To fully realize the commercial viability of Pt in fuel cells, the usage of scarce Pt must be reduced while the activity and durability in 02 reduction reaction （ORR） must be enhanced. Here we report a metallic stac...To fully realize the commercial viability of Pt in fuel cells, the usage of scarce Pt must be reduced while the activity and durability in 02 reduction reaction （ORR） must be enhanced. Here we report a metallic stack design achieving these goals for ORR, based on atomically precise materials synthesis. Au@Pd@Pt nanostructures with atomically thin Pt shells and high-index surfaces form an excellent platform for integrating the effects of electronic structures, surface facets, and substrate stabilization to boost ORR performance. Au@Pd@Pt trisoctahedrons （TOH） achieve mass activity 6.1 times higher than that of commercial Pt/C and dramatically enhanced durability beyond 1.0 V vs. a reversible hydrogen electrode in oxidation potential. Meanwhile, Pt comprises only 3.2% of the nanostructures. To further improve the ORR activity and demonstrate the versatility of our strategy, we implement the same design in PtNi alloy electrocatalysts. The Au@Pd@PtNi TOHs exhibit mass activity 14.3 times higher than that of commercial Pt/C as well as excellent durability. This work demonstrates an alternative strategy for fabricating high-performance and low-cost catalysts, and highlights the importance of simultaneous surface and interfacial engineering with atomic precision in designing catalysts.展开更多
InAs-based quantum dots(QDs)are promising heavy-metal-free semiconductors for infrared emission technologies,offering tunable bandgaps via quantum confinement and excellent charge-carrier transport properties.Building...InAs-based quantum dots(QDs)are promising heavy-metal-free semiconductors for infrared emission technologies,offering tunable bandgaps via quantum confinement and excellent charge-carrier transport properties.Building on these advantages,we report the synthesis of QDs tailored for emission in the near-infrared(NIR)and short-wave infrared(SWIR)regions,emphasizing the critical role of capping ligands in controlling surface facet populations and nanocrystal morphology.Specifically,we demonstrate that the choice of ligand plays a critical role in determining the morphology and surface characteristics of InAs QDs.Using dioctylamine as a ligand results in InAs QDs with a spherical or tetrapod morphology,where nonpolar(110)facets are predominantly exposed on the surface.In contrast,oleic acid as a ligand promotes the formation of tetrahedralshaped QDs with polar(111)crystalline planes being more prominently exposed.Using a one-pot synthesis approach,we successfully synthesized InAs/InZnP/ZnSe/ZnS core-multi-shell structures that effectively minimize interfacial defects.QDs with dioctylamine-capped core exhibit significantly higher photoluminescence quantum yield(PLQY)compared to those with oleic acid-capped cores.We achieved a PLQY of 39%at 1260 nm and 7.3%at 1420 nm with QDs using dioctylamine,representing efficiency values among the best reported in both the NIR and SWIR regions.Transient absorption(TA)spectroscopy reveals that dioctylaminecapped QDs exhibit reduced ground-state bleaching differences across excitation wavelengths compared to oleic acid-capped QDs,indicating significantly reduced interfacial trap states.These findings highlight the importance of ligand-driven facet control in the context of minimizing interfacial defect formation.展开更多
文摘To fully realize the commercial viability of Pt in fuel cells, the usage of scarce Pt must be reduced while the activity and durability in 02 reduction reaction （ORR） must be enhanced. Here we report a metallic stack design achieving these goals for ORR, based on atomically precise materials synthesis. Au@Pd@Pt nanostructures with atomically thin Pt shells and high-index surfaces form an excellent platform for integrating the effects of electronic structures, surface facets, and substrate stabilization to boost ORR performance. Au@Pd@Pt trisoctahedrons （TOH） achieve mass activity 6.1 times higher than that of commercial Pt/C and dramatically enhanced durability beyond 1.0 V vs. a reversible hydrogen electrode in oxidation potential. Meanwhile, Pt comprises only 3.2% of the nanostructures. To further improve the ORR activity and demonstrate the versatility of our strategy, we implement the same design in PtNi alloy electrocatalysts. The Au@Pd@PtNi TOHs exhibit mass activity 14.3 times higher than that of commercial Pt/C as well as excellent durability. This work demonstrates an alternative strategy for fabricating high-performance and low-cost catalysts, and highlights the importance of simultaneous surface and interfacial engineering with atomic precision in designing catalysts.
基金supported by the National Research Foundation of Korea(NRF)under Project Numbers RS-2024-00350615,NRF-2021M3H4A3A01062960,and 2022R1A5A1033719the Korea Planning&Evaluation Institute of Industrial Technology(KEIT)under Project Number 20019417,and RS-2024-00440884.
文摘InAs-based quantum dots(QDs)are promising heavy-metal-free semiconductors for infrared emission technologies,offering tunable bandgaps via quantum confinement and excellent charge-carrier transport properties.Building on these advantages,we report the synthesis of QDs tailored for emission in the near-infrared(NIR)and short-wave infrared(SWIR)regions,emphasizing the critical role of capping ligands in controlling surface facet populations and nanocrystal morphology.Specifically,we demonstrate that the choice of ligand plays a critical role in determining the morphology and surface characteristics of InAs QDs.Using dioctylamine as a ligand results in InAs QDs with a spherical or tetrapod morphology,where nonpolar(110)facets are predominantly exposed on the surface.In contrast,oleic acid as a ligand promotes the formation of tetrahedralshaped QDs with polar(111)crystalline planes being more prominently exposed.Using a one-pot synthesis approach,we successfully synthesized InAs/InZnP/ZnSe/ZnS core-multi-shell structures that effectively minimize interfacial defects.QDs with dioctylamine-capped core exhibit significantly higher photoluminescence quantum yield(PLQY)compared to those with oleic acid-capped cores.We achieved a PLQY of 39%at 1260 nm and 7.3%at 1420 nm with QDs using dioctylamine,representing efficiency values among the best reported in both the NIR and SWIR regions.Transient absorption(TA)spectroscopy reveals that dioctylaminecapped QDs exhibit reduced ground-state bleaching differences across excitation wavelengths compared to oleic acid-capped QDs,indicating significantly reduced interfacial trap states.These findings highlight the importance of ligand-driven facet control in the context of minimizing interfacial defect formation.
