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The luminescence of rare earth ions (Eu2+, Ce3+, and Eu3+)-doped inorganic solids is attractive for the screening of phosphors applied in solid-state lighting and displays and significant to probe ...

Control of morphology in the synthesis of Rh nanocrystals can be used to precisely tailor the electronic surface structure; this in turn directly influences their performance in catalysis applications. Many works bring attention to the development of Rh nanostructures with low-index surfaces, but limited effort has been placed on the study of high-index and surface-defect-enriched nanocrystals as they are not favored by thermodynamics due to the involvement of high-energy surfaces and increased surface-to-volume ratios. In this work, we demonstrate an aqueous synthesis of concave Rh nanotetrahedra (CTDs) serving as efficient catalysts for energy conversion reactions. CTDs are surface-defect-rich structures that form through a slow growth rate and follow the four-step model of metallic nanoparticle growth. By tuning the surfactant concentration, the morphology of Rh CTDs evolved into highly excavated nanotetrahedra (HETDs) and twinned nanoparticles (TWs). Unlike the CTD surfaces with abundant adatoms and v...

Conventional gas sensors work upon changes in mechanical or conductive properties of sensing materials during a chemical process, which may limit availabilities of size miniaturization and design simplification. However, fabrication of miniaturized sensors with superior sensitivities in real-time and label-free probing of chemical reactions or catalytic processes remains highly challenging, in particular with regard to integration of materials into a desired smaller volume without losing the recyclability of sensing properties. Here, we demonstrate a unique bimetallic nanostructure, the Au–Pd–Au core–shell–frame nanobrick, as a promising archetype for fabrication of miniaturized sensors at nanoscale. Upon analysis of the aqueous synthesis, both ex situ and in situ, the formation of Au frames is consistent with selective deposition and aggregation of NaBH4-reduced Au nanoparticles at the corners and edges of cubic Pd shells, where the {100} surfaces, capped by iodide ions, are growth-limited. By virtue of ...

Eu2+ local environments in various crystallographic sites enable the different distributions of the emission and excitation energies and then realize the photoluminescence tuning of the Eu2+ doped solid state phosphors. Herein we report the Eu2+-doped Ca10M(PO4)7 (M = Li, Na, and K) phosphors with β-Ca3(PO4)2-type structure, in which there are five cation crystallographic sites, and the phosphors show a color tuning from bluish-violet to blue and yellow with the variation of M ions. The difference in decay rate monitored at selected wavelengths is related to multiple luminescent centers in Ca10M(PO4)7:Eu2+, and the occupied rates of Eu2+ in Ca(1), Ca(2), Ca(3), Na(4), and Ca(5) sites from Rietveld refinements using synchrotron power diffraction data confirm that Eu2+ enters into four cation sites except for Ca(5). Since the average bond lengths d(Ca–O) remain invariable in the Ca10M(PO4)7:Eu2+, the drastic changes of bond lengths d(M–O) and Eu2+ emission depending on the variation from Li to Na and K can ...

Platinum was coated on the surfaces of copper nanocubes to form Cu–CuPt core–alloy–frame nanocrystals with a rhombic dodecahedral (RD) shape. Co-reduction of Pt2+ ions and residual Cu+ ions in the supernatant of the Cu nanocube solution followed by the interdiffusion of Cu and Pt atoms over the core–shell interface allowed their formation. Growth in the ⟨100⟩ directions of the {100}-terminated Cu nanocubes resulted in the {110}-faceted rhombic dodecahedra. By the introduction of additional Pt precursor, the {100} vertices of the Cu–CuPt RD nanocrystals could be selectively extended to form spiny CuPt RD nanocrystals. After removing the Cu core template, both CuPt alloy RD and spiny CuPt alloy RD nanoframes (NFs) were obtained with Pt/Cu ratios of 26/74 and 41/59, respectively. Abundant surface defects render them highly active catalysts due to the open frame structure of both sets of NFs. The spiny RD NFs showed superior specific activity toward the oxygen reduction reaction, 1.3 and 3 times to those of t...