A single-atom Fe–N2 embedded in nitrogen-doped porous carbon as a bifunctional photocatalyst for efficient removal of marine petroleum pollutants

Petroleum and its refined products enter the marine environment during the extraction process, causing serious pollution. Herein, a bifunctional Fe–N2 single-atom embedded in nitrogen-doped porous carbon photocatalyst (FC) was fabricated for the efficient removal of marine petroleum pollutants. The combination of highly dispersed Fe–N2 active sites, large surface area, high porosity, and good conductivity results in excellent photocatalytic activities. The FC catalyst exhibited a 96.7% degradation rate in the oxidative removal of bisphenol A (BPA) and a 63.4% reduction of Cr(VI) within 1 ​h, whereas the reaction equilibrium rate constants of 0.0132 ​min−1 and 0.0505 ​min−1 were reached, respectively. FC with good stability and reusability could reach 88.3% and 53.5% removal rate of BPA and Cr(VI) after 5 cycles. Radical quenching experiments and electron spin resonance (ESR) confirmed that ‧OH and e− were the most driving active species for photo-oxidation and reduction, respectively. Besides, the FC catalyst was applied to an actual seawater system and the simulation results showed a good removal rate (82.7% of BPA and 50.9% of Cr(VI) within 1 ​h). The BPA oxidation pathway in the system was proposed and the toxicity of each intermediate was accessed. This work offers a new way to construct single-atom functionalized carbon-based catalysts for marine pollution control.