In-situ fabrication of carbon nitride/sulfone-containing covalent organic framework composite with S-scheme charge transfer for enhanced photocatalytic hydrogen evolution

To enhance hydrogen evolution under visible light, we developed a composite photocatalyst through the in-situ growth of a sulfone-containing β-ketoenamine covalent organic framework (TpTSN-COF) on graphitic carbon nitride (CN). This in-situ growth method facilitated intimate interfacial contact and uniform dispersion of TpTSN-COF on the CN surface, which is crucial for efficient charge transfer. The optimized composite, CN-COF₄₀, showed a remarkable hydrogen evolution rate, approximately 8.5 times higher than that of pristine CN under visible-light irradiation. This significant enhancement is attributed to the formation of an S-scheme heterojunction between TpTSN-COF and CN, which promotes efficient spatial separation of photogenerated electrons and holes, suppressing their recombination. These findings highlight that the strategic combination of sulfone-containing COFs with CN via in-situ growth offers a promising avenue for designing highly active and stable photocatalysts for solar-driven hydrogen production.