The growth of high-quality single crystals of graphene by chemical vapor deposition on copper (Cu) has not always achieved control over domain size and morphology, and the results vary from lab to lab under presumably similar growth conditions. We discovered that oxygen on the Cu surface substantially decreased the graphene nucleation density by passivating Cu surface active sites. Control of surface oxygen enabled repeatable growth of centimeter-scale single-crystal graphene domains. Oxygen also accelerated graphene domain growth and shifted the growth kinetics from edge-attachment-limited to diffusion-limited. Correspondingly, the compact graphene domain shapes became dendritic. The electrical quality of the graphene films was equivalent to mechanically exfoliated graphene, in spite of being grown in the presence of oxygen.

We describe a surfactant-driven method to synthesize highly monodisperse CdSe-seeded CdS tetrapods with differing arm lengths and diameters in order to examine their effects on self-assembly. We exploited the phenomena of weak-and strong-binding capping groups to tune the arm length and diameter with uniform shape and achieved >95% yield. Afterward, we utilize these particles to overcome some of the key problems in the assembly of anisotropic shaped particles. Intriguingly, we found that tetrapods with certain arm lengths pack like fishbone chains, which was greatly dependent on particle shape and size. These ordered assembly phenomena were understood with the assistance of computer simulations, which strongly support our experimental observations. Importantly, this work presents a synthetic route toward shape tuning in CdSe-seeded CdS tetrapod structures, which has great influence on their self-assembly behavior at the solution/substrate interface.

How does your garden grow? A facile method can tune the anisotropic growth of TiO2 onto differently shaped gold nanoparticles to form Janus, eccentric, and concentric geometries (see picture). The Janus Au‐TiO2 nanostructures were found to be energetically stable using calculations, and they possess the highest catalytic activity out of all three geometries due to the highly accessible, exposed gold core on one side.