Metal doped graphene or carbon nanotubes for electrocatalysts and graphene nanoribbons for 2D molecular electronics spectroscopy

Abstract

I will discuss metal doped or hybrid carbon materials for electrocatalysts and graphene nanoribbons (GNRs) for electronics/spintronics, and 2D molecular electronics spectroscopy (2D-MES). To design a catalyst showing superior activity for a specific electrochemical reaction, a specific single metal atom can be embedded into doped graphene. As an example, we grew graphitic tubes (GTs) using melamine in the presence of Fe/Co/Cu through heating in an N2 gas atmosphere. Then, FeCo3 nanoparticles are encapsulated inside GTs. Further, on GT surface an ultralow amount of Pt (only ~1 μg) was electrochemically deposited. Then, Pt single atoms were embedded in GT surface, while some Pt clusters were additionally formed on GT surface. The synergistic effect between the Pt clusters and single Pt atoms significantly enhanced the catalytic activity for hydrogen evolution. With a 1/80th Pt loading of a commercial 20% Pt/C catalyst, in 0.5 M H2SO4, the catalyst achieved 10 mA cm−2 at an overpotential of 18 mV, and showed a turnover frequency of 7.22 s−1 (96 times higher than that of the Pt/C catalyst) and long-term durability [Nat. Energy 2018]. Such remarkable efficiency originates from small free energy of H adsorption of single Pt atoms coordinated by C2N2 and drastic increase in conductivity by the presence of Pt clusters. We also mention a large scale synthesis of Fe3Co alloy inside the melamine-derived N-rich GTs, which shows outstanding oxygen reduction reaction activity with high power density of 117 mW cm−2 as a cathode material in an alkaline anion exchange membrane fuel cell [Adv. Energy Mater. 2018]. Finally, we address the GNR based 2D-MES, DNA finger printing as well as electronic/spintronic devices [Nat. Nanotech. 2008; 2011; ACS Nano 2014; J. Phys. Chem. Lett. 2016].