2D/2D Z-scheme-based α-Fe₂O₃ @NGr heterojunction implanted with Pt single-atoms for remarkable photocatalytic hydrogen evolution

Direct Z-scheme designs perform well in light-to-fuel conversion. Here, an active and stable ternary Z-scheme core-shell heterojunction for photocatalytic hydrogen evolution (PHE) is fabricated consisting of hexagonal 2D α-Fe₂O₃ (as photocatalyst II) and 2D nitrogen-doped graphene (NGr as photocatalyst I) functionalized with the Pt single-atoms (SAs) cocatalyst. Under visible light, the 2D/2D α-Fe₂O₃ @NGr₃[sbnd]Pt_SAs (NGr shell thickness of 3 nm and Pt loading of 0.5 wt%) achieves a remarkable PHE of 6.4 µmol mg_cat⁻¹ h^–1, which is 16.4- and 3.28-times higher than those of free NGr (0.39 µmol mg_cat⁻¹ h^–1) and binary α-Fe₂O₃ @NGr₃ (1.95 µmol mg_cat⁻¹ h^–1), thus outperforming the currently-advanced PHE catalysts. The outstanding performance is due to the superiority of a direct 2D/2D Z-scheme core-shell fabrication, including a large surface area for light harvesting, facile charge separation and transfer, and the workability of Pt SAs sites. Theoretical investigations provide additional insight into the mechanistic process of the ternary system for PHE reactions.