Direct Z-Scheme Heterojunction Catalysts Constructed by Graphitic-C<sub>3</sub>N<sub>4</sub> and Photosensitive Metal-Organic Cages for Efficient Photocatalytic Hydrogen Evolution

oleh: Chuying Lv, Su Qin, Yang Lei, Xinao Li, Jianfeng Huang, Junmin Liu

Format: Article
Diterbitkan: MDPI AG 2022-03-01

Deskripsi

The demand for improving the activity, durability, and recyclability of metal-organic cages (MOCs) that work as photocatalytic molecular devices in a homogeneous system has promoted research to combine them with other solid materials. An M<sub>2</sub>L<sub>4</sub> type photosensitive metal-organic cage MOC-Q2 with light-harvesting ligands and catalytic Pd<sup>2+</sup> centers has been synthesized and further heterogenized with graphitic carbon nitride to prepare a robust direct Z-scheme heterojunction photocatalyst for visible-light-driven hydrogen generation. The optimized g-C<sub>3</sub>N<sub>4</sub>/MOC-Q2 (0.7 wt%) sample exhibits a high H<sub>2</sub> evolution activity of 6423 μmol g<sup>−1</sup> h<sup>−1</sup> in 5 h, and a total turnover number of 39,695 after 10 h, significantly superior to the bare MOC-Q2 used in the homogeneous solution and the comparison sample Pd/g-C<sub>3</sub>N<sub>4</sub>/L-4. The enhanced performances of g-C<sub>3</sub>N<sub>4</sub>/MOC-Q2 can be ascribed to its direct Z-scheme heterostructure, which effectively improves the charge separation and transfer efficiency. This work presents a rational approach of designing a binary photocatalytic system through combing micromolecular MOCs with heterogeneous semiconductors for water splitting.