Graphdiyne (g-CnH2n-2) nanosheets encapsulated Cu-Co Prussian blue Analogues formed double S-scheme heterojunction for wide spectrum photocatalytic H2 evolution

Abstract

The frontier of sustainable energy research includes the advancement and creation of stable and efficient photocatalysts for the process of photocatalytic hydrogen evolution (PHE). Graphdiyne (GDY), an innovative carbon allotrope, demonstrates a narrow band gap and exceptional photogenerated charge mobility, making it extremely promising in the field of photocatalysis. In addition, Prussian Blue Analogues (PBA) are a unique category of metal–organic frameworks (MOFs) with open framework structures and strong stability. Compounds formed by ligands and various metal ions in PBA materials exhibit excellent performance. This work primarily enhances wide spectrum PHE by in situ growing GDY nanosheets onto Cu-Co PBA to construct a double S-scheme Cu-Co PBA@GDY/CuI (CCGC) heterojunction. The amorphous GDY can provide abundant active sites for photocatalytic hydrogen evolution reaction. Furthermore, the nanosheet properties of GDY were confirmed using Atomic Force Microscopy (AFM). The highest PHE rate of Cu-Co PBA@GDY/CuI-10 (CCGC-10) reaches 12947.8 μmol h−1 g−1 with a apparent quantum efficiency (AQE) of is 4.37 % at 520 nm, and exhibits good cycling stability. Based on the bandgap matching theory, the spatial behavior of photogenerated carriers in GDY, CuI, and Cu-Co PBA was effectively controlled, resulting in a close interface with a double S-scheme heterojunction charge transfer in Cu-Co PBA@GDY/CuI. The S-scheme photogenerated charge transfer pathway in CCGC was further confirmed through in-situ XPS, electron spin resonance (ESR) and work function (Wf). This work proposes a novel approach for the synthesis of solar energy conversion composite photocatalysts based on GDY and PBA.