Exciton‐Mediated Energy Transfer in Heterojunction Enables Infrared Light Photocatalysis

Abstract Although a few semiconductors can directly absorb infrared light, their intrinsic properties like improper band‐edge position and strong electron–hole interaction restrict further photocatalytic applications. Herein, we propose an exciton‐mediated energy transfer strategy for realizing efficient infrared light response in heterostructures. Using black phosphorous/polymeric carbon nitride (BP/CN) heterojunction, CN could be indirectly excited by infrared light with the aid of nonradiatively exciton‐based energy transfer from BP. At the same time, excitons are dissociated into free charge carriers at the interface of BP/CN heterojunction, followed by hole injection to BP and electron retainment in CN. As a result of these unique photoexcitation processes, BP/CN heterojunction exhibits promoted conversion rate and selectivity in amine–amine oxidative coupling reaction even under infrared light irradiation. This study opens a new way for the design of efficient infrared light activating photocatalysts.