Palm kernel shell(PKS)biochars with different levels of carbon conversion were initially prepared using a tube furnace,after which the reactivity of each sample was assessed with a thermogravimetric analyzer under a C...Palm kernel shell(PKS)biochars with different levels of carbon conversion were initially prepared using a tube furnace,after which the reactivity of each sample was assessed with a thermogravimetric analyzer under a CO_2 atmosphere.The pore structure and carbon ordering of each biochar also examined,employing a surface area analyzer and a Raman spectroscopy.Thermogravimetric results showed that the gasification index R_sof the PKS biochar decreased from 0.0305 min^(-1) at carbon conversion(x)=20% to 0.0278 min^(-1)at x=40%.The expansion of micropores was the dominant process during the pore structure evolution,ad mesopores with sizes ranging from 6 to 20,48 to 50 nm were primarily generated during gasification under a CO_2/H_2O mixture.The proportion of amorphous carbon in the PKS biochar decreased significantly as x increased,suggesting that the proportion of ordered carbon was increased during the CO_2/H_2O mixed gasification.A significantly reduced total reaction time was observed when employing a CO_2/intermittent H_2O process along with an 83.46% reduction in the steam feed,compared with the amount required using a CO_2/H_2O atmosphere.展开更多
The deposition onto an ordered mesoporous carbon（OMC）support of well dispersed PtM（M = Ru,Fe,Mo）alloy nanoparticles（NPs）were synthesized by a direct replication method using SBA-15 as the hard template,furfuryl ...The deposition onto an ordered mesoporous carbon（OMC）support of well dispersed PtM（M = Ru,Fe,Mo）alloy nanoparticles（NPs）were synthesized by a direct replication method using SBA-15 as the hard template,furfuryl alcohol and trimethylbeneze as the primary carbon sources,and metal acetylacetonate as the alloying metal precursor and secondary carbon source.The physicochemical properties of the PtM-OMC catalysts were characterized by N2 adsorption-desorption,X-ray diffraction,transmission electron microscopy,X-ray absorption near edge structure,and extended X-ray absorption fine structure.The alloy PtM NPs have an average size of 2-3 nm and were well dispersed in the pore channels of the OMC support.The second metal（M）in the PtM NPs was mostly in the reduced state,and formed a typical core（Pt）-shell（M）structure.Cyclic voltammetry measurements showed that these PtM-OMC electrodes had excellent electrocatalytic activities and tolerance to CO poisoning during the methanol oxidation reaction,which surpassed those of typical activated carbon-supported PtRu catalysts.In particular,the PtFe-OMC catalyst,which exhibited the best performance,can be a practical anodic electrocatalyst in direct methanol fuel cells due to its superior stability,excellent CO tolerance,and low production cost.展开更多
The performance of fuel-cell related electrocatalysis is highly dependent on the morphology,size and composition of a given catalyst.In terms of rational design of Pt-based catalyst,one-dimensional(1 D)ultrafine Pt al...The performance of fuel-cell related electrocatalysis is highly dependent on the morphology,size and composition of a given catalyst.In terms of rational design of Pt-based catalyst,one-dimensional(1 D)ultrafine Pt alloy nanowires(NWs)are considered as a commendable model for enhanced catalysis on account of their favorable mass/charge transfer and structural durability.However,in order to achieve the noble metal catalysts in higher efficiency and lower cost,building high-index facets and shaping hollow interiors should be integrated into 1 D Pt alloy NWs,which has rarely been done so far.Here,we report the first synthesis of a class of spiny Pd/PtFe core/shell nanotubes(SPCNTs)constructed by cultivating PtFe alloy branches with rich high-index facets along the 1 D removable Pd supports,which is driven by the galvanic dissolution of Pd substrates concomitant with Stranski-Krastanov(S-K)growth of Pt and Fe,for achieving highly efficient fuel-cells-related electrocatalysis.This new catalyst can even deliver electrochemical active surface area(ECSA)of 62.7 m^(2)gPt^(-1),comparable to that of commercial carbonsupported Pt nanoparticles.With respect to oxygen reduction catalysis,the SPCNTs showcase the remarkable mass and specific activity of 2.71 A mg^(-1)and 4.32 mA cm^(-2),15.9 and 16.0 times higher than those of commercial Pt/C,respectively.Also,the catalysts exhibit extraordinary resistance to the activity decay and structural degradation during 50,000 potential cycles.Moreover,the SPCNTs serve as a category of efficient and stable catalysts towards anodic alcohol oxidation.展开更多
基金Supported by the Key Project of the Natural Science Foundation of Shandong Province(ZR2015QZ02)the Key Research&Development Program of Shandong Province(2016GSF117005)+1 种基金the introduction of scientific and technological innovation team of Ningxia Hui Autonomous Region(2016)Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(2017-K22)
文摘Palm kernel shell(PKS)biochars with different levels of carbon conversion were initially prepared using a tube furnace,after which the reactivity of each sample was assessed with a thermogravimetric analyzer under a CO_2 atmosphere.The pore structure and carbon ordering of each biochar also examined,employing a surface area analyzer and a Raman spectroscopy.Thermogravimetric results showed that the gasification index R_sof the PKS biochar decreased from 0.0305 min^(-1) at carbon conversion(x)=20% to 0.0278 min^(-1)at x=40%.The expansion of micropores was the dominant process during the pore structure evolution,ad mesopores with sizes ranging from 6 to 20,48 to 50 nm were primarily generated during gasification under a CO_2/H_2O mixture.The proportion of amorphous carbon in the PKS biochar decreased significantly as x increased,suggesting that the proportion of ordered carbon was increased during the CO_2/H_2O mixed gasification.A significantly reduced total reaction time was observed when employing a CO_2/intermittent H_2O process along with an 83.46% reduction in the steam feed,compared with the amount required using a CO_2/H_2O atmosphere.
基金supported by the Ministry of Science and Technology(NSC98-2113-M001-017-MY3,NSC101-2113-M001-020-MY3),Taiwan,China~~
文摘The deposition onto an ordered mesoporous carbon（OMC）support of well dispersed PtM（M = Ru,Fe,Mo）alloy nanoparticles（NPs）were synthesized by a direct replication method using SBA-15 as the hard template,furfuryl alcohol and trimethylbeneze as the primary carbon sources,and metal acetylacetonate as the alloying metal precursor and secondary carbon source.The physicochemical properties of the PtM-OMC catalysts were characterized by N2 adsorption-desorption,X-ray diffraction,transmission electron microscopy,X-ray absorption near edge structure,and extended X-ray absorption fine structure.The alloy PtM NPs have an average size of 2-3 nm and were well dispersed in the pore channels of the OMC support.The second metal（M）in the PtM NPs was mostly in the reduced state,and formed a typical core（Pt）-shell（M）structure.Cyclic voltammetry measurements showed that these PtM-OMC electrodes had excellent electrocatalytic activities and tolerance to CO poisoning during the methanol oxidation reaction,which surpassed those of typical activated carbon-supported PtRu catalysts.In particular,the PtFe-OMC catalyst,which exhibited the best performance,can be a practical anodic electrocatalyst in direct methanol fuel cells due to its superior stability,excellent CO tolerance,and low production cost.
基金the Xplorer Prize,the Beijing Natural Science Foundation(JQ18005,Z190010)the National Natural Science Foundation of China(NSFC)(51671003,and 21771156)+3 种基金National R&D Program of China(2017YFA0206701)the China Postdoctoral Science Foundation(2019M660290)the state Key Laboratory of Solidification Processing in NPU(SKLSP202004)the Start-up supports from Peking University and Young Thousand Talented Program.
文摘The performance of fuel-cell related electrocatalysis is highly dependent on the morphology,size and composition of a given catalyst.In terms of rational design of Pt-based catalyst,one-dimensional(1 D)ultrafine Pt alloy nanowires(NWs)are considered as a commendable model for enhanced catalysis on account of their favorable mass/charge transfer and structural durability.However,in order to achieve the noble metal catalysts in higher efficiency and lower cost,building high-index facets and shaping hollow interiors should be integrated into 1 D Pt alloy NWs,which has rarely been done so far.Here,we report the first synthesis of a class of spiny Pd/PtFe core/shell nanotubes(SPCNTs)constructed by cultivating PtFe alloy branches with rich high-index facets along the 1 D removable Pd supports,which is driven by the galvanic dissolution of Pd substrates concomitant with Stranski-Krastanov(S-K)growth of Pt and Fe,for achieving highly efficient fuel-cells-related electrocatalysis.This new catalyst can even deliver electrochemical active surface area(ECSA)of 62.7 m^(2)gPt^(-1),comparable to that of commercial carbonsupported Pt nanoparticles.With respect to oxygen reduction catalysis,the SPCNTs showcase the remarkable mass and specific activity of 2.71 A mg^(-1)and 4.32 mA cm^(-2),15.9 and 16.0 times higher than those of commercial Pt/C,respectively.Also,the catalysts exhibit extraordinary resistance to the activity decay and structural degradation during 50,000 potential cycles.Moreover,the SPCNTs serve as a category of efficient and stable catalysts towards anodic alcohol oxidation.
