Conjugated poly(benzothiadiazole)/g-C3N4 heterojunctions via halogenation for enhanced visible-light photocatalytic selective oxidation of sulfides

Porous organic polymers have been considered potential materials for synthesizing molecules by selective activation of bonds of visible light photocatalytic catalysis. However, the low charge mobility and weak interface conductivity prohibited further application. Herein, three new polymers with fluorene as donor and benzothiadiazole by halogen substitution (F or Cl) as acceptor unit were successfully synthesized and further constructed heterostructure with g-C3N4. DClB-BTDF/g-C3N4 heterojunctions exhibited superior photocatalytic activity for the selective oxidation of sulfides to sulfoxides under visible-light illumination, the highest activity reached > 98 % of conversion in a short time, which was more than two times higher than that of pristine DClB-BTDF. This is mainly attributed to the enhanced carrier separation efficiency of DClB-BTDF/g-C3N4. Our finding could provide further insights into the design and synthesis of the halogenation strategy of polymer/g-C3N4 heterojunctions. [Display omitted] •Three benzothiadiazole-conjugated polymers were synthesized and finely tuned through halogen substitution.•Three polymers/g-C3N4 heterojunctions were assembled for the selective oxidation of sulfides.•Excellent photocatalytic product selectivities (up to 99 %) were displayed for the selective oxidation of sulfides.