Ternary CdS@MoS2–Co3O4 Multiheterojunction Photocatalyst for Boosting Photocatalytic H2 Evolution

Turning the carrier dynamics in heterojunction photocatalysts is a direct and effective strategy for improving the solar energy conversion efficiency of photocatalysts. Herein, we report a ternary CdS@MoS2–Co3O4 multiheterojunction photocatalyst consisting of the p–n junction of MoS2–Co3O4 and the type-I junction of CdS@MoS2, wherein MoS2 located at the frontier between CdS and Co3O4 acts as an intermediate bridge. The type-I junction allows the directional transfer of photoinduced charge from CdS to MoS2, suppressing the photocorrosion of CdS. Notably, the single-particle photoluminescence technique demonstrates the sequential one-direction hole transfer from MoS2 to Co3O4 aroused by the p–n junction, resulting in a long-lifetime charge separation in the carrier lifetime (54–58 ns). Compared to the bare CdS and type-I CdS@MoS2, the CdS@MoS2–Co3O4 photocatalyst affords a 347-fold and 3.5-fold enhancement of the H2 evolution rate, a quantum efficiency of 28.6% at 450 nm, and a 20 h of long-term stability. This work provides a new understanding of the rational regulation of the charge-transfer mechanism of type-I systems by constructing multiheterojunction photocatalysts.