Enhancement of Interfacial Charge Transportation Through Construction of 2D–2D p–n Heterojunctions in Hierarchical 3D CNFs/MoS_2/ZnIn_2S_4 Composites to Enable High-Efficiency Photocatalytic Hydrogen Evolution

摘要

Hierarchical three-dimensional (3D) carbon nanofibers (CNFs)/molybdenum disulfide (MoS_2)/ZnIn_2S_4 composites with p-n heterojunctions between the basal planes of two-dimensional (2D) phases are fabricated, using in situ spinning-based chemical vapor deposition together with hydrothermal processing. It is found that large and intimately interfaced 2D-2D planes between the n-type ZnIn_2S_4 and the CNFs-supported p-type MoS_2 enable evident junction rectification effect, which facilitates interfacial charge separation to assist effective suppression of the recombination of photogenerated electrons and holes. In addition, the p-type MoS_2 nanosheets with high in-plane conductivity and narrower bandgap are highly effective in providing larger quantities of photoinduced electrons, which can be readily injected into the outer n-type ZnIn_2S_4 coating for the reduction of H_2O into H_2, whereas the holes are driven into the CNF cores by the junction field to be finally scavenged. The large specific surficial area of the sulfides provides abundant sulfur-rich sites active for H_2 evolution. Consequently, the optimal CNFs/MoS_2/ZnIn_2S_4 composite with 5 mmoL MoS_2 loading exhibits robust H_2 evolution under simulate sunlight irradiation, achieving a remarkably enhanced photocatalytic H_2 production rate over 151.42mmoL⋅h~(-1)⋅g~(-1) and a high apparent quantum yield of 20.88% at 365 nm, which is 4.65 times higher than that of pristine ZnIn_2S_4.