“…Unlike the usual case that the polymer totally decomposes into amorphous carbon, owing to the catalytic effect of Fe, the amorphous carbon on the surface of Fe 3 C turns into graphitic carbon, resulting in Fe 3 C/graphitic carbon core‐shell structures. Recently, biomolecular‐assisted synthetic methods are considered as promising approaches for preparing nanosized materials, and l ‐cysteine has attracted great attention as a complexing, reducing agent, and simultaneously being a sulfur source . (For the l ‐cysteine molecule, there are various functional groups, namely, –NH 2 , –COOH, and –SH, which have a strong tendency to coordinate with inorganic cations and metals.…”