We present a simple approach to improving the quality of CVD grown graphene, exploiting a Cu(111) foil catalyst. The catalyst is epitaxially grown by evaporation on a single crystal sapphire substrate, thickened by electroplating, and peeled off. The exposed surface is atomically flat, easily reduced, and exclusively of (111) orientation. Graphene grown on this catalyst under atmospheric CVD conditions and without wet chemical prereduction produces single crystal domain sizes of several hundred micrometers in samples that are many centimeters in size. The graphene produced in this way can easily be transferred to other substrates using well-established techniques. We report mobilities extracted using field-effect (as high as 29 000 cm2 V–1 s–1) and Hall bar measurement (up to 10 100 cm2 V–1 s–1).

The ability to control the charge-potential landscape at solid-liquid interfaces is pivotal to engineer novel devices for applications in sensing, catalysis and energy conversion. The isoelectric point (pI)/point of zero charge (pzc) of graphene plays a key role in a number of physico-chemical phenomena occurring at the graphene-liquid interface. Supported by theory, we present here a methodology to identify the pI/pzc of (functionalized) graphene, which also allows for estimating the nature and extent of ion adsorption. The pI of bare graphene (as-prepared, chemical vapor deposition (CVD)-grown) is found to be less than 3.3, which we can continuously modify up to 7.5 by non-covalent electrochemical attachment of aromatic amino groups, preserving the favorable electronic properties of graphene throughout. Modelling all the observed results with detailed theory, we also show that specific adsorption of ions and the substrate play only an ancillary role in our capability to tune the pI of graphene.

Due to their high surface-to-volume ratio, cylindrical Bi2Te3 nanowires are employed as model systems to investigate the chemistry and the unique conductive surface states of topological insulator nanomaterials. We report on nanoangle-resolved photoemission spectroscopy (nano-ARPES) characterization of individual cylindrical Bi2Te3 nanowires with a diameter of 100 nm. The nanowires are synthesized by electrochemical deposition inside channels of ion-track etched polymer membranes. Core level spectra recorded with submicron resolution indicate a homogeneous chemical composition along individual nanowires, while nano-ARPES intensity maps reveal the valence band structure at the single nanowire level. First-principles electronic structure calculations for chosen crystallographic orientations are in good agreement with those revealed by nano-ARPES. The successful application of nano-ARPES on single one-dimensional nanostructures constitutes a new avenue to achieve a better understanding of the electronic structure of topological insulator nanomaterials.