Ultrafast Hot Electron Transfer and Trap-State Mediated Charge Carrier Separation toward Enhanced Photocatalytic Activity in g-C₃N₄/ZnIn₂S₄ Heterostructure

Abstract

Comprehensive understanding of charge carrier dynamics in the heterostructure based photocatalytic materials will strengthen their candidature as future solar energy harvesting resources. Here, in this work, the g-C₃N₄(CN)/ZnIn₂S₄ (ZIS) heterostructure was successfully synthesized and a direct spectroscopic correlation was established between excited-state charge carrier dynamics and enhanced photocatalytic activity using ultrafast transient absorption (TA) spectroscopy. TA analysis demonstrated the dominance of hot electron transfer over the band edge one. The photogenerated hot electrons migrated from the high-energy excitonic states of CN toward ZIS in the subpicosecond time scale. Broad-band (UV to NIR) ultrafast transient pump-probe spectroscopy revealed the collective effect of hot electron transfer as well as trap-state mediated electron delocalization in the enhanced photocatalytic H₂ evolution. This work reveals the role of photogenerated carriers in the photocatalytic performance of the CN/ZIS heterostructure and would create a new avenue toward the advancement of CN based heterostructure in photocatalytic devices.