From cost perspective, replacing the noble metal cores with a less expensive metal could also lower the overall materials cost and make commercial applications of core shell NPs more favorable. For instance, the Pd/Pt core shell NPs show enhanced activity for the oxygen reduction reaction and methanol oxidation 8, 12, whose enhancement of catalytic performance can be attributed to the lowering of the surface electronic d-band center 14, 15, 16. Compared with the physical mixture of monometallic NPs or the alloyed bimetallic NPs, the enhanced properties of core shell structure may originate from the lattice strain, bonding interaction and electron transfer due to the unique core shell interface 12, 13. It is found that the formation of core shell NPs could further enhance the activity, selectivity and stability 9, 10, 11. This SAMs assisted area-selective ALD method of core shell structure fabrication greatly expands the applicability of ALD in fabricating novel structures and can be readily applied to the growth of NPs with other compositions.īimetallic nanoparticles (NPs) have attracted great attention due to their unique properties for catalytic applications 1, 2, 3, 4, 5, 6, 7, 8. Such core shell structures can be realized by using regular ALD recipes without special adjustment. The size, shell thickness and composition of the NPs can be controlled precisely by varying the ALD cycles. Since new nucleation sites can be effectively blocked by surface ODTS SAMs in the second deposition stage, we demonstrate the successful growth of Pd/Pt and Pt/Pd NPs with uniform core shell structures and narrow size distribution. Take the usage of pinholes on SAMs as active sites for the initial core nucleation and subsequent selective deposition of the second metal as the shell layer. The method involves utilizing octadecyltrichlorosilane (ODTS) self-assembled monolayers (SAMs) to modify the surface. Overall, this study points to the roughening and increased chemical disorder at the surface during the shell growth process, which is not readily captured by the conventional characterization tools such as electron microscopy.We report an atomic scale controllable synthesis of Pd/Pt core shell nanoparticles (NPs) via area-selective atomic layer deposition (ALD) on a modified surface. DFT calculations permitted the separation of the the Cd-111/113 chemical shielding into its different components, revealing that the varying strength of paramagnetic and spin-orbit shielding contributions are responsible for the chemical shielding trend of cadmium chalcogenides. ![]() The cadmium chemical shielding was found to be proportionally dependent on the number and nature of coordinating chalcogen-based ligands. The improved sensitivity and resolution of DNP enhanced PASS-PIETA permits the identification and study of the core, shell, and surface species of CdSe and CdSe/CdS core/shell NPLs heterostructures at all stages of c-ALD. Ligand exchange and CdS shell growth onto colloidal CdSe nanoplatelets (NPLs) using colloidal atomic layer deposition (c-ALD) were investigated by solid-state nuclear magnetic resonance (NMR) experiments, in particular, dynamic nuclear polarization (DNP) enhanced phase adjusted spinning sidebands-phase incremented echo-train acquisition (PASS-PIETA).
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