Understanding of the Dual Roles of Phosphorus in Atomically Distributed Fe/Co-N₄P₂ over Carbon Nitride for Photocatalytic Debromination from Tetrabromobisphenol A

Atomically dispersed Fe and Co on carbon nitride under an external phosphine (PH3) atmosphere (P-Fe1Co1/CN) are prepared. Combined with the results of calculations and experiments, the formed P-induced bimetallic single atoms of Fe/Co-N4P2 can provide more reactive sites to enhance optical performance. Meanwhile, the introduced P can coordinate with Fe and Co and change the sole nitrogen coordination environment via the bridging effect. Herein, on the one hand, the structure of Fe–P–Co enhances interactions of single atoms in heterogeneous metals, and, on the other hand, the formed Fe/Co-N4P2 effectively changes the electron configuration in coordination centers. All of the abovementioned findings can enhance the photocatalytic performance of P-Fe1Co1/CN, achieving 96% removal and 51% debromination rates from tetrabromobisphenol A under visible light irradiation. The two efficiencies can be further improved under UV–vis light irradiation. The findings of this work reveal the dual roles of P in bimetallic single-atom catalysts, provide a facile method to synthesize P-assisted bimetal single-atom photocatalysts, and highlight the great potential of carbon nitride-based single atoms as photocatalysts.