Atomic-level compositions, structures, and surface properties of nitrogen-functionalized nanoporous carbons

Nanoporous nitrogen-functionalized carbon materials exhibit a combination of desirable properties that include high N contents, high fractions of N moieties at surface sites, 3-nm pores to promote diffusion, and electron conductivity to surface N environments where reactions occur. Such properties have been challenging to understand and control, due to the materials’ non-stoichiometric compositions, high electrical conductivities, heterogeneous surfaces, and complicated structural order and disorder that have important influences on their transport, adsorption, and reaction behaviors. Nevertheless, nanoporous N-carbons can be probed over multiple length scales by using 2D NMR spectroscopy, X-ray scattering, and DFT modeling, to correlate insights on local bonding environments and interactions with macroscopic material properties. Interestingly, the types, quantities, and distributions of N-heteroatom environments, notably those at surface sites, depend strongly on the composition and physical properties of the nanopore-generating template used. The analyses correlate the atomic-scale compositions, nanoscale structures, and macroscopic O₂ and sulfur reduction properties of nanoporous N-carbons as promising non-precious-metal cathode electrocatalysts for fuel cells and batteries.