For many years the scientific community has believed in a promising future for carbon nanotubes for various applications in such diverse fields as polymer reinforcement, adsorption, catalysis, electronics and medicine. Industrial production of carbon nanotubes and -fibers and the subsequent availability and decrease of price, have rendered this vision feasible. In the last years, several carbon nanomaterial products have been marketed by major chemical companies. In this work, we present an extensive characterization of a representative set of commercially available carbon nanomaterials. Special focus has been put on their quality, i.e. presence of metal or carbonaceous impurities but also homogeneity and structural integrity. The observations are of importance for subsequent use in catalysis where the presence of impurities or defects in the nanostructure can dramatically modify the activity of the catalytic material..

Abstract:Reduction of MoO 3 with hydrogen (5-100 vol %) in the temperature range from 573 to 833 K was studied by in situ X-ray diffraction and X-ray absorption spectroscopy. The experiments performed focused on elucidating phase composition and Quantitative XRD analysis reveals a sigmoidal shape of the evolution of the MoO 3 and MoO 2 phases during reduction of MoO 3 and an increase in the crystallite size of the phases present. This Oswald ripening indicates that a nucleation-growth kinetic mechanism governs the reduction of MoO 3 under the conditions studied.The results presented in this work clearly demonstrate the potential of a combined application of in situ XRD and XAFS to reveal phase composition and kinetics of solid-state reactions.

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The “Seven Pillars” of oxidation catalysis proposed by Robert K. Grasselli represent an early example of phenomenological descriptors in the field of heterogeneous catalysis. Major advances in the theoretical description of catalytic reactions have been achieved in recent years and new catalysts are predicted today by using computational methods. To tackle the immense complexity of high-performance systems in reactions where selectivity is a major issue, analysis of scientific data by artificial intelligence and data science provides new opportunities for achieving improved understanding. Modern data analytics require data of highest quality and sufficient diversity. Existing data, however, frequently do not comply with these constraints. Therefore, new concepts of data generation and management are needed. Herein we present a basic approach in defining best practice procedures of measuring consistent data sets in heterogeneous catalysis using “handbooks”. Selective oxidation of short-chain alkanes over mixed metal oxide catalysts was selected as an example.

In the transition from graphene to graphite, the addition of each individual graphene layer modifies the electronic structure and produces a different material with unique properties. Controlled growth of few-layer graphene is therefore of fundamental interest and will provide access to materials with engineered electronic structure. Here we combine isothermal growth and etching experiments with in situ scanning electron microscopy to reveal the stacking sequence and interlayer coupling strength in few-layer graphene. The observed layer-dependent etching rates reveal the relative strength of the graphene–graphene and graphene–substrate interaction and the resulting mode of adlayer growth. Scanning tunnelling microscopy and density functional theory calculations confirm a strong coupling between graphene edge atoms and platinum. Simulated etching confirms that etching can be viewed as reversed growth. This work demonstrates that real-time imaging under controlled atmosphere is a powerful method for designing synthesis protocols for sp2 carbon nanostructures in between graphene and graphite.