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The nitrogen/oxygen self-doped porous biochar (NO/PBC) and NO/PBC supported CuFeO 2 (CuFeO 2 -NO/PBC) were prepared and mixed as cathode catalysts for gas diffusion electrode (GDE) fabrication. The fabricated GDE could realize H 2 O 2 electrogeneration and activate H 2 O 2 to produce active radicals through NO/PBC and CuFeO 2 , respectively. The GDE with the NO/PBC to CuFeO 2 -NO/PBC ratio of 1:1 (CuFeO 2 -NO/PBC-GDE-1.0) possessed more superior catalytic performance for tetracycline degradation in heterogeneous photo-electro-Fenton (hetero-PEF) system under visible light than other as-fabricated GDEs. The •OH was primary species, and •O 2 - was auxiliary species for hetero-PEF degradation of tetracycline through CuFeO 2 -NO/PBC-GDE-1.0. The electron on the cathode surface and photoinduced electron could accelerate Fe3+/ Fe2+ and Cu2+/ Cu+ redox cycle, promoting •OH/•O 2 - production and tetracycline degradation. The toxicity estimation of tetracycline and intermediates, TOC removal and Escherichia coli growth inhibition confirmed that the remission of overall toxicity, the inhibition of antibacterial property and the mineralization of tetracycline were achieved in hetero-PEF system. [Display omitted] • CuFeO 2 -NO/PBC was prepared by hydrothermal method using NO/PBC as a support. • CuFeO 2 -NO/PBC-GDE-1.0 was fabricated for the hetero-PEF degradation of tetracycline. • CuFeO 2 -NO/PBC-GDE-1.0 could generate and activate H 2 O 2 to produce active radicals • Cathode electron and photoinduced electron promoted regeneration of Fe2+ and Cu+. • Hetero-PEF system relieved the toxicity and antibacterial property of tetracycline. [ABSTRACT FROM AUTHOR]

The heterogeneous visible-light driven photo-electro-Fenton (H-VL-PEF) system was built to degrade tetracycline using nitrogen/oxygen biomass self-doped porous carbon (NO/PC) cathode catalyst coupling CuFeO 2 /biochar particle catalyst. The NO/PC possessed the H 2 O 2 selectivity of 85.3%, and the gas diffusion electrode with NO/PC as cathode catalyst (NO/PC-GDE) exhibited fine H 2 O 2 electrogeneration performance and stability. The generated electrons on CuFeO 2 /biochar by electrostatic induction and light excitation promoted Fe3+/ Fe2+ and Cu2+/ Cu+ redox cycle, which was beneficial for HO•/O 2 •- formation and tetracycline degradation. The introduction of CuFeO 2 /biochar catalyst and visible light could reduce energy consumption and promote tetracycline mineralization. The CuFeO 2 /biochar loads, initial pH and current density of H-VL-PEF system were optimized. The degradation pathway of tetracycline was speculated based on the intermediates identified by HPLC/MS. Escherichia coli growth inhibition experiments and toxicity prediction analysis demonstrated that the comprehensive toxicity of tetracycline was alleviated due to the catalytic degradation of H-VL-PEF system. [Display omitted] • Heterogeneous visible-light driven photo-electro-Fenton (H-VL-PEF) system was built. • Nitrogen/oxygen biomass self-doped porous carbon (NO/PC) had fine H 2 O 2 selectivity. • Cathode with NO/PC as electrocatalyst had good stability for H 2 O 2 generation. • H-VL-PEF system promoted regeneration of Fe2+ and Cu+ on CuFeO 2 /biochar catalyst. • The toxicity was alleviated after tetracycline was degraded in H-VL-PEF system. [ABSTRACT FROM AUTHOR]