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.

Rational design and cost-effective fabrication of layered double hydroxides (LDHs) nanosheets with extraordinary electrochemical performance is a key challenge for hybrid supercapacitors (HSCs). Herein, we report a facile in situ growth methodology to eco-friendly synthesize hydrophilic NiCo-LDHs nanosheets on biomass waste-derived porous carbon (BC) for robust high-performance HSC cathode. The in situ growth process under ultrasonication realizes the rational arrangement of NiCo-LDHs nanosheets on the surface of BC, which effectively increases the specific surface area, promotes the electronic conductivity and enhances the wettability of NiCo-LDHs nanosheets without affecting their thickness values. With the beneficial effects of ultrathin thickness of LDHs nanosheets (6.20 nm), large specific surface area (2324.1 m² g⁻¹), low charge transfer resistance (1.65 Ω), and high wettability with electrolyte (34°–35°), the obtained Ni₂Co₁-LDHs/BC50 electrode possesses an ultra-high specific capacitance of 2390 F g⁻¹ (956 C g⁻¹) at 1 A g⁻¹, which is superior to most reported values. Furthermore, an assembled Ni₂Co₁-LDHs/BC50//YP-80F HSC delivers a maximum specific energy of 52.47 Wh kg⁻¹ at 375 W kg⁻¹, and maintains a high capacitance retention of 75.9% even after 4000 cycles. This work provides a facile approach to fabricate LDHs nanosheets based cathode materials for high-performance HSCs.