Activated energy transfer pathway in carbon nitride nanosheets promotes molecular oxygen activation for robust and efficient water decontamination

Carbon nitride (CN)-based photocatalytic processes hold promise for water decontamination, during which the widely acknowledged charge transfer pathway is unfortunately characterized by severe chemical stability challenges. Herein, the intensive yet underestimated energy transfer pathway is achieved in CN nanosheets for durable, efficient, and sustainable water purification. Upon simple oxygen activation in air, the synthesized nanosheets come with an optimal pollutant removal rate constant of 0.18 min −1 under visible light irradiation, far exceeding that of state-of-the-art photocatalysts. It is revealed that the enhanced exciton binding energy inside the CN nanosheets triggers strong exciton effects, promoting the accumulation of triplet-state excitons by regulating the energy gap. The accumulated triplet excitons almost accomplish the transition from oxygen exclusively to singlet oxygen via the energy transfer pathway, which ultimately contributes to the robust degradation of the pollutants. This work proposes a viable strategy to enhance the exciton effect within CN, upon which efficient water treatment technology driven by energy transfer pathways can be expected.