No abstract

The development of next‐generation molecular‐electronic, electrocatalytic, and energy‐storage systems depends on the availability of robust materials in which molecular charge‐storage sites and conductive hosts are in intimate contact. It is shown here that electron transfer from single‐walled carbon nanotubes (SWNTs) to polyoxometalate (POM) clusters results in the spontaneous formation of host–guest POM@SWNT redox‐active hybrid materials. The SWNTs can conduct charge to and from the encapsulated guest molecules, allowing electrical access to >90% of the encapsulated redox species. Furthermore, the SWNT hosts provide a physical barrier, protecting the POMs from chemical degradation during charging/discharging and facilitating efficient electron transfer throughout the composite, even in electrolytes that usually destroy POMs.

Carbon nanodots are a new and intriguing class of fluorescent carbon nanomaterials and are considered a promising low cost, nontoxic alternative to traditional inorganic quantum dots in applications such as bioimaging, solar cells, photocatalysis, sensors and others. Despite the abundant available literature, a clear formation mechanism for carbon nanodots prepared hydrothermally from biomass precursors along with the origins of the light emission are still under debate. In this paper, we investigate the relationships between the chemical structure and optical properties of carbon nanodots prepared by the hydrothermal treatment of glucose. Our major finding is that the widely reported excitation-dependent emission originates from solvents used to suspend the as-prepared carbon nanodots, while emission from dry samples shows no excitation-dependence. Another important highlight is that the hydrothermal conversion of biomass-derivatives under subcritical conditions leads to a heterogeneous mixture of amorphous-like nanoparticles, carbon onion-type and crystalline carbons composed of at least three different phases. The potential chemical reaction pathways involved in the formation of these hydrothermal carbon products along with a comprehensive structural and optical characterization of these systems is also provided.

Twisted two‐dimensional aromatic frameworks have been prepared by overcrowding the nodes with bulky and rigid substituents. The highly distorted aromatic framework with alternating out‐of‐plane substituents results in diminished interlayer interactions that favor the exfoliation and dispersion of individual layers in organic media.

Catalysis of chemical reactions by nanosized clusters of transition metals holds the key to the provision of sustainable energy and materials. However, the atomistic behaviour of nanocatalysts still remains largely unknown due to uncertainties associated with the highly labile metal nanoclusters changing their structure during the reaction. In this study, we reveal and explore reactions of nm-sized clusters of 14 technologically important metals in carbon nano test tubes using time-series imaging by atomically-resolved transmission electron microscopy (TEM), employing the electron beam simultaneously as an imaging tool and stimulus of the reactions. Defect formation in nanotubes and growth of new structures promoted by metal nanoclusters enable the ranking of the different metals both in order of their bonding with carbon and their catalytic activity, showing significant variation across the Periodic Table of Elements. Metal nanoclusters exhibit complex dynamics shedding light on atomistic workings of nanocatalysts, with key features mirroring heterogeneous catalysis.