Figure 1.

Homogenization of ND surface chemistry. The ND surface comprises different groups including sp² carbon structures (dark gray), carboxylic acid, hydroxyl groups, lactones, ketones and ethers (left). The actual surface moieties and their relative abundances are dictated by the production methods and subsequent purification steps. ND surface homogenization schemes include: (A) Carboxylation via oxidation, (B) Hydroxylation via four different strategies, (C) Hydrogenation via thermal annealing or microwave plasma treatment, (D) Amination, and (E) Halogenation via several different approaches.