Graphitic　carbon　nitride　(g-C3N4)　is　a　promising　metal-free　photocatalyst;　however,　its　high　carrier　recombination　rate　and　insufficient　redox　capacity　limit　its　degradation　effect　on　antibiotics.　In　order　to　overcome　these　shortcomings,　the　photocatalytic　activity　is　improved　by　regulating　the　spin　polarization　state,　constructing　the　internal　electric　field,　and　applying　the　external　piezoelectric　field.　In　this　paper,　the　chlorine-doped　and　nitrogen-deficient　porous　carbon　nitride　composite　carbon　quantum　dots　(Nv-Cl/UPCN@CQD)　has　been　synthesized　successfully.　The　doping　position　of　chlorine　and　spin　polarization　properties　are　verified　by　DFT　calculation.　The　key　intermediates　*O2−　and　*OOH　for　the　synthesis　of　reactive　oxygen　species　were　detected　by　in-situ　infrared　testing,　which　promotes　the　production　of　•O2−　and　H2O2.　The　degradation　rate　constant　of　Nv-Cl/UPCN@CQD　for　removal　of　tetracycline　is　8.45　times　higher　than　that　of　g-C3N4.　The　active　oxygen　production　and　degradation　efficiency　of　piezoelectric　photocatalysis　under　the　synergistic　effect　of　intense　stirring　and　vis-light　irradiation　are　much　higher　than　those　of　photocatalysis　and　piezoelectric　catalysis,　and　the　conversion　of　H2O2　to　•OH　is　promoted　by　piezoelectric　field.　This　paper　provides　a　reliable　way　to　improve　the　performance　of　piezoelectric　photocatalysts　by　adjusting　their　energy　band,　electronic　structure　and　piezoelectric　force.　©　2024　Elsevier　Ltd