Zeolites play a crucial part in acid-base heterogeneous catalysis. Fundamental insight into their internal architecture is of great importance for understanding their structure-function relationships. Here, we report on a new approach correlating confocal fluorescence microscopy with focused ion beam-electron backscatter diffraction, transmission electron microscopy lamelling and diffraction, atomic force microscopy and X-ray photoelectron spectroscopy to study a wide range of coffin-shaped MFI-type zeolite crystals differing in their morphology and chemical composition. This powerful combination demonstrates a unified view on the morphology-dependent MFI-type intergrowth structures and provides evidence for the presence and nature of internal and outer-surface barriers for molecular diffusion. It has been found that internal-surface barriers originate not only from a 90 degrees mismatch in structure and pore alignment but also from small angle differences of 0.5 degrees-2 degrees for particular crystal morphologies. Furthermore, outer-surface barriers seem to be composed of a silicalite outer crust with a thickness varying from 10 to 200 nm.

Carbon dots (CDs) have become one of most promising fluorescent materials in recent days, because of their promising photoluminescence and photocatalytic properties. However, the practical applicabilities for emissive and catalytic devices are still debatable, because of the lack of fundamental understanding behind the structure–property correlations. Herein, we have developed different types of nitrogen-doped CDs (N-CDs) by varying different nitrogen-containing precursors through a simple bottom-up based carbonization technique. Depending on the nature of nitrogen atom precursor, we are able to critically control the subpopulations of various intrinsic constituents of N-CDs, i.e., aromatic domains, amorphous domains, and small molecular fluorophores inside N-CDs. Detailed structural and elemental features have been correlated with the underpinning photophysical processes by means of steady-state and time-resolved fluorescence spectroscopy. In addition, the effect of temperature on overall photoluminescence properties has been corroborated with the internal structure of N-CDs. Finally, we have investigated the photocatalytic properties and the detailed photocatalysis mechanisms by scavenging the active species originated upon light irradiation. Results suggest that photocatalytic efficiency is maximum at a larger extent of amorphous domains and in the presence of nitrogen atoms specifically located at the edges, while photoluminescence intensity is higher at larger extent of molecular fluorophores and aromatic domains. Therefore, these fundamental investigations will open up new possibilities considering the optimizations of heteroatom functionalized CDs for their on-demand applicabilities in emitting as well as photocatalytic devices.

In Co 3 O 4 systems, the oxygen vacancy is reported to improve the oxygen evolution reaction (OER) activity because of higher Co 2+ /Co 3+ surface ratio. In situ studies have revealed Co 3+ site reducibility as the key factor for OER activity of cobalt oxide-based systems. In this context, we have synthesized and analyzed OER activity of two Co 3 O 4 systems; c-Co 3 O 4 with higher oxygen defects or Co 2+ /Co 3+ ratio and n-Co 3 O 4 with relatively less Co 2+ /Co 3+ ratio but more Co 3+ reducibility. The systems, n-and c-Co 3 O 4 show overpotential of 380 and 440 mV at 10 mA/cm 2 and Tafel slope of 153 and 53 mV/dec, respectively, for OER. Electrochemical characterization reveals that the lowering of OER onset potential is influenced by Co 3+ reducibility rather than defects in Co 3 O 4 systems while adsorption capacitance arising from surface irregularities, pores and their geometry, and Co 3+ -O h sites cause an increase in the Tafel slope values or decrease in OER kinetics. The correlation of the key factors such as Co 3+ reducibility and oxygen defects of two different Co 3 O 4 systems toward OER activity can aid the designing of highly efficient cobalt oxide-based OER catalysts. KEYWORDS: nanocrystalline cobalt oxide, Co 2+ /Co 3+ ratio, Co 3+ -O h reducibility, OER kinetics, impedance study

In situ atomic force microscopy was used to directly investigate the growth processes of the oriented metal-organic framework HKUST-1 grown on self-assembled monolayers on gold.

Free-standing ultra-thin hybrid films of reduced graphene oxide (rGO) with Au, Ag and Pd nanoparticles are generated at an aqueous/organic interface by in situ chemical reduction and spontaneous assembly.The reduction is initiated at a 'bare' interface or a 'modified' interface in a single step or two-step synthetic strategy. The hybrid materials are characterized by UV-visible, infra-red and Raman spectroscopies, X-ray diffraction, scanning electron (SEM), transmission electron (TEM) and atomic force microscopies (AFM). UVvisible spectra confirm the presence of isolated metal nanoparticles grafted on to rGO layers and Raman spectra signal a charge transfer across the constituent metal nanoparticles and rGO in the hybrid material.SEM and AFM studies show that the morphology of the hybrid films constitutes a homogeneous dispersion of metal nanoparticles and rGO for reduction at the 'bare' interface, and a random grafting of metal nanoparticles on rGO for reduction at the 'modified' interface. A mechanism for the formation of the films is proposed that involves a simultaneous transport and reduction of GO sheets and metal precursor at the interface or a directed reduction of metal precursor on rGO surface, facilitated by external aids. The utility of these hybrid films as catalysts is exemplified in p-nitrophenol reduction. Our method provides a fast, simple and inexpensive route to obtain free-standing hybrid films of rGO with metal nanoparticles for various applications.

The electrochemical urea oxidation reaction (UOR) provides a cost-effective way of generating hydrogen owing to its low thermodynamic energy barrier. Although UOR is an effective way to generate hydrogen, sustained...

Layered nickel alkanethiolates are found to exhibit antiferromagnetic coupling along the S-Ni-S chain with the ordering temperature increasing linearly with decreasing alkyl chain length. Theoretical calculations are performed to study the origin of magnetic moments and interactions in these layered systems.

Octane (C 8 ), dodecane (C 12 ), and hexadecane (C 16 ) thiolates of palladium, as well as their binary mixtures covering the entire range of compositions, have been prepared from organic media and characterized using powder X-ray diffraction (XRD), infrared spectroscopy (FTIR), and scanning tunneling microscopy (STM). All thiolatessmono as well as mixedsadopt bilayered lamellar structures as evidenced by XRD and STM. In monothiolates, the thickness of the bilayer as measured by the d 001 spacing is governed by the length of the alkyl chain, while in hybrid bilayers, the thickness depends on the binary composition as well. In C 8 -C 12 and C 12 -C 16 bilayers, in which the difference in the chain lengths of the constituent thiols is four methylene units, the thickness varies nearly proportionally to the weighted average of the chain lengths. In contrast, the C 8 -C 16 system shows a steplike behavior with only a few compositions (C 8 , 60-80%) exhibiting intermediate d values. The alkyl chains are in all-trans conformation in monothiolates, while in hybrid bilayers, especially in C 12 -C 16 , gauche defects are observed, their concentration being the highest around 50:50 composition. Interestingly, these hybrid thiolates seem to provide adequate free volume to entrap small molecular species.