3D/2D Fe–Co–Co Prussian blue analogues/graphdiyne S-scheme heterojunctions for broad-spectrum photocatalytic H2 evolution

Abstract

Graphdiyne (GDY), a unique carbon allotrope, has emerged as an exceptional photocatalytic material characterized by its wide-spectrum response, and high specific surface area and excellent chemical stability. Nevertheless, its photocatalytic hydrogen evolution (PHE) efficiency is constrained by poor photogenerated carrier separation. In this work, we construct an innovative S-scheme Fe–Co–Co PBA/GDY heterojunction by coupling Fe–Co–Co Prussian blue analogues (Fe–Co–Co PBA) and amorphous GDY nanosheets for enhanced broad-spectrum photocatalytic hydrogen production (PHE). The amorphous GDY nanosheets and Fe–Co–Co PBA with large specific surface area, can provide abundant active sites for proton adsorption. In situ XPS, ESR test and DFT calculations confirm the S-scheme charge transfer mechanism of the Fe–Co–Co PBA/GDY heterojunction. This unique S-scheme architecture capitalizes on the synergistic effects of interfacial built-in electric field and band bending to facilitate efficient spatial charge separation through selective recombination of electrons in GDY with holes in Fe–Co–Co PBA, while preserving the strongest redox potentials by retaining holes in GDY and electrons in Fe–Co–Co PBA. Consequently, the optimized 25 %Fe–Co–Co PBA/GDY composite exhibits an exceptional hydrogen production rate of 2433.89 μmol g⁻¹ h⁻¹, which was 7.23 and 6.18 times enhancements over pristine Fe–Co–Co PBA and GDY. This work demonstrates the great potential of GDY-based S-scheme photocatalyst for high-performance solar-to-hydrogen conversion.