This report describes the electrochemical behavior of a family of “core‐shell” electrocatalysts consisting of a carbon nitride (CN) “shell” matrix and a “core” of conducting carbon nanoparticles (NPs). The CN “shell” matrix embeds PdCoNi alloy NPs and covers homogeneously the carbon “core”. The chemical composition of the materials is determined by inductively‐coupled plasma atomic emission spectroscopy (ICP‐AES) and microanalysis; the structure is studied by powder X‐ray diffraction (powder XRD); the morphology is investigated by high‐resolution transmission electron microscopy (HR‐TEM). The surface activity and structure are probed by CO stripping. The oxygen reduction reaction (ORR) kinetics, reaction mechanism, and tolerance towards contamination from chloride anions are evaluated by cyclic voltammetry with the thin‐film rotating ring‐disk electrode (CV‐TF‐RRDE) method. The effect of N concentration in the matrix (which forms “coordination nests” for the Pd‐based alloy NPs bearing the active sites) on the ORR performance of the electrocatalysts is described. Results show that N atoms: 1) influence the evolution of the structure of the materials during the preparation processes, and 2) interact with alloy NPs, affecting the bifunctional and electronic ORR mechanisms of active sites and the adsorption/desorption processes of oxygen molecules and contaminants. Finally, the best PdCoNi electrocatalyst shows a higher surface activity in the ORR at 0.9 V vs. RHE with respect to the Pt‐based reference (388 μA cmPd‐2 vs. 153 μA cmPt‐2).

The incorporation of highly luminescent core-shell quantum dots (QDs) within a metal-organic framework (MOF) is achieved through a one-pot method. Through appropriate surface functionalization, the QDs are solubilized within MOF-5 growth media. This permits the incorporation of the QDs within the evolving framework during the reaction. The resulting QD@MOF-5 composites are characterized using X-ray fluorescence, cross-sectional confocal microscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and small-angle X-ray scattering. The synergistic combination of luminescent QDs and the controlled porosity of MOF-5 in the QD@MOF-5 composites is harnessed within a prototype molecular sensor that can discriminate on the basis of molecular size.

Here, it is demonstrated that energy transfer in a blend of semiconducting polymers can be strongly reduced by non‐covalent encapsulation of one constituent, ensured by threading of the conjugated strands into functionalized cyclodextrins. Such macrocycles control the minimum intermolecular distance of chromophores with similar alignment, at the nanoscale, and therefore the relevant energy transfer rates, thus enabling fabrication of white‐light‐emitting diodes (CIE coordinates: x = 0.282, y = 0.336). In particular, white electroluminescence in a binary blend of a blue‐emitting, organic‐soluble rotaxane based on a polyfluorene derivative and the green‐emitting poly(9,9‐dioctylfluorene‐alt‐benzothiadiazole (F8BT) is achieved. Morphological and structural analyses by atomic force microscopy, fluorescence mapping, µ‐Raman, and fluorescence lifetime microscopy are used to complement optical and electroluminescence characterization, and to enable a deeper insight into the properties of the novel blend.

Deep X‐ray lithography (DXRL) allows the highly controlled patterning of mesoporous films (see figure). This technique requires no resist, enabling direct patterning without causing mesostructure degradation. Increase of silica polycondensation and partial removal of the templating agent is induced by synchrotron radiation. Selective functionalization of the mesoporous objects is achieved by combining DXRL with dip‐pen writing.

We report core-level and valence-band ͑VB͒ photoemission data of C 60 molecules adsorbed at room temperature ͑RT͒ on Si͑111͒. The measurements have been carried out as a function of C 60 coverage ͓from 0.20 monolayer ͑ML͒ up to 2.2 ML͔ and annealing temperature ͑from RT up to 1300 K͒. From the VB spectra no increasing of the Fermi-level photoemission intensity has been observed for all the coverages investigated thereby indicating that no charge transfer occurs at the interface. Remarkable changes take place on the 1-ML spectrum as the annealing temperature is increased up to the disruption of the C 60 cages and the following formation of SiC. ͓S0163-1829͑99͒02623-5͔ INTRODUCTIONC 60 epitaxial growth on different metal and semiconductor substrates has attracted much interest in the last few years. Such systems can be used both as templates for the deposition of single-crystalline C 60 -thick films and to study the interaction between C 60 molecules and different elements.Solid C 60 is a molecular solid and molecules interact each other mainly through van der Waals forces. 1 The character of the bond between fullerene molecules and different substrates varies widely depending on many different factors. Strong charge transfer from metal atoms to the C 60 molecules has been observed in C 60 absorption on noble metals, Ni, etc., 2 while, for example, on Pt͑111͒ and Al͑110͒ the interaction has primarily covalent character with negligible charge transfer. 3,4 Recently, an intense experimental work has been done to study the interaction between C 60 and different Si surfaces. C 60 interaction with Si surfaces is strong: fullerene does not desorb from silicon surfaces even at 1300 K and fragment to form SiC film at temperatures above 1000 K. [5][6][7][8] One reason of this kind of research is to find the right way to use fullerenes as precursors to grow well-ordered SiC films for electronic devices with improved quality with respect to more standard methods. 9 The C 60 /Si͑111͒ system, though widely investigated is still not well understood and a series of controversies is open. The character of the bond has been found to depend on the C 60 coverage and on the annealing or growing temperature. 10,11 Scanning tunneling microscopy ͑STM͒ and Highresolution electron-energy-loss spectroscopy ͑HREELS͒ studies suggest that C 60 bond on Si(111)-(7ϫ7) surfaces is characterized by charge transfer from Si dangling bonds to C 60 when the molecules are adsorbed on the surface at RT and up to an annealing temperature of Ϸ870 K, while the bond is primarily covalent at higher annealing temperatures. 7,12-14 HREELS measurements, from the energy shift of the four dipole active modes T 1u and same H g modes, give an estimation of the charge transferred up to 4 Ϯ1 electrons/molecule. 6,13 However, these assignments have to be analyzed carefully. Actually, the energy shift of the vibrational modes depends not only on the charge state of the C 60 molecules, but also on different physical parameters, 15 such as, for example, on the structural ...