Systematic control of grain boundary densities in various platinum(Pt)nanostructures was achieved by specific peptide-assisted assembly and coagulation of nanocrystals.A positive quadratic correlation was observed bet...Systematic control of grain boundary densities in various platinum(Pt)nanostructures was achieved by specific peptide-assisted assembly and coagulation of nanocrystals.A positive quadratic correlation was observed between the oxygen reduction reaction(ORR)specific activities of the Pt nanostructures and the grain boundary densities on their surfaces.Compared to commercial Pt/C,the grain-boundary-rich strain-free Pt ultrathin nanoplates demonstrated a 15.5 times higher specific activity and a 13.7 times higher mass activity.Simulation studies suggested that the specific activity of ORR was proportional to the resident number and the resident time of oxygen on the catalyst surface,both of which correlate positively with grain boundary density,leading to improved ORR activities.展开更多
of main observation and conclusion The heterojunction-type structure has shown significant merits in tuning the optical properties and carrier physics.Inspired by the excellent absorption capability of halide perovski...of main observation and conclusion The heterojunction-type structure has shown significant merits in tuning the optical properties and carrier physics.Inspired by the excellent absorption capability of halide perovskite materials for visible light,a series of CsPbBr3/TiO2 heterojunction-type photocatalysts with various all-inorganic-perovskite/TiO2 ratios are successfully fabricated by the ligand-assisted reprecipitation(LARP)method.The heterojunction structure extends the light absorption of TiO2 with good chemical and structural stability.A Pb-O interaction at the CsPbBr3/TiO2 interface is observed by the XPS and confirmed by the TRPL showing improved interface carrier transport and stability.The heterojunction-type catalyst shows drastically enhanced photocatalytic activity towards the direct oxidation of toluene with 02 molecule,as an important reaction for organic chemical synthesis.The optimized sample shows an activity of 2356μmol·g^-1·h^-1 at 75℃,4 times of that of the naked CsPbBr3 nanocrystals,and 3 times of that of the bare TiO2.Based on the investigation with trapping agents,a reaction mechanism is hence proposed suggesting that the photo-generated hole may be involved in the rate-limiting step.This work demonstrates the potential of inorganic halide perovskite-based heterojunction structure for photocatalytic applications.展开更多
Controlled syntheses of PtNi metal nanocrystals with unique structures for catalyzing oxygen reduction reactions （ORRs） have attracted great interest. Here, we report the one-step synthesis of single-crystal PtNi oc...Controlled syntheses of PtNi metal nanocrystals with unique structures for catalyzing oxygen reduction reactions （ORRs） have attracted great interest. Here, we report the one-step synthesis of single-crystal PtNi octahedra with in situ-developed highly concave features and self-confined composition that are optimal for ORR. Detailed studies revealed that the Pt-rich seeding, subsequent Pt/Ni co-reduction, and Pt-Ni interfusion resulted in uniform single-crystal PtNi octahedra, and that the combination of Ni facet segregation and oxygen etching of a Ni-rich surface led to the concavity and confined Ni content. The concave PtNi nanocrystals exhibited much higher ORR performance than the commercially available Pt/C catalyst in terms of both specific activity （29.1 times higher） and mass activity （12.9 times higher） at 0.9 V （vs. reversible hydrogen electrode （RHE））. The performance was also higher than that of PtNi octahedra without concavity, confirming that the higher activity was closely related to its morphology. Moreover, the concave octahedra also exhibited remarkable stability in ORR （93% mass activity remained after 10,000 cycles between 0.6 and 1.1 V vs. RHE） owing to the passivation of the unstable sites.展开更多
基金We acknowledge the Microstructure Laboratory for Energy Materials （MLEM） at CUP for the technical support with TEM. We also acknowledge the funding support from the National Natural Science Foundation of China （No. 21303265）, Ph.D. Programs Foundation of Ministry of Education of China （No. 20130007120012） and Young Talent Award of CUP （No. YJRC-2013-46）.
文摘二金属的磅 <sub> x </sub > 有明确的昆虫形态学的 Cu <sub> y </sub> nanocrystals (NC ) 经由一条湿化学途径被综合。有约 20 nm 表演的尺寸的同样综合的凸的 NC 暴露了低索引(111 ) 种子上的方面和豆荚上的各种各样的高索引的方面。生长机制沿着 cuboctahedral 上的结晶的方向播种的 <100> 包含了比较喜欢的生长。合成协议能被用于磅 <sub> x </sub 的合成 > 有各种各样的 Cu/Pt 比率的 Cu <sub> y </sub> NC。向氧减小反应(ORR ) 在碳黑色上支持的昆虫 PtxCuy NC 的电镀物品催化的活动被学习。昆虫 PtCu <sub>2</sub>/C 催化剂展出最高特定的活动(3.7 妈 / 厘米 <sub > 磅 </sub><sup>2</sup>) 和集体活动(2.4 A/mg <sub > 磅 </sub>) 报导了为磅 <sub> x </sub 标明日期 > Cu <sub> y </sub> 。有磅 <sub> x </sub 的另外的词法形式的比较 > Cu <sub> y </sub> 显示提高的活动从词法因素发源。豆荚上的高索引的方面以及丰富的边和步的存在能相当解释提高的催化活动。昆虫磅 <sub> x </sub > Cu <sub> y </sub>/C 催化剂也在加速的耐久性测试以后显示出高词法的稳定性和活动。同样综合的昆虫磅 <sub> x </sub > Cu <sub> y </sub> NC 为质子交换膜燃料房间作为阴极电镀物品催化剂有高潜力。
基金E.Z.and Y.H.acknowledge the Electron Imaging Center of Nanomachines at University of California,Los Angeles for TEM support.Y.H.acknowledges support from the Office of Naval Research under grant number N000141812491National Science Foundation DMREF 1437263.S.W.and H.H.acknowledge support by the National Science Foundation(DMREF 1623947,CBET 1530790,OAC 1931587,and CMMI 1940335)+1 种基金The allocation of computational resources is acknowledged at the Argonne Leadership Computing Facility,which is a DOE Office of Science User Facility supported under contract DE-AC02-06CH11357,and at the Summit supercomputer supported by the National Science Foundation(ACI-1532235 and ACI-1532236)The authors declare no competing financial interests.Use of beamline ISS 8-ID of the National Synchrotron Light Source(NSLS)II was supported by the NSLS-II,Brookhaven National Laboratory,under U.S.DOE Contract No.DE-SC0012704.
文摘Systematic control of grain boundary densities in various platinum(Pt)nanostructures was achieved by specific peptide-assisted assembly and coagulation of nanocrystals.A positive quadratic correlation was observed between the oxygen reduction reaction(ORR)specific activities of the Pt nanostructures and the grain boundary densities on their surfaces.Compared to commercial Pt/C,the grain-boundary-rich strain-free Pt ultrathin nanoplates demonstrated a 15.5 times higher specific activity and a 13.7 times higher mass activity.Simulation studies suggested that the specific activity of ORR was proportional to the resident number and the resident time of oxygen on the catalyst surface,both of which correlate positively with grain boundary density,leading to improved ORR activities.
基金This work is financially supported by the National Natural Science Foundation of China(21975028,51673025)National Key Research and Development Program of China(2016YFBO700700)the start-up funding of BIT.
文摘of main observation and conclusion The heterojunction-type structure has shown significant merits in tuning the optical properties and carrier physics.Inspired by the excellent absorption capability of halide perovskite materials for visible light,a series of CsPbBr3/TiO2 heterojunction-type photocatalysts with various all-inorganic-perovskite/TiO2 ratios are successfully fabricated by the ligand-assisted reprecipitation(LARP)method.The heterojunction structure extends the light absorption of TiO2 with good chemical and structural stability.A Pb-O interaction at the CsPbBr3/TiO2 interface is observed by the XPS and confirmed by the TRPL showing improved interface carrier transport and stability.The heterojunction-type catalyst shows drastically enhanced photocatalytic activity towards the direct oxidation of toluene with 02 molecule,as an important reaction for organic chemical synthesis.The optimized sample shows an activity of 2356μmol·g^-1·h^-1 at 75℃,4 times of that of the naked CsPbBr3 nanocrystals,and 3 times of that of the bare TiO2.Based on the investigation with trapping agents,a reaction mechanism is hence proposed suggesting that the photo-generated hole may be involved in the rate-limiting step.This work demonstrates the potential of inorganic halide perovskite-based heterojunction structure for photocatalytic applications.
基金We acknowledge support from the National Science Foundation （NSF） through award DMR-1437263 on catalysis studies and the Office of Naval Research （ONR） under award N00014-15-1-2146 for synthesis efforts. X. F. D. acknowledges support from the U.S. Department of Energ34 Office of Basic Energy Sciences, Division of Materials Science and Engineering through award DE-SC0008055. E. B. Z. received additional support from China Scholarship Council （CSC） scholarships. We also thank the Electron Imaging Center of Nanomachines at CNSI for TEM support.
文摘Controlled syntheses of PtNi metal nanocrystals with unique structures for catalyzing oxygen reduction reactions （ORRs） have attracted great interest. Here, we report the one-step synthesis of single-crystal PtNi octahedra with in situ-developed highly concave features and self-confined composition that are optimal for ORR. Detailed studies revealed that the Pt-rich seeding, subsequent Pt/Ni co-reduction, and Pt-Ni interfusion resulted in uniform single-crystal PtNi octahedra, and that the combination of Ni facet segregation and oxygen etching of a Ni-rich surface led to the concavity and confined Ni content. The concave PtNi nanocrystals exhibited much higher ORR performance than the commercially available Pt/C catalyst in terms of both specific activity （29.1 times higher） and mass activity （12.9 times higher） at 0.9 V （vs. reversible hydrogen electrode （RHE））. The performance was also higher than that of PtNi octahedra without concavity, confirming that the higher activity was closely related to its morphology. Moreover, the concave octahedra also exhibited remarkable stability in ORR （93% mass activity remained after 10,000 cycles between 0.6 and 1.1 V vs. RHE） owing to the passivation of the unstable sites.
