Rational　design　of　electrocatalysts　with　improved　catalytic　properties　is　critical　to　achieving　high　removal　efficiency　of　halogenated　organic　pollutants　by　electrocatalytic　reduction.　In　this　study，PdCu　nanoalloy　catalysts　were　prepared　by　using　chemical　co-reduction.　The　microstructures　and　electrochemical　properties　of　the　catalysts　were　characterized　by　scanning　electron　microscope　（SEM），high-resolution　transmission　electron　microscopy　（HRTEM），energy　dispersive　X-ray　spectroscopy　（EDX），X-ray　diffractometer　（XRD），X-ray　photoelectron　spectroscopy　（XPS）analysis，linear　sweep　voltammetry（LSV）and　electrochemical　impedance　spectra（EIS）.　Subsequently，the　degradation　mechanism　of　florfenicol　（FLO，one　of　typical　halogenated　antibiotics）by　PdCu　nanoalloy　catalysts　in　electrocatalytic　reduction　was　investigated.　The　results　showed　that　Pd　and　Cu　were　uniformly　distributed　in　nanoparticles.　The　PdCu　catalysts　have　excellent　electrocatalytic　capacity，kinetic　performances，and　electron　transfer　rate.　The　removal　efficiency　of　FLO　was　as　high　as　97.5%　within　120　min　under　the　voltage　of　-1.3　V　vs.　Hg/Hg2SO4，much　higher　than　that　of　metallic　nanoparticle　catalysts　Pd（82.9%）and　Cu（67.4%）.　Neutral　pH　benefits　FLO　degradation.　Quenching　experiments　showed　that　the　adsorbed　atomic　hydrogen　played　an　important　role　in　FLO　removal.　Furthermore，results　from　mechanism　study　using　liquid-mass　spectrometry（LC-MS/MS）revealed　that　the　electrocatalytic　reduction　of　FLO　over　PdCu　nano-alloy　catalysts　was　achieved　by　stepwise　dehalogenation，that　was，dechlorination　occurred　first　followed　by　defluorination.　This　study　provides　a　promising　catalyst　scheme　for　efficient　reduction　of　halogenated　organic　pollutants　through　electrocatalytic　reactions.　©　2024　Science　Press.　All　rights　reserved.