Trilayer CdS/carbon nanofiber (CNF) mat/Pt-TiO_2 composite structures for solar hydrogen production: Effects of CNF mat thickness

Abstract

Solar H_2 production by photocatalytic water splitting is a promising technology that permits direct H_2 production from the clean and abundant resources of water and solar light. We successfully fabricated trilayer heterostructures of CdS/carbon nanofiber (CNF) mat/Pt-deposited TiO_2 (Pt-TiO_2) for solar H_2 production. The CNF mat was prepared by electrospinning and carbonization. CdS and Pt-TiO_2 were coated on the front and back of the CNF mat by doctor blading. Under visible-light irradiation on the CdS side, the addition of the Pt-TiO_2 coating improved the H_2 production by a factor of 3.4. This suggests that the H_2 production reaction could occur on Pt-TiO_2, which is not active under visible irradiation; therefore, the CNF mat could act as an efficient photogenerated electron-transfer mediator from CdS to Pt-TiO_2. The H_2 production rates of the trilayer CdS/CNF/Pt-TiO_2 heterostructures were strongly affected by the thickness of the CNF mat and the carbonization temperatures used in production, which affect the resistance of the CNF mat between the CdS and Pt-TiO_2 sides. The results clearly demonstrated that the CNF acted as an efficient electron-transfer mediator as well as a support material.

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