Building a Z-scheme heterojunction with Keggin-type heteropolymer modified two-dimensional g-C3N4 for significant photocatalytic performance†
Abstract
Building Z-scheme heterojunction systems is a high-efficiency pathway to improve the utilization of visible light. Herein, CsxPW11M/g-C3N4 (M = Co, Fe) was successfully prepared by the simple grinding and calcination technology with a Z-scheme heterojunction structure. This Z-scheme heterojunction structure could significantly improve the separation and utilization efficiency of photogenerated carriers while enhancing the redox capacity and photocatalytic activity. The energy band structure of Keggin-type polymers was optimized by modulating the coordination metal. The prepared composites have specific high photocatalytic properties and good reusability. The photocatalytic degradation activity of the prepared CsxPW11M (M = Co, Fe) modified 2D g-C3N4 materials was investigated using two different types of pollutants. Currently, when the loading capacity of CsxPW11M in the CsxPW11M/g-C3N4 sample reached 3 wt%, the photocatalyst of this composite material showed the best photocatalytic degradation performance. Meanwhile, the active species of the response were explored through free radical trapping experiments and ESR characterization, indicating that h+,˙O2 and ˙1O2 played a key role. The suitable band structure and the correct charge analysis, as well as the investigation of the transfer mechanism, provided new ideas for the construction of a Z-scheme heterojunction structure using Keggin-type transition metal-substituted heteropolymers and 2D g-C3N4. It improves the performance of conventional catalysts.