Dynamic Coordination Engineering of Z-Scheme (FFV)2PdCl2/C3N4 Heterojunction for Superior Photocatalytic Hydrogen Evolution

Abstract

Realizing highly efficient photocatalytic hydrogen evolution reaction (HER) is a key challenge. Herein, a (FFV)₂PdCl₂ complex is developed with dynamic coordination engineering between the Pd^II site and Fluoflavin (FFV) ligands, and couple it with graphite carbon nitride (g-C₃N₄) ultrathin nanosheets to construct a novel Z-scheme heterojunction ((FFV)₂PdCl₂/C₃N₄). The resultant heterojunction delivers a HER activity of 648 µmol  h⁻¹ under visible light (λ ≥ 400 nm) illumination and an apparent quantum yield up to 40.1% at 400 nm, far superior to those g-C₃N₄-based catalysts reported previously. Mechanistic and theoretical studies reveal that the dynamic coordination between the Pd^II site and FFV ligands not only significantly accelerates the electron transfer from g-C₃N₄ to (FFV)₂PdCl₂ and then to the Pd^II sites via a Z-scheme mechanism, but also effectively maintain the efficacy and stability of the Pd^II active sties, and thus the (FFV)₂PdCl₂/C₃N₄ with a ultralow Pd-loading amount (ca. 0.1 wt.%) exhibits the impressive activity and durability. The present dynamic coordination and structural evolution of (FFV)₂PdCl₂ are also applicable for significantly improving the HER performance of other semiconductors, thus paving a potential way for manufacturing highly efficient and active H₂ production systems.