This paper presents a systematic study of the growth mechanism for Pd nanobars synthesized by reducing Na_(2)PdCl_(4) with L-ascorbic acid in an aqueous solution in the presence of bromide ions as a capping agent.Tran...This paper presents a systematic study of the growth mechanism for Pd nanobars synthesized by reducing Na_(2)PdCl_(4) with L-ascorbic acid in an aqueous solution in the presence of bromide ions as a capping agent.Transmission electron microscopy(TEM)and high-resolution TEM analyses revealed that the growth at early stages of the synthesis was dominated by particle coalescence,followed by shape focusing via recrystallization and further growth via atomic addition.We also investigated the detailed surface structure of the nanobars using aberration-corrected scanning TEM and found that the exposed{100}surfaces contained several types of defects such as an adatom island,a vacancy pit,and atomic steps.Upon thermal annealing,the nanobars evolved into a more thermodynamically favored shape with enhanced truncation at the corners.展开更多
基金This work was supported in part by the Natural Science Foundation(No.DMR-0804088)startup funds from Washington University in St.Louis.P.H.C.C.was also partially supported by the Fulbright Program and the Brazilian Ministry of Education(CAPES).Part of the work was performed at the Nano Research Facility(NRF),a member of the National Nanotechnology Infrastructure Network(NNIN),which is supported by the National Science Foundation(No.ECS-0335765).
文摘This paper presents a systematic study of the growth mechanism for Pd nanobars synthesized by reducing Na_(2)PdCl_(4) with L-ascorbic acid in an aqueous solution in the presence of bromide ions as a capping agent.Transmission electron microscopy(TEM)and high-resolution TEM analyses revealed that the growth at early stages of the synthesis was dominated by particle coalescence,followed by shape focusing via recrystallization and further growth via atomic addition.We also investigated the detailed surface structure of the nanobars using aberration-corrected scanning TEM and found that the exposed{100}surfaces contained several types of defects such as an adatom island,a vacancy pit,and atomic steps.Upon thermal annealing,the nanobars evolved into a more thermodynamically favored shape with enhanced truncation at the corners.
