TiO2-seashell　composites　prepared　via　a　sol-gel　method　were　used　to　generate　carbonate　radicals　(•CO3−)　under　solar　light　irradiation.　•CO3−,　a　selective　radical,　was　employed　to　degrade　the　target　tetracycline　hydrochloride　contaminant.　A　series　of　characterizations　was　carried　out　to　study　the　structure　and　composition　of　the　synthesized　TiO2-seashell　composite.　This　material　exhibits　excellent　solar　light-driven　photochemical　activity　in　the　decomposition　of　tetracycline　hydrochloride.　The　possible　pathway　and　mechanism　for　the　photodegradation　process　were　proposed　on　the　basis　of　high-resolution　electrospray　ionization　time-of-flight　mass　spectrometry　experiments.　Finally,　we　investigated　the　reusability　of　the　TiO2-seashell　composite.　This　study　is　expected　to　provide　a　new　facile　pathway　for　the　application　of　•CO3−　radicals　to　degrade　special　organic　pollutants　in　water.　©　2020　Dalian　Institute　of　Chemical　Physics,　the　Chinese　Academy　of　Sciences