Figure 2.

(a) Schematic diagram of the preparation of Fe₁Co₁−ONS and Fe₁Co₁−ONP. SEM images of (b) Fe₁Co₁−ONP and (c) Fe₁Co₁−ONS. Reproduced from Ref. [29] with permission from WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim, Copyright 2017.