Constructing artificial photosynthetic system based on graphdiyne double heterojunction to enhance REDOX capacity and hydrogen evolution efficiency

Abstract

Although traditional type II heterojunction designs for artificial photosynthesis show promise for photocatalytic hydrogen production, their redox capacity is somewhat limited due to the spatial separation of hydrogen evolution and oxidation reactions at less favorable sites. To overcome this limitation, ohmic junctions based on type II heterojunctions have been designed to enhance hydrogen evolution by transferring electrons to the metal component. In this study, a copper powder graphdiyne (Cu-GDY) composite catalyst with ohmic angle contact was synthesized by coupling copper foil with hexa-hexylbenzene. Incorporating Cu-GDY into CoGdO₃ results in an interleaved band structure forming a type II heterojunction at the contact interface. This configuration overcomes the issue of the unfavorable conduction band position of CoGdO₃, thereby promoting charge transfer. The internal electric field created by the Fermi level difference between Cu-GDY and CoGdO₃, increase in REDOX capacity is the main reason for the increase of carrier separation rate. In addition, the plasmonic properties of copper expand the active reaction sites and promote the hydrogen evolution reaction. The composite catalyst exhibits b a hydrogen production rate that is 10.5 times higher than that of the individual catalysts. This work demonstrates that the formation of two distinct contact interfaces between Cu-GDY and CoGdO₃ significantly improves the electron transfer and hydrogen evolution performance.