Metal or non-metal doped carbon dots as catalysts for the photodegradation of 4-nitrophenol

Dual-metal-doped carbon dots (M@CDs) containing NiFe and RuFe were generated through a one-step hydrothermal route and systematically characterized. Their catalytic performance toward the photodegradation of 4-nitrophenol (4-NP) under UV irradiation (λ = 365 nm) was compared with that of undoped and non-metal (N- and S-doped) CDs. Both NiFe@CDs and RuFe@CDs displayed significantly enhanced catalytic efficiency, following pseudo-first-order kinetics, with NiFe@CDs achieving up to 94% degradation. The improvement is attributed to synergistic charge-transfer interactions between metallic dopants of various oxidation states, which promote charge separation and increase the availability of reactive species during the photodegradation.