Giant Internal Electric Field in Ni-Modified Perylenetetracarboxylic Acid Supramolecule via Metal-Coordination Engineering for Efficient Photocatalytic H2 Evolution.

Abstract

Developing efficient supramolecular photocatalysts is essential for green H2 production using solar energy, yet their performance is often limited by inefficient photogenerated charge separation. Herein, this study innovatively employs the coordination-driven self-assembly of Ni2+ ions and perylenetetracarboxylic acid (PTA) to construct a Ni-PTA supramolecular photocatalyst, achieving significantly enhanced photocatalytic H2 evolution performance. Experimental and theoretical results confirm that Ni2+ ions are inserted into PTA interlayers via monodentate coordination with carboxyl groups, inducing pronounced charge polarization and substantially augmenting the molecular dipole moment of Ni-PTA. The enhanced dipole establishes a giant internal electric field (IEF) within Ni-PTA, thereby reducing exciton binding energy and increasing charge-separation efficiency by 4.2-fold. Thus, Ni-PTA exhibits excellent and stable photocatalytic H2 evolution, with a rate of 496.7 µmol h-1, 3.8 times higher than that of self-assembled PTA supramolecules. Meanwhile, a notable apparent quantum efficiency of 16.5% at 420 nm is achieved, surpassing most reported supramolecular photocatalysts. Furthermore, the Ni-PTA film sample also shows stable operation with a H2 evolution rate of 17.7 mmol m-2 h-1, demonstrating promising practical applicability. In summary, this work highlights that metal-coordination engineering enhances the IEF of supramolecular photocatalysts for promoting charge separation, providing a new design strategy for efficient photocatalysts.