This　study　examines　the　use　of　SrAl2O4:　Eu2+,　Dy3+　long-afterglow　materials　doped　into　g-C3N4/TiO2　coatings　for　photodegradation.　The　prepared　sample　was　tested　for　the　purification　of　automotive　exhaust　fumes,　with　the　optimal　mass　ratio　of　g-C3N4/TiO2　and　SrAl2O4:　Eu2+,　Dy3+　determined　to　be　1:1.　Characterization　tests,　including　XRD,　FT-IR,　XPS,　and　TG-DSC,　were　conducted　to　evaluate　the　microstructure　and　properties　of　the　samples.　Under　poor　lighting　conditions,　g-C3N4/TiO2　reduced　CH　and　NOx　by　59　ppm　and　13　ppm　within　4　h,　respectively,　while　g-C3N4/TiO2/SrAl2O4:　Eu2+,　Dy3+　decreased　CH　and　NOx　by　98ppm　and　34ppm,　respectively,　resulting　in　a　significant　improvement　in　degradation　efficiency.　The　addition　of　long-afterglow　materials　significantly　improves　the　efficiency　of　photocatalysts　in　purifying　exhaust　fumes　in　low-light　environments,　providing　potential　value　for　all-weather　exhaust　treatment　in　the　future.