Supramolecular Zinc Porphyrin Photocatalyst with Strong Reduction Ability and Robust Built-In Electric Field for Highly Efficient Hydrogen Production

摘要

The ultrathin 2D self-assembled tetrakis (4-carboxyphenyl) zinc porphyrin (SA-ZnTCPP) is successfully fabricated for photocatalytic hydrogen production. The H-2 evolution rate is 3487.3 mu mol g(-1) h(-1) under wide-spectrum (300-698 nm), which is increased by approximate to 85 times compared with metal-free self-assembled tetrakis (4-carboxyphenyl) porphyrin (SA-TCPP). The significant promotion in photocatalytic activity of SA-ZnTCPP comes from the deep conduction band (-1.01 V) contributed by the elevation of orbital energy level of porphyrin after Zn2+ coordination. In addition, the strong built-in electric field boosts the rapid separation and mobility of photogenerated carriers. Consequently, the strong reduction driving force and faster electron transfer kinetics result in highly efficient photocatalytic hydrogen production of SA-ZnTCPP. This work improves the understanding of the structure-property relationship of metalloporphyrin-based supramolecular photocatalysts and provides a general strategy at the molecular level for performance optimization of photocatalysts.