Rational establishment of metal ion confinement and direct charge transport of Fe-X-C in ZnFe2O4/NBGA system for enhanced degradation of emerging pollutants.

The Photo-Fenton-like reaction offers a novel avenue for the efficient and thorough mineralization of emerging pollutants while is constrained by metal ion leaching and a declination in catalytic performance. This study presented the development of a ZnFe2O4/NBGA (named as ZFO/NBGA) catalytic system including strategically established Fe-X-C (X = N, B) links and a three-dimensional hierarchical architecture. The Fe-X-C bond functions as a conduit to modulate the charge environment at active sites, and the three-dimensional nitrogen and boron-doped graphene aerogel (noted as NBGA) accelerates charge and ion transfer. Experimental findings demonstrated that the ZFO/NBGA catalytic system achieved 99.5% TC removal activity for PDS activation under visible light irradiation within 50 min. The reaction rate constant (k) reached 9.9 × 10-2 min-1, which is 6.6 times higher than that of pure ZnFe2O4. Additionally, the anti-interference ability in complex water environments was validated. Crucially, the catalyst exhibited exceptional stability and economic sustainability, maintaining 79.89% degradation efficiency after 6 consecutive cycles with negligible metal leaching (Zn < 1.0 mg/L, Fe < 0.3 mg/L). The primary active species were •O2-, h+, and 1O2. LSCM evaluated the degradation pathways of contaminants, and the toxicity of the resultant chemicals were examined. DFT calculations elucidated that improved performance resulted from directional electron transport, which prolonged carriers life-time, and the d-band center of ZFO/NBGA, situated closer to the Fermi level, optimized the adsorption and desorption of intermediates. This work may offer novel insights into the mechanisms of metal-based carbon catalysts for the efficient remediation of emerging pollutants, which is essential for the establishment of ecologically sustainable catalytic approaches.