Probing 15 N- 15 N Correlations in g-C 3 N 4 Samples with Solid-State NMR SHA+ Pulse Sequence

Abstract

The performance of solid-state NMR proton-driven spin-diffusion (PDSD) and second-order Hamiltonian among analogous nuclei plus (SHA+) sequences for probing 15N-15N through-space correlations in 15N-labelled g-C3N4 samples were compared at high magnetic fields with moderate magic angle spinning (MAS) frequencies. It was found that, relative to the PDSD sequence, the SHA+ sequence is more efficient in terms of yielding polarization transfer between the 15N atoms as long as one of the nitrogen atoms bonds to protons. The results are useful in guiding the choice of solid-state nuclear magnetic resonance (SS-NMR) sequences for studying nitrogen-doped carbon-based materials.