Figure 3

13C CP-MAS NMR difference spectra, showing the total carbon increase with 13C labelling. A (control with no 13C enrichment) to B (with 13C enrichment), 3.9% and B to C (with 13C enrichment and sulfur addition), 64.7%.

13C CP-MAS NMR difference spectra, showing the total carbon increase with 13C labelling. A (control with no 13C enrichment) to B (with 13C enrichment), 3.9% and B to C (with 13C enrichment and sulfur addition), 64.7%.