The　active　graphite　felt　(GF)　catalytic　layer　was　effectively　synthesized　through　a　wet　ultrasonic　impregnationcalcination　method,　modified　with　CB　and　PTFE,　and　implemented　in　a　pioneering　side-aeration　electrochemical　in-situ　H2O2　reactor.　The　optimal　mass　ratio　(CB:　PTFE　1:4)　for　the　modified　cathode　catalytic　layer　was　determined　using　a　single-factor　method.　Operating　under　optimum　conditions　of　initial　pH　5,　0.5　L/min　air　flow,　and　a　current　density　of　9　mA/cm2,　the　system　achieved　a　remarkable　maximum　H2O2　accumulation　of　560　mg/L,　with　the　H2O2　production　capacity　consistently　exceeding　95　%　over　6　usage　cycles.　The　refined　mesoporous　structure　and　improved　three-phase　interface　notably　amplified　oxygen　transfer,　utilization,　and　H2O2　yield.　Side　aeration　led　to　an　oxygen　concentration　near　the　cathode　reaching　20　mg/L,　representing　a　fivefold　increase　compared　to　the　3.95　mg/L　achieved　with　conventional　bottom　aeration.　In　the　final　application,　the　reaction　system　exhibited　efficacy　in　the　degradation　of　landfill　leachate　concentrate.　After　a　60-minute　reaction,　complete　removal　of　chroma　was　attained,　and　the　TOC　degradation　rate　surpassed　60　%,　marking　a　sixfold　improvement　over　the　conventional　system.　These　results　underscore　the　substantial　potential　of　the　system　in　H2O2　synthesis　and　environmental　remediation.