Non-metallic　atom　doping　is　a　good　strategy　to　promote　the　cathode　performance　in　the　electro-Fenton　process.　Therefore,　a　mixed-valence　copper　(I　and　II)　phosphate　(Cu2PO4)　catalyst　on　P-doped　etched　graphite　felt　(EGF),　with　a　strip-groove　rough　surface,　was　prepared　in　this　study.　The　P-doped　Cu2PO4/EGF　electrode　completely　removed　sulfamethoxazole　(SMX)　from　contaminated　water　within　90　min　over　a　wide　pH　range　of　5.6–9　and　removed　99.6%　of　SMX　at　pH　11.　Quenching　experiments　showed　that　the　main　reactive　oxygen　species　(ROS)　was　[rad]O2–.　According　to　density　functional　theory　calculations,　the　adsorption　reaction　energy　(EP　=　−2.149)　of　P　atoms　doped　on　the　EGF　surface　was　lower　than　that　of　pyrrolic　nitrogen　atoms　(EN　=　−0.434),　indicating　that　they　were　more　conducive　to　oxygen　adsorption.　Finally,　we　investigated　the　mechanism　of　P-doped　Cu2PO4/EGF　adsorption　and　the　catalytic　production　of　[rad]O2–　from　O2.　Four　main　degradation　pathways　were　identified　based　on　the　intermediates　identified　during　degradation.　Toxicity　analysis　of　the　intermediates　showed　that　electro-Fenton　degradation　reduced　the　ecotoxicity　of　SMX.　The　enhanced　electrocatalytic　activity　obtained　by　P　doping　of　heterogeneous　catalysts　provides　a　new　method　for　preparing　efficient　and　stable　composite　electrodes　for　pollutant　degradation.　©　2024　Elsevier　B.V.