CeO_(2)-C nanofibrous catalyst delivers an excellent OER property in both alkaline and acidic solutions.Impressively,the overpotentials to reach 10 mA·cm^(−2)are only 279 and 283 mV in the alkaline and acidic electrolyte,respectively,with favorable long-term stabilities.In addition,the two-electrode overall water splitting set-ups equipped with Ir-CeO_(2)-C NFs as anode and commercial Pt/C as cathode provide a cell voltage of 1.54 and 1.53 V to drive 10 mA·cm^(−2)in the alkaline and acidic electrolyte,respectively,which are much lower than Pt/C||IrO_(2)and lots of transition metal oxides-based electrolyzers.This research presents an efficient means to design OER catalysts with superior properties in both alkaline and acidic solutions.
基金Supported by the National Natural Science Foundation of China(No.21476177)
文摘Ordered mesoporous ceria and ceria-zirconia with high specific surface area were prepared by nanocasting of a mesoporous silica KIT-6 template and used for soot oxidation.The as-synthesized ordered mesoporous ceria and ceria-zirconia were characterized by XRD,TEM,Nitrogen adsorption-desorption,Raman spectroscopy,and XRF.The results indicate that mesoporous ceria and ceria-zirconia possess highly ordered mesoporous structure,and exhibited excellent catalytic performance in soot oxidation.T_（50） of mesoporous ceria and ceria-zirconia are 475 and 470 ℃,respectively.The high catalytic activity of mesoporous materials can be attributed to the mesoporous structure and small crystallite size.Moreover,aged mesoporous materials exhibit high catalytic activity.
文摘Modified substrates as outer heterogeneous catalysts was employed to reduce the soot generated from incomplete combustion of diesel or diesel/biodiesel blends, a process that harms the environment and public health. The unique storage properties of ceria （CeO2） makes it one of the most efficient catalysts available to date. Here, we proposed that ceria-based catalysts can lower the temperature at which soot combustion occurs; more specifically, from 610℃ to values included in the diesel exhausts operation range （300-450℃）. The sol-gel method was used to synthesize mixed oxide-based catalysts （CeO2：ZnO）; the resulting catalysts were deposited onto cordierite substrates. In addition, the morphological and structural properties of the material were evaluated by XRD, BET, TPR-H2, and SEM. Thermogravimetric （TG/DTA） analysis revealed that the presence of the catalyst decreased the soot combustion temperature by 200℃ on average, indicating that the oxygen species arise at low temperatures in this situation, promoting highly reactive oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy （DRS） showed that catalyst-impregnated cordierite samples efficiently oxidized soot in a diesel/biodiesel stationary motor： soot emission decreased by more than 70%.
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.
