Proton exchange membrane fuel cells(PEMFCs)have been identified as a highly promising means of achieving sustainable energy conversion.A crucial factor in enhancing the performance of PEMFCs for further potential ener...Proton exchange membrane fuel cells(PEMFCs)have been identified as a highly promising means of achieving sustainable energy conversion.A crucial factor in enhancing the performance of PEMFCs for further potential energy applications is the advancement in the field of catalyst engineering that has led to remarkable performance enhancement in facilitating the oxygen reduction reaction(ORR).Subsequently,it is important to acknowledge that the techniques used in preparation of membrane electrode assemblies(MEAs),the vital constituents of PEMFCs,also possess direct and critical influence on exhibiting the full catalytic activity of meticulously crafted catalysts.Here,a succinct summary of the most recent advancements in Pt catalysts for ORR was offered and their underly catalytic mechanism were discussed.Then,both laboratory-scale and industrial-scale MEA fabrication techniques of Pt catalysts were summarized.Furthermore,a detailed analysis of the connections between materials,process,and performance in MEA fabrication was presented in order to facilitate the development of optimal catalyst layers.展开更多
The aerobic oxidation of glycerol provides an economically viable route to glyceraldehyde, dihydroxyacetone and glyceric acid with versatile applications, for which monometallic Pt, Au and Pd and bimetallic Au-Pt, Au-...The aerobic oxidation of glycerol provides an economically viable route to glyceraldehyde, dihydroxyacetone and glyceric acid with versatile applications, for which monometallic Pt, Au and Pd and bimetallic Au-Pt, Au- Pd and Pt-Pd catalysts on TiO2 were examined under base-free conditions. Pt exhibited a superior activity relative to Pd, and Au-Pd and Pt-Pd while Au was essentially inactive. The presence of Au on the Au-Pt/TiO2 catalysts led to their higher activities （normalized per Pt atom） in a wide range of Au/Pt atomic ratios （i.e. 1/3-7/1 ）, and the one with the Au/Pt ratio of 3/1 exhibited the highest activity. Such promoting effect is ascribed to the increased electron density on Pt via the electron transfer from Au to Pt, as characterized by the temperature-programmed desorption of CO and infra-red spectroscopy for CO adsorption. Meanwhile, the presence of Au on Au-Pt/TiO2, most like due to the observed electron transfer, changed the product selectivity, and facilitated the oxidation of the secondary hydroxyl groups in glycerol, leading to the favorable formation of dihydroxyacetone over glyceraldehyde and glyceric acid that were derived from the oxidation of the primary hydroxyl groups. The synergetic effect between Au and Pt demonstrates the feasibility in the efficient oxidation of glycerol to the targeted products, for example, by rational tuning of the electronic properties of metal catalysts.展开更多
Insufficient electrochemical stability is a major challenge for carbon materials in oxygen reduction reaction （ORR） due to carbon corrosion and insufficient metal-support interactions. In this work, titania is explo...Insufficient electrochemical stability is a major challenge for carbon materials in oxygen reduction reaction （ORR） due to carbon corrosion and insufficient metal-support interactions. In this work, titania is explored as an alternative support for Pt catalysts. Oxygen deficient titania samples including TiO2-x and TiO2_xNy were obtained by thermal treatment of anatase TiO2 under flowing H2 and NH3, respectively. Pt nanoparticles were deposited on the titania by a modified ethylene glycol method. The samples were characterized by N2-physisorption, X-ray diffraction and X-ray photoelectron spectroscopy. The ORR activity and long-term stability of supported Pt catalysts were evaluated using linear sweep voltammetry and chronoamperometry in 0.1 mol/L HC104. Pt/TiO2_x and Pt/TiO2_xNy showed higher ORR activities than Pt/TiO2 as indicated by higher onset potentials. Oxygen deficiency in TiO2-x and TiO2-xNy contributed to the high ORR activity due to enhanced charge transfer, as disclosed by electrochemical impedance spectroscopy studies. Electrochemical stability studies revealed that Pt/TiOE_x exhibited a higher stability with a lower current decay rate than commercial Pt/C, which can be attributed to the stable oxide support and strong interaction between Pt nanoparticles and the oxygen-deficient TiO2-x support.展开更多
In order to study the properties of supporting Pt catalysts for methanol oxidation,carbon-nanotubes are used by electrochemical deposition method. Different deposition turns,different cyclic voltammetry scanning speed...In order to study the properties of supporting Pt catalysts for methanol oxidation,carbon-nanotubes are used by electrochemical deposition method. Different deposition turns,different cyclic voltammetry scanning speeds and processing time with ascorbic acid are investigated in this paper. The micrographs of Pt / CNTs catalysts are characterized by scanning electron microscopy,the electro-catalytic properties of Pt / CNTs catalysts for methanol oxidation are investigated by cycle voltammetry and chronoamperometry. The results show that the size of platinum will be greater with the faster scanning speed. After dissolution in ascorbic acid,Pt nanoparticles disperse uniformly. The obtained Pt / CNTs catalysts show a high electro-catalytic activity and stability.展开更多
Pt/FeSnO（OH）_5 was synthesized as a novel catalyst for VOCs oxidation. Compared with Pt/γ-Al_2O_3 during catalytic oxidation of benzene, Pt/Fe Sn O（OH）5 showed better catalytic activity. After characterization of...Pt/FeSnO（OH）_5 was synthesized as a novel catalyst for VOCs oxidation. Compared with Pt/γ-Al_2O_3 during catalytic oxidation of benzene, Pt/Fe Sn O（OH）5 showed better catalytic activity. After characterization of the catalysts by XRD, SEM, TEM, EDS, XPS, BET, TGA and DTA, we found most Pt could be reduced to metallic state when the hydroxyl catalyst was used as supporter, and the metallic Pt in Pt/Fe Sn O（OH）5 was more active than the oxidized Pt in Pt/γ-Al_2O_3 in catalytic oxidation of VOCs. Pt/FeSnO（OH）_5 shows both good catalytic activity and high stability, which may be a promising catalyst. This study may also be helpful for the design and fabrication of new catalysts.展开更多
A series of Sn‐incorporated SBA‐15materials with high specific surface areas and highly orderedmesoporous structures were synthesized by a facile one‐pot method and used as catalyst supports.A reference sample was ...A series of Sn‐incorporated SBA‐15materials with high specific surface areas and highly orderedmesoporous structures were synthesized by a facile one‐pot method and used as catalyst supports.A reference sample was also prepared using a conventional impregnation method.The catalystswere characterized using various methods,and their activities in propane dehydrogenation wereinvestigated.The incorporation of Sn into the SBA‐15matrix led to strong interactions between Snspecies and the support,and these helped to maintain the oxidation states of Sn species during thereaction.Substitution with Sn changed the interfacial properties of the Pt species and improved thefunction and effect of the Sn promoter.The catalytic activities and stabilities of the Pt catalysts supportedon Sn‐incorporated SBA‐15were better than those of the impregnated sample.However,thecatalytic performance deteriorated when an excessive amount of Sn was introduced and the interactionsamong Pt,Sn species,and the support became weaker.The Pt/0.5Sn‐SBA‐15catalyst gavethe best propene selectivity,i.e.,98.5%,with a corresponding propane conversion of about43.8%.展开更多
High-loading Pt/C catalysts play an important role in the fabrication of membrane electrode assemblies with thin catalytic layer,which enhance mass transport and maintain the balance of water and heat.Unfortunately,as...High-loading Pt/C catalysts play an important role in the fabrication of membrane electrode assemblies with thin catalytic layer,which enhance mass transport and maintain the balance of water and heat.Unfortunately,as the loading increases,the agglomeration and growth of Pt nanoparticles(NPs)occur,causing unsatisfactory performance.Here,we present an efficient method for preparing of highly dispersed and small-sized Pt/C catalysts with Pt loadings varying from 39.01 wt%to 66.48 wt%through the high-temperature shock technique.The high density and ultrafine(~2.5 nm)Pt NPs are successfully anchored onto Vulcan XC-72R carbon black without the use of additional capping agents or surfactants.The modified carbon supports enhance the affinity for Pt precursors,contributing to loading efficiencies of 95%or more,while also providing abundant sites for the nucleation and fixation of Pt NPs,thus preventing agglomeration.In the context of the hydrogen evolution reaction in acidic media,the as-synthesized high-loading Pt/C catalysts show remarkable activity and stability,outperforming the state-of-the-art commercial Pt/C.This is mainly because the combined effects of ultrasmall and uniform Pt NPs,optimized electronic structure of Pt site,superhydrophilicity and effective anchoring of Pt NPs.The polymer electrolyte membrane electrolyzer integrated with Pt60/OX72R and commercial IrO2 reaches 1 A cm^(-2)at 1.77 V and operates stably for 120 hours with a negligible voltage decay.This new strategy is fast,scalable and cost-effective for large-scale production of metal-supported catalysts,especially for the high-loading ones.展开更多
Supported metal catalysts are the backbone of heterogeneous catalysis,playing a crucial role in the modern chemical industry.Metal-support interactions(MSIs)are known important in determining the catalytic performance...Supported metal catalysts are the backbone of heterogeneous catalysis,playing a crucial role in the modern chemical industry.Metal-support interactions(MSIs)are known important in determining the catalytic performance of supported metal catalysts.This is particularly true for single-atom catalysts(SACs)and pseudo-single-atom catalysts(pseudo-SACs),where all metal atoms are dispersed on,and interact directly with the support.Consequently,the MSI of SACs and pseudo-SACs are theoretically more sensitive to modulation compared to that of traditional nanoparticle catalysts.In this work,we experimentally demonstrated this hypothesis by an observed size-dependent MSI modulation.We fabricated CoFe_(2)O_(4) supported Pt pseudo-SACs and nanoparticle catalysts,followed by a straightforward water treatment process.It was found that the covalent strong metal-support interaction(CMSI)in pseudo-SACs can be weakened,leading to a significant activity improvement in methane combustion reaction.This finding aligns with our recent observation of CoFe_(2)O_(4) supported Pt SACs.By contrast,the MSI in Pt nanoparticle catalyst was barely affected by the water treatment,giving rise to almost unchanged catalytic performance.This work highlights the critical role of metal size in determining the MSI modulation,offering a novel strategy for tuning the catalytic performance of SACs and pseudo-SACs by fine-tuning their MSIs.展开更多
Tuning Strong Metal-support Interactions(SMSI)is a key strategy to obtain highly active catalysts,but conventional methods usually enable TiO_(x) encapsulation of noble metal components to minimize the exposure of nob...Tuning Strong Metal-support Interactions(SMSI)is a key strategy to obtain highly active catalysts,but conventional methods usually enable TiO_(x) encapsulation of noble metal components to minimize the exposure of noble metals.This study demonstrates a catalyst preparation method to modulate a weak encapsulation of Pt metal nanoparticles(NPs)with the supported TiO_(2),achieving the moderate suppression of SMSI effects.The introduction of silica inhibits this encapsulation,as reflected in the characterization results such as XPS and HRTEM,while the Ti^(4+) to Ti^(3+) conversion due to SMSI can still be found on the support surface.Furthermore,the hydrogenation of cinnamaldehyde(CAL)as a probe reaction revealed that once this encapsulation behavior was suppressed,the adsorption capacity of the catalyst for small molecules like H_(2) and CO was enhanced,which thereby improved the catalytic activity and facilitated the hydrogenation of CAL.Meanwhile,the introduction of SiO_(2) also changed the surface structure of the catalyst,which inhibited the occurrence of the acetal reaction and improved the conversion efficiency of C=O and C=C hydrogenation.Systematic manipulation of SMSI formation and its consequence on the performance in catalytic hydrogenation reactions are discussed.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51802059,21905070 and 22075062)Shenzhen Science and Technology Program(Nos.JCYJ20210324120400002 and SGDX20210823103803017)+4 种基金the Key Research and Development Program of Shandong Province(No.2022CXGC010305)Heilongjiang Postdoctoral Fund(No.LBHZ18066),Heilongjiang Touyan Team(No.HITTY-20190033)the Fundamental Research Funds for the Central Universities(No.FRFCU5710051922)the High-Level Professional Team in Shenzhen(No.KQTD20210811090045006)Guangdong Basic and Applied Basic Research Foundation(No.2022B1515120001)。
文摘Proton exchange membrane fuel cells(PEMFCs)have been identified as a highly promising means of achieving sustainable energy conversion.A crucial factor in enhancing the performance of PEMFCs for further potential energy applications is the advancement in the field of catalyst engineering that has led to remarkable performance enhancement in facilitating the oxygen reduction reaction(ORR).Subsequently,it is important to acknowledge that the techniques used in preparation of membrane electrode assemblies(MEAs),the vital constituents of PEMFCs,also possess direct and critical influence on exhibiting the full catalytic activity of meticulously crafted catalysts.Here,a succinct summary of the most recent advancements in Pt catalysts for ORR was offered and their underly catalytic mechanism were discussed.Then,both laboratory-scale and industrial-scale MEA fabrication techniques of Pt catalysts were summarized.Furthermore,a detailed analysis of the connections between materials,process,and performance in MEA fabrication was presented in order to facilitate the development of optimal catalyst layers.
基金supported by the National Basic Research Program of China (2011CB201400 and 2011CB808700)the National Natural Science Foundation of China (21373019, 21173008 and 21433001)
文摘The aerobic oxidation of glycerol provides an economically viable route to glyceraldehyde, dihydroxyacetone and glyceric acid with versatile applications, for which monometallic Pt, Au and Pd and bimetallic Au-Pt, Au- Pd and Pt-Pd catalysts on TiO2 were examined under base-free conditions. Pt exhibited a superior activity relative to Pd, and Au-Pd and Pt-Pd while Au was essentially inactive. The presence of Au on the Au-Pt/TiO2 catalysts led to their higher activities （normalized per Pt atom） in a wide range of Au/Pt atomic ratios （i.e. 1/3-7/1 ）, and the one with the Au/Pt ratio of 3/1 exhibited the highest activity. Such promoting effect is ascribed to the increased electron density on Pt via the electron transfer from Au to Pt, as characterized by the temperature-programmed desorption of CO and infra-red spectroscopy for CO adsorption. Meanwhile, the presence of Au on Au-Pt/TiO2, most like due to the observed electron transfer, changed the product selectivity, and facilitated the oxidation of the secondary hydroxyl groups in glycerol, leading to the favorable formation of dihydroxyacetone over glyceraldehyde and glyceric acid that were derived from the oxidation of the primary hydroxyl groups. The synergetic effect between Au and Pt demonstrates the feasibility in the efficient oxidation of glycerol to the targeted products, for example, by rational tuning of the electronic properties of metal catalysts.
基金the China Scholarship Council for a research grant
文摘Insufficient electrochemical stability is a major challenge for carbon materials in oxygen reduction reaction （ORR） due to carbon corrosion and insufficient metal-support interactions. In this work, titania is explored as an alternative support for Pt catalysts. Oxygen deficient titania samples including TiO2-x and TiO2_xNy were obtained by thermal treatment of anatase TiO2 under flowing H2 and NH3, respectively. Pt nanoparticles were deposited on the titania by a modified ethylene glycol method. The samples were characterized by N2-physisorption, X-ray diffraction and X-ray photoelectron spectroscopy. The ORR activity and long-term stability of supported Pt catalysts were evaluated using linear sweep voltammetry and chronoamperometry in 0.1 mol/L HC104. Pt/TiO2_x and Pt/TiO2_xNy showed higher ORR activities than Pt/TiO2 as indicated by higher onset potentials. Oxygen deficiency in TiO2-x and TiO2-xNy contributed to the high ORR activity due to enhanced charge transfer, as disclosed by electrochemical impedance spectroscopy studies. Electrochemical stability studies revealed that Pt/TiOE_x exhibited a higher stability with a lower current decay rate than commercial Pt/C, which can be attributed to the stable oxide support and strong interaction between Pt nanoparticles and the oxygen-deficient TiO2-x support.
基金Sponsored by the Fundamental Research Funds for the Central Universities(Grant No.HIT.ICRST.2010005)
文摘In order to study the properties of supporting Pt catalysts for methanol oxidation,carbon-nanotubes are used by electrochemical deposition method. Different deposition turns,different cyclic voltammetry scanning speeds and processing time with ascorbic acid are investigated in this paper. The micrographs of Pt / CNTs catalysts are characterized by scanning electron microscopy,the electro-catalytic properties of Pt / CNTs catalysts for methanol oxidation are investigated by cycle voltammetry and chronoamperometry. The results show that the size of platinum will be greater with the faster scanning speed. After dissolution in ascorbic acid,Pt nanoparticles disperse uniformly. The obtained Pt / CNTs catalysts show a high electro-catalytic activity and stability.
基金supported by the National Natural Science Foundation of China(No.51102047,51472050)the Natural Science Foundation of Fujian Province(No.2013J05027)the Fujian Province Education-science Project for Middle-aged and Young Teachers(No.JA13050)
文摘Pt/FeSnO（OH）_5 was synthesized as a novel catalyst for VOCs oxidation. Compared with Pt/γ-Al_2O_3 during catalytic oxidation of benzene, Pt/Fe Sn O（OH）5 showed better catalytic activity. After characterization of the catalysts by XRD, SEM, TEM, EDS, XPS, BET, TGA and DTA, we found most Pt could be reduced to metallic state when the hydroxyl catalyst was used as supporter, and the metallic Pt in Pt/Fe Sn O（OH）5 was more active than the oxidized Pt in Pt/γ-Al_2O_3 in catalytic oxidation of VOCs. Pt/FeSnO（OH）_5 shows both good catalytic activity and high stability, which may be a promising catalyst. This study may also be helpful for the design and fabrication of new catalysts.
基金supported by the Science & Technology Support Plan Projects of Sichuan Province (2016GZ0371)National Natural Science Foun-dation of China (NNSFC,21476145,21506111)~~
文摘A series of Sn‐incorporated SBA‐15materials with high specific surface areas and highly orderedmesoporous structures were synthesized by a facile one‐pot method and used as catalyst supports.A reference sample was also prepared using a conventional impregnation method.The catalystswere characterized using various methods,and their activities in propane dehydrogenation wereinvestigated.The incorporation of Sn into the SBA‐15matrix led to strong interactions between Snspecies and the support,and these helped to maintain the oxidation states of Sn species during thereaction.Substitution with Sn changed the interfacial properties of the Pt species and improved thefunction and effect of the Sn promoter.The catalytic activities and stabilities of the Pt catalysts supportedon Sn‐incorporated SBA‐15were better than those of the impregnated sample.However,thecatalytic performance deteriorated when an excessive amount of Sn was introduced and the interactionsamong Pt,Sn species,and the support became weaker.The Pt/0.5Sn‐SBA‐15catalyst gavethe best propene selectivity,i.e.,98.5%,with a corresponding propane conversion of about43.8%.
文摘High-loading Pt/C catalysts play an important role in the fabrication of membrane electrode assemblies with thin catalytic layer,which enhance mass transport and maintain the balance of water and heat.Unfortunately,as the loading increases,the agglomeration and growth of Pt nanoparticles(NPs)occur,causing unsatisfactory performance.Here,we present an efficient method for preparing of highly dispersed and small-sized Pt/C catalysts with Pt loadings varying from 39.01 wt%to 66.48 wt%through the high-temperature shock technique.The high density and ultrafine(~2.5 nm)Pt NPs are successfully anchored onto Vulcan XC-72R carbon black without the use of additional capping agents or surfactants.The modified carbon supports enhance the affinity for Pt precursors,contributing to loading efficiencies of 95%or more,while also providing abundant sites for the nucleation and fixation of Pt NPs,thus preventing agglomeration.In the context of the hydrogen evolution reaction in acidic media,the as-synthesized high-loading Pt/C catalysts show remarkable activity and stability,outperforming the state-of-the-art commercial Pt/C.This is mainly because the combined effects of ultrasmall and uniform Pt NPs,optimized electronic structure of Pt site,superhydrophilicity and effective anchoring of Pt NPs.The polymer electrolyte membrane electrolyzer integrated with Pt60/OX72R and commercial IrO2 reaches 1 A cm^(-2)at 1.77 V and operates stably for 120 hours with a negligible voltage decay.This new strategy is fast,scalable and cost-effective for large-scale production of metal-supported catalysts,especially for the high-loading ones.
文摘Supported metal catalysts are the backbone of heterogeneous catalysis,playing a crucial role in the modern chemical industry.Metal-support interactions(MSIs)are known important in determining the catalytic performance of supported metal catalysts.This is particularly true for single-atom catalysts(SACs)and pseudo-single-atom catalysts(pseudo-SACs),where all metal atoms are dispersed on,and interact directly with the support.Consequently,the MSI of SACs and pseudo-SACs are theoretically more sensitive to modulation compared to that of traditional nanoparticle catalysts.In this work,we experimentally demonstrated this hypothesis by an observed size-dependent MSI modulation.We fabricated CoFe_(2)O_(4) supported Pt pseudo-SACs and nanoparticle catalysts,followed by a straightforward water treatment process.It was found that the covalent strong metal-support interaction(CMSI)in pseudo-SACs can be weakened,leading to a significant activity improvement in methane combustion reaction.This finding aligns with our recent observation of CoFe_(2)O_(4) supported Pt SACs.By contrast,the MSI in Pt nanoparticle catalyst was barely affected by the water treatment,giving rise to almost unchanged catalytic performance.This work highlights the critical role of metal size in determining the MSI modulation,offering a novel strategy for tuning the catalytic performance of SACs and pseudo-SACs by fine-tuning their MSIs.
基金the National Natural Science Foundation of China(21576291,22003076)National Natural Science Foundation of China-Outstanding Youth foundation(22322814)the Fundamental Research Funds for the Central Universities(23CX03007A,22CX06012A)are gratefully acknowledge。
文摘Tuning Strong Metal-support Interactions(SMSI)is a key strategy to obtain highly active catalysts,but conventional methods usually enable TiO_(x) encapsulation of noble metal components to minimize the exposure of noble metals.This study demonstrates a catalyst preparation method to modulate a weak encapsulation of Pt metal nanoparticles(NPs)with the supported TiO_(2),achieving the moderate suppression of SMSI effects.The introduction of silica inhibits this encapsulation,as reflected in the characterization results such as XPS and HRTEM,while the Ti^(4+) to Ti^(3+) conversion due to SMSI can still be found on the support surface.Furthermore,the hydrogenation of cinnamaldehyde(CAL)as a probe reaction revealed that once this encapsulation behavior was suppressed,the adsorption capacity of the catalyst for small molecules like H_(2) and CO was enhanced,which thereby improved the catalytic activity and facilitated the hydrogenation of CAL.Meanwhile,the introduction of SiO_(2) also changed the surface structure of the catalyst,which inhibited the occurrence of the acetal reaction and improved the conversion efficiency of C=O and C=C hydrogenation.Systematic manipulation of SMSI formation and its consequence on the performance in catalytic hydrogenation reactions are discussed.
