Z-Scheme Strategy in Polymeric Graphitic C3N5/CdS Core-Shell Heterojunction Drives Long-Lived Carriers Separation for Robust Visible-Light Hydrogen Production

The intrinsic charge carriers' recombination and excited states decay greatly suppress the active species survival and photo(electro)catalytic performance. Inspired by Z-scheme strategy, the polymeric nitrogen-rich carbon nitride/cadmium sulfide (g-C3N5/CdS) core-shell heterojunction is constructed to optimize photocatalytic performance. The optimal hydrogen production rate of g-C3N5/CdS heterojunction catalyst under visible light without adding extra cocatalyst is up to 7860 mu mol h(-1) g(-1), which is 3 and 71 times higher than that of pure CdS and g-C3N5 photocatalysts, respectively. The femtosecond transient absorption spectroscopy is employed to observe the kinetic decay of carriers in the heterojunction, revealing the ultrafast charge trapping process (tau(1) = 52.3 ps) and long-lived excited states (tau(3) = 1109.2 ps) in g-C3N5/CdS photocatalyst. Meanwhile, density functional theory calculation results comprehensively suggest the promoted charge separation in heterojunction. Cost-effective Z-scheme g-C3N5/CdS photocatalyst in this work shows a great potential for sustainable and high-efficiency solar-to-H-2 conversion.

Automated summary

Inspired by the Z-scheme strategy, a polymeric nitrogen-rich carbon nitride/cadmium sulfide (g-C3N5/CdS) core-shell heterojunction is constructed to optimize the photocatalytic performance, effectively suppressing the recombination of charge carriers and excited state decay. The g-C3N5/CdS heterojunction catalyst achieves a hydrogen production rate of 7860 μmol h(-1) g(-1) under visible light without extra cocatalyst, which is significantly higher than both pure CdS and g-C3N5 photocatalysts. The ultrafast charge trapping process and long-lived excited states in the g-C3N5/CdS photocatalyst are observed through femtosecond transient absorption spectroscopy, while density functional theory calculations confirm the enhanced charge separation in the heterojunction.