Pyrene-benzothiadiazole-based Polymer/CdS 2D/2D Organic/Inorganic Hybrid S-scheme Heterojunction for Efficient Photocatalytic H2 Evolution

ABSTRACT Nowadays, conjugated polymers have garnered numerous attention as a new class of organic photocatalysts due to their tunable electronic properties, low cost, excellent stability and sufficient light-absorption performance. In particular, pyrene-benzothiadiazole-based conjugated polymer (PBBP) has been considered to be a new type of conjugated polymers for photocatalytic H 2 evolution. However, the poor charge separation seriously limits its practical application in H 2 evolution. In this work, a PBBP-based polymer/CdS 2D/2D organic/inorganic S-scheme heterojunction photocatalyst with a strong internal electric field is, for the first time, prepared for efficient photocatalytic hydrogen evolution. The pyrene-benzothiadiazole-based conjugated polymers (PBBP) are synthesized by the Suzuki-Miyaura reactions. Then, the hybrid heterojunction photocatalysts are fabricated by coupling CdS with it through the ultrasonic mixing method. As a result, the highest H 2 -production rate of 15.83 mmol h −1 g −1 is achieved on 20% PBBP/CdS composite under visible-light irradiation, nearly 2.7 times higher than that of pure CdS. The apparent quantum efficiency (AQE) of 20% PBBP/CdS composite could reach 8.66% at λ = 420 nm. The enhanced activity could be attributed to the construction of S-scheme heterojunction, which accelerates the recombination of carriers with weaker redox ability and maintains the strong reducibility of electrons in CdS. This work provides a protocol for pyrene-benzothiadiazole-based conjugated polymers to prepare S-scheme heterojunction photocatalysts based on organic/inorganic coupling.