The oxide supports play a crucial role in anchoring and promoting the active metal species by geometric confinement and chemical interaction.The design and synthesis of the well-defined oxide support with specific mor...The oxide supports play a crucial role in anchoring and promoting the active metal species by geometric confinement and chemical interaction.The design and synthesis of the well-defined oxide support with specific morphology such as size,shape,and exposed facets have attracted extensive research efforts,which directly reflects on their catalytic performance.In this study,using an Au/CeO_(2)-nanorod model catalyst,we demonstrate an edge effect on the Au/CeO_(2)interfacial structure,which shows a prominent effect on the structure-performance relationship in the CO oxidation reaction.This specific“edge-interface”structure features an“edge-on”Au nanoparticles position on rod-shaped CeO_(2)support,confirmed by atomic-scale electron microscopy characterization,which introduces additional degrees of freedom in coordination environment,chemical state,bond length,and strength.Combined with theocratical calculations and in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)investigations,we confirmed that this“edge-interface”has distinct adsorption properties due to the change of O vacancy formation energy as well as the chemical states of Au resulting from the electron transfer and redistribution between the metal and the support.These results demonstrate a non-conventional geometric effect of rod-shaped supported metal catalysts on the catalytic performance,which could provide insights into the atomic-precise utilization of catalysts.展开更多
Alloy nanostructures have been extensively exploited in both thermal and electrochemical catalysis due to their beneficial“synergetic effects”and being cost-effective.Understandings of the alloy nanostructures inclu...Alloy nanostructures have been extensively exploited in both thermal and electrochemical catalysis due to their beneficial“synergetic effects”and being cost-effective.Understandings of the alloy nanostructures including phases,interfaces,and chemical composition are prerequisites for utilizing them as efficient electrocatalysts.Here,we use carbon-supported CuAu nanoparticles as a model catalyst to demonstrate the phase-separation induced variation of electrochemical performance for the CO_(2)reduction reaction.Driven by thermal oxidation,the CuOx phase gradually separates from the original CuAu nanoparticles,and different carbon supports,i.e.,graphene vs.carbon nanotube lead to a reversed trend in the selectivity towards CO production.Through detailed structural and chemical analysis,we find the extent of phase separation holds the key to this variation and could be used as an effective method to tune the electrochemical properties of the alloy phase.展开更多
Metal–zeolite catalysts are vital in chemical and fuel production for their great stability,stereo-selectivity,and atom economy.When metal species keep shrinking their sizes to the subnanometer region,their spatial d...Metal–zeolite catalysts are vital in chemical and fuel production for their great stability,stereo-selectivity,and atom economy.When metal species keep shrinking their sizes to the subnanometer region,their spatial distribution in the zeolite framework/channels could have a great impact on their catalytic performance.Here,we precisely control the Pt species loaded on a silicalite-1 zeolite and characterize their structural status to the catalytic performance for CO oxidation.We find that Pt species exits as few-atom clusters encapsulated in the channels and destructively embedded Pt nanoparticles in the framework,besides the conventional surface-supported Pt.By utilizing effective Pt sites and limiting their sizes in the zeolite,we can maximize the catalytic CO oxidation performance of 1 at.% Pt-loaded zeolite catalysts to achieve a T100 as low as 90 ℃ and a stable reaction above 216 h.展开更多
基金financial support for this work from the National Natural Science Foundation of China (21422303, 21573049, 21872043, 81602643)Beijing Natural Science Foundation (2142036)+1 种基金Youth Innovation Promotion AssociationSpecial Program of “One Belt One Road” of CAS~~
文摘能够大规模同时提升电极的催化效率和稳定性对光电化学分解水系统的开发具有重要意义.硅是一种地球储量丰富且成熟的工业材料,由于其合适的带隙(1.1 eV)和优异的导电性,已被广泛用于光电化学制氢反应.然而,缓慢的表面催化反应和在电解液中的不稳定性限制了其在太阳能制氢中的实际应用.III-IV族半导体材料也具有较高的载流子传输特性且被广泛用于光电器件.其中,GaP的直接带隙和间接带隙分别为2.78和2.26 eV,可与硅组成串联型光电极用于光电化学分解水.然而,GaP的光腐蚀电位位于禁带中,很容易在光电催化过程中发生光腐蚀而导致性能大幅下降.本文报道了一种新型的GaP/GaPN核/壳纳米线修饰的p型硅(p-Si)串联型光阴极,同未修饰的p-Si相比,其光电化学制氢性能更高.这可归因于以下几点:(1)p-Si和GaP纳米线之间形成的p-n结促进了电荷分离;(2)GaPN相对于GaP具有更低的导带边位置,进一步促进了光生电子向电极表面的转移;(3)纳米线结构既缩短了光生载流子的收集距离,又增加了比表面积,从而加快了表面反应动力学.此外,在GaP中引入氮元素还提高了体系的光吸收和稳定性.我们所提出的高效、简便的改进策略可应用于其他的太阳能转换体系.利用简单的化学气相沉积法制备GaP/GaPN核/壳纳米线修饰的p-Si光阴极.首先在p-Si衬底上利用Au纳米颗粒作为催化剂生长GaP纳米线;然后,去除Au催化剂,并在氨气中退火便形成了GaP/GaPN核壳纳米线.高分辨透射电子显微镜,拉曼光谱和X射线光电子谱的表征结果均证实了氨气退火使得GaP纳米线表面形成了GaPN的薄壳层,同时证明了GaP/GaPN核壳纳米线具有可调的核壳结构.在模拟太阳光下作为光阴极用于光解水制氢反应时,GaP/GaPN核壳纳米线修饰的p-Si光阴极的起始电位为~0.14 V,而未修饰的p-Si电极的起始电位大约在?0.77 V.而且,GaP/GaPN核/壳纳米线修饰的p-Si光阴极比未修饰的p-Si光阴极具有更高的光电流密度,在水的还原电位下,其光电流密度为?0.3 mA cm^-2,且饱和光电流密度在?0.76 V时达到了?8.8 mA cm^-2.此外,GaP/GaPN核/壳纳米线修饰的p-Si光阴极的光电化学活性在10 h内没有发生明显下降.由此可见GaP/GaPN核/壳纳米线可以规模化有效地提升Si光电极的催化效率和稳定性.
基金the National Natural Science Foundation of China(Nos.22172110 and 12364018)the Guangxi Science and Technology Major Program(No.AA23073019).
文摘The oxide supports play a crucial role in anchoring and promoting the active metal species by geometric confinement and chemical interaction.The design and synthesis of the well-defined oxide support with specific morphology such as size,shape,and exposed facets have attracted extensive research efforts,which directly reflects on their catalytic performance.In this study,using an Au/CeO_(2)-nanorod model catalyst,we demonstrate an edge effect on the Au/CeO_(2)interfacial structure,which shows a prominent effect on the structure-performance relationship in the CO oxidation reaction.This specific“edge-interface”structure features an“edge-on”Au nanoparticles position on rod-shaped CeO_(2)support,confirmed by atomic-scale electron microscopy characterization,which introduces additional degrees of freedom in coordination environment,chemical state,bond length,and strength.Combined with theocratical calculations and in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)investigations,we confirmed that this“edge-interface”has distinct adsorption properties due to the change of O vacancy formation energy as well as the chemical states of Au resulting from the electron transfer and redistribution between the metal and the support.These results demonstrate a non-conventional geometric effect of rod-shaped supported metal catalysts on the catalytic performance,which could provide insights into the atomic-precise utilization of catalysts.
基金support from the National Natural Science Foundation of China(No.22172110)。
文摘Alloy nanostructures have been extensively exploited in both thermal and electrochemical catalysis due to their beneficial“synergetic effects”and being cost-effective.Understandings of the alloy nanostructures including phases,interfaces,and chemical composition are prerequisites for utilizing them as efficient electrocatalysts.Here,we use carbon-supported CuAu nanoparticles as a model catalyst to demonstrate the phase-separation induced variation of electrochemical performance for the CO_(2)reduction reaction.Driven by thermal oxidation,the CuOx phase gradually separates from the original CuAu nanoparticles,and different carbon supports,i.e.,graphene vs.carbon nanotube lead to a reversed trend in the selectivity towards CO production.Through detailed structural and chemical analysis,we find the extent of phase separation holds the key to this variation and could be used as an effective method to tune the electrochemical properties of the alloy phase.
基金financially supported by the National Natural Science Foundation of China (22172110)
文摘Metal–zeolite catalysts are vital in chemical and fuel production for their great stability,stereo-selectivity,and atom economy.When metal species keep shrinking their sizes to the subnanometer region,their spatial distribution in the zeolite framework/channels could have a great impact on their catalytic performance.Here,we precisely control the Pt species loaded on a silicalite-1 zeolite and characterize their structural status to the catalytic performance for CO oxidation.We find that Pt species exits as few-atom clusters encapsulated in the channels and destructively embedded Pt nanoparticles in the framework,besides the conventional surface-supported Pt.By utilizing effective Pt sites and limiting their sizes in the zeolite,we can maximize the catalytic CO oxidation performance of 1 at.% Pt-loaded zeolite catalysts to achieve a T100 as low as 90 ℃ and a stable reaction above 216 h.
