Superior photodegradation of organic compounds and H2O2 production over tungsten oxide/carbon nitride heterojunction with sizable heptazine units: Dual polycondensation and interface engineering

A novel ultrathin tungsten oxide/carbon nitride heterojunction photocatalyst with exceptional physical and optical properties was rationally prepared through thermal polycondensation of a preorganized supramolecular structure along with ammonium tungstate(VI). Investigation of the structure, morphology, electrical and optical properties of the photocatalysts showed an intimate and stubborn interface between WO3 nanoparticles and ultrathin carbon nitride nanosheets with highly condensed heptazine units. Significant optical enhancement in the whole solar spectrum was obtained with superior photocatalytic activities toward photodegradation of rhodamine B (RhB) and tetracycline within 8 and 15 min, respectively. It also displayed the enhanced hydrogen peroxide production rate of 161 μmol L-1 under visible light irradiation. Superoxide radicals, hydroxyl radicals, and holes were determined to be the main active species. Moreover, the heterojunction based on the Z-scheme mechanism completely degraded the tetracycline to small non-toxic fragments with a higher value of lethal dose (LD50). These outstanding performances result from synergistic approaches that lead to the modified polycondensation process, unprecedented redox ability, and the boosted optical properties.