Ultrathin Bi2Se3/CdS composite for efficient photocatalytic hydrogen evolution via high interfacial charge separation and photothermal effect

Abstract

Introducing the photothermal effect to promote the photocatalytic H₂ rate is a good strategy and is gradually gaining attention. In this work, a series of ultrathin Bi₂Se₃/CdS nanocomposites were prepared by hydrothermal method and in situ precipitation method. Notably, CdS nanoparticles are monodispersed on the surface and aggregated at the edge of ultrathin Bi₂Se₃ nanosheets, as shown by the TEM images, implying the formation of a tight interface and rich active sites with a large area. As expected, the composite displays an excellent photocatalytic H₂ rate under visible light irradiation, which is about 3.2 times higher than that of pristine CdS. The DRS analysis shows that Bi₂Se₃ endowed the Bi₂Se₃/CdS composite with a stronger absorption ability and a wider visible absorption range. The PL, SPV, and electrochemical tests all demonstrate that the transfer and separation of electron–holes are greatly enhanced. Furthermore, the composite exhibits good solar-to-heat conversion efficiency under full-spectrum light illumination, which is beneficial to the charge activation and transfer rate. Based on the obtained band structure, the superior photocatalytic ability of the Bi₂Se₃/CdS composite is ascribed to the synergetic effect of the heterojunction and the strong solar-to-heat conversion. The work provides a strategy for employing photothermal conversion to improve solar energy conversion.