One of the most attractive applications of carbon nanomaterials is as catalysts, due to their extreme surface-to-volume ratio. The substitution of C with heteroatoms (typically B and N as p- and n-dopants) has been explored to enhance their catalytic activity. Here we show that encapsulation within weakly doping macrocycles can be used to modify the catalytic properties of the nanotubes towards the reduction of nitroarenes, either enhancing it (n-doping) or slowing it down (p-doping). This artificial regulation strategy presents a unique combination of features found in the natural regulation of enzymes: binding of the effectors (the macrocycles) is noncovalent, yet stable thanks to the mechanical link, and their effect is remote, but not allosteric, since it does not affect the structure of the active site. By careful design of the macrocycles’ structure, we expect that this strategy will contribute to overcome the major hurdles in SWNT-based catalysts: activity, aggregation, and specificity.

A mild impregnation of graphene acid (GA) with Pd(OAc)₂ yields Pd nanoparticles with a size that can be easily controlled by the amount of the Pd precursor, and with a sharp and tunable size distribution ranging from 1 nm up to 9 nm. The spectroscopic and microscopic characterization of the GA–Pd composites reveals a strong interaction between the metal and the carboxyl groups of the GA support, and suggests a nanoparticle growth mechanism entailing counterion metathesis followed by a GA promoted reduction. The GA–Pd nanohybrids are highly active catalysts in the Suzuki–Miyaura cross coupling reaction under environmentally-friendly conditions. TOF values exceeding 30 000 h⁻¹, high selectivity toward the coupling product and versatility for a large variety of substrates are reported. Given the large amount of carboxyl groups, the catalysts are exceptionally stable, and no appreciable metal leaching is observed during the reaction. Notably, at variance with conventional carbon and graphene supports, the GA supported Pd nanoparticles show a bifunctional activity and can yield biphenyl adducts upon oxidative homocoupling of arylboronic acids.