Highly efficient flower-like ZnIn2S4/CoFe2O4 photocatalyst with p-n type heterojunction for enhanced hydrogen evolution under visible light irradiation

The construction of a p-n heterojunction structure is considered to be an effective method to improve the separation of electron-hole pairs in photocatalysts. A series of ZnIn2S4/CoFe2O4 (ZIS/CFO) photocatalysts with p-n heterojunctions were prepared via a method involving ultrasonication and calcination. The synthesized photocatalysts were tested and analyzed via various testing techniques, and their hydrogen evolution rates were evaluated. Compared with pure ZIS, ZIS/CFO with different mass ratios of CFO to ZIS showed improved photocatalytic hydrogen production performance, and the optimal photoactivity showed a nearly 12-fold increase, which can be attributed to the formation of p-n junctions and the formed internal electric field, accelerating the separation of electron-hole pairs and effectively improving the photocatalytic hydrogen evolution rate. The excellent stability of the ZIS/CFO composite was proven by three cycle experiments. In addition, the ZIS/CFO composite also possessed excellent magnetic properties to realize facial magnetic recoverability. This work paves the way for the design and preparation of magnetically recoverable p-n heterojunction photocatalysts.